Oscillations in the premotor cortex: single-unit activity from awake, behaving monkeys

Area of Science:

• Neuroscience
• Motor Control
• Neural Oscillations

Background:

• The dorsal premotor cortex (PMd) plays a crucial role in motor planning and execution.
• Understanding the neural dynamics within the PMd is essential for deciphering how movement intentions are encoded.

Purpose of the Study:

• To investigate the presence and characteristics of fast neuronal oscillations in the dorsal premotor cortex.
• To determine if these oscillations are directionally selective and reflect specific aspects of intended actions.

Main Methods:

• Recorded single-unit activity from the dorsal premotor cortex of four rhesus monkeys performing a directional forelimb movement task.
• Analyzed neuronal activity using autocorrelation histograms (ACHs) and joint interspike-interval (ISI) plots to identify oscillations.
• Investigated oscillation properties during a delay period preceding movement execution.

Main Results:

• 13% of recorded units (78/579) exhibited periodic peaks in ACHs, with mean oscillation frequency around 27 Hz.
• An additional 5% of units (26/579) showed oscillatory features in joint ISI plots.
• Oscillations were found to be directionally selective in 60% of delay-period oscillators (37/61), suggesting a link to specific movement intentions.

Conclusions:

• Fast neuronal oscillations are present in the dorsal premotor cortex and are likely entrained by extrinsic rhythmic drive.
• Directional selectivity of these oscillations indicates they encode specific aspects of intended actions, contributing to motor control.