Original Research ARTICLE

Front. Integr. Neurosci., 30 March 2011 | doi: 10.3389/fnint.2011.00003

Amygdala stimulation evokes time-varying synaptic responses in the gustatory cortex of anesthetized rats

Martha E. Stone, Arianna Maffei and Alfredo Fontanini*
  • Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, USA

Gustatory stimuli are characterized by a specific hedonic value; they are either palatable or aversive. Hedonic value, along with other psychological dimensions of tastes, is coded in the time-course of gustatory cortex (GC) neural responses and appears to emerge via top-down modulation by the basolateral amygdala (BLA). While the importance of BLA in modulating gustatory cortical function has been well established, the nature of its input onto GC neurons is largely unknown. Somewhat conflicting results from extracellular recordings point to either excitatory or inhibitory effects. Here, we directly test the hypothesis that BLA can evoke time-varying – excitatory and inhibitory – synaptic responses in GC using in vivo intracellular recording techniques in urethane anesthetized rats. Electrical stimulation of BLA evoked a post-synaptic potential (PSP) in GC neurons that resulted from a combination of short and long latency components: an initial monosynaptic, glutamatergic potential followed by a multisynaptic, GABAergic hyperpolarization. As predicted by the dynamic nature of amygdala evoked potentials, trains of five BLA stimuli at rates that mimic physiological firing rates (5–40 Hz) evoke a combination of excitation and inhibition in GC cells. The magnitude of the different components varies depending on the frequency of stimulation, with summation of excitatory and inhibitory inputs reaching its maximum at higher frequencies. These experiments provide the first description of BLA synaptic inputs to GC and reveal that amygdalar afferents can modulate gustatory cortical network activity and its processing of sensory information via time-varying synaptic dynamics.

Keywords: amygdala, hedonics, in vivo intracellular, taste, top-down

Citation: Stone ME, Maffei A and Fontanini A (2011) Amygdala stimulation evokes time-varying synaptic responses in the gustatory cortex of anesthetized rats. Front. Integr. Neurosci. 5:3. doi: 10.3389/fnint.2011.00003

Received: 17 January 2011; Paper pending published: 30 January 2011;
Accepted: 17 March 2011; Published online: 31 March 2011

Edited by:

John J. Foxe, Albert Einstein College of Medicine, USA

Reviewed by:

Donald A. Wilson, New York University School of Medicine, USA
Robert Lundy, University of Louisville, USA

Copyright: © 2011 Stone, Maffei and Fontanini. This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use,

*Correspondence: Alfredo Fontanini, Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY 11794-5230, USA. e-mail: alfredo.fontanini@stonybrook.edu

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