3D reconstruction of a large intercalated (L-ITC) neuron (TJX-31A) recorded in the amygdala of an adult rat in vivo. Reconstruction by Daniela Busti and Ben Micklem.The group of Marco Capogna, in collaboration with other Unit members and with the group of the ex-Unit member Francesco Ferraguti report in the Journal of Neuroscience 35 (5): 2044-2057, 2015 the organisation of a novel GABAergic neuron type of the rodent amygdala, the so-called large intercalated cell (L-ITCc). They identified them with juxtacellular recording/labelling in vivo.
L-ITCs are GABAergic, strongly express metabotropic glutamate receptor 1a, the GABA-A receptor a1 subunit and moderate levels of parvalbumin. Furthermore, L-ITCs are innervated by fibres enriched with metabotropic glutamate receptors 7a and/or 8a. In contrast to small-sized spiny ITCc, L-ITCc possess thick, highly-branched dendrites, and long-range axonal projections innervating interneurons in the basolateral amygdaloid complex. The axons of L-ITCs also project to distant brain areas such as the perirhinal, entorhinal and endopiriform cortices. In vivo recorded L-ITCc are strongly activated by noxious stimuli, such as hindpaw pinches or electrical foot-shocks, consistent with monosynaptic innervation shown from nociceptive intralaminar thalamic nuclei. The authors propose that, during salient sensory stimulation, L-ITCs disinhibit local and distant principal neurons, acting as “hub cells”, to orchestrate the activity of a distributed network.