A paradigmatic working memory (attractor) cell in it cortex

Abstract

We discuss paradigmatic properties of activity of single cells comprising an attractor -- a developed stable delay activity distribution. To demonstrate these properties and a methodology for measuring their values, we present a detailed account of the spike activity recorded from one single cell in infero-temporal (IT) cortex of a monkey performing a delayed match-to-sample (DMS) task of visual images. In particular, we discuss and exemplify: 1. the relation between spontaneous activity and activity immediately preceding the first stimulus in each trial during a series of DMS trials; 2. the effect on the visual response (i.e. activity {\bf during} stimulation) of stimulus degradation (moving in the space of IT afferents); 3. the behaviour of the delay activity (i.e. activity {\bf following} visual stimulation) under stimulus degradation (attractor dynamics, and the basin of attraction); and, 4. the propagation of information between trials -- the vehicle for the formation of (contextual) correlations by learning a fixed stimulus sequence, as found in Miyashita 1988. In the process of the discussion and demonstration, we expose effective tools for the identification and characterisation of attractor dynamics.