Electrophysiological correlates of movement initiation

Area of Science:

• Neuroscience
• Motor Control
• Electrophysiology

Background:

• Movement-related potentials, such as the readiness potential (BP), are recorded using electroencephalogram (EEG) or magnetoencephalogram (MEG).
• The BP precedes self-initiated movements by over one second and has two main components: an early symmetric one and a late asymmetric one.

Purpose of the Study:

• To identify the cortical generators of the early and late components of the readiness potential (BP).
• To elucidate the roles of the supplementary motor area (SMA) and primary motor cortex (MI) in movement preparation and execution.

Main Methods:

• Averaging EEG/MEG signals time-locked to self-initiated volitional acts.
• Analysis of regional cerebral blood flow (rCBF) studies to confirm generator localization.

Main Results:

• The early BP component is generated by the supplementary motor area (SMA).
• The late, asymmetric BP component is generated by the primary motor cortex (MI).
• The SMA appears crucial for movement timing and initiation, especially in complex motor sequences.

Conclusions:

• The SMA and MI play distinct roles in the preparation and execution of voluntary movements.
• The early BP component reflects motivational or timing aspects, while the late component relates to motor cortex synaptic facilitation.
• Further research is needed to fully understand the SMA's role in motor learning and control.