Dendritic calcium conductances generate high-frequency oscillation in thalamocortical neurons.

Abstract

Cortical-projecting thalamic neurons, in guinea pig brain slices, display high-frequency membrane potential oscillations (20-80 Hz), when their somata are depolarized beyond -45 mV. These oscillations, preferentially located at dendritic sites, are supported by the activation of P/Q type calcium channels, as opposed to the expected persistent sodium conductance responsible for such rhythmic behavior in other central neurons. Short hyperpolarizing pulses reset the phase and transiently increase the amplitude of these oscillations. This intrinsic thalamic electroresponsiveness may serve as a cellular-based temporal binding mechanism that sharpens the temporal coincidence of cortical-feedback synaptic inputs, known to distribute at remote dendritic sites on thalamic neurons.