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Gwin JT, Gramann K, Makeig S, Ferris DP. Removal of movement artifact from high-density EEG recorded during walking and running. J Neurophysiol 103: 3526 -3534, 2010. First published April 21, 2010 doi:10.1152/jn.00105.2010. Although human cognition often occurs during dynamic motor actions, most studies of human brain dynamics examine subjects in static seated or prone conditions. EEG signals have historically been considered to be too noise prone to allow recording of brain dynamics during human locomotion. Here we applied a channel-based artifact template regression procedure and a subsequent spatial filtering approach to remove gait-related movement artifact from EEG signals recorded during walking and running. We first used stride time warping to remove gait artifact from high-density EEG recorded during a visual oddball discrimination task performed while walking and running. Next, we applied infomax independent component analysis (ICA) to parse the channel-based noise reduced EEG signals into maximally independent components (ICs) and then performed component-based template regression. Applying channelbased or channel-based plus component-based artifact rejection significantly reduced EEG spectral power in the 1.5-to 8.5-Hz frequency range during walking and running. In walking conditions, gait-related artifact was insubstantial: event-related potentials (ERPs), which were nearly identical to visual oddball discrimination events while standing, were visible before and after applying noise reduction. In the running condition, gait-related artifact severely compromised the EEG signals: stable average ERP time-courses of IC processes were only detectable after artifact removal. These findings show that highdensity EEG can be used to study brain dynamics during whole body movements and that mechanical artifact from rhythmic gait events may be minimized using a template regression procedure. I N T R O D U C T I O NA noninvasive method for recording human electrocortical brain dynamics during mobile activities could have far-reaching benefits (Makeig et al. 2009). Cognitive neuroscientists exploring embodied cognition could study brain dynamics associated with cognitive processes during whole body interactions within natural environments. Studies of human motor control would no longer be limited to studies of constrained movements. Bioengineers might be able to use such a method to derive control signals for neurorehabilitation and prosthetic technologies. An unanswered question in neuroscience is to what extent human cortex participates in the generation of rhythmic motor behaviors, in particular those motor behaviors associated with locomotion. The answer seems to lie in a multifaceted control strategy including descending, peripheral, and central control (Yang and Gorassini 2006). An ability to measure brain dynamics during locomotion may provide additional information regarding the significance of descending control.EEG is the only noninvasive brain imaging modality that uses sensors that are light enough ...

The ability to cognitively regulate emotional responses to aversive events is essential for mental and physical health. One prerequisite of successful emotion regulation is the awareness of emotional states, which in turn is associated with the awareness of bodily signals [interoceptive awareness (IA)]. This study investigated the neural dynamics of reappraisal of emotional responses in 28 participants who differed with respect to IA. Electroencephalography was used to characterize the time course of emotion regulation. We found that reappraisal was accompanied by reduced arousal and significant modulation of late neural responses. What is more, higher IA facilitated downregulation of affect and was associated with more pronounced modulation of underlying neural activity. Therefore, we conclude that IA not only advances the consolidation of somatic markers required for guiding individual behaviour but also creates processing advantages in tasks referring to these bodily markers.