Synaptic Organization of the Cerebral Cortex and its Role in Epilepsy

Abstract

This chapter discusses synaptic organization of the cerebral cortex and its role in epilepsy. A lack of synaptic inhibition is not sufficient to produce epileptic activity in the cortex. However, disinhibition can play an important role in epilepsy, as it can unmask abnormal excitatory phenomena and lower the threshold for elicitation of self-sustained seizures. Inhibition can also play a role in the prevention of the spread of focal epileptic activity to neighboring areas. The synaptic design of the cerebral cortex shows two characteristic features, namely, recurrent inhibition and excitation. Recurrent inhibition is a feature common to practically all subsystems of the central nervous system, whereas recurrent excitation is unique to the cortex. The specifically cortical organizational principle is relevant for the capability of the cortex to develop self-sustained epileptic activity. Any disturbance on the excitatory side can lead to cortical seizure activity, as the cortex is especially sensitive to hyperexcitation because of the excitatory connections between its neurons.