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Probability Interpretation of Population Codes

Terence D. Sanger
Massachusetts Institute of Technology
Room E25-526
Cambridge, MA 02139
(617)253-5769 tds@ai.mit.edu

Preference: Oral
Topic: Theory; Distributed Representations

Abstract:

Although theoretical neural network models frequently assume that the firing rates of individual neurons carry the analog signals used for computations, it is becoming clear that in many sensory and motor systems, information is encoded as patterns of activity over large populations of cells [Georgopoulos et al. 1988, for example,]. I seek to address several different but related questions concerning such populations. I investigate the computational properties of certain types of population codes by using a probabilistic interpretation of their structure. I show the existence of simple algorithms for nonlinear supervised learning as well as for unsupervised learning based on information maximization [Linsker 1988,Linsker 1989]. And I show that although in general it is not possible to find a unique external variable that is coded by a population [Sanger 1994], it is possible to use information maximization principles to find the external variable that is represented best by the population.





Terence D. Sanger
Mon Aug 21 18:36:58 EDT 1995