Abstract View
GABA RECEPTORS CONTRIBUTE TO SYNAPTIC INTEGRATION IN LATERAL AMYGDALA NEURONS.
S.Rosis*; L.R.Johnson; J.E.LeDoux
Ctr. for Neural Sci., NYU, New York, NY, USA
In classical fear conditioning a neutral conditioned stimulus (CS) such as a tone, is paired with an aversive unconditioned stimulus (US) such as a shock. The CS thereby acquires the capacity to elicit a fear response. This type of associative learning is thought to require co-activation of principle neurons in the lateral nucleus of the amygdala (LA) by two sets of synaptic inputs, a weak CS and a strong US. The two inputs are believed to be integrated within single LA neurons to produce long-term plasticity at the weak CS input. Whole cell patch clamp recordings were made from LA principle neurons. Thalamic and cortical afferent pathways were stimulated, both of which transmit CS and US information to the LA. Though this approach does not clearly distinguish CS and US fibers in the two pathways, it nevertheless provides a first approximation of synaptic integration that occurs in the LA neurons when CS and US are paired during fear conditioning. We find that LA principle neurons sum thalamic and cortical inputs sub-linearly (n=12, p<0.01). In the presence of picrotoxin (50M), a selective GABAA antagonist, individual LA neurons sum thalamic and cortical inputs supra-linearly (n=12, p<0.01), suggesting that the sub-linearity in the absence of picrotoxin is accounted for by GABAA mediated currents presumably arising from inhibitory interneurons. The supra-linearity in the presence of picrotoxin could not be accounted for by active somatic conductances. These data suggest that LA principal neurons possess voltage-gated conductances within their dendritic arbor. Moreover, these voltage-gated conductances act in concert with GABAA mediated currents to contribute to synaptic integration. Further understanding of how these currents act together to mediate synaptic summation will provide insights into the potential intracellular mechanisms of US and CS integration and plasticity in the lateral amygdala.
Support Contributed By: R37 MH38774, R01 MH46516
Citation:
S. Rosis, L.R. Johnson, J.E. LeDoux. GABAA RECEPTORS CONTRIBUTE TO SYNAPTIC INTEGRATION IN LATERAL AMYGDALA NEURONS. Program No. 623.2. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2003. Online.