Steep early negative slopes can be demonstrated in pre-movement bereitschaftspotential

Area of Science:

• Neuroscience
• Motor Control
• Electrophysiology

Background:

• The readiness potential (RP) is a well-known electroencephalogram (EEG) signal preceding voluntary movement.
• Traditional analysis of RP using classical averaging may obscure underlying neural processes.
• The early component of the RP (BP1) has been investigated for its precise timing and neural correlates.

Purpose of the Study:

• To investigate the nature of the early component (BP1) of the readiness potential.
• To determine if early negative shifts in EEG precede movement at varying intervals.
• To explore the impact of different averaging techniques on RP waveform interpretation.

Main Methods:

• Surface EEG and EMG were recorded from 12 volunteers during self-paced wrist flexions.
• Two hundred trials per subject were collected and analyzed.
• Single trials were averaged individually and also grouped by the timing of early negative shifts for time-group averaging.

Main Results:

• Early steep negative shifts preceding movement were identified in 97.2% of trials, with variable timing across subjects.
• Individual averages showed classical RP characteristics, while time-group averages revealed an early steep negative shift followed by a plateau and a later steep shift.
• Electrode position significantly affected both early and late slopes, with the Cz electrode showing the largest values; early slopes lacked laterality, suggesting pre-frontal involvement.

Conclusions:

• The formation of early negative shifts in time-group averages likely results from the synchronization of a mental process.
• This synchronization, when dispersed uniformly in classical averaging, appears as a slow early component.
• The findings suggest a more dynamic and temporally specific neural process underlying movement preparation than previously assumed.