GABAergic interneurons in the basolateral complex (BLC) of the amygdala are a part of the emotional-learning circuitry of the brain and receive excitatory inputs from all sensory modalities via cortex and thalamus. Although the BLC, which is made up of the lateral amygdala (LA), basal amygdala (BA) and accessory basal nucleus, is under the influence of a strong inhibition brought about by local interneurons, little is known about the diversity, characteristics and functioning of these interneurons. In this study, I have characterised the BLC interneuron population using a transgenic mouse model in which enhanced green fluorescent protein has been tagged to the GAD67 promoter. This promoter is specifically expressed in all GABAergic interneurons, enabling us to visualise interneurons under UV light. Whole-cell recordings were made from GAD67 interneurons in the BLA to study their membrane and synaptic properties. On the basis of their firing properties, interneurons in the BLC were classified into six distinct groups. The calcium-binding proteins calbindin, calretinin and parvalbumin were found to be expressed differently in the LA and BA interneurons, with the majority of the interneurons in the LA expressing calretinin, whereas those in the BA mostly expressed parvalbumin. We also found diversity in the expression of postsynaptic glutamate receptors in the BLC. Long-term potentiation induced at the interneurons was specific to the cortical inputs in the LA. LTP was expressed only in interneurons that either lacked NMDA receptors or had NMDA receptors with fast decay kinetics. This form of LTP was mediated by calcium-permeable AMPA receptors and required a postsynaptic calcium rise for its induction This study shows that the interneurons in the BLC are a heterogenous population with respect to the expression of calcium-binding proteins, axonal morphology, synaptic and membrane properties. This heterogeneity in interneuron population may be essential for the specialised roles various types of interneurons play in the functioning of the amygdala and in emotional learning.
| Identifer | oai:union.ndltd.org:ADTP/254035 |
| Creators | Jai Polepalli |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
Page generated in 0.0018 seconds