Increased activity without changes in coupling between somata and apical dendrites during visual mismatches

Unexpected reversals in natural movie sequences increase calcium activity in both distal apical dendrites and somata of layer 5 pyramidal neurons in mouse visual cortex.

• Why it matters: Cortical prediction theories require measuring top-down and bottom-up signals during matched versus mismatched sensory inputs, but prior experiments struggled to record them simultaneously across compartments.
• What they did: Using dual-plane 2-photon calcium imaging across four visual cortex regions, mice viewed habituated movie reversals or Gabor orientation sequences; dendritic and somatic responses were compared, and volumetric imaging tested dendrite–soma coupling.
• The result: Natural reversals produced increased activity that declined with repeated exposure, consistent with prediction-error-like responses, while Gabor mismatches showed no clear dendritic or somatic increase and no coupling changes.

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