LTP in the rat basal amygdala induced by perirhinal cortex stimulation in vivo

The present study examined the effects of ventral perirhinal cortex (vPRC) stimulation on evoked field potentials (EPs) in the basal amygdala (BN), using extracellular recording techniques. Single pulse stimulation of the vPRC reliably evoked a negative field potential in the BN that was missing in the lateral nucleus. Paired-pulses delivered to the vPRC induced a short-lasting facilitation at intervals between 15 and 120 ms. Application of brief theta burst stimulation to the vPRC produced an enduring long-term potentiation (LTP) that reached 150% of control values. The induction of LTP was not accompanied by a decrease in paired-pulse facilitation. These results suggest that emotional learning involving complex stimulus representations may be mediated by cortico-amygdalar projections amenable to LTP. (C) 2000 Lippincott Williams and Wilkins.