Adaptive Value Normalization in the Prefrontal Cortex Is Reduced by Memory Load.

Area of Science:

• Neuroscience
• Cognitive Science
• Decision Making

Background:

• Neural adaptation is crucial for representing diverse inputs, including reward values.
• Adaptive value coding often relies on contextual information from the environment or memory.
• The impact of memory retrieval and maintenance on value adaptation remains unclear.

Purpose of the Study:

• To investigate whether working memory load modulates the prefrontal cortex's (PFC) capacity for value adaptation.
• To examine how remembering versus visually presented risk context affects neural value coding.
• To identify the neural mechanisms underlying value adaptation under different memory demands.

Main Methods:

• Measured hemodynamic responses in the prefrontal cortex (PFC) during risky decision-making tasks.
• Manipulated working memory load by having participants either remember or visually view risky alternatives.
• Employed a second study with a secondary working memory task to confirm findings.
• Utilized formal model comparison, including divisive normalization, to analyze PFC activity.

Main Results:

• PFC responses adapted to contextual risk information, showing steeper coding of safe alternative value in lower-risk contexts.
• Value adaptation in the PFC was significantly reduced under higher working memory load (remembering risk vs. visual presentation).
• Increased memory maintenance demands impaired normalization of neural value representations, linked to reduced suppression of background activity.

Conclusions:

• Mnemonic processes, specifically working memory load, can constrain the normalization of neural value representations in the PFC.
• The way contextual information is accessed (memory retrieval vs. direct perception) critically influences value adaptation.
• Findings highlight the interplay between memory systems and value representation in decision-making.