HeterosynapticLong-TermPotentiationofInhibitory InterneuronsintheLateralAmygdala

ElizabethP.BauerandJosephE.LeDoux W.M.KeckFoundationLaboratoryofNeurobiology,CenterforNeuralScience,NewYorkUniversity,NewYork,NewYork10003 Long-termpotentiation(LTP)ofsynaptictransmissioninthelateralamygdala(LA)isbelievedtounderlietheformationandretention offearmemories.Toexploretheroleofinhibitorytransmissioninamygdalaplasticity,werecordedfromLAinhibitoryinterneuronsin vitro before and after tetanization of the thalamo-LA pathway, one of the major inputs to LA involved in fear learning. Tetanization resulted in LTP of the EPSPs elicited in both the tetanized thalamic pathway and the untetanized cortical pathway to LA. This LTP was NMDA-dependent and associated with a decrease in paired-pulse facilitation in both pathways. In LA excitatory cells, LTP of interneurons resulted in an increase in the amplitude of GABAergic IPSPs in both input pathways. Finally, isolated GABAergic IPSPs between inhibitory and excitatory neurons could be potentiated as well. Plasticity of inhibitory transmission within the LA may therefore contributesignificantlytoLA-mediatedfunctions,suchasfearconditioning.