The "window' T-type calcium current in brain dynamics of different behavioural states

All three forms of recombinant low voltage-activated T-type Ca2+ channels (Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3) exhibit a small, though clearly evident, window T-type Ca2+ current (I-Twindow) which is also present in native channels from different neuronal types. In thalamocortical (TC) and nucleus reticularis thalami (NRT) neurones, and possibly in neocortical cells, an I-Twindow-mediated bistability is the key cellular mechanism underlying the expression of the slow (<1 Hz) sleep oscillation, one of the fundamental EEG rhythms of non-REM sleep. As the I-Twindow-mediated bistability may also represent one of the cellular mechanisms underlying the expression of high frequency burst firing in awake conditions, I-Twindow is of critical importance in neuronal population dynamics associated with different behavioural states.