The thalamocortical circuit and the generation of epileptic spikes in rat models of focal epilepsy.

We investigate thalamocortical interactions in the tetanus toxin and the cortical stimulation rat models of epilepsy. Using local field potential recordings from the cortex and the thalamus of the rat, the nonlinear regression index is calculated to create the direction index in order to study neurodynamics during seizures. Coarse time-scale analysis reveals that the cortex drives the thalamus for the majority of the time during seizures. However, fine time-scale analysis provides evidence that epileptic spikes are driven from the thalamus. This new result has implications for understanding, diagnosing and using electrical stimulation to treat epileptic seizures.