A time memory engram embedded in a light-entrainable circadian clock

Mice demonstrated anticipatory nose-poking behavior in response to food availability, even when their primary circadian pacemaker was disabled.

• Mice exhibited strong anticipatory nose poking prior to mealtime when food was available for only 4 hours at night.
• When food availability was shifted to daytime, mice quickly adapted by expressing daytime anticipatory nose poking without transitional behavior.
• Nighttime anticipatory nose poking persisted in mice even after food was no longer provided during that period.
• Changes in anticipatory behavior aligned with shifts in the light-dark cycle, indicating a potential relationship with light exposure.
• Food anticipatory behavior in mice lacking a functional primary circadian pacemaker suggests an alternative, extra-SCN oscillator may encode meal timing.

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