| GABA RECEPTORS CONTRIBUTE TO SYNAPTIC INTEGRATION IN LATERAL AMYGDALA NEURONS. | |
| S.Rosis*; L.R.Johnson; J.E.LeDoux | |
|
|
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 (50 M), 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. |
|
 |
|