Integrative Center for Learning and Memory (ICLM) Journal Club – Peyman Golshani, M.D., Ph.D.

May 12, 2023

9:30am – 10:30am


Gonda 1357

Cortico-cortical Feedback Engages Active Dendrites in Visual Cortex
Nature, 2023

Peyman Golshani, M.D., Ph.D.
Department of Neurology
David Geffen School of Medicine at UCLA

Gonda Research Center 1357

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Abstract: Sensory processing in the neocortex requires both feedforward and feedback information flow between cortical areas.In feedback processing, higher-level representations provide contextual information to lower levels, and facilitate perceptual functions such as contour integration and figure?ground segmentation. However, we have limitedunderstanding of the circuit and cellular mechanisms that mediate feedbackinfluence. Here we use long-range all-optical connectivity mapping in miceto show that feedback influence from the lateromedial higher visual area (LM) to the primary visual cortex (V1) is spatially organized. When the source and target of feedback represent the same area of visual space, feedback is relatively suppressive. By contrast, when the source is offset from the target in visual space, feedback is relatively facilitating. Two-photoncalcium imaging data show that this facilitating feedback is nonlinearly integrated in the apical tuft dendrites of V1 pyramidal neurons: retinotopically offset (surround) visual stimuli drive local dendritic calcium signalsindicative of regenerative events, and two-photon optogenetic activation of LM neurons projecting to identified feedback-recipient spines in V1 can drive similar branch-specific local calcium signals. Our results show how neocortical feedback connectivity and nonlinear dendritic integration can together form a substrate to support both predictive and cooperative contextual interactions.