Do scalp-recorded slow potentials during neuro-feedback training reflect the cortical activity?

Area of Science:

• Neuroscience
• Epilepsy Research
• Biomedical Engineering

Background:

• Neurofeedback (NFB) training utilizes self-regulation of slow potentials (SPs) for epilepsy seizure suppression.
• Scalp-recorded SPs are susceptible to artifacts, such as galvanic skin response (GSR), potentially compromising NFB efficacy.

Purpose of the Study:

• To evaluate the correlation between scalp-recorded SPs and intracranial EEG.
• To determine the origin of SPs used in NFB for epilepsy treatment.

Main Methods:

• Simultaneous scalp and subdural SP recordings during NFB in 10 epilepsy patients.
• DC-EEG machine used for NFB training during invasive recordings.
• Event-related coherence analysis applied to vertex electrode SPs.

Main Results:

• A significant negative correlation (r = -0.916, p < 0.001) between electrode distance and SP coherence was observed.
• Coherence of SPs decreased with increasing distance between subdural and scalp electrodes.

Conclusions:

• Scalp-recorded SPs from the vertex primarily reflect cortical activity from high lateral convexity.
• Findings suggest NFB SPs originate from cortical sources, not artifacts like GSR.