The development of independent secondary ("mirror") discharges in the monkey: failure to replicate earlier findings.

Various factors that might influence the development of the independent secondary focus ("mirror" focus) in the monkey were investigated. Not 1 of 29 monkeys developed independent secondary discharges when we varied: area and length of boundary of the primary epileptogenic agent; ease of passage of agent through pia; nature of chemical agent; mechanical manipulation of homotopic cortex; or site of application of primary agent. The possible reasons for the discrepancy between this negative outcome and our earlier success in obtaining independent foci are discussed.