PT - JOURNAL ARTICLE AU - Csaba Szinyei AU - Thomas Heinbockel AU - Julia Montagne AU - Hans-Christian Pape TI - Putative Cortical and Thalamic Inputs Elicit Convergent Excitation in a Population of GABAergic Interneurons of the Lateral Amygdala AID - 10.1523/JNEUROSCI.20-23-08909.2000 DP - 2000 Dec 01 TA - The Journal of Neuroscience PG - 8909--8915 VI - 20 IP - 23 4099 - http://www.jneurosci.org/content/20/23/8909.short 4100 - http://www.jneurosci.org/content/20/23/8909.full SO - J. Neurosci.2000 Dec 01; 20 AB - Synaptic circuitry in the rat lateral amygdala (AL) was studied in brain slices using electrophysiological recordings. Electrical stimulation of external and internal capsules evoked an EPSC followed by a sequence of GABAA and GABABreceptor-mediated IPSC in principal neurons. Paired stimulation of either afferents resulted in a significant reduction (∼45%) of the second GABAA receptor-mediated IPSC. A priming stimulation, consisting of a priming pulse to one pathway followed by a pulse to the other pathway, resulted in a strong depression of the second IPSC basically identical to that during paired stimulation. Paired- and primed-pulse depressions were largely relieved by 10 μm CGP 55845A, indicating regulation through presynaptic GABAB receptors. Furthermore, putative interneurons responded with EPSCs of constant latencies to minimal stimulation of both cortical and thalamic fibers, indicating convergent monosynaptic input. At higher stimulation strength, an ∼15% reduction of EPSCs occurred in interneurons after paired and primed stimulation, which was not sensitive to CGP 55845A. These findings indicate that a rather homogeneous population of interneurons exists in the AL with respect to their afferent connectivity, in that they receive convergent input through putative thalamic and cortical fibers, both directly and indirectly (through principal neurons), and mediate inhibitory control of postsynaptic principal neurons. This symmetrically built GABAergic circuitry can be of functional significance, given the distinctive role of the two afferent input systems for the mediation of different components of fear responses and the importance of GABAergic mechanisms for limitation of excessive neuronal activity.