Reinforcement Learning Recruits Somata and Apical Dendrites across Layers of Primary Sensory Cortex.

Lacefield CO., Pnevmatikakis EA., Paninski L., Bruno RM.

The mammalian brain can form associations between behaviorally relevant stimuli in an animal's environment. While such learning is thought to primarily involve high-order association cortex, even primary sensory areas receive long-range connections carrying information that could contribute to high-level representations. Here, we imaged layer 1 apical dendrites in the barrel cortex of mice performing a whisker-based operant behavior. In addition to sensory-motor events, calcium signals in apical dendrites of layers 2/3 and 5 neurons and in layer 2/3 somata track the delivery of rewards, both choice related and randomly administered. Reward-related tuft-wide dendritic spikes emerge gradually with training and are task specific. Learning recruits cells whose intrinsic activity coincides with the time of reinforcement. Layer 4 largely lacked reward-related signals, suggesting a source other than the primary thalamus. Our results demonstrate that a sensory cortex can acquire a set of associations outside its immediate sensory modality and linked to salient behavioral events.

DOI

10.1016/j.celrep.2019.01.093

Type

Journal article

Journal

Cell Rep

Publication Date

19/02/2019

Volume

26

Pages

2000 - 2008.e2

Keywords

GCaMP, apical dendrites, barrel cortex, detection, reward, two-photon, vibrissa, voltage-gated calcium, Animals, Calcium Signaling, Dendrites, Female, Male, Mice, Mice, Inbred C57BL, Reinforcement, Psychology, Sensory Receptor Cells, Somatosensory Cortex, Vibrissae

Permalink Original publication