Spatial Distribution of Low- and High-Voltage-Activated Calcium Currents in Neurons of the Deep Cerebellar Nuclei

Abstract

The spatial distribution of low-voltage-activated (LVA) and high-voltage-activated (HVA) barium currents was investigated in neurons of the deep cerebellar nuclei (DCN) by combining barium imaging with voltage clamp. The current-induced fluorescence signal (DeltaF/F) of the HVA current was five times higher then the LVA-induced signal at the soma, but both signals were approximately equal in size in distant dendrites. This position-dependent shift of DeltaF/F indicates a non-uniform distribution of the underlying calcium channels. The higher weight of the LVA signal in the dendrites suggests that the LVA might be of particular relevance for the dendritic integration of synaptic inputs.

Ionic Factors Governing Rebound Burst Phenotype in Rat Deep Cerebellar Neurons

“…A DAP can arise from any of several active current sources that varies according to cell type, including Ca 2ϩ (Jung et al 2001;Metz et al 2005;Nelson et al 2005b;Yuste et al 1994;Zhang et al 1993 (Gauck et al 2001). These findings would be consistent with an active backpropagation of Na ϩ spikes into dendrites and the subsequent activation of voltage-gated Ca 2ϩ channels, as observed in other cells (Golding et al 1999;Yuste et al 1994).…”

Reliability of triggering postinhibitory rebound bursts in deep cerebellar neurons

“…Since this work was conducted in a slice preparation, the results pertain only to the proximal dendrites. 11,27,28 Indeed, membrane hyperpolarizations at the soma were instead found to be associated with a decrease in internal Ca 2+ levels during and shortly after the end of a hyperpolarizing pulse. 28 Each of these results suggest that much of the Ca 2+ -mediated rebound depolarization is actually generated at dendritic locations.…”

Molecular Physiology of Low-Voltage-Activated T-type Calcium Channels

“…This difference has been attributed to loss of channels that were localized on dendrites (97). In fact, T-type channels appear to be preferentially localized to dendrites (77,135,195,199,328).…”