Gill Seminars
Upcoming Speakers
SAVE THE DATE!
Wednesday, September 25, 2013
INDIANA UNIVERSITY BLOOMINGTON CAMPUS
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Fall, 2013
Susan Amara, Ph.D.
University of Pittsburgh
Seminar will be held in MSBII, Room 102 at 4:00 p.m.
Title: Pending
Abstract: Pending.
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September 25, 2013
Bruce L. McNaughton, Ph.D.
The University of Lethbridge
Seminar will take place in the Indiana Memorial Union, Whittenberger Auditorium during the 2013 Gill Symposium.
Title: Doughnuts in the Brain: A Toroidal Attractor Theory of the Cognitive Map
Abstract: The hippocampal formation of the mammalian brain is crucial to the storage and consolidation of 'episodic' memories: memories for experiences that unfold in space and time. It accomplishes its role in memory using so-called 'place-cells', which provide a unique code reflecting the spatio-temporal context of experiences. This code serves as a tag or 'index' that links together sub-components of a given experience which are stored in distributed form throughout the neocortex. The index code is generated by complex interactions of cellular and network mechanisms whose understanding has been greatly facilitated by technologies that enable monitoring cellular activity from large numbers of neurons in the brains of behaving animals. These interactions enable integration of self-motion information to keep track of spatial location, and append information about external and internal events onto the resulting internal spatial coordinate system, thus generating a 'cognitive map'. Networks in thalamus and midbrain ('head-direction cells') compute relative head orientation (azimuth) as animals rotate their heads; cells in medial entorhinal cortex ('grid cells') fire in a regular, 2-D periodic, spatial pattern (‘grid field’) when an animal moves about its world. Head-direction and grid cells can be explained by a theory in which pre-wired synaptic matrices determine ring (1-D) or toroidal (2-D; ‘doughnut-like’) manifolds of allowed states (‘attractors’) of network activity. The speed by which the neuronal state is updated relative to the animal’s physical motion in space sets the scale of the 2-D grid field, and there are multiple such grid cell modules, each with a different movement gain, and thus each expressing a different spatial scale. Next, hippocampal place cells, which receive grid field information at multiple spatial scales, provide unique codes for spatial location, possibly by a Fourier synthesis-like summation on their inputs. Finally, inputs from other brain regions, representing features and events in the world, or internal states such as goals, modulate the rate (but not relative location) of place cell firing, thus generating a unique, conjunctive code for ‘what’ happened ‘where’. Although they exhibit a high degree of experience-dependent plasticity, these networks appear to be wired up by a self-organizing process in early post-natal development in a manner that is independent of experience (a priori). Thus, in a sense, Immanuel Kant was correct: "Space… originates from the mind's nature in accord with a stable law as a scheme, as it were, for coordinating everything sensed externally".
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September 25, 2013
Loren M. Frank, Ph.D.
University of California, San Francisco
Seminar will take place in the Indiana Memorial Union, Whittenberger Auditorium during the 2013 Gill Symposium.
Title: Neural Substrates of Memory and Decision-Making
Abstract: The hippocampus is a brain structure known to be critical for forming and retrieving memories for the experiences of daily life. How, exactly, it does so has remained a mystery for some time, but recent progress indicates that specific patterns of neural activity can be linked to specific memory functions. In this talk I will discuss work from my laboratory that provides such a link. We have shown that hippocampal replay events can reactivate patterns of brain activity from a previous experience in awake animals and that disrupting these events interferes with learning and memory-guided decision-making. Further, we have found that the intensity of replay activity is predictive of whether an upcoming choice will be correct or incorrect. Our results suggest that the awake replay of place cell sequences plays a central role in deliberative processes that underlie memory-guided decision making.
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April 23, 2014
Grace Zhai, Ph.D.
University of Miami, Miller School of Medicine
Seminar will be held in MSBII, Room 102 at 4:00 p.m.
Title: Pending
Abstract: Pending
