Reward Expectation Reduces Representational Drift in the Hippocampus

Area of Science:

• Neuroscience
• Cognitive Science
• Memory Research

Background:

• Spatial memory relies on dynamic neural patterns in the hippocampus, known as representational drift.
• Representational drift can impact memory updating and retrieval, with reward expectation potentially influencing this process.

Approach:

• Investigated the hypothesis that diminished reward expectation exacerbates hippocampal representational drift.
• Compared neural representations in the CA1 region under high versus absent reward expectation conditions.
• Analyzed single-cell place-field reliability and reinstatement across days.

Key Points:

• High reward expectation limited representational drift, showing gradual re-emergence of CA1 representations over successive trials.
• Absence of reward expectation led to increased drift, with no significant re-emergence of previous day's representations.
• Lowered reward expectation increased the proportion of unreliable place fields, which were less likely to be reinstated.

Conclusions:

• Heightened reward expectation enhances memory encoding and retrieval.
• Reliable place fields, maintained by reward expectation, are gradually reinstated across days, minimizing representational drift.
• Reward expectation plays a crucial role in stabilizing hippocampal neural representations for robust memory function.