Gamma activity and reactivity in human thalamic local field potentials

Area of Science:

• Neuroscience
• Human Physiology

Background:

• Oscillatory activity around 70 Hz in the basal ganglia is observed in Parkinson's disease patients and linked to movement.
• The physiological role and arousal involvement of this basal ganglia activity remain unclear.

Purpose of the Study:

• To investigate the presence and characteristics of ~70 Hz oscillatory activity in the human thalamus.
• To determine the relationship between thalamic oscillations, movement, arousal, and sleep-wake cycles.
• To explore the link between thalamic and basal ganglia oscillatory activity.

Main Methods:

• Depth recordings of thalamic local field potentials (LFPs) in 29 patients undergoing deep brain stimulation surgery.
• Analysis of oscillatory activity in relation to movement, sleep stages (slow wave sleep, REM sleep), and startle stimuli.
• Simultaneous LFP recordings from thalamus and globus pallidus in 11 patients.

Main Results:

• Sharply tuned ~70 Hz oscillatory activity was identified in the thalamus of 13 patients across various pathologies.
• Thalamic oscillations were modulated by movement and arousal states, suppressed during slow wave sleep and present during REM sleep.
• This ~70 Hz activity was absent in untreated Parkinson's patients and showed coherence with pallidal LFPs.

Conclusions:

• The human thalamus exhibits ~70 Hz oscillatory activity with motor and arousal-related modulation, mirroring basal ganglia findings.
• This subcortical oscillatory activity may play a role in coordinating movement and regulating arousal.
• Findings suggest a potential functional link between thalamic and basal ganglia oscillations at ~70 Hz.