Preprint available

[Angelo Arleo]

    Dear Connectionists,
the following paper is to appear in Biological Cybernetics,
Special Issue on Navigation in Biological and Artificial
Systems:

===================================================
"Spatial Cognition and Neuro-Mimetic Navigation:
  A Model of Hippocampal Place Cell Activity"

 Angelo Arleo and Wulfram Gerstner
 Centre for Neuro-Mimetic Systems, MANTRA
 Swiss Federal Institute of Technology Lausanne
===================================================

A preprint of the paper is available at the site:
ftp://lamiftp.epfl.ch/pub/arleo/BC99/paper.ps.Z

Comments and suggestions are particularly welcome.
Best regards,
    Angelo Arleo

==================================================
Extended Abstract
A computational model of hippocampal activity
during spatial cognition and navigation tasks is
presented. The spatial representation in our model
of the rat hippocampus is built on-line during
exploration via two processing streams. An allothetic
vision-based representation is built by unsupervised
Hebbian learning extracting spatio-temporal properties
of the environment from visual input. An idiothetic
representation is learned based on internal movement-
related information provided by path integration.
On the level of the hippocampus, allothetic and idiothetic
representations are integrated to yield a stable representation
of the environment by a population of localized overlapping
CA3-CA1 place fields.
The hippocampal spatial representation is used as
a basis for goal-oriented spatial behavior. We focus on the
neural pathway connecting the hippocampus to the nucleus
accumbens. Place cells drive a population of locomotor
action neurons in the nucleus accumbens. Reward-based
learning is applied to map place cell activity into action cell
activity. The ensemble action cell activity provides navigational
maps to support spatial behavior.
We present experimental results obtained with a mobile
Khepera robot.
=================================================



--
_________________________________________________________________________

     ____/  __  /  ____/  /  Angelo Arleo
    /      /   /  /      /   Laboratory of Microcomputing (LAMI-DI)
   ____/  ____/  ____/  /    Swiss Federal Inst. of Technology Lausanne
  /      /      /      /     (EPFL) CH-1015 Ecublens, Lausanne
_____/ _/     _/     _____/  Tel/Fax: ++41 21 693 6696 / 5263
                             E-mail: angelo.arleo at di.epfl.ch
                             Web: http://diwww.epfl.ch/lami/team/arleo
_________________________________________________________________________