3 channels.

Therefore, we may propose that CaV2.3 channels, in addition to other players, including T-type Ca2+ channels, the SR-ER Ca2+ ATPase (SERCA), and SKs ( Cueni et al., 2008, Huguenard, 1996, Llinas, 1988 and Perez-Reyes, 2003), have a critical role in oscillatory burst discharges in RT neurons. Simulation of such oscillatory discharges in a model neuron further strengthens our proposal: a simulated neuron lacking CaV2.3 component of Ca2+ currents mimics very closely the firing pattern of the mutant neurons in the experimental setting ( Figure S5). For details on simulation see Supplemental Experimental Procedures. CaV2.3 channels appear to play an important role in boosting the excitability of RT neurons. A significant reduction in the number of intraburst spikes in the first LT burst was observed in CaV2.3−/− RT neurons Bleomycin datasheet GW3965 cell line compared to the wild-type ( Figure 3). Similarly, in response to depolarizing

inputs, a significant reduction in the number of intraburst spikes and in the frequency of subsequent tonic firing was observed in CaV2.3−/− neurons ( Figure 6), suggesting that CaV2.3 channels contribute to excitability of those neurons. Potential influence of the AHP on the frequency of the subsequent tonic firing has been excluded by finding no statistically significant correlation between the amplitude of the preceding AHP and the frequency of the subsequent tonic firing, supporting our interpretation (data not shown). Moreover, an application

of apamin to wild-type RT neurons in the presence of TTX unmasked a slowly decaying plateau potential ( Cueni et al., 2008). The nonselective calcium-activated cationic current permeating Na+, K+, and Ca2+ ( Luzhkov and Aqvist, 2001) could be a possible candidate of the long-lasting plateau potential that was profoundly reduced in CaV2.3−/− neurons, suggesting Pentifylline that an initial LT Ca2+ influx further recruits CaV2.3 channels, which ensure the prolonged depolarization needed for increased firing activity of RT neurons. A similar role for CaV2.3 channels was also noted in the hyperexcitability induced by apamin ( Figure S2). Cellular and circuit properties of thalamic neurons give rise to thalamocortical oscillations in arousal/sleep states as well as seizures. RT neurons are known for their propensity to generate rhythmic burst discharges (Fuentealba and Steriade, 2005). It has been proposed that rhythmic burst discharges of RT neurons mediate inhibitory postsynaptic potentials in thalamocortical cells through GABAA and GABAB receptors (Kim et al., 1997). The GABAB receptor-mediated opening of K+ channels induces rebound bursting in a large proportion of thalamocortical neurons, leading to a paroxysmal activity (Beenhakker and Huguenard, 2009, Crunelli and Leresche, 1991, Steriade et al., 1993 and von Krosigk et al.