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J Neurophysiol. 2015 Jan 15;113(2):509-23. doi: 10.1152/jn.00568.2014. Epub 2014 Oct 22.

A model of order-selectivity based on dynamic changes in the balance of excitation and inhibition produced by short-term synaptic plasticity.

Author information

1
Integrative Center for Learning and Memory, Departments of Neurobiology and Psychology, UCLA, Los Angeles, California.
2
Integrative Center for Learning and Memory, Departments of Neurobiology and Psychology, UCLA, Los Angeles, California dbuono@ucla.edu.

Abstract

Determining the order of sensory events separated by a few hundred milliseconds is critical to many forms of sensory processing, including vocalization and speech discrimination. Although many experimental studies have recorded from auditory order-sensitive and order-selective neurons, the underlying mechanisms are poorly understood. Here we demonstrate that universal properties of cortical synapses-short-term synaptic plasticity of excitatory and inhibitory synapses-are well suited for the generation of order-selective neural responses. Using computational models of canonical disynaptic circuits, we show that the dynamic changes in the balance of excitation and inhibition imposed by short-term plasticity lead to the generation of order-selective responses. Parametric analyses predict that among the forms of short-term plasticity expressed at excitatory-to-excitatory, excitatory-to-inhibitory, and inhibitory-to-excitatory synapses, the single most important contributor to order-selectivity is the paired-pulse depression of inhibitory postsynaptic potentials (IPSPs). A topographic model of the auditory cortex that incorporates short-term plasticity accounts for both context-dependent suppression and enhancement in response to paired tones. Together these results provide a framework to account for an important computational problem based on ubiquitous synaptic properties that did not yet have a clearly established computational function. Additionally, these studies suggest that disynaptic circuits represent a fundamental computational unit that is capable of processing both spatial and temporal information.

KEYWORDS:

context-dependent suppression and enhancement; disynaptic circuit; order-selectivity; short-term synaptic plasticity

PMID:
25339707
PMCID:
PMC4297794
DOI:
10.1152/jn.00568.2014
[Indexed for MEDLINE]
Free PMC Article

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