Rockwood Memorial Lecture

2014

INC sponsors the H. Paul Rockwood Memorial Lectureship held annually. The Rockwood Memorial Lectureship Fund was gifted to the Institute by Mr. and Mrs. Jerome Rockwood in memory of their late son's interest, studies, and work in the neural computation field.

The Rockwood Memorial Lectures are endowed by Mr. and Mrs. Jerome Rockwood in memory of their late son, Paul, who received a B.S. in Computer Science from UCSD in 1980 and then obtained a second degree B.A. in Psychology in 1981. In 1983 he started a company, Integral Solutions, to develop a universal language translation, but died tragically in a mountaineering accident before he could fulfill his promise.

Doughnuts in the Brain: A Toroidal Attractor Theory of the Cognitive Map

Who:
Dr. Bruce McNaughton
Distinguished Professor, Department of Neurobiology and Behavior Center for the Neurobiology of Learning and Memory University of California, Irvine

When:
4:00 - 5:30, Monday, April 14, 2014

Where:
San Diego Supercomputer Center Auditorium, Floor B-2, 10100 Hopkins Dr., La Jolla, CA 92093

Abstract:

The hippocampal formation 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".