Differential encoding of temporal context and expectation under representational drift across hierarchically...

Area of Science:

• Neuroscience
• Computational Neuroscience

Background:

• The traditional view of sensory cortices encoding only incoming stimuli is challenged by recent findings.
• Behavioral state, movement, and trial history significantly influence neural responses, but the role of context and expectation remains unclear.

Approach:

• Investigated neural responses to expected and unexpected naturalistic visual stimuli in primary visual cortex (V1), posterior medial area (PM), and retrosplenial cortex (RSP) of behaving mice using 2-photon imaging.
• Analyzed how temporal context and expectation modulate neural population activity and its hierarchical organization.

Key Points:

• Image identity encoding decreased along the visual hierarchy (V1 to RSP).
• Temporal context and image identity were conjunctively encoded and modulated by expectations.
• V1 and PM showed enhanced responses to unexpected stimuli (oddballs), signaling expectation violation.
• RSP responses to oddballs mimicked the expected stimulus, suggesting a different predictive coding role.

Conclusions:

• Hierarchically connected visual areas differentially encode temporal context and expectation, aligning with predictive coding.
• Neural responses exhibit rapid representational drift, with RSP drift being stimulus-independent, possibly for internal temporal modeling.