Behavior-related changes in dopamine and ascorbate release
FSCV is an important tool that will be used to study the role DA might play in weakening association between a CS and a US. Classic theories of DA state that DA is associated with pleasure, acting as a natural reward system. However, further studies have questioned the classic model, indicating that DA is actually associated with anticipation of a reward. To study this, we inserted an electrode into the striatal region of the brain that is capable of measuring extracellular DA concentrations. After conditioning the rat to respond to an unconditioned stimulus (US) using classic Pavlovian methods, we measured DA release during the conditioned stimulus (CS) and during the US. We are also interested in seeing whether food presented will reinstate DA signal to the CS in extinction after behavioral performance reaches zero. Therefore, after extinction, we reinserted the electrode and measured DA concentrations during the CS and US again. Unfortunately, we were unable to replicate the experiment perfectly due to complications with the lab animals. The rats responded to the CS during the 1st 4 days as shown in Figure A. However, when the electrode was put in place, the rats stopped responding to the CS. Our previous results do show DA mediated association between CS and the US, and that food presentation does reinstate DA signal after extinction.
Ascorbate (AA) is an antioxidant vitamin which is released into the striatum of the brain during behavioral activation. A mouse model of Huntington’s disease has 140 CAG repeats knocked into the Huntington’s gene. These knock in (KI) mice show a deficit in extracellular AA. Furthermore, deficits in AA are known to impair motor response. In order to study this deficit, we used slow scan voltammetry to measure extracellular AA concentrations in KI mice. KI mice appear to have deficits in both AA release and associated behaviors. We evaluated the cause of this deficit by treating the KI mice with d-amphetamine sulfate (5mg/kg sc). This drug promotes corticostriatal glutamate transport, resulting in increased striatal AA release, and uptake in extracellular glutamate. Compared to wild type (WT) mice, KI mice have lower striatal AA after treatment with d-amphetamine sulfate, indicating that alterations in corticostriatal glutamate transmission may contribute to the AA deficit in Huntington’s KI mice. This difference is even more noticeable in male KI mice, indicating a possible gender role in the progression of the disease.

REU Mentors:  George Rebec, Department of Psychological and Brain Sciences

Investigations of learning and memory in an animal model of autism
Autism spectrum disorder is a neurodevelopment disorder that affects speech, communication, behavior, and social cognition (Behrmann et al). Although there are animal models for the disorder, none of them has investigated the behavioral aspect of the disease within the neurological context. Injections with the anticonvulsant compound valproic acid (VPA) intraperitoneally at 600mg/kg on embryonic day 12.5 in pregnant dams induce autistic like features in the pups. The aim of this study is to investigate this animal model for autism in several behavioral tasks with the long-term goal of comparing any possible behavioral deficits with those reported in humans with autism. The tasks employed here included: 1) eye blink- conditioning (a Pavlovian conditioning task), and 2) the Morris water maze (MWM, a spatial memory task), and 3) a delayed match to place (DMP, a spatial working memory task in which the escape platform location is changed daily) with or without prior training in the Morris water maze. “Autistic” rats were trained to perform these paradigms and then compared to saline controls. In the eye blink-conditioning task the animals were trained with an optimal 200 msec ISI, followed by training with a non-optimal 600 msec ISI. We find higher amplitude CRs in the autistic rats, and shorter CR latencies with the longer ISI.
In the MWM task, VPA rats showed a slowed acquisition of the escape response. In the DMP task, the autistic rats showed no working memory deficit whether the animals received prior training in the MWM task or not. Autistic rats did show impairments in Trial 1 performance in the DMP task relative to controls early in training, but only when they were not initially trained in the MWM task, suggesting impairment in the development of an efficient search strategy for the novel platform location. These results suggest that this model of autism may be a valid one as the behavioral deficits found can, at least in part, be attributed to brain anomalies shared with autistic humans.
REU Mentor:   Preston Garraghty, Department of Psychological and Brain Sciences

The effects of light intensity on motion perception in the Eastern Fence Lizard, (Sceloporus undulatus) and Southern Sagebrush Lizard, (Sceloporus graciosus).
Motion detection is utilized in prey, predator, and mate detection as well as communication. Environmental conditions, such as light intensity, habitat structure, and spectral quality, are likely to have a great effect on an animal’s ability to detect various signals. We examined how total light intensity affects motion perception in diurnal lizards from the genus Sceloporus (S. undulatus and S. graciosus). We tested motion detection latency by recording optokinetic response times to two light intensity (10 Lx and 400 Lx) and two motion frequency treatments (1 Hz and 4 Hz). We found some evidence for differences between males of two populations of S. undulatus that correspond to major differences in their photic environments. Male Sceloporus undulatus cowlesi from White Sands, New Mexico were better able to detect motion at low light intensities whereas male Sceloporus undualtus consobrinus from the typical scrub habitat in the Chihuahuan Desert in New Mexico were better able to detect motion in bright light. Sex differences in motion detection corresponded better with previously-observed differences in the function of visual displays. Female S. graciosus were consistently better able to detect motion than were males. Because of small sample sizes, these differences were not statistically significant.
REU Mentors:  Emilia Martins and Saul Nava, Department of Biology

The reproductive behavioral displays of male Sceloporus towards females.
Male Sceloporus have been shown to choose among females in choice tests. Sceloporus females, on the other hand, do not have preferences but only reject when males are attempting to mate. In previous experiments, simultaneous choice tests have been done to show preference among Sceloporus with not much emphasis being put on the individuals’ behaviors. We compared behavioral tests to other methods of choice that have been used in the past in order to see how males might behave towards females in the wild and to see if any relationship exists between sequential and simultaneous tests. In the sequential behavioral tests, males were allowed to interact for forty minutes with one of two females, and then later tested with the second female. The behavioral displays were scored using an ethogram, and females were determined as either preferred or not preferred depending on the difference in displays exhibited towards each. Behavioral preferences were compared to female preferences in outside enclosure and indoor arena choice tests (both simultaneous), and the time at which the female laid eggs. Although results were not statistically significant, major trends were seen in the data. Males showed a random pattern of preference when comparing total simultaneous choice to the sequential choice. However, the simultaneous choice tests conducted indoors gave results that were very different from the sequential behavioral tests, whereas the simultaneous tests conducted in large outdoor enclosures gave results similar to the sequential tests.
REU Mentors:  Emilia Martins and Mayte Ruiz

Electrocommunication signal repertoire in Parapteronotus hasemani
Apteronotid electric fish species (Family Apteronotidae) communicate using frequency modulations of their electric organ discharge (EOD). Some species use this behavior to convey information regarding sex, body size, reproductive status and aggressive intent. The modulations are often sexually dimorphic and exist in several varieties. In Parapteronotus hasemani we aimed to test for the differences in chirping behavior between sexes and to inspect the signal repertoire. Due to size constraints it was not possible to sex all of the fish. However the chirp repertoire was described for this species. We used a playback of simulated EODs to examine the types of signals produced. The playback stimuli had frequency values of ±5, ±20, and ±150 Hz relative to the subject’s baseline EOD frequency. We compared production of each chirp if fish produced them in response to the stimulus. Four distinct kinds of signals in were measured: gradual frequency rises (GFR), rasps, long (duration) chirps, and short chirps. All of these differed in their structure and fell into separate clusters on a scatter plot of frequency modulation vs. time. Fish produced fewer GFRs in response to presence of a stimulus at all playback frequencies. They also showed a decrease in rasp proportion as a response to different stimulus frequencies. Fish increased long chirp rate in response to playback frequencies closer to their own. Conversely, fish produced more short chirps to stimuli furthest from their own baseline EOD. Additionally it was found that overall chirp duration was positively correlated with each subject’s baseline EOD frequency. Understanding the structure of these different responses in P. hasemani will allow us to compare them with other apteronotid species.
REU Mentors:  Troy Smith and Cameron Turner, Department of Biology

Possible influences of positive scent stimuli on the behavior of captive polar bears (Ursus maritimus).
Predatory animals in captivity often exhibit stereotypic behaviors, such as pacing, which are repetitive and seemingly pointless. One theory is that these stereotypic behaviors are used as a replacement for species typical behaviors that the animals may exhibit in the wild, for example, pacing may be a substitute for traveling long distances to find food. Previous studies have shown that environmental enrichment in certain zoo animals may help to decrease these stereotypic behaviors. This study will attempt to use environmental enrichment on two captive polar bears (Ursus maritimus), one female and one male, to encourage behavior more closely related to natural foraging. Previous studies have presented animals with a single food enrichment item, but the effects on the animal only last as long as the food available to the animal lasts. By presenting the animals with a stimulus on a fixed interval schedule, such as the beef and fish scent stimulus presented every minute, the animals may be encouraged to search for food around their exhibit and decrease their stereotypic behaviors. They will be monitored five days a week for an hour and half total each day: a half hour before, during, and after the presentation of the scent stimulus. There were five days of baseline observation where no spray bottle was present, five days of scent stimulus, five days of baseline with a water spray bottle, and the last five days were scent stimulus days. The presentation of the spray was always in the same area in the visitor viewing area of the polar bear exhibit area. The animals will not be able to consume food at that time, but the smell of food may help to decrease their stereotypic behaviors and increase recognizable focal foraging behaviors, since the bears can smell odors from far distances. Both polar bears seemed to respond to the scent stimulus by smelling the air during the spray period of observation, but the amount of time spent performing non-stereotypic and stereotypic behaviors appeared to vary from day to day independent of scent stimulus. Data and further results are in the process of being analyzed.
REU Mentors:  Bill Timberlake and Eddie Fernandez, Department of Psychological and Brain Sciences

Seasonal changes in immunity track changes in energetics and not reproduction in female Siberian hamsters (Phodopus sungorus).
Non-tropical organisms must deal with marked seasonal fluctuations in their environments. Photoperiod is the primary environmental signal organisms use to predict such changes. In order to maintain a positive energy balance year-round, a variety of physiological and behavioral adaptations have evolved, including seasonal changes in reproduction and immunity. Exposure to short day (SD) lengths (i.e., “winter”) inhibits reproductive activity and triggers gonadal regression and decreased body mass. The physiological signal that transduces photoperiod is the pineal hormone melatonin, which is secreted only during the duration of dark hours, thus encoding the amount of light. The goal of this study was to determine the effects of melatonin on glucoprivation-mediated changes in immune function in Siberian hamsters. Specifically, daily timed injections of melatonin or saline were given to induce SD-like conditions; a subset of hamsters from each group received multiple injections of 2-deoxy-D-glucose (2-DG), a glucose analog, to induce a state of glucoprivation. Immune responses were quantified by measuring anti keyhole limpet hemocyanin (KLH) antibodies and bacterial killing capacity. The results demonstrate that both melatonin and 2-DG inhibited antibody production compared to control animals. Specifically, animals within the SD-like melatonin treatment had lowered antibody production in response to 2-DG as compared with the control animals. Within the LD group there was no effect of 2-DG on antibody production. Furthermore, there was a trend towards increased bacterial killing ability with 2-DG in the SD-like treatment group compared to the other groups. There was no effect of melatonin or 2-DG on cortisol concentrations in any group. SD-like melatonin caused an overall decrease in specific fat pad masses and body weight, but there was no effect of melatonin on reproductive mass. Fat pad and body masses, but not reproductive mass, were also significantly positively correlated with immune function. These data suggest that the immune effects are likely to be driven by changes in resource availability (i.e., energy) rather than changes in reproduction. Collectively, these data provide support for the role of energetic trade-offs between competing physiological functions in mediating seasonal responses.
REU Mentors:  Greg Demas and Devin Zysling, Department of Biology

Odor preference in huddling by rat pups: Comparison between the metabolic consequences of huddling and the sensation of localized warmth as an inducer of odor-guided huddling.
During the first two postnatal weeks, rat pups huddle with warm objects, either animate or inanimate. Huddling with a warm object in a cooler environment reduces loss of body heat and conserves metabolic energy. By Postnatal Day (PD) 15, pups huddle preferentially with targets bearing species-typical odors. Nevertheless, the odors that elicit and maintain huddling contact can be reassigned by pairing that odor with the experience of the thermotactile component (warmth) of maternal care.
It is possible that the sensation of huddling with a localized source of heat constitutes the mechanism for establishing odor-guided huddling. Alternatively, the metabolic consequences of huddling may be sufficient to induce a specific odor-guided huddling preference. The present study was designed to compare the induction of huddling preferences derived from the metabolic consequences of huddling with those derived from the sensation of localized warmth. Two treatment groups were studied, with each group receiving two kinds of conditioning on alternate days, from PD 9 – 14. Pups in Treatment Group 1 were exposed for 2-hr/day on alternate days to a furry, warm (36°C) tube bearing a fixed amount of odor A (e.g., lemon), all in a cooler (23°c) compartment. On the other days, these pups were exposed to the same amount of odor B (e.g., orange) within a cool (23°C) ambience. Treatment Group 2 received the same regime of access to a scented warm tube in a cool ambience and, on alternate days, these pups were exposed to odor B in a warmer ambience (26°C) that had been shown to be metabolically equivalent to the warm tube condition. Results suggest no effect of treatment on odor preference in huddling. When the treatment variable was excluded from the analysis, however, a sex dependent effect of localized warmth on odor preference was found. . Female pups preferred to huddle with an odor associated with a warm tube compared to an odor associated with no tube; males had no odor bias in huddling.
This study suggests that the metabolic consequences of huddling facilitate development of odor-guided huddling on PDs 9-14. Nevertheless, it will be useful to extend the conditioning period and/or introduce the conditioning to pups that are younger. For future research, sex should be considered as a significant factor for establishment of odor-guided huddling. Neuroendocrinological studies could be helpful to explore mechanisms underlying development of filial huddling by rat pups.
REU Mentors:  Jeff Alberts and Sayuri Kojima, Department of Psychological and Brain Sciences

Repeatability in guppy inspection behavior, alone and in groups.
Guppies, Poecilia reticulata, in the wild "inspect" potential predators. The rate at which a guppy inspects is influenced by the historical predation level experienced by their population and interactions with social partners. It is not known how consistent an individual's behavior is in response to repeated interactions with a predator or how consistent an individual's behavior is in the context of its social group. We utilized a strain of guppies originating from a high predation population of the Quare River that has been in the lab for more than six generations. We tested focal individuals three times alone or twice in a group in the presence of a cichlid model to determine how repeatable individual behavior is alone and within a social group. Individuals were scored for time spent in agitated swimming, in close proximity of the model, foraging, frozen and oriented on the model and how often they inspected the model. Focal individuals tested alone appear to habituate to the model and therefore exhibit low repeatabilities for all measured behavior. Guppies are known to socially learn and are unlikely to interact with predators in the absence of conspecifics. Low repeatabilities are thus not surprising. The second experiment was therefore tailored to both minimize learning and reflect more realistic social settings, providing a more accurate measure of repeatability. The results of the second experiment show much higher repeatabilities for all behaviors. Guppy antipredator behavior is therefore more consistent across repeated encounters with predators in the context of their social groups, suggesting that social context may play a significant role in the evolution of guppy antipredator behaviors.
REU Mentors:  Butch Brodie and Heather Bleakley, Department of Biology

Cue competition and integration in a blocking procedure in the water maze as a function of beacon type and whether it was switched between Stage 1 and Stage 2 of training.
In a blocking procedure in the water maze, subjects are typically trained in Stage 1 to find an escape platform using a Beacon, and in Stage 2 to find the platform using a combination of Beacon and added Landmarks. Timberlake, Sinning, & Leffel. (2006), and male rats, found both cue competition and integration with the Room cues depending on the type of Beacon (Pole or Hanging) and form of training (with or against background cues) in Stage 1. Random Pole Beacons produced cue competition, and Fixed Hanging Beacons produced facilitation relative to a control receiving Stage 2 training only. The purpose of the present research was to determine if (1) cue competition also occurred with females receiving Random Background training with Pole Beacons but not Hanging Beacons; (2) the effects of changing the Beacon type between Stages 1 and 2 disrupted cue competition effects as predicted from Roberts & Pearce (1999) and (3) whether the direction of change mattered as might be assumed if the novel pole detracted from learning the Room cues in Stage 2.
REU Mentor:  Bill Timberlake, Department of Psychological and Brain Sciences

Effects of social environment on boldness behavior in laboratory and wild zebrafish
Many studies have demonstrated that behavior has both a heritable and environmental basis. Traits may be inherited or innate, socially influenced by watching others behave or affected by external factors, like stress. Studies have also shown that younger animals are more likely to acquire behaviors from older individuals, consequently making the stage of development at which they are exposed to social stimuli another important factor that can affect behavior. In this experiment I determined whether the social environment of individuals can have an effect on boldness in laboratory and wild zebrafish (Danio rerio). I created mixed strain groups and varied the stages of development at which laboratory and wild zebrafish were housed together. These groups included: mixed as eggs, mixed three weeks after hatching and mixed at 5 months of age. A pure tank of each strain was used as a control. Each group was assayed for shoaling tendency, activity level in an unfamiliar environment, predator avoidance and feeding latency after stress. The results from these tests demonstrate that there is a significant difference in boldness between wild and domesticated strains, with the domesticated strain being bolder. The domesticated strains displayed higher activity level, less predator avoidance, and lower feeding latency. It was also demonstrated that the social environment and stage of development in which that individual was exposed to a particular behavior does not have an effect on the acquirement of behaviors. An explanation for this could be that boldness is innate and resistant to social learning. Future experiments could be done to see if other behaviors, for example reproductive behavior, are more influenced genetically or by their social environment.
REU Mentors:  Jason A. Moretz/ Emilia P. Martins, Department of Biology

Serotonin projections to the inferior colliculus: A retrograde tracing analysis of raphe nuclei in mice
The purpose of this study was to further understand the modulatory effects of the neuromodulator serotonin (5-HT) in the inferior colliculus (IC), an important midbrain structure involved in auditory processing. This was accomplished in mice via quantification of cell distributions in different raphe nuclei, which are known to send serotonergic projections to the IC. We examined the distribution of serotonin cells in the raphe nuclei in mice by using the retrograde transport of green fluorescent retrobeads, pressure injected (0.1-1 µl) unilaterally or bilaterally into the inferior colliculus. This was combined with fluorescent immunostaining for serotonin after a 2-7-day survival period. Fifty-micron-thick brain sections were collected, immunostained for serotonin, and visualized with fluorescence microscopy. An abundance of retrogradely-labeled cells were present proximal to the IC injection site(s). Comparatively across different raphe nuclei, more retrogradely-labeled cells were found in the dorsal raphe nuclei (DRN) compared to fewer in the median raphe nuclei (MnR), with a few also appearing in the raphe magnus. Within just the DRN, further quantification of labeled cells revealed that labeled cells were mostly located in the medial wing, while there were fewer cells in the lateral wings. These results show that 1) mice are similar to other animals in the sources of serotonergic projections to the IC and 2) projections to the IC mostly come from a specific region of the DRN.
REU Mentor:  Laura Hurley, Department of Biology

Thermal environment influences morphology of developing Norway rats
Previously, Villarreal, Schlegel, and Prange (2005) reported that cool (17°C) housed rats develop shorter ears and tails than moderate (25°C) housed rats. In addition, they found cool-housed rats develop a preference for warmer air temperatures than moderate-housed rats. In order to elucidate possible biological mechanisms for the development of this seemingly counterintuitive thermal preference, we further assessed how the thermal environment influences morphological development of rats. Terminal morphology measures (body mass, body mass without coat, coat mass as a percent of body mass, and adrenal gland mass as a percent of body mass) of 32 22-day-old, 32 43-day-old, and 28 85-day-old rats were recorded. Results indicated that 22 and 43-day-old cool-housed rats had lower body mass with and without their coat than moderate-housed rats, p < 0.05. And 22 and 43-day-old cool-housed rats had higher coat mass as a percent of body mass than moderate-housed rats, p < 0.05. These results suggest the thermal environment substantially shapes the body morphology of juvenile rats. No differences were found on these measures in 85-day-old rats. In addition, no differences in adrenal gland mass as a percent of body mass were found at all 3 ages assessed. These results indicate that the morphological differences between cool and moderate housed-rats are not likely due to the cool temperature inducing a stress response. The results from this study have lead us to posit that the development of the previously observed thermal preference of cool-housed rats for warmer air temperatures than moderate-housed rats may be in part due to the lower body mass of juvenile cool-housed rats.
REU Mentor:  Henry D. Prange and Jill Villarreal, Medical Sciences

Effects of chronic stress on water maze performance in rats
Chronic stress has been shown to have the ability to impair learning in humans and in rats. These effects appear to be mediated by damage to the hippocampus that results from stress hormone release during exposure to chronic stress. Research on humans and rats has found stress to be related to hippocampal damage as well as memory and learning impairment. This study examines the effects of chronic stress on spatial learning in rats. Spatial learning was assessed by performance in the delayed matching-to-place paradigm in a water maze. Previous research with this paradigm has validated impaired spatial learning resulting from hippocampal lesions, stress hormone treatment, and stress. For this study, chronic stress was induced through long-term, inescapable restraint. Stressed animals were found to have deficits in Trial 1 performance for the nine Training Days and deficits in Trial 2 performance for 10-minute inter-trial intervals. Ongoing research will seek to statistically verify these results.
REU Mentor:  Preston E. Garraghty, Department of Psychology

Energy allocation and sickness behavior in Siberian hamsters
Many non-tropical mammals have evolved in fluctuating environments where resource availability can be vastly different across the seasons of the year. In response to these environmental changes, animals have evolved seasonal physiological and behavioral responses that allow them to anticipate and prepare for oncoming challenges in order to increase overall fitness. For example, during times of low resource availability (e.g. winter) animals will reallocate energy reserves into immediate survival challenges such as thermogenesis and reduce allocations to less critical responses (e.g. reproduction and immunity. In addition, many behavioral adaptations have co-evolved with energetic investment strategies to increase survival. Day length (photoperiod) is the primary cue mediating seasonal changes, and photoperiodic changes in the pineal hormone melatonin act as the biochemical signal mediating photoperiod responses. The purpose of the present study was to examine the physiological and behavioral costs of mounting an immune response and the role of melatonin in mediating these responses. Specifically we hypothesized that overall immune response and sickness behavior will be attenuated in melatonin (mel) implanted Siberian hamsters (Phodopus sungorus) as compared with control animals. Two experiments were conducted to test this hypothesis. Experiment 1 was tested the effects of food restriction on immune response in mel and control implanted animals. This was done by measuring antibody production response to an injection of the antigen keyhole limpet hemocyanin (KLH). Experiment 2 was conducted to determine the effects of lipopolysaccharide (LPS), an antigen that produces a robust sickness response, on a battery of sickness behaviors various in mel and control implanted animals. The results of these studies will be presented.
REU Mentor:  Gregory E. Demas and Devin Zysling, Department of Biology

Does 1 + 1 really equal 2? Genotypic and phenotypic interactions in expressed social behavior of Poecilia reticulata.
The phenotype of a group of animals reflects both the behavior of individuals and potentially interactions among individuals. We examined whether the phenotype of the group reflects additive, non-additive or a combination of additive and non-additive effects on the behavior of individuals within the group. We also sought to investigate whether the group phenotype as a whole could be described as additive, or whether it is different than the sum of its parts. We utilized an inbred strain of common guppies, Poecilia reticulata, which provides virtually homozygous subjects, eliminating variation in behavior resulting from genetic variation and allowing us to isolate interactions at the phenotypic level. All guppies were exposed to a predator stimulus and subjected to two test trials, once alone and once in a group, in random order. They were scored for time spent in close proximity to and oriented on the model, time spent foraging and agitated, and number of inspections. We found no net change in the mean phenotype displayed by individuals tested alone and individuals tested in a group. However, we did find evidence of non-additive effects within groups, with individuals differentially altering their behavior in response to the phenotype of other individuals within the group. Despite low repeatability an individual’s behavior alone is the best predictor of its behavior in a group. Our study therefore suggests that group phenotype is additive and therefore predicted, at least in part, by the mean individual phenotype.
REU Mentor:  Edmund Brodie III and Heather Bleakley, Department of Biology

Mobile versus stationary viewpoints affect blocking and facilitation between beacon and landmark learning in the floor maze
Blocking, when preexistent learning about one cue inhibits learning about a new, redundant cue, is known to occur readily in the temporal domain. In the spatial domain, its presence is not as clear. It is generally accepted that spatial learning is more complicated than can be described by the basic theories of associative learning, and spatial information may be encoded and integrated in multiple system. This experiment sought to examine the effects of moving versus stationary release and beacon positions on the interactions between beacon and landmark learning in rats. A square floor maze with four symmetrical quadrants was used, each quadrant containing a reward cup. A release basket was positioned in the center of each maze wall. Four treatment groups of Sprague-Dawley rats were studied: Moving Release/Static Beacon, Moving Release/ Moving Beacon, Static Release/Static Beacon, and Static Release/Moving Beacon. Each group received two trials per day for twelve days of training under these conditions, followed by the addition of landmarks and eight subsequent days of training in which all release and beacon positions were made static. A series of tests followed the training days. Overall, groups receiving a moving beacon in the first stage showed significantly higher latencies; this corresponds with an overall higher number of reward cups checked on the path to the goal. Groups receiving a moving release position in the first stage appear to learn more about the relevance of the beacon to the goal, while those receiving a static release position showed favor towards landmark cues. In the absence of a beacon, however, moving release groups demonstrated knowledge of landmark cues. Overall, this indicates that rats may encode knowledge of both beacon and landmark position simultaneously while demonstrating preference for one cue set, and this encoding is facilitated by receiving varied perspectives on the spatial area to be learned.
REU Mentors:  William D. Timberlake and Eddie Fernandez, Department of Psychology

Effects of 5-alpha dihydrotestosterone on the frequency modulation and udration of chirping behavior in Apteronotus albifrons.
Males and females of the species Apteronotus albifrons communicate through the sexually dimorphic EOD (electric organ discharge) frequency modulations they emit. Some of the short-term modulations are known as chirps, and males and females do seem to vary on the structure of these chirps. Androgens are thought to be at least partly responsible for the fact that males have a lower EOD frequency and that their chirps have a different structure than those of females. Androgen treatment has been found to lower the EOD frequency of females but has no effect on the rate or propensity of chirping in this species. The purpose of this study was to investigate whether the androgen 5-alpha dihydrotestosterone (DHT) has an effect on the structure of the chirps when implanted in both male and female A. albifrons. The DHT implants did not have the predicted effect on the EOD frequencies of the females, which would have served as an index of the effectiveness of the hormone treatment. This study did find, however, that females tended to increase the frequency modulation of the categorized low frequency modulations over time whereas the opposite was true of males. DHT implants tended to increase the frequency modulation of these low frequency chirps while control implants tended to decrease the frequency modulation of low frequency chirps over time. Even though the DHT implants did not have an effect on EOD frequency, these results suggest that it may have subtler effects on the structure of at least low frequency modulations. No effects were seen for the duration of chirps. This study should be repeated for conclusive findings about the effects of androgens on the structure of chirps in A. albifrons and analysis of the structure of chirp responses to specific stimulus frequencies should be pursued.
REU Mentor:  Troy Smith, Department of Biology

Electrophysiological evaluation of mice knocked-in with 140 CAG repeats
Huntington disease (HD) is a progressive, neurological disorder that is genetically inherited. It is autosomal dominant, where onset of the disease occurs with inheritance of one HD allele. The knock-in HD mice have 140 CAG repeats and are characterized by onset as late as 1 year of age, a much slower progression of disease in comparison to other models like the R6/2 line, with little known about the affected striatal region of the brain. Assessing the striatal function in the slow progression model, striatal electrophysiological activity was recorded between knock-in mice with 140 CAG repeats and wildtype littermate controls and neuronal firing rate was evaluated. Results suggest that there are no significant differences between knock-in and wildtype mice but there is a trend of higher firing rate for wildtype, control mice. Gender was also analyzed resulting in a sex difference in firing rates in the knock-in mice and, independently, in the wildtype mice; knock-in males also show some difference in firing rates when compared with wildtype males. The yielded results offer new insights that vary from the hypothesized mechanisms underlying HD previously found in the R6/2 strain and implicate some role of gender and testosterone-dopamine interaction as an explanation for the sex difference found in this relatively new HD model.
REU Mentor:  George V. Rebec, Department of Psychology

Song-sharing in lizards?: An exploration of display type-matching using a robotic lizard.
Neighboring male Sagebrush lizards, Sceloporus graciosus, produce and exchange species-typical push-up displays which vary in both syntax and delivery. This study tests for 1) the possibility of display-type matching in this species, and 2) behavioral differences in response to repeated exposure to two signal types. Two signal types (typical, atypical) were delivered to subjects using a mechanized lizard both in short-term tests and in repeated exposures for ten days. In short-term tests, lizards paid more attention to the robotic lizard when it produced atypical displays than when it produced the species-typical headbob display. After repeated exposures to the robotic lizard, subjects gave similar responses regardless of the display it produced, including a general increase in activity in comparison to behavior during short-term tests. Repeated exposures to different signals revealed only slight suggestion of differences between the displays produced. These findings suggest that lizards change behavior after repeated exposure to push-up displays, but provide little evidence for display-type matching.
REU Mentor:  Emilia P. Martins, Department of Biology

An assessment of classical eyeblink conditioning in rats using a tone and light CS and three interstimulus intervals
The modality of the conditioned stimulus (CS) and length of the interstimulus interval (ISI) used in classical eyeblink conditioning can affect an animal’s ability to produce a conditioned response (CR) which is correctly timed to coincide with the onset of the unconditioned stimulus (US). The current study explores this relationship between CS modality, ISI length and CR production. Rats were trained using one of two CS modalities, either a light or a tone, and one of three ISI lengths, either 280 ms, 580 ms or 880 ms, yielding six conditioning groups. Animals trained with the 280 ms or 580 ms ISIs show robust learning across all seven conditioning days regardless of CS modality. CRs in the 280 ms groups were the most accurately timed, with timing accuracy sharply decreasing at longer ISIs. Furthermore, the acquisition curve for animals trained with the tone and the 880 ms ISI was unusually high and almost flat, suggesting that there may be a confounding effect of the tone which is artificially heightening the CR count.
REU Mentor:  Joseph E. Steinmetz, Department of Psychology

Localization and Quantification of Substance P in Four Major Auditory Nuclei of the Mexican Free-Tailed Bat Tadarida brasiliensis Brain
Substance P (SP) is a neuroactive peptide that is involved in a variety of somatosensory functions and has excitatory effects in the central nervous system. Although several studies document the presence of SP in the auditory nuclei of rodents, analogous studies have not been done in the echolocating Mexican Free-Tailed bat. This study’s main purpose is to localize and quantify the amount of SP staining in the lower auditory system of this bat species. Immunohistochemical procedures were used to stain slices of the brain for SP. The slices were then visualized with fluorescence microscopy to determine the presence or absence of substance P in the facial nucleus, chosen as a control area, and in four major auditory nuclei: the cochlear nucleus, the lateral lemniscus, the lateral superior olive and the inferior colliculus. This study shows that, in comparison with adjacent areas and the control, there is little substance P present in the above-mentioned auditory nuclei of the Mexican Free-Tailed bat.
REU Mentor:  Laura M. Hurley, Department of Biology

Stickleback response to sign stimuli: comparing results of Field and laboratory experiments
The three spined stickleback, Gasterosteus aculeatus, has played an important role in ethology ever since they were investigated by Niko Tinbergen and found to have interesting and clearly identifiable behaviors. However, most of our knowledge of the stickleback comes from studies performed in aquaria. To assess and compare the established data found from tank research, we performed parallel aquaria and field studies at a marine laboratory in Asko, Sweden. We used already established protocol to compare the response of ten male sticklebacks in aquaria and ten males in the field using the following sign stimuli: simultaneous presentations of supergravid and normal gravid female dummies; normally gravid lordosis posture dummy female; red versus non-red male dummies. Males in aquaria showed strong responses to all the dummies, but males in the field had almost no response to any of the stimuli. The results of the experiments performed in the tank suggest that the fish in Sweden have similar behavioral responses to those found in previous aquaria experiments. However, the responses of the fish in the field indicated a dramatic decline in behavior toward the same sign stimuli, although both lab and field males were from the same areas. These results suggest that further comparative studies between field and lab conditions to gain a better understanding of the mechanisms behind the extreme differences found in male stickleback response behavior to sign stimuli in the field. This applies to many animal behavior studies as it is likely that most animals may behave differently in the field and lab due to differences in the amount of stimulation
REU Mentor:  William J. Rowland and Teresa Dzieweczynski, Department of Biology

The Effect of Rearing Temperature on Thermal Preference
The present study addressed if and when rat (Rattus norvegicus) pups will exhibit a behavioral preference for their rearing environment during the pre-weaning stage of development (postnatal day 0-21; P0-P21). During pregnancy dams where housed at 25oC. On P0 dams and their litter of 8 (n = 16, N = 32), were transferred to either a 17oC or a 25oC room. Morphological measurements were recorded every other day. Temperature preference was tested on P7, P14, and P21 with two 2-choice test (17oC vs. 25oC, and 25oC vs. 33oC). There was no significant difference across rearing temperature in morphology. Regardless of rearing condition and temperature preference trial, pups spent the majority of the trial in the warmer temperature zone. Mean estimated preferred temperatures for pups reared at 25oC were; 28oC, 29oC, 28oC, for P7, P14, and P21, and 29oC, 27oC, 27oC, for pups reared at17oC.
REU Mentor:  Henry D. Prange, Medical Sciences and Jill Villarreal, Department of Psychology

Behavioral test of an introduced population of threespine stickleback (Gasterosteus aculeatus) in Lake Michigan
Threespine stickleback have recently (8-20 years ago) invaded the Great Lakes. To date, there are several papers documenting the appearance and migration of this fish but there are no studies on their behavior in this new environment. Threespine stickleback are an ideal system to study because their behavior is very recognizable and they have been consistently studied for over 200 years. I wanted to study whether this new population responded to dummies of conspecifics and if they responded similarly to a population of stickleback from Long Island, of which we have data. The population of Lake Michigan stickleback most likely originated from an Atlantic population via the St. Lawrence Seaway. I ran tests on 18 males collected from Trail Creek in Michigan City, IN and documented their reaction to dummies of conspecifics. I compared these responses to data from a population from Long Island, which is possibly similar to the fish from where the Great Lake stickleback originated. The Lake Michigan stickleback reacted as expected, with the majority of courting directed to dummy females and attacks directed to the dummy males. These results suggest that the Lake Michigan population is a possible source of stickleback for future studies using dummies of conspecifics. In general, the Long Island fish responded more frequently than the Lake Michigan fish to the dummies. Further testing should be conducted to determine what factors caused the differences in behavior that we observed between the two populations.
REU Mentor:  William J. Rowland and Richard Granquist, Department of Biology

The influence of social conditions associated with social defeat on immune function in Siberian hamster (Phodopus sungorus)
Previous research has shown physical and psychological stress can negatively impact immune function. Activation of the hypothalamic pituitary adrenal (HPA) axis by a stressor triggers a host of physiological responses including the release of the stress hormone cortisol from the adrenal cortex. The present experiment investigated the social and environmental characteristics that suppress immune function in male Siberian hamsters (Phodopus sungorus). It was predicted that the greater concentration of cortisol found in the blood would correspond with the more severe social defeat session and thus the greatest immune suppression. Social defeat sessions (i.e. the introduction of an intruder hamster into a dominant resident cage) lasted for 15 minutes for five consecutive days and acted as a psychosocial stressor on the experimental hamsters. Experimental intruding hamsters were subjected to one of four conditions: hamsters were placed in 1) a clean cage, 2) a “dirty” cage without the resident present, 3) a cage separating the intruder and resident or 4) in direct contact with the resident. Prior to social defeat sessions each intruder was immunized with Keyhole Limpet Hemocyanin (KLH), an innocuous antigen that triggers a robust antibody response. Blood samples were tested for cortisol concentrations and anti-KLH immunoglobulin (IgG) concentrations. Cortisol levels were highest respectively in the intruder with direct contact with residents, separated cages, clean cages and the lowest concentration in dirty cages. Anti-KLH IgG concentrations followed the same trend found in cortisol concentrations. Contrary to the experimental hypothesis, these data reveal that immune function was enhanced by the severity of the social defeat
REU Mentor:  Gregory E. Demas and Devin Zysling, Department of Biology

Differences in the inspection behavior in Poecilia reticulate populations at different risk of predation
Common guppies, Poecilia reticulata, are small livebearing fish. In response to predators, guppies perform an inspection behavior, which has been suggested to provide longer survival periods, visual alarm signaling, predator deterrence and mate attraction. The majority of studies addressing differences in inspection behavior in response to levels of predation have been observational field studies. As such, we looked for differences in the frequency of inspection behavior between populations with a known predatory history under controlled laboratory conditions. In addition to interpopulation differences, some studies indicate intersex differences as well, and differences in inspection behavior between the sexes may have strong evolutionary implications for populations. Given the lack of consensus in the literature and the potential importance in understanding the selective forces operating on populations, the second question we wish address with this study is whether males and females differ in inspection frequency under predation risk. Eight to twelve fish from each of four different strains from the Quare II, Turure, Aripo and Oropuche Rivers in Trinidad were tested in groups of four to determine the number of times individuals in the group inspected, the amount of time spent in inspection, time spent in close proximity to the predator, latency to approach the predator and time doing other activities. While populations varied significantly in time spent hiding, number of inspection bouts and time spent in close proximity to the predator, only one behavior (hiding) was significantly correlated with the predation history of the population. Within three populations the sexes did not differ in any measure of inspection, however in a single population, females were marginally significantly slower to approach the predator than were males. As such, we did not find significant evidence to suggest that sexes vary in the inspection behavior. We did however demonstrate differences between populations which may correlate with predation history or other life history factors.
REU Mentor:  Edmund Brodie III and Heather Bleakley, Department of Biology

Developing a non-invasive method for measuring hormones in the Sagebrush Lizard (Sceloporus graciosus)
Injections and blood drawing are frequently used methods of applying and measuring hormones in subjects. An important question that arises for animal behavior scientists is: Can there be a less invasive way of applying and measuring hormones that is still accurate? This question is key because the pain and disturbance of an injection or bleeding can traumatize the animal which can alter behavior and hormone measures. In this experiment, we tested non-invasive femoral pore secretion assays for testosterone. A total of 44 males and 24 females were treated using a dermal patch which was applied using self-adhesive medical dressing. Treatment A was gonadotropin releasing hormone (GnRH) in a sesame oil vehicle. Treatment B was testosterone (T) in a sesame oil vehicle. Treatment C was sesame oil used as a control. There were fewer femoral pore secretion spots in lizards treated with GnRH and T as compared to controls. But the same pattern was observed also in FPS before treatment was applied. Therefore, our results do not support the use of the number of FPS spots as a method for inferring testosterone levels. An increase in size after treatment was noted, but not measured. Size may be an important consideration for future studies.
REU Mentor:  Emilia P. Martins, Department of Biology

The effects of variable-time (VT) food schedules on stereotypic behaviors in a captive adult polar bear (Ursus maritimus)
Stereotypic behaviors have been defined as repetitive movements or patters having no apparent goal or function (Mason 1991). Many variables have been correlated with stereotypies, but very little experimental research examined the functions these behaviors may serve. The following study examined how VT food schedules affect stereotypic and general activity in an adult polar bear at the Indianapolis Zoo. During observation, 21 behaviors across 5 locations were measure during baseline (no food) conditions and two VT conditions (VT-5min; VT-1min). The purpose of this project is to: (1) experimentally examine the effects that VT schedules have on stereotypic behaviors (2) examine the role of natural foraging patters in stereotypic behavior. Previously, fixed time (FT) schedules significantly reduced stereotypic activity when compared to baseline conditions. In captivity polar bears have a high incidence and frequency of stereotypies. Many captive endangered species are also known to perform stereotypic behaviors. The use of this strategy may provide a simple method to promote the health and welfare of numerous captive species.
REU Mentor:  William D. Timberlake and Eduardo J. Fernandez, Department of Psychology

Hormonal control of electrocommunication behavior in Apteronotus albifrons: Effects of Ovaprim on the production of short-term frequency modulations
In the electric fish genus Apteronotus, electric organ discharges (EODs) are often modulated to produce transient social signals known as short-term frequency modulations (STFMs). In the brown ghost knifefish (Apteronotus leptorhynchus), STFMs are sexually dimorphic in both quantity (number of STFMs/minute) and structure (frequency excursion and duration). In the black ghost knifefish (Apteronotus albifrons), males and females produce the same number of STFMs while STFM structure is dimorphic (Dunlap et al., 1998; Dunlap and Larkins-Ford, 2003; Kolodziejski et al., in press). However, A. albifrons have never been successfully bred in captivity and their mating behavior is poorly understood. It therefore remains unclear whether the lack of sexual dimorphism in STFM number in A. albifrons is real, or a consequence of insufficient breeding stimulation in captivity. In the current study, Ovaprim, a reproductive stimulant, was administered to male and female A. albifrons to aid in stimulating electrocommunication behavior typical of breeding fish. Behavioral tests were conducted 1, 7, and 14 days after treatment. No sex difference was seen in the total number of STFMs produced by A. albifrons before Ovaprim treatment. However after Ovaprim treatment, females produced significantly more STFMs than males. Females also produced more high frequency STFMs than males after treatment. These results suggest that Ovaprim stimulation affects both STFM number and structure with differential effects in each sex.
REU Mentor:  G. Troy Smith and Hanna Kolodziejski, Department of Biology

Betta be aggressive: using dummy fish to control audience behavior while examining audience effects in male Siamese fighting fish (Betta splendens)
There has been a trend in animal communication studies to study subjects in communication network rather than signaler-receiver relationships. Perhaps one way to do this is to examine how an audience might affect social interactions such as male contests. Recent investigations of audience effect in Betta splendens have shown that males modify their behavior towards another male when a live female or male audience is present. When using live conspecifics, one must take into account that the audience will not always behave the same and therefore the audience becomes a variable and may influence the results. In addition, if the audience is interacting with the subjects it is not really an audience but rather a third party of the interaction. Interacting males were tested under four treatments (dummy female, male and neutral fish and no audience) and their aggressive behavior was assessed. We measured the time spent by opponent and spent by audience also the following behaviors: gill erection, tail beats, and bites. There was no significant difference found among the treatments for any of the behaviors. This differs from previous studies using live audiences, which found that male-male interactions were influenced by the sex of the audience present. This shows that some factor other than just the mere presence of an audience affects the aggressive behavior of the interacting males. It can be concluded that when running an audience effect study using live subjects, one should consider whether the audience is a passive or active participant in the interaction. This study indicates that it is difficult to comprehend when a subject goes from being an audience to one of the interacting parties and, thus, we may need to redefine what an audience is.
REU Mentor:  William J. Rowland and Teresa Dzieweczynski, Department of Biology

The Effects of Corners of a Room on Blocking in the Morris Water Maze
The Morris water maze is a 1.52 M diameter pool containing a platform submerged just below the surface of the water that an animal must find using beacons and/or landmarks in order to escape the water. The current study addressed associative blocking in a water maze situation using rats as subjects. Associative blocking occurs when a rat learns an initial cue, often a proximal beacon, to find a platform but fails to learn subsequent cues, often distal landmarks, added to the room. Although several studies have found evidence supporting the occurrence of blocking, some studies have found facilitation in the form of improvement in learning about the second set of cues by the early training. The purpose of the current experiment was to further examine the determinants of blocking versus facilitation in a water maze situation. It was hypothesized that the corners of the room may have contributed to the facilitation of learning the distal room cues that occurred in previous studies. Two similar studies differing only in type of beacon were used in this experiment. The first study used a less salient displaced hanging beacon and the second study used a more salient pole beacon that protruded from the platform. Neither blocking nor facilitation of room cues was observed in either study. However, evidence suggests that salience of the beacon has some effect on preference of cues used to locate the platform. Rats that were trained with the displaced beacon (less salient) seemed to prefer to use room cues, while rats that were trained using the pole beacon (more salient) preferred to use a hanging beacon similar in shape to the pole beacon to locate the platform.
REU Mentor:  William D. Timberlake, Joe Leffel and Allison Kukuch, Department of Psychology

The Function of Beak Movement in the Vocalizations of the Monk Parakeet (Myiopsitta monachus)
The Monk Parakeet uses a complex system of vocal communication during social interactions. Avian communication has long been an important model in the neuroethological approach to studying human brain function. Despite sharing with humans a sensitive period for complex learning and development, performance-based feedback, and a discrete set of brain structures, birds have been considered to lack the vocal tract resonance filter that is crucial to speech production. However, consistent beak movement during sound production suggests that beak gape affects vocal production and recent studies suggest that songbird’s vary their beak gape to track fundamental frequency during songs, thereby maximizing the amplitude of some of the frequencies produced. We suspect that the parakeet’s use beak gape to shift frequency emphasis in the broadband spectrum of their calls. Using six parakeets, we measured the beak gape and energy distribution of alarm calls. Currently we are examining the data collected to identify correlations. If a significant correlation is found between beak gape and energy distribution of calls, it would suggest a system similar to the formants found in human speech. If parakeets produce formants, then we can conclude the post-production vocal processing system of parrots is more similar to human speech than to bird songs.

2003 REU Mentor:  Roderick Suthers and Gabriel Beckers

Effects of Male Status and Social Environment on Female Behavior in Sagebrush Lizards, Sceloporus graciosus
Although Sceloporus graciosus are typically territorial, they form dominance hierarchies at high densities. Social status in such groups may alter which lizards are able to interact within the group and how individuals respond to each other. In this study, we attempted to determine what physical attributes might predict male status, whether females respond differently to males of different status, and whether females with recent social experience respond differently than females without recent social experience to males. Males were measured for body size, tail length and symmetry of femoral pores, all predictors of dominance in other species. Dominance hierarchies were established by grouping four males and two females in each of six indoor enclosures. Dominant and subordinate males from each group were identified and presented to females in a y-maze. Secondly, females were presented chemical secretions from both dominant and subordinate males in their home cages and behaviorally assayed. We determined that dominant status is not related to symmetry of femoral pores, snout-vent length, or tail length, but that there is a positive but not significant correlation between weight and dominant status. Within the y-maze behavioral test, females with recent social experience did not differ from females without recent social experience in the amount of time spent with either subordinate or dominant males. We did find however, that females spent significantly more time with males possessing shorter tails than they did with males possessing longer tails. For the behavioral assay, we found that there is no difference in the amount of time the females spent near the dominant, subordinate or control samples, nor were there differences in observed numbers of behavior. However, females without recent social experience spent significantly more time near the samples, tongue flicked the samples significantly more often and were significantly more agitated.

2003 REU Mentor:  Bronwyn Bleakley and Emília Martins

The Effect of Serotonin on the Auditory System of the Mexican Free-Tailed Bat
Although previous studies show that serotonin can either inhibit or facilitate single auditory neurons, little is known about the overall effect of serotonin in the auditory system. Therefore, in this experiment, we looked at the impact of serotonin in the entire lower auditory system of the Mexican free-tailed bat by measuring the auditory brainstem response (ABR). This was accomplished by injecting the bats with fenfluramine, a drug that increases serotonin levels. Prior to injection with fenfluramine the bats were anesthetized with ketamine/xylazine or torbugesic to reduce their activiy. In making baseline measurements we encountered more variation in the peak latencies of the ABRs than reported in the literature. This variation is possibly correlated with level of alertness or anesthesia. If an anesthetic has an effect on the ABR it might influence data interpretation by changing the latency of the peaks, which could be mistaken for the fenfluramine effect. On top of this variation, fenfluramine did not change the peak latencies of the ABR. From these results we draw two conclusions. The first conclusion is that the ABRs in our study varied more than those that have been reported. Possibilities that would account for this are differences in our techniques from those reported or differences in the auditory system of the bat from those of other mammals. Our second conclusion is that fenfluramine either has no effect on the ABR latency or that its effect is smaller than the variation we encountered. Future experiments that can be done to further this study include doing this experiment during the bats natural wake cycle or doing a temperature control study because temperature can also affect peak latency.

2003 REU Mentor:  Laura Hurley

Audience Effect on Interactions of Betta splendens
Prior studies on eavesdropping in Betta splendens found that males increased the number of tail beats and gill flaring, and decreased the number of bites, a behavior used predominantly in male - male interactions, when in the presence of a female audience. Other investigations observed that when a male audience was present, interacting males decreased the time they spent near their opponent and increased the number of bites. We video taped male - male interactions with and without a female audience under 3 nesting conditions: 1 male with a nest, both males with nests and neither male had a nest. We then used the recordings to measure the number of tail beats and bites, gill flare erection rate, time spent near the opponent and the audience, and the time spent near the bubble nest (if present). Our investigation of audience effect on interactions between male B. splendens has shown only a significant difference in conspicuous displays. We found that subjects increased gill flare erection rate when a female audience was present. The amount of tail beats, bites, and the time spent near the male opponent showed no significant change in the presence of either audience. We also investigated whether or not the presence of a bubble nest influenced how female audience affects the male - male interactions. We found that the interacting males who had bubble nests neither increased nor decreased their aggressiveness toward their opponent. Even though we found no effect of the nest, we believe it was important to study because it has never been looked at before. Differences in our investigation and previous ones may be accounted for by the fact that previous investigators used a small number of males that interacted repeatedly. Some males even interacted multiple times. Our investigation only used each male once in an interaction. These differences also could have been affected by the time allowed for interaction. Our investigation allowed pre-exposure to the audience for 5 minutes and 20 minutes for interaction. Prior studies allowed 3 minutes of pre-exposure and 10 minutes of interaction time. The results of our study suggests that having a female audience does affect the aggressive display behavior of interacting male Betta splendens.

2003 REU Mentor:  Teresa Dzieweczynski and Dr. William Rowland

Attempts to Hormonally Manipulate Sexual Behavior of Female Threespine Stickleback (Gasterosteus aculeatus)
I investigated how sexual motivation affects male preference in female threespine stickleback (Gasterosteus aculeatus). I attempted to increase sexual arousal by treating female subjects with Ovaprim, an aquaculture drug that contains gonadotrophic releasing hormone (GnRH) used to induce spawning behavior in fishes. I first tested all subjects’ responses to two moving dummies, one representing a nuptially colored male and the other a neutrally colored male. I then injected the females intraperitonially with either Ovaprim (experimental group) or a propylene glycol control and retested each subject at 6, 10, 24, 30, and 48 h post-injection. Females were then injected a second time, and tested again at 6, 24, and 30 h post-second injection. “Following dummy behavior” decreased from pre- to post-injection in both experimental and control females, and no females directed strong courtship response to either dummy. This weak response suggests that the subjects were out of condition and tested too late in the spawning season. If the females’ gonads were well past their maximal development, this might preclude any effect of Ovaprim, which increases development and hormone secreting activity of the gonads. The disturbance from the injection procedure may also have contributed to the absence of a clear sexual response in the Ovaprim-treated fish. These potential complications thus preclude me from drawing any conclusions about the effectiveness or ineffectiveness of Ovaprim as a modifier of sexual behavior in female threespine stickleback.

2003 REU Mentor:  Richard Granquist and Dr. William Rowland

Signal Perception in Lizards: Motion Cues and General Body Morphology as Releasers of Aggressive Behavior in the Sagebrush Lizard (Sceloporus graciosus)
Many lizards communicate through visual displays, which are used primarily in territorial acquisition and defense. In this study, we examined the importance of general morphology in aggressive behavior of sagebrush lizards (Sceloporus graciossus). Thirty-two males with the exception of one due to equipment failure were used in the experiment. The males were presented with two programmed models, a robotic lizard and a red cube, which performed the aggressive displays of a sagebrush lizard. Previous studies using models have indicated that many animals tend to respond to sign stimuli or releasers that resemble the general morphology of their species. Behavior responses to robot stimulus have produced the same results as live conspecifics. Our goal was to determine the importance of motion cues, relative to general morphology, in eliciting aggressive behavior in lizards. To test this, four treatments were shown to the male lizards, which consisted of robot lizard/aggressive, robot lizard/still, cube/aggressive display, and cube still. We hypothesized that the sagebrush lizards would respond more to the displaying robot because of the general morphology and displaying behavior. Each experimental trial was videotaped and later scored on specific aggressive behavior. The lizards approached the lizard model (moving or still) more than the cube. They responded differently to motion depending on whether it was the lizard model or a cube. Each lizard differed in overall responses to each treatment.

2003 REU Mentor:  Dr. Terry Ord and Dr. Emilia Martins

Pretraining Norway Rats with Distal Cues does not Block Control of Foraging by Proximal Cues
Animals use objects and distant landmarks in their environment as points of reference for remembering potential locations for nesting, safety and finding food. The purpose of our study was to discover if initial training of rats with a subset of spatial cues would interfere with (block) the learning of additional spatial cues. The traditional concept of blocking is grounded in associative learning models of cue competition. These models claim that once a predictive cue (a CS) produces a conditioned response (a CR) at its asymptotic level, no further associations can be made between other stimuli (CSs) and the CR. Previous research using the Morris water maze (a spatial task that requires the animal to find the location of a hidden escape platform in a large circular pool) has provided considerable evidence that pretraining with a beacon close to the platform interferes with learning to find the platform using room landmarks. (Rodrigo, et. al, 1997; Roberts & Pearce 1999) In our study we followed the experimental design of water maze studies but instead of observing escape behavior to a platform, we examined foraging behavior in a large open field, and we reversed the direction of potential blocking. We tested whether rats that received pretraining with distal room cues (landmarks) were able to learn that an additional proximate cue (a beacon) also predicted the location of food. Given the blocking hypothesis, we expected pretraining with room cues to interfere with learning the prediction by the beacon. Given the alternative hypothesis--that animals should learn readily about proximate cues--we expected that pretraining with only the room cues would not block learning about the beacon.

During training each rat was placed in a 10’ square arena with four cups positioned at equal distances from its corners. Food could only be found in one cup that remained in the same location for each rat during both training stages. The blocking group was given twelve days to learn to locate food by using only room cues as a reference. Then, both blocking and control groups received twelve days of compound conditioning with both room cues and a beacon placed near and above the food cup present.

We performed three tests to assess the degree to which the beacon guided foraging in the absence of the landmarks: first, by presenting the beacon alone in the absence of room cues; second, by moving the beacon to a new position to determine the extent to which the rats explored the quadrant indicated by the room cues versus the beacon and other two quadrants; and third, by removing both the room cues and beacon to examine whether rats were able to locate the food cup based only on a basic orientation in the room. We observed order of choices and time spent in the room cues and beacon quadrants.

Overall, our results show that blocking does not occur in a spatial foraging task when pretraining with distant landmarks precedes compound conditioning with a proximate cue. Further, when compound conditioning is the only training received, a beacon does not overshadow learning the predictive value of distal landmarks, given that room cues were used by the control group as a more reliable reference when the beacon was shifted from its usual position.

2003 REU Mentor:  Joe Leffel and Dr. William Timberlake

Four Leaf Clovers and Rabbit’s Foots: The Role of Prior Training in “Superstitious” Behavior
Researchers have long speculated on the basis of pigeons’ behavior on a short fixed time (FT) schedule in which the animal receives food every 15 seconds no matter what behavior they are performing. Skinner (1948) first described the pigeons’ behavior on this schedule as “superstitious;” he thought that the behaviors that appeared on the FT schedule were arbitrary and maintained by coincidental pairings with food. Other researchers hypothesized that behaviors on FT schedules were a form of stimulus substitution (Simmelhag & Staddon, 1971) or a part of a niche related foraging sequence (Timberlake & Lucas, 1985). The purpose of this experiment was to determine whether prior training would change the behavior that appeared on a subsequent FT schedule. If the behavior after training remained the same as during training, then there may be a role of accidental reinforcement in determining behavior under a FT schedule. If, on the other hand, the behavior shifted into wall directed behavior, this would be a clear indication that accidental reinforcement is not the primary mechanism driving behavior but rather a niche related foraging mechanism. Eight pigeons were trained to turn or approach the back wall of a chamber on a FI-15s, in which the first correct response after 15 seconds was rewarded, and were then placed on a FT-15s schedule while their behavior was tracked every 3 seconds. By day 4 of the FT-15s schedule, 5 out of 8 of the pigeons dropped into the typical pattern seen in a FT schedule of locomotion followed by wall directed behavior at the hopper wall with very little other behavior occurring during the sessions. Two back wall trained birds’ behaviors were altered by the training and began to alternate wall directed behavior at the hopper wall and the glass wall of the chamber. Finally, one bird maintained the trained behavior of turning for 10 sessions before beginning to break down into wall directed behavior. Prior training seems to have some persisting results on behavior that occurs during fixed time food presentations, but the fact that all behaviors were eventually replaced by some form of wall directed behavior suggests some kind of niche related foraging mechanism is directing behavior under the FT schedule.

2003 REU Mentor:  Eddie Fernandez and William Timberlake

Spiny Mouse (Acomys cahirinus) Parent-Offspring Contact Patterns in a 3-Chamber Habitat: Litter Birth to Postnatal Day 8
In a lab environment spiny mice have been reported to exhibit biparental care (Makin & Porter, 1984; Szijarto, Coffee, Boyle, Bailey, Mulé, Iacovone, & Deni, 1985). These reports, however, are based on limited time samples that may inaccurately represent sire involvement in offspring care. In this study, families were housed in a 3-chamber habitat that allowed the mice to actively determine proximity and contact with one another. Parent-offspring contact patterns [Dam-Pup(s), Sire-Pup(s), and Dam-Sire-Pup(s)] of 4 families were described on postnatal days 0, 2, 4, 6, and 8 of their second litter, using 24-hr time-lapse video samples with a12:12 light-dark cycle (lights on at 0700). Average intra-observer reliability was greater than 95%. The results from this study indicated that the time spiny mouse families spend in Dam-Sire-Pup(s) contact increases as time spent in Dam-Pup(s) contact decreases with pup age.