AMYGDALOID KINDLING IN BRAIN-STEM BISECTED CATS

Results of previous studies suggested that the brainstem participates in amygdaloid (AM) kindled seizure generalization and the positive tra nsfer effect at the secondary site AM. This study was undertaken to de fine the role of the brainstem in the patterning of AM kindling, the m aintenance of AM kindled seizure and the formation of the positive tra nsfer effect (PTE) at the secondary site AM in cats, Seven animals wit h midsagittal bisection of the brainstem were subjected to primary sit e and secondary site AM kindling and primary site retest. All the anim als were kindled at the primary site. However, the following significa nt differences from the pattern seen in intact animals were observed: (1) reversed direction of stage 4 seizure, with circling from the cont ralateral to the ipsilateral, (2) a marked kindled seizure stage insta bility, and (3) frequent abortive termination of the kindled seizure. At the secondary site AM, all the animals showed a complete absence of the positive transfer effect, with two out of seven animals failing t o progress beyond stage 2. A negative transfer or an interference afte r-effect remained preserved at the secondary site kindling and primary site retest. The findings indicate that the bisected midsagittal area in the brainstem plays an important role not only in the patterning a nd maintenance of the kindled seizure but also in the formation of the transhemispheric positive transfer effect in feline AM kindling. (C) 1998 Elsevier Science B.V.