HIGH-FREQUENCY STIMULATION OF THE BASOLATERAL AMYGDALA FACILITATES THE INDUCTION OF LONG-TERM POTENTIATION IN THE DENTATE GYRUS IN-VIVO

We investigated the effect of high-frequency stimulation of the basola teral amygdala (BLA) on the induction of long-term potentiation (LTP) in the medial perforant path (PP)-dentate gyrus (DG) synapses of anest hetized rats. A conditioning stimulation (100 pulses at 100 Hz) of the ipsilateral BLA did not change the DG synaptic potential. However, wh en the BLA conditioning stimulation was applied at the same time as a weak tetanic stimulation of PP (20 pulses at 20 Hz) which alone did no t induce LTP, robust DG LTP was induced. Simultaneous application of c ontralateral BLA stimulation and PP weak tetanus did not induce LTP. M oreover, the ipsilateral BLA stimulation enhanced the magnitude of LTP induced by a moderate tetanic stimulation of PP (30 pulses at 60 Hz), but did not further enhance the LTP induced by a strong tetanic stimu lation of PP (100 pulses at 100 Hz). These results suggest that the ip silateral BLA neurons modulate the induction of DG LTP in vivo.