Dendritic Control of Rhythmicity

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Science  10 Aug 2001:
Vol. 293, Issue 5532, pp. 1015-1017
DOI: 10.1126/science.293.5532.1015e

It has been shown that GABAergic interneurons can synchronize the firing behavior of their postsynaptic target cells. However, different types of interneurons innervate different parts of their targets, and earlier studies addressing synchronization either did not examine the location of the inhibitory input or concentrated on perisomatic mechanisms.

Szabadics et al. have combined electrophysiological recordings with light and electron microscopy in a painstaking analysis of the interactions between inhibitory interneurons at dendritic contacts. They concentrated on regularly spiking nonpyramidal cells contacting each other through chemical synapses, gap junctions, or a combination of both. Dendritic GABAergic synapses, which were exclusively unidirectional, were effective in timing spikes in postsynaptic cells. This phasing was effective at β (19 hertz) but not at γ frequency (37 hertz). Combined chemical and electrical connections caused β and γ frequency synchronization, but at both frequencies, the postsynaptic action potentials were rhythmically timed with a phase lag. These data indicate the existence of a network of regularly spiking nonpyramidal cells that speak to each other through dendritic synapses and are capable of engaging in coherent activity in functionally relevant frequency ranges. — PRS

J. Neurosci.21, 5824 (2001).

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