Piriform cortex is an ictogenic trigger zone in the primate brain.

objectiveArea tempestas, a functionally defined region in the anterior piriform cortex, was identified as a crucial ictogenic trigger zone in the rat brain in the 1980s. However, whether the primate piriform cortex can trigger seizures remains unknown. Here, in a nonhuman primate model, we aimed to localize a similar trigger zone in the piriform cortex and, subsequently, evaluated the ability of focal inhibition of the substantia nigra pars reticulata (SNpr) to suppress the evoked seizures.

methodsFocal microinjection of the γ-aminobutyric acid type A (GABA

resultsWe documented a well-defined region highly susceptible to bicuculline-induced seizures in the piriform cortex, just posterior to the junction of the frontal and temporal lobes, indicating that a functional homolog to the rodent area tempestas is present in the primate brain. Focal infusion of glutamate receptor antagonists into the area tempestas revealed that α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated, but not N-methyl-D-aspartate-mediated, neurotransmission was necessary for the expression of seizures. Pharmacological inhibition of the SNpr robustly suppressed area tempestas-evoked seizures. SIGNIFICANCE: Together, these data point to the area tempestas as a potent ictogenic zone in the primate brain and underscore the antiseizure effects of inhibition of the SNpr. Building on decades of studies in rodents, our present findings emphasize the relevance of these targets to the primate brain and provide further rationale for exploring these targets for clinical use.