Experimental Assessment of Epileptogenesis in the Monkey Cerebral Cortex

Evidence is accumulating which indicates that the capacity of cortical neurons to exhibit seizure discharge is related directly to distorted function of cellular structures mediating the direct cortical response.⁷,⁸Current proposals hold that such distortion of function involves primarily the cortical dendrites.⁷,⁸,¹⁷Direct cortical responses (DCR) evoked by a brief single stimulus applied to any cortical locus in the immediate vicinity of the recording electrodes³are found to be of greatest amplitude in those areas which are most easily caused to discharge by repetitive electrical excitation and are poorly developed in loci which are resistant to after-discharge.⁷Additionally, test conditions, such as light sleep or the administration of pentylenetetrazol (Metrazol), which enhance seizure susceptibility in the cortex cause an increase in the amplitude of the DCR, while other induced states, such as deep sedation, known to depress seizure activity result in a diminution or disappearance of