Observations on the "dependent stage" of the "mirror focus"

The present communication was part of a larger study in which penicillin induced epileptogenic activity in the hippocampus of the "cerveau isolé cat" was investigated. The discharge contralateral to the side of the PCN focus, i.e., the mirror focus, was dependent upon the integrity of the commissural pathways. Interhippocampal latencies of bisynchronous epileptogenic discharge varied between 0 and 50 msec (mean 20). Interestingly the discharges could occur absolutely simultaneously and even more surprising, the mirror focus discharge occasionally led that in the primary focus! An interpretation as to how this might occur is given.