Do scalp-recorded slow potentials during neuro-feedback training reflect the cortical activity?
OBJECTIVE
Neuro-feedback (NFB) training by the self-regulation of slow potentials (SPs) <0.5 Hz recorded from the vertex scalp has been applied for seizure suppression in patients with epilepsy. However, SP is highly susceptible to artifact contamination, such as the galvanic skin response (GSR). This study aimed to evaluate the correlation between SPs recorded from the scalp and intracranial electroencephalography (EEG) by event-related coherence analysis.


METHODS
The scalp and subdural SPs were simultaneously recorded during NFB training by the DC-EEG machine while undergoing invasive recordings before epilepsy surgery in 10 patients with refractory partial epilepsy. The SPs at the vertex electrode were used as a reference for coherence analysis.


RESULTS
The coherence of SPs negatively correlated with the distance between the subdural and scalp electrodes. A significant negative correlation was noted between the linear subdural-scalp electrode distance and the coherence value (r =  - 0.916, p < 0.001).


CONCLUSION
Scalp-recorded SPs from the vertex area primarily reflect the cortical activity of high lateral convexity.


SIGNIFICANCE
Our results strongly suggest that SPs in NFB recorded from the vertex scalp electrode is derived from the cortices of high lateral convexity but not from the artifacts, such as GSR.
['Fumuro|Tomoyuki|T|', 'Matsuhashi|Masao|M|', 'Matsumoto|Riki|R|', 'Usami|Kiyohide|K|', 'Shimotake|Akihiro|A|', 'Kunieda|Takeharu|T|', 'Kikuchi|Takayuki|T|', 'Yoshida|Kazumichi|K|', 'Takahashi|Ryosuke|R|', 'Miyamoto|Susumu|S|', 'Ikeda|Akio|A|']
D000328:Adult D002540:Cerebral Cortex D004569:Electroencephalography D004828:Epilepsies, Partial D005071:Evoked Potentials D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D058765:Neurofeedback D012535:Scalp D055815:Young Adult
Neuro-feedback (NFB) Slow potential (SP) Electroencephalography (EEG) Coherence Electrocorticogram (ECoG) Slow cortical potential (SCP)