Differential alterations of intracellular [Ca] dynamics induced by cocaine and methylphenidate in thalamocortical ventrobasal neurons.

The ventrobasal (VB) thalamus relay nucleus processes information from rodents' whiskers, projecting to somatosensory cortex. Cocaine and methylphenidate (MPH) have been described to differentially alter intrinsic properties of, and spontaneous GABAergic input to, VB neurons. Here we studied using bis-fura 2 ratiometric fluorescence the effects of cocaine and MPH on intracellular [Ca] dynamics at the soma and dendrites of VB neurons. Cocaine increased baseline fluorescence in VB and compartments. Peak and areas of fluorescence amplitudes were reduced by cocaine treatment in somas and dendrites at different holding potentials. MPH treatment did not alter ratiometric fluorescence at either somatic or dendritic levels. These novel cocaine-mediated blunting effects on intracellular [Ca] might account for alterations in the capacity of thalamocortical neurons to maintain oscillations, as well as their ability to integrate synaptic afferents.