A method to study global spatial patterns related to sensory perception in scalp EEG

Abstract

a b s t r a c tPrior studies of multichannel ECoG from animals showed that beta and gamma oscillations carried perceptual information in both local and global spatial patterns of amplitude modulation, when the subjects were trained to discriminate conditioned stimuli (CS). Here the hypothesis was tested that similar patterns could be found in the scalp EEG human subjects trained to discriminate simultaneous visual-auditory CS. Signals were continuously recorded from 64 equispaced scalp electrodes and band-pass filtered. The Hilbert transform gave the analytic phase, which segmented the EEG into temporal frames, and the analytic amplitude, which expressed the pattern in each frame as a feature vector. Methods applied to the ECoG were adapted to the EEG for systematic search of the beta-gamma spectrum, the time period after CS onset, and the scalp surface to locate patterns that could be classified with respect to type of CS. Spatial patterns of EEG amplitude modulation were found from all subjects that could be classified with respect to stimulus combination type significantly above chance levels. The patterns were found in the beta range (15-22 Hz) but not in the gamma range. They occurred in three short bursts following CS onset. They were non-local, occupying the entire array. Our results suggest that the scalp EEG can yield information about the timing of episodically synchronized brain activity in higher cognitive function, so that future studies in brain-computer interfacing can be better focused. Our methods may be most valuable for analyzing data from dense arrays with very high spatial and temporal sampling rates.

Spatial patterning of the neonatal EEG suggests a need for a high number of electrodes

“…Capturing these with novel dense array EEG devices, akin to what has been recently achieved with adult EEG (Brockmeier et al, 2012;Panagiotides et al, 2010;Ruiz et al, 2010), may open a novel window to capturing the details of emerging large scale brain processes, such as those related to perception and cognition (Bressler and Menon, 2010).…”

Locating spatial patterns of waveforms during sensory perception in scalp EEG

“…In [2], the authors characterized frames at specific frequency bands and proposed criteria for identifying them. The authors studied the 'frames' as global spatial patterns related to sensory perception and showed these patterns can be used to discriminate simultaneous visual-auditory stimuli [2].…”

“…The procedure in [2] for identifying frames consists of linear filtering followed by a series of acceptance criteria. After narrowband filtering the EEG at predefined frequencies, the Hilbert transform is used to estimate the analytic phase and amplitude of the filtered signal.…”

Reflections on a giant of brain science

“…His original work had focus on olfaction (Viana Di Prisco and Freeman 1985;Skarda and Freeman 1987), which in the past decades has been extended to other senses, including visual, auditory, and somatosensory cortices, as well as multisensory Gestalts (Kay and Freeman 1998;Ohl et al 2001). In recent years, many of these results are validated in noninvasive EEG measurements, as well (Pockett et al 2009;Ruiz et al 2010). 2.…”

“…Intensive work has been conducted to describe dynamic transitions in cognitive processing as part of the action-perception. Recent scalp EEG studies evidence that AM and PM patterns are also observable by non-intrusive experimental techniques (Pockett et al 2009;Ruiz et al 2010).…”