Nk. Mahanty et P. Sah, CALCIUM-PERMEABLE AMPA RECEPTORS MEDIATE LONG-TERM POTENTIATION IN INTERNEURONS IN THE AMYGDALA, Nature, 394(6694), 1998, pp. 683-687
Fear conditioning is a paradigm that has been used as a model for emot
ional learning in animals'. The cellular correlate of fear conditionin
g is thought to be associative N-methyl-D-aspartate (NMDA) receptor-de
pendent synaptic plasticity within the amygdala(1-3). Here we show tha
t glutamatergic synaptic transmission to inhibitory interneurons in th
e basolateral amygdala is mediated solely by lpha-amino-3-hydroxy-5-me
thyl-4-isoxazolepropionic acid (AMPA) receptors. In contrast to AMPA r
eceptors at inputs to pyramidal neurons, these receptors have an inwar
dly rectifying current-voltage relationship, indicative of a high perm
eability to calcium(4 5), Tetanic stimulation of inputs to interneuron
s caused an immediate and sustained increase in the efficacy of these
synapses. This potentiation required a rise in postsynaptic calcium, b
ut was independent of NMDA receptor activation. The potentiation of ex
citatory inputs to interneurons was reflected as an increase in the am
plitude of the GABAA-mediated inhibitory synaptic current in pyramidal
neurons. These results demonstrate that excitatory synapses onto inte
rneurons within a fear conditioning circuit show NMDA-receptor indepen
dent long-term potentiation. This plasticity might underlie the increa
sed synchronization of activity between neurons in the basolateral amy
gdala after fear conditioning(6).