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Wheels of Motion: Oscillatory Potentials in the Motor Cortex
Published in Alexa Riehle, Eilon Vaadia, Motor Cortex in Voluntary Movements, 2004
The mu rhythm ERD occurs in both the somatosensory and the motor cortex, and is roughly centered on the representation of the body part moved or stimulated.46 In other words, a moving arm does not block mu in the face area, and vice versa. However, there are conflicting findings; indeed the ease of finding mu ERD virtually proves that it is far more widespread than the sensorimotor zone being activated. The study by Crone and colleagues47 sheds some light on this issue. Using a subdural recording grid, they found a difference between the early and late phases of a motor response. In the early phase, mu ERD occurred in a diffuse spatial pattern that was
ECoG-Based BCIs
Published in Chang S. Nam, Anton Nijholt, Fabien Lotte, Brain–Computer Interfaces Handbook, 2018
In contrast to broadband gamma, low-frequency oscillatory activity provides an index of cortical excitability (Fitzgibbon et al. 2004; Haegens et al. 2011; Howard et al. 2003; Kubanek et al. 2015, 2013; Miltner et al. 1999; Sederberg et al. 2003; Singer and Gray 1995; Szczepanski et al. 2014; Womelsdorf et al. 2006) and plays a central role in the dynamic modulation of cortical function in response to varying task demands (Fries 2005; Jensen and Mazaheri 2010; Schalk 2015). Thus, even though low-frequency activity is likely produced by electrical events in certain (putatively subcortical) populations of neurons, it has proven to be a useful metric of the modulation of the cortex that is different from cortical excitation indexed by broadband gamma. Oscillations at different frequencies subserve different cortical regions. For example, activity in the alpha (8–12 Hz) band is prevalent throughout the sensorimotor system (e.g., Kubanek et al. 2015, 2013) where it is usually referred to as the mu rhythm that is well described in the classical EEG literature (Chatrian 1976) (see Figure 16.5Brunner et al. 2009). Typically, the mu rhythm and the closely associated beta (18–26 Hz) rhythm are relatively focused spectrally and appear as peaks in the power spectrum but are relatively widespread spatially (see Figure 16.5a, bottom). Although their peak amplitude modulates with actual or imagined movements (Crone et al. 1998b; Pfurtscheller and Cooper 1975) (see Figure 16.6Schalk 2006), activity in mu or beta bands appears to reveal only modest information about localized differential cortical processing (Toro et al. 1994). Outside the sensorimotor system, alpha oscillations are also prevalent in the visual system (e.g., Van Dijk et al. 2008) and auditory system (e.g., Potes et al. 2014, 2012). In contrast, oscillations in the theta (4–8 Hz) band are pervasive in prefrontal and hippocampal networks (Anderson et al. 2009; Dürschmid et al. 2014; Fujisawa and Buzsáki 2011). Across all these types of systems and oscillations, oscillatory amplitude is typically large during rest, and reduced while the subject is engaging in corresponding function (e.g., Figure 16.6).
Mirroring Communicative Actions: Contextual Modulation of Mu Rhythm Desynchronization in Response to the ‘Back-Of-Hand’ Action in 9-Month-Old Infants
Published in Developmental Neuropsychology, 2022
Sriranjani Karthik, Eugenio Parise, Ulf Liszkowski
Mu rhythm desynchronization (MRD) over the sensorimotor cortex has been established as a signature of mirror system activity in infants (Cuevas, Cannon, Yoo, & Fox, 2014; Marshall & Meltzoff, 2011). It is evident during execution and observation of goal-directed instrumental actions, like, for example, grasping, that enables an individual to obtain and manipulate the object directly. Less is known about the influence of contextual factors on the observed actions on MRD, which may indeed render infants’ perception of an action as goal-directed in the first place. Classic ‘direct-matching’ accounts (Rizzolatti, Fogassi, & Gallese, 2001) have suggested that infant’s mirror system activity is a result of directly matching the observed action on their own action repertoire (e.g., van Elk, van Schie, Hunnius, Vesper, & Bekkering, 2008), making further contextual information unnecessary. However, an alternative ‘action reconstruction’ account (Csibra, 2008) suggests that infants understand an instrumental action as goal-directed independently of their action repertoire, through top-down processes of goal detection. On this account, the mirror neuron system activity derives from emulating the goal, even by means of different instrumental actions when the observed action is not yet in the infant’s motor repertoire (de Klerk, Southgate, & Csibra, 2016; Southgate & Begus, 2013).
The Post-Movement Beta Rebound and Motor-Related Mu Suppression in Children
Published in Journal of Motor Behavior, 2020
Junyi Hao, Wenfeng Feng, Lingli Zhang, Yu Liao
Overall, studies found more consistency between adult and children of their motor-related mu activation. Specifically, while adult subjects executing an action. Mu rhythm and beta rhythm both decrease remarkably in power; this decrease can also be observed during movement observation and imagination (e.g., Cochin et al., 1998; Leocani, Toro, Manganotti, Zhuang, & Hallett, 1997; McFarland et al., 2000). Such power suppression is thought to reflect the event-related desynchronization (ERD) of neurons from the motor cortex (Pfurtscheller, 1981), and link to mental representation of the action (Cheyne, 2013; Cochin et al., 1999). Mu ERD accompany with movement were observed as early as 3 months of age (Berchicci et al., 2011; Marshall, Young, & Meltzoff, 2011; Southgate et al., 2009; Southgate, Johnson, Karoui, & Csibra, 2010). The mu ERD for infants is modulated by reach-grasp competence, and 9-month-old infants who had more reach-grasp competence exhibited more mu ERD while observing reaching-grasping actions (Cannon et al., 2016). Moreover, the mu ERD of 7-month-old infants can predict later propensity to imitate others’ goal-directed behavior (Filippi et al., 2016). These studies consistently suggested that the mu rhythm is an early-engaged neural mechanism for action learning and monitoring, and it is modulated by experience.
Event-related Desynchronization of Mu Rhythms During Concentric and Eccentric Contractions
Published in Journal of Motor Behavior, 2018
Joo-Hee Park, Heon-Seock Cynn, Kwang Su Cha, Kyung Hwan Kim, Hye-Seon Jeon
MATLAB R2008a (The MathWorks, Natick, MA) was used to analyze the EEG data. Among the 32 electrodes, we selected and analyzed C3 (left hemisphere) and C4 (right hemisphere) because they represent the sensorimotor cortex, and it is known that mu rhythms (8–13 Hz) are measured in those areas of the brain (Marshall, Young, & Meltzoff, 2011; Muthukumaraswamy, Johnson, & McNair, 2004). Attenuation of the mu rhythm has been observed in response to action execution for passive and reflex movements (Chatrian, Petersen, & Lazarete, 1959) and watching others' movements (Gastaut & Bert, 1954). Mu rhythm attenuation represents desynchronization of neural activity, which suggests a significant increase in brain activation (Pfurtscheller, Neuper, Andrew, & Edlinger, 1997). Mu rhythm channels with noise contamination were excluded, and the remaining channels in good condition were averaged and used as a reference. The reference electrode was set by linking the mastoid electrodes, with the ground electrode placed between Fpz and Fz. The EEG signal was filtered using a band-pass filter (0.03–100 Hz) and a notch filter at 60 Hz. Subsequently, the ocular and muscular artifacts were removed using independent component analysis. After removing the artifacts, we performed further single-trial waveform analysis to prevent high frequency signals such as muscular artifacts, which can contaminate EEG data. To process the EEG spectral analysis, we applied continuous wavelet transform with a complex Morlet wavelet to each single-trial EEG (Tallon-Baudry, Bertrand, Delpuech, & Pernier, 1996). The frequency ranged from 1 to 100 Hz.