Role of the thalamic reticular nucleus in the generation of rhythmic thalamo-cortical activities subserving spike and waves

The role of the reticular thalamic nucleus (RTN) in pacing rhythmic cortical activities subserving spike-waves (SW) discharges has been investigated in rats. Intracellular recordings from thalamic slices in vitro demonstrated that RTN neurons from control animals possess a set of Ca²⁺/K⁺ membrane conductances which enable them to produce rhythmic oscillatory activities. In vivo, studies of Ca²⁺-conductance blockade by intrathalamic injections of Cd²⁺ were performed on 24 callosotomized Wistar rats displaying spontaneous SW discharges, bred at the Centre de Neurochimie, Strasbourg. A significant decrement in ipsilateral SW activity was consistently observed in all RTN-injected animals 40 min after Cd²⁺ injection. By contrast, animals which received Cd²⁺ injection into the ventroposterior complex (VP) showed only small changes in ipsilateral SW. It is concluded that Ca²⁺-dependent oscillatory properties of the RTN are critical for the expression of genetically determined SW discharges in the Wistar model.