Specific expression of low-voltage-activated calcium channel isoforms and splice variants in thalamic local circuit interneurons.

It has been suggested that the specific burst firing patterns of thalamic neurons reflect differential expression of low-voltage-activated (LVA) Ca(2+) channel subtypes and their splice variants. By combining electrophysiological, molecular biological, immunological, and computational modeling techniques we here show that diverging LVA Ca(2+) currents of thalamocortical relay (TC) and GABAergic interneurons of the dLGN correlate with a differential expression of LVA Ca(2+) channel splice variations and isoforms (alpha1G-a in TC; alpha1G-bc and alpha1I in interneurons). Implementation of the observed LVA Ca(2+) current differences into a TC neuron model changed the burst firing from TC-like to interneuron-like. We conclude that alternative splicing of the alpha1G isoform in dLGN TC and interneurons, and the exclusive expression of the alpha1I isoform in interneurons play a prominent role in setting the different LVA Ca(2+) current properties of TC and interneurons, which critically contribute to the diverging burst firing behavior of these neurons.