Seminários em Neurociências 2011.1

Segunda-feira 06/06/2011 10:50h Sala 4 – Escola de Ciência e Tecnologia

 

O-LM neurons in CA1, identified by a novel marker, gates asynchronous inputs to pyramidal cell dendrites

Prof. Richardson N. Leão (Instituto de Cérebro, UFRN; Institutet för Neurovetenskap, Uppsala Universitet, Uppsala, Sweden)

It has been suggested that interactions between neuronal groups are greatly enhanced by synchronised activity; however, oscillatory states would impair the responsiveness of the network to unsynchronised inputs. If so, networks might be equipped with mechanisms of desynchronisation to diverge the network’s responsiveness to non-coherent inputs. Here, we describe a population of neurons confined to the stratum oriens of the hippocampus CA1 capable of gating dendritic inputs in pyramidal cells. These neurons are particularly sensitive to nicotine and can be genetically identified and differentiated from other CA1 interneurons by specific nicotinergic markers. Paired recordings show that activation of these nicotine-sensitive interneurons mask synaptic potentials evoked at distal pyramidal cell dendrites. Dendritic patch clamp recordings during gamma oscillations induced by kainate show that synaptic potentials recorded at pyramidal cell dendrites have a lesser degree of synchrony to gamma cycles than synaptic potentials recorded at the soma. In the presence of nicotine, somatic synaptic potentials show an even greater degree of synchrony and an opposite effect is observed when GABAergic transmission is selectively knocked out in the nicotine-sensitive neurons. Our results identify a novel class of hippocampal interneurons controlling the degree of permissiveness to asynchronous inputs to the CA1 network.

Notícia cadastrada em: 30/05/2011 16:06
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