Higher-dimensional neurons explain the tuning and dynamics of working memory cells

Journal of Neuroscience, 2006

Ray Singh, Chris Eliasmith

Abstract

Measurements of neural activity in working memory during a somatosensory discrimination task show that the content of workingmemory is not only stimulus dependent but also strongly time varying. We present a biologically plausible neural model that reproducesthe wide variety of characteristic responses observed in those experiments. Central to our model is a heterogeneous ensemble of two-dimensional neurons that are hypothesized to simultaneously encode two distinct stimuli dimensions. We demonstrate that the spikingactivity of each neuron in the population can be understood as the result of a two-dimensional state space trajectory projected onto the tuning curve of the neuron. The wide variety of observed responses is thus a natural consequence of apopulation of neurons with a diverse set of preferred stimulus vectors and response functions in this two-dimensional space. In addition, we propose a taxonomy of networktopologies that will generate the two-dimensional trajectory necessary to exploit this population. We conclude by proposing someexperimental indicators to help distinguish among these possibilities.

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Journal
Journal of Neuroscience
Volume
26
Pages
3667-3678

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