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Neuron. 2016 Aug 3;91(3):540-547. doi: 10.1016/j.neuron.2016.06.028. Epub 2016 Jul 14.

Bottom-Up and Top-Down Input Augment the Variability of Cortical Neurons.

Author information

1
Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, Massachusetts 02115, USA.
2
Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
3
Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA.
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Contributed equally

Abstract

Neurons in the cerebral cortex respond inconsistently to a repeated sensory stimulus, yet they underlie our stable sensory experiences. Although the nature of this variability is unknown, its ubiquity has encouraged the general view that each cell produces random spike patterns that noisily represent its response rate. In contrast, here we show that reversibly inactivating distant sources of either bottom-up or top-down input to cortical visual areas in the alert primate reduces both the spike train irregularity and the trial-to-trial variability of single neurons. A simple model in which a fraction of the pre-synaptic input is silenced can reproduce this reduction in variability, provided that there exist temporal correlations primarily within, but not between, excitatory and inhibitory input pools. A large component of the variability of cortical neurons may therefore arise from synchronous input produced by signals arriving from multiple sources.

PMID:
27427459
PMCID:
PMC5149417
DOI:
10.1016/j.neuron.2016.06.028
[Indexed for MEDLINE]
Free PMC Article

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