Activity of Ventral Medial Thalamic Neurons during Absence Seizures and Modulation of Cortical Paroxysms by the Nigrothalamic Pathway

• DOI: 10.1523/jneurosci.4677-06.2007
• Publication Date: 2007-01-25T04:28:57Z
• Authors: Jeanne Tamar Paz; Mario Chavez; Sandrine Saillet; Jean-Michel Deniau; Stéphane Charpier
• Keywords: Bursting; Premovement neuronal activity

Absence seizures are characterized by bilaterally synchronous spike-and-wave discharges (SWDs) in the electroencephalogram, which reflect abnormal oscillations corticothalamic networks. Although it was suggested that basal ganglia could modulate, via their feedback circuits to cerebral cortex, occurrence of SWDs, cellular and network mechanisms underlying such a subcortical control absence remain unknown. The GABAergic projections from substantia nigra pars reticulata (SNR) thalamocortical neurons ventral medial (VM) thalamic nucleus provide potent for ganglia. present vivo study provides first description activity VM during genetic epilepsy rats Strasbourg, well established model epilepsy. Cortical paroxysms were accompanied rhythmic bursts action potentials. Pharmacological blockade excitatory inputs nigrothalamic led transient interruption correlated with change cells, increased frequency converted into sustained arrhythmic firing pattern. Simultaneously, cortical exhibited decrease rate associated an increase membrane polarization input resistance. These new findings demonstrate inhibition SNR changes targets, turn affect excitability and, consequently, generation epileptic discharges. Thus, nigro-thalamo-cortical pathway may on-line system seizures.