How Many Electrodes Are Really Needed for EEG-Based Mobile Brain Imaging?

Abstract

A noninvasive method for imaging the human brain during mobile activities could have far reaching benefits for studies of human motor control, for research and treatment of neurological disabilities, and for brain-controlled powered prosthetic limbs or orthoses. Several recent studies have demonstrated that electroencephalography (EEG) can be used to image the brain during locomotion provided that signal processing techniques, such as independent Component Analysis (ICA), are used to parse electrocortical activity from artifact contaminated EEG. However, these studies used high-density 256-channel EEG sensor arrays, which are likely too time-consuming to setup in a clinical or field setting. Therefore, it is important to evaluate how reducing the number of EEG channel signals affects the electrocortical source signals that can be parsed from EEG recorded during standing and walking while concurrently performing a visual oddball discrimination task. Specifically, we computed temporal and spatial correlations between electrocortical sources parsed from high-density EEG and electrocortical sources parsed from reduced-channel subsets of the original high-density EEG. For this task, our results indicate that on average an EEG montage with as few as 35 channels may be sufficient to record the two most dominate electrocortical sources (temporal and spatial R2 > 0.9). Correlations for additional electrocortical sources decreased linearly such that the least dominant sources extracted from the 35 channel dataset had temporal and spatial correlations of approximately 0.7. This suggests that for certain applications the number of EEG sensors used for mobile brain imaging could be vastly reduced, but researchers and clinicians must consider the expected distribution of relevant electrocortical sources when determining the number of EEG sensors necessary for a particular application.

Electroencephalographic evidence for improved visual working memory performance during standing and exercise

“…Fortunately, advancements in signal processing techniques and hardware now render exercise‐concurrent EEG viable (see Nathan & Contreras‐Vidal, ; Reis, Hebenstreit, Gabsteiger, von Tscharner, & Lochmann, ). For example, independent component analysis (ICA) can effectively extract not only blinks and saccades, but also motion artefacts (such as rhythmic body movements) from otherwise unusable cortical signals (Gwin et al ., ; Lau, Gwin, & Ferris, ). Mobile brain‐imaging (MoBi) EEG systems have also been shown to produce typical ERP components between seated rest and during self‐generated full‐body motion such as walking (De Sanctis Butler, Green, Snyder, & Foxe, 2012; Gramann, Gwin, Bigdely‐Shamlo, Ferris, & Makeig, ).…”

Effect of the Neurofeedback-EEG Training During Physical Exercise on the Range of Mental Work Performance and Individual Physiological Parameters in Swimmers

“…It is generally accepted (Gramann et al 2010;Gwin et al 2011;Lau et al 2012) that humans use multiple strategies for locomotion and motor control and are capable of controlling the rhythmic muscle activity. The effectiveness of the Neurofeedback method in inducing changes in behaviors is evaluated in particular through the measurement of the speed and accuracy of the planned action (Saleh et al 2006).…”

EEG correlates of sensorimotor processing: independent components involved in sensory and motor processing

“…This suggests that after a certain number of channels, increasing the number of channels does not result in the detection of additional independent sources of brain activity in stationary subject conditions using the experimental paradigm in this study. More unconstrained human behaviours in varying environmental conditions with substantive head motion would likely benefit from a higher number of EEG channels 32 .

Figure 3Examples of ( A ) Sensorimotor, ( B ) Motor, ( C ) Sensory, and ( D ) Unspecified ICs. The exact procedure of grouping of all ICs into the four groups is described below.

…”