Interhemispheric transfer of extinction of the passive avoidance reaction in rats.

Abstract

Interhemispheric transfer of forced extinctions of passive avoidance reactions (PAR) was studied in rats using unilateral functional decortication by cortical spreading depression (CSD). In Experiment 1, bilaterally acquired PAR extinguished during left CSD was significantly reduced during retention tests performed with right CSD. In Experiment 2, PAR was elaborated during left CSD and extinguished during right CSD; retention tests during left CSD revealed significant transfer of PAR extinction. In Experiment 3, no extinction appeared during retention tests with brains intact of bilaterally established PAR extinguished during bilateral CSD. Nonlateralized subcortical storage of PAR memory traces participating is postulated. These traces are involved and seem to be accessible through the intact cerebral cortex only, both in acquisition and extinction.