Changes in brain rhythms and connectivity tracking fear acquisition and reversal

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Computational Neuroscience

Background:

• Fear conditioning is a key model for studying threat, anxiety, and their environmental modifications.
• Understanding the neural dynamics of fear acquisition and reversal is crucial for anxiety disorder research.

Purpose of the Study:

• To investigate the temporal evolution of brain rhythms (theta, alpha, gamma) during fear conditioning and reversal.
• To analyze power changes and Granger connectivity in electroencephalographic (EEG) signals.

Main Methods:

• Recorded EEG signals from healthy volunteers during Pavlovian fear conditioning and reversal.
• Reconstructed neuroelectrical activity on the cortex to analyze power and connectivity in theta, alpha, and gamma bands.

Main Results:

• Significant increase in theta power in the left midcingulate cortex during fear acquisition, present from initial trials.
• Significant decrease in alpha power across a left posterior-frontal and parietal network, developing over trials.
• Changes in theta and alpha power persisted during reversal, though less pronounced.
• Increased functional connectivity in theta and alpha bands observed, particularly during late reversal.
• No significant changes detected in the gamma band.

Conclusions:

• Increased theta rhythm in the cingulate cortex supports fear acquisition and fast cortical synchronization.
• Decreased alpha power may indicate partial activation of motor/somatosensory areas contralateral to the shock.
• Late reversal connectivity changes suggest long-term synaptic alterations for contingency reversal.