title: Activity-dependent changes in excitability of perirhinal cortex networks in vitro.
abstract: Rat brain slices comprising the perirhinal cortex (PC) and a portion of the lateral nucleus of the amygdala (LA), in standard medium, can generate synchronous oscillatory activity that is associated with action potential discharge and reflects the activation of glutamatergic and GABAergic receptors. We report here that similar synchronous oscillatory events are recorded in the PC in response to single-shock, electrical stimuli delivered in LA. In addition, we found that the latency of these responses progressively increased when the stimulus interval was varied from 10 to 1 s; for example, the response latency during stimuli delivered at 1 Hz was more than twofold longer than that seen during stimulation at 0.1 Hz. This prolongation in latency occurred after approximately 5 stimuli, attained a steady value after 24-35 stimuli, and recovered to control values 30 s after stimulation arrest. These frequency-dependent changes in latency continued to occur during NMDA receptor antagonism but weakened following application of GABAA and/or GABAB receptor blockers. Our findings identify a new type of short-term plasticity that is mediated by GABA receptor function and may play a role in decreasing neuronal network synchronization during repeated activation. We propose that this frequency-dependent adaptive mechanism influences the excitability of limbic networks, thus potentially controlling epileptiform synchronization.
authors.affiliation: Montreal Neurological Institute, McGill University, 3801 Rue University, Montreal, QC, H3A 2B4, Canada.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Biagini
authors.forename: Margherita
authors.initials: M
authors.lastname: D'Antuono
authors.forename: Yuji
authors.initials: Y
authors.lastname: Inaba
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kano
authors.forename: David
authors.initials: D
authors.lastname: Ragsdale
authors.forename: Massimo
authors.initials: M
authors.lastname: Avoli
mesh_terms: D000200:Action Potentials; D000818:Animals; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D009473:Neuronal Plasticity; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D055366:Synaptic Potentials; D013702:Temporal Lobe / Q000187:drug effects / Q000502:physiology*
chemical_list: D018756:GABA Antagonists