Anterior Thalamic Excitation and Feedforward Inhibition of Presubicular Neurons Projecting to Medial Entorhinal Cortex

Mérie Nassar (1) , Jean Simonnet (2) , Li-Wen Huang , Bertrand Mathon (3) , Ivan Cohen (4, 5) , Michael H K Bendels , Mathieu Beraneck (1) , Michael H.K. Bendels , Richard Miles (2) , Desdemona Fricker (1)

1 UMR 8119 - Centre de neurophysique, physiologie, pathologie
2 ICM - Institut du Cerveau et de la Moëlle Epinière = Brain and Spine Institute
3 UPMC - Université Pierre et Marie Curie - Paris 6
4 NPS-03 - Réseau cortical et couplage neurovasculaire = Cortical Network and Neurovascular
5 NPS - Neuroscience Paris Seine

The presubiculum contains head direction cells that are crucial for spatial orientation. Here, we examined the connectivity and strengths of thalamic inputs to presubicular layer 3 neurons projecting to the medial entorhinal cortex in the mouse. We recorded pairs of projection neurons and interneurons while optogenetically stimulating afferent fibers from the anterior thalamic nuclei (ATN). Thalamic input differentially affects presubicular neurons: layer 3 pyramidal neurons and fast-spiking parvalbumin expressing (PV) interneurons are directly and monosynaptically activated, with depressing dynamics, while somatostatin (SST) expressing interneurons are indirectly excited, during repetitive ATN activity. This arrangement ensures that the thalamic excitation of layer 3 cells is often followed by disynaptic inhibition. Feed-forward inhibition is largely mediated by PV interneurons which have a high probability of connection to presubicular pyramidal cells, and it may enforce temporally precise head direction tuning during head turns. Our data point to the potential contribution of presubicular microcircuits for fine-tuning thalamic head direction signals transmitted to medial entorhinal cortex.

Domains: Neurons and Cognition [q-bio.NC]; Neurobiology

Mérie Nassar, Jean Simonnet, Li-Wen Huang, Bertrand Mathon, Ivan Cohen, et al.. Anterior Thalamic Excitation and Feedforward Inhibition of Presubicular Neurons Projecting to Medial Entorhinal Cortex. Journal of Neuroscience, 2018, 38 (28), pp.6411-6425. ⟨10.1523/JNEUROSCI.0014-18.2018⟩. ⟨hal-02110910⟩