William D. Timberlake
Abstracts of Selected Publications

ABSTRACT
In a world of increasing demands and diminishing resources, the understanding and control of behavior is likely to be a key to successful relations between human and nonhuman animals. The traditional laboratory study of animal behavior, centered on systematic manipulation of single variables, has provided powerful causal laws connecting manipulations to effects, but these laws have proved surprisingly difficult to transport to field and applied settings. The recent increase in anthropomorphic interpretations of behavior has the advantage of emphasizing the contribution of the animal rather than the experimenter, but by itself anthropomorphism holds little possibility of improved understanding and prediction. I argue for development of a causal-system approach that captures an animal's point-of-view without unnecessary assumptions of a human-like mental life. By realizing this approach within the structural framework and regulatory processes of behavior systems, it should be possible to develop a model of animal behavior that integrates and expands data from laboratory, field, and applied settings, and may contribute to successful relations between human and nonhuman animals.
© 1997 Elsevier Science B.V. All rights reserved.

ABSTRACT
In two experiments, we explored how the foraging behavior of Norway rats was influenced by different arrangements of artificial paths and vertical landmarks. The rats used the paths successively less for orienting to food in treatments in which paths led to food but were crooked, in which paths led only halfway to food, and in which paths were misaligned with respect to food. The arrangement of paths influenced the rats' rate of energy intake in the beginning of the experiment, whereas the arrangement of beacons did not. With experience, the rats employed different orientation strategies in the presence of different arrangements of paths or beacons, and, by the final 4 days, all groups achieved statistically indistinguishable net rates of return. The rates of energy intake were similar because the rats in different treatments traveled similar distances per session, despite differing arrangements of paths and landmarks.
© 1998 Psychonomic Society, Inc.

ABSTRACT
In the first phase of Experiment 1 rats were trained with a backward serial conditioned stimulus (CS) with three 8-s elements (Food-Near-Intermediate-Far, where the name of the element denotes its temporal proximity to food). In the second phase of this experiment, different groups received a novel lever presented in compound with a different CS element. In the first phase of Experiment 2, rats were also trained with a similar backward serial CS; but, in the second phase, the entire serial CS was shifted to a forward pairing (Far-Intermediate-Near-Food), and again different groups received a novel lever in compound with a different CS element. In the first phase of Experiment 3, a serial CS was explicitly unpaired with food. The second phase of this experiment was identical to that of Experiment 2. The results showed that lever contact was lowest during the Near element in Experiment 1, highest during the same element in Experiment 2, and indistinguishable among all the elements in Experiment 3. These outcomes support the behavior systems hypothesis that backward CSs come to control a sequence of post-food search modes that can influence subsequent pre-food search.
© 1998 by Academic Press. All rights of reproduction in any form reserved.

ABSTRACT
Scheduled daily injections of methamphetamine (MA) produced locomotor activity that preceded and followed the usual time of injection in rats housed under conditions of constant, moderately dim light and temporally distributed feeding. A circadian basis for pre-injection time activity was supported by its anticipatory timing in the apparent absence of reliable preceding external cues and by its persistence on a test day on which the rats remained undisturbed. Post-injection time locomotor activity also persisted on the test day, occurring from 24 to 29 h after the final MA injections. These results indicate that MA injections engage circadian processes underlying locomotor activity, and they raise the possibility that intake of drugs of abuse by humans may facilitate drug taking or relapse at times of day related to previous drug use.
© 1998 Elsevier Science Ireland Ltd. All rights reserved.

ABSTRACT
Two experiments used a behavior systems approach to relate the form of responses during an interfood clock to the temporal distance of the individual clock stimuli to food. Stimuli proximate to food should better control a focal search mode and related responses, whereas stimuli temporally distant from food should better control a general search mode and related responses. Experiment 1 conditioned two groups of rats with a sequence of four equal-length 12-sec clock stimuli that terminated with food and then tested for the conditioning of a general search mode by presenting an unconditioned moving probe stimulus (either a rollling ball bearing or a rotating mechanical door) during each of the clock stimuli. Consistent with a behavior systems view, contact with the ball bearing was markedly greater during a clock stimulus distant from food. The absence of similar differential contact of the door across the clock stimuli showed that the effect was specific to the ball bearing rather than a general response to stimulus dimensions of movement and sound. Experiment 2 showed that the general search mode was controlled by the clock stimulus rather than the passage of time.
© 1998 Psychonomic Society, Inc.

ABSTRACT
Large meals scheduled at great-that-circadian periods (such as T=31 hours) tend to elicit enhanced activity approximately 24 hours subsequent to receipt. These studies characterized the process responsible for this meal-engendered "Circadian ensuing activity" (meal CEA). Female Sprague-Dawley rats were housed in stations containing a running wheel, pellet dispenser, and lights. young, middle-aged, or suprachiasmatic-nucleus (SCN) lesioned rats were given two one-hour meals every 31 or 34 hours. Meals were separated by alternating short and long fasts. Most young intact rats engaged in enhanced activity separated by alternating short and long fasts. Most young intact rats engaged in enhanced activity approximately 24 hours subsequent to the start of the two meal series. This Circadian ensuing activity: Underwent large, abrupt daily displacements in response to daily meal delays; was manifested to some degree at all times of day; had an amplitude that was modulated by circadian time of day; was attenuated in middle-aged rats; was evident in SCN-lesioned rats; and oscillated following termination of the feeding schedule. A single experience with food at a novel time of day can "reset" an SCN-independent oscillating process responsible for a circadian activity pattern. CEA has features not readily accommodated by present models of "Food-anticipatory activity". The readiness with which the process can be reset implies a keen sensitivity to shifts in the time of food availability but could also produce aberrant behavioral patterns. A T>24 hour feeding schedule appears to be an ideal procedure with which to study the specific food-related factors responsible for resetting circadian processes and producing a subsequent reallocation of daily activity.

ABSTRACT
Norway rats have been shown to depend on short-term spatial memory to find food on a radial arm maze (RAM), but what locomotor search tactics are involved in using this memory effectively? Four experiments distinguished tactics of distance minimizing, central-place search, trail following, thigmotactic search, and random search by using different configurations of a RAM placed flat on the floor of an arena These search tactics make similar predictions on an elevated RAM: but predict different outcomes on a floor RAM because the rats are free to approach the food from any direction. After initial trials dominated by exploration, rats traveled along arms to food, even when the resultant distance was up to three times the minimum distance. With no food present, rats also traveled along arms; with no arms up to present, they traveled along walls to food. It appears that both maze arms and arena walls engage mechanisms related to trail following in rats.
© 1999 Psychonomic Society, Inc.

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