Neural signature of flexible coding in prefrontal cortex

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• Working memory relies on the prefrontal cortex's ability to form novel associations.
• Fast Hebbian synaptic plasticity is key for new associations, but its neuronal basis is unclear.

Purpose of the Study:

• To investigate rapid, history-dependent changes in neural population codes within the prefrontal cortex.
• To identify neuronal signatures of synaptic plasticity during the reassociation of stimulus features in working memory.

Main Methods:

• Developed a trialwise index of neural pattern similarity to detect rapid code changes.
• Utilized a computational model to hypothesize conditions for synaptic strength alteration.
• Recorded neural responses in the prefrontal cortex during a task requiring feature reassociation.

Main Results:

• Neural response similarity decreased after feature reassociation, specifically in the prefrontal cortex.
• These history-dependent changes occurred independently of traditional neuronal selectivity.
• Findings were not attributable to prior trial firing or neural adaptation.

Conclusions:

• The prefrontal cortex exhibits dynamic neural coding that adapts to changing associative demands.
• Synaptic plasticity underlies rapid updates in neuronal tuning, enabling flexible working memory.
• This study provides direct evidence for rapid, experience-dependent plasticity in prefrontal cortex circuits.