Motivation-dependent communication between cortex and brainstem

Medullary motor neurons show a phase-based population code for lick direction, and cortico-medullary coupling is stronger during appetitive licks than consummatory licks in mice.

• Why it matters: It is unclear how distinct action codes in the brainstem are specified and how cortex reshapes them across motivational states like hunger versus satiety.
• What they did: Mice performed appetitive pre-reward licks and consummatory post-reward licks with different satiety attenuation; simultaneous recordings from secondary motor cortex and motor medulla assessed time-locking and lick-direction coding.
• The result: Cortex–medulla correlations were stronger during appetitive licks, and optogenetic perturbation plus multi-region recurrent network models support causal cortico-medullary dependency on motivational context.

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