Dorsal hippocampal kindling produces long-lasting changes in the origin of spontaneous discharges in the piriform versus perirhinal cortex in vitro.
In an in vitro slice preparation of the amygdala-piriform-perirhinal cortex (A-P area), it was shown previously (McIntyre, D.C., Plant, J. R., 1993. Long-lasting changes in the origin of spontaneous discharges from amygdala-kindled rats: piriform vs. perirhinal cortex in vitro, Brain Res. 624, 268-276) that the infrequent spontaneous field potentials that initially originated in or near the perirhinal (PRh) cortex of slices from control rats began instead in the piriform (Pir) cortex of amygdala-kindled rats. This change in onset was only observed in the A-P area ipsilateral to the kindled amygdala. In the present experiment, we determined whether similar changes in activity were evident following kindling from a different limbic site, the dorsal hippocampus (DH). Kindling of the DH resulted in changes in the origin of the spontaneous discharges in the A-P area similar to amygdala kindling but, importantly, the changes involved both hemispheres. In addition, the origin of spontaneous discharges in slices from partial kindled rats (those that received as many hippocampal afterdischarges as the fully kindled rats but had not developed generalized convulsive responses) initially were similar to control tissue, but, during 0 Mg(2+) perfusion, changed more quickly than control tissue to mimic the profile of generalized kindled rats. The enduring changes in A-P area excitability caused by previous generalized kindling highlights the importance of the A-P area in convulsive generalization of limbic-kindled seizures.
McIntyre
D C
DC
Department of Psychology, Institute of Neuroscience, Life Science Research Building Carleton University, Ottawa, Canada. dmcintyr@ccs.carleton.ca
Plant
J R
JR
Kelly
M E
ME
D000818:Animals; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D007696:Kindling, Neurologic / Q000502:physiology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D010477:Perfusion; D051381:Rats; D020318:Rats, Long-Evans
D008274:Magnesium