Neuronal thalamic gap junctions: identity, location and role in slow EEG rhythms of (patho)physiological states (360G-Wellcome-078403_B_05_Z)

Synchronized activity among thalamic and cortical neurones underlies the EEG expression of different behavioural state-dependent rhythms, whereas its alterations may lead to EEG paroxysms such as the spike-and-wave discharges (SWDs) of absence epilepsy. Our in vitro studies have identified a key role for gap junctions (GJs) among the glutamatergic thalamocortical (TC) neurones in the expression of synchronized, low-frequency thalamic oscillations, that define two behavioural states, i.e. the alpha rhythm and the slow ( < 1 Hz) sleep rhythm. In addition, connexin 36 (Cx-36)-based GJs among GABAergic nucleus reticularis thalami (NRT) neurones is known to support synchronized oscillations in this thalamic nucleus in vitro. Here we propose:1. to identify in vivo the contribution of GJs among TC neurones and among NRT cells to the expression of SWDs and of three EEG rhythms: the alpha rhythm, sleep spindles and the slow ( < 1 Hz) sleep rhythm;2. to identify the sites of GJ coupling in TC and NRT neurones, and the molecular identity of the Cx(s) present in TC neurones using electron microscopy, and triple labelling of dye-coupled neurones and immunocytochemistry with specific Cx antibodies.This multi-disciplinary approach from two laboratories with established expertise in their respective field will shed light into the role of thalamic GJs in EEG rhythms of fundamental importance in health and in one of the generalized epilepsies.