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Summary: Neuron, Vol. 47, 437445, August 4, 2005, Copyright ©2005 by Elsevier Inc. DOI 10.1016/j.neuron.2005.06.009
Synaptic Mechanisms of Forward
Suppression in Rat Auditory Cortex
Michael Wehr and Anthony M. Zador* regation (Bregman, 1990). The precise relationships
between cortical forward suppression, other corticalCold Spring Harbor Laboratory
1 Bungtown Road physiological phenomena, and perceptual phenomena
such as forward masking and stream segregation re-Cold Spring Harbor, New York 11724
main unclear.
Because most thalamic neurons can follow click
Summary trains at several tens of hertz or higher, forward suppres-
sion is thought to be mainly cortical in origin (Creutzfeldt
In the auditory cortex, brief sounds elicit a powerful et al., 1980; Miller et al., 2002). What are the mechanisms
suppression of responsiveness that can persist for by which these response properties are created in the
hundreds of milliseconds. This forward suppression auditory cortex? Intrinsic intracellular mechanisms (such
(sometimes also called forward masking) has usually as postdischarge adaptation) do not appear to be re-
been attributed to synaptic (GABAergic) inhibition. sponsible (Calford and Semple, 1995). This suggests
Here we have used whole-cell recordings in vivo to that forward suppression arises at the circuit level, from
assess the role of synaptic inhibition in forward sup- the action of the synaptic inputs driving a neuron's re-
pression in auditory cortex. We measured the excit- sponse.
atory and inhibitory synaptic conductances elicited Postsynaptic GABAergic inhibition has been widely
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