Projection-specific integration of convergent thalamic and retrosplenial signals in the presubicular head direction cortex Authors

Overview & Synopsis

Head-direc on (HD) signals func on as the brain's internal compass. They are organized as an a ractor, and anchor to the environment via visual landmarks. Here we examine how thalamic HD signals and visual landmark informa on from the retrosplenial cortex combine in the presubiculum. We find that monosynap c excitatory connec ons from anterior thalamic nucleus and from retrosplenial cortex converge on single layer 3 pyramidal neurons in the dorsal por on of mouse presubiculum. Independent dual wavelength photos mula on of these inputs in slices leads to ac on poten al genera on preferen ally for near-coincident inputs, indica ng that layer 3 neurons can transmit a visually matched HD signal to medial entorhinal cortex. Layer 4 neurons, which innervate the lateral mammillary nucleus, form a second step in the associa on of HD and landmark signals. They receive li le direct input from thalamic and retrosplenial axons. We show that layer 4 cells are excited di-synap cally, transforming regular spiking ac vity into bursts of ac on poten als, and that their firing is enhanced by cholinergic agonists. Thus, a coherent sense of orienta on involves projec on specific translaminar processing in the presubiculum, where neuromodula on facilitates landmark upda ng of HD signals in the lateral mammillary nucleus.