Quantitative Signal Characteristics of Electrocorticography and Stereoelectroencephalography: The Effect of Contact Depth

Abstract

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White Matter Signals Reflect Information Transmission Between Brain Regions During Seizures

“…A higher depth means the contact is deeply embedded within WM and has little surrounding GM tissue) 5,6 . Alternative definitions have shown similar results when comparing GM and WM signals in previous studies 6 , however, we still provide complimentary analyses using both definitions here. We found that both distance from GM ( p < 5 x 10 −10 ) and WM depth ( p < 0.05) are still significantly related to FC (Fig.…”

“…The focus, instead, has been on the analysis of gray matter functional activity as it relates to neurobiology and disease, because the signals can be orders of magnitude larger (Fig. 1b-c) 4–6 , and gray matter is predominantly thought to be where neural computation takes place. Excitingly, some research groups have shown the existence of neuronal cell bodies in deeper white matter tissue 10 , the release of neurotransmitter vesicles in white matter 11 , and the existence of detectable white matter blood-oxygenation level dependent (BOLD) signals across a range of different tasks 12 .…”

“…While epileptologist routinely use bipolar montage in EEG interpretation, the research community does not. A few studies 5,6 noted differences in EEG features like power, phase-amplitude coupling, and functional connectivity measurements between the different montages. Makin et al 2020 57 emphasize that if the electrodes are common average referenced, it can “smear the effects of some electrodes across the grid”.…”

“…Indeed, analyses on interictal recordings of select EEG features have shown differences in white matter (Fig. 1c) 2,4–6 . Any differences in amplitude, frequency, or timing of activity can be problematic for localizing the SOZ, which is a vital step in achieving eventual seizure freedom in medically refractory epilepsy patients 14 .…”

Patterns of Focal- and Large-Scale Synchronization in Cognitive Control and Inhibition: A Review

“…Intracranial stereoelectroencephalography (SEEG) and electrocorticography (ECoG) are invasive electrophysiological recordings of brain activity (Young et al, 2019 ). Although only applied to clinical populations, the direct recording from the brain tissue allows a relatively superior geographical resolution.…”