From space to episodes : modeling memory formation in the hippocampal-neocortical system

This thesis describes the use of mathematical, statistical, and computational methods to analyze, in two paradigmatic areas, what the hippocampus and associated structures do, and how they do it. The first model explores the formation of place fields in the hippocampus. This model is constrained by hippocampal anatomy and physiology and data on the effects of environmental manipulations on the place cell representation. It is based on an attractor network model of area CA3 in which recurrent interactions create place cell representations from location- and direction-specific activity in the entorhinal cortex, all under neuromodulatory influence. In unfamiliar environments, mossy fiber inputs impose activity patterns on CA3, and recurrent collaterals and perforant path inputs are subject to graded Hebbian plasticity. Attractors are thus sculpted in CA3, and are associated with entorhinal activity patterns. In familiar environments, place fields are controlled by the way that perforant path inputs select amongst the attractors. Depending on training experience, the model generates place fields that are either directional or non-directional, and whose changes when the environment undergoes simple geometric transformations are in accordance with experimental data. Representations of multiple environments can be stored and recalled with little interference, and have the appropriate degrees of similarity in visually similar environments.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Brain and Cognitive Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Káli, Szabolcs, 1972-

Advisor dc:contributor.advisor

• Peter Dayan.

• Brain and Cognitive Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8186

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8186