Optimal Degrees of Synaptic Connectivity

Ashok Litwin-Kumar*, Kameron Decker Harris, Richard Axel, Haim Sompolinsky, L. F. Abbott

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

186 Scopus citations

Abstract

Synaptic connectivity varies widely across neuronal types. Cerebellar granule cells receive five orders of magnitude fewer inputs than the Purkinje cells they innervate, and cerebellum-like circuits, including the insect mushroom body, also exhibit large divergences in connectivity. In contrast, the number of inputs per neuron in cerebral cortex is more uniform and large. We investigate how the dimension of a representation formed by a population of neurons depends on how many inputs each neuron receives and what this implies for learning associations. Our theory predicts that the dimensions of the cerebellar granule-cell and Drosophila Kenyon-cell representations are maximized at degrees of synaptic connectivity that match those observed anatomically, showing that sparse connectivity is sometimes superior to dense connectivity. When input synapses are subject to supervised plasticity, however, dense wiring becomes advantageous, suggesting that the type of plasticity exhibited by a set of synapses is a major determinant of connection density.

Original languageEnglish
Pages (from-to)1153-1164.e7
JournalNeuron
Volume93
Issue number5
DOIs
StatePublished - 8 Mar 2017

Bibliographical note

Publisher Copyright:
© 2017 Elsevier Inc.

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