Parvalbumin interneuron mediated feedforward inhibition controls signal output in the deep layers of the perirhinal ‐entorhinal cortex

This study explored the role of interneuron mediated inhibition, activated by electrical stimulation in the agranular insular cortex (AiP), in the deep layers of the PER and LEC. Activated synaptic input by AiP stimulation rarely evoked action potentials in the PER‐LEC deep layer excitatory principal neurons, most probably because the evoked synaptic response consisted of a small excitatory and large inhibitory conductance. Furthermore, parvalbumin positive (PV) interneurons ‐ a subset of interneurons projecting onto the axo‐somatic region of principal neurons ‐ received synaptic input earlier than principal neurons, suggesting recruitment of feedforward inhibition. This synaptic input in PV interneurons evoked varying trains of action potentials, explaining the fast rising, long lasting synaptic inhibition received by deep layer principal neurons. Altogether, the excitatory input from the AiP onto deep layer principal neurons is overruled by strong feedforward inhibition. PV interneurons, with their fast, extensive stimulus‐evoked firing, are able to deliver this fast evoked inhibition in principal neurons. This indicates an essential role for PV interneurons in the gating mechanism of the PER‐LEC network. This article is protected by copyright. All rights reserved.

Source: Hippocampus - January 17, 2018 Category: Neurology Authors: Janske G.P. Willems, Wytse J. Wadman, Natalie L. M. Cappaert Tags: Research Article Source Type: research