A Preparatory Cranial Potential for Saccadic Eye Movements in Macaque Monkeys

Area of Science:

• Neuroscience
• Cognitive Science
• Primate Research

Background:

• Voluntary movement preparation involves accumulating neural activity.
• The lateralized readiness potential (LRP) is a human EEG signal preceding manual movements.
• Preparatory EEG potentials for saccadic eye movements are less understood in humans and nonhuman primates.

Purpose of the Study:

• To describe a lateralized readiness potential (LRP) over the frontolateral cortex in macaque monkeys.
• To investigate noninvasive electrophysiological signatures of saccadic eye movement preparation in nonhuman primates.
• To compare preparatory EEG signals with neural spiking activity in the frontal eye field (FEF).

Main Methods:

• Electroencephalography (EEG) recordings in macaque monkeys.
• Observation of lateralized electrical potentials ramping before saccade execution.
• Comparison of EEG polarization with neural spiking in the frontal eye field (FEF).

Main Results:

• A homologous LRP was observed over the frontolateral cortex in macaque monkeys.
• Lateralized potentials ramped before both rewarded and nonrewarded contralateral saccades.
• Frontolateral polarization did not differentiate between saccade generation and inhibition, unlike FEF neural spiking.

Conclusions:

• The study describes a noninvasive electrophysiological signature of saccadic preparation in nonhuman primates.
• The findings suggest EEG measures can bridge invasive neural recordings and noninvasive human studies of eye movement control.
• The observed LRP may serve as a noninvasive correlate of intracortical spiking activity in saccadic control circuits.