Movement related activity in the high gamma range of the human EEG

Epilepsy Center, University Clinics, Albert-Ludwigs-University, Freiburg, Germany.
NeuroImage (Impact Factor: 6.36). 07/2008; 41(2):302-10. DOI: 10.1016/j.neuroimage.2008.02.032
Source: PubMed


Electrocorticographic (ECoG) recordings obtained using intracranially implanted electrodes in epilepsy patients indicate that high gamma band (HGB) activity of sensorimotor cortex is focally increased during voluntary movement. These movement related HGB modulations may play an important role in sensorimotor cortex function. It is however currently not clear to what extent this type of neural activity can be detected using non-invasive electroencephalography (EEG) and how similar HGB responses in healthy human subjects are to those observed in epilepsy patients. Using the same arm reaching task, we have investigated spectral power changes both in intracranial ECoG recordings in epilepsy patients and in non-invasive EEG recordings optimized for detecting HGB activity in healthy subjects. Our results show a common HGB response pattern both in ECoG and EEG recorded above the sensorimotor cortex contralateral to the side of arm movement. In both cases, HGB activity increased around movement onset in the 60-90 Hz range and became most pronounced at reaching movement end. Additionally, we found EEG HGB activity above the frontal midline possibly generated by the anterior supplementary motor area (SMA), a region that was however not covered by the intracranial electrodes used in the present study. In summary, our findings show that HGB activity from human sensorimotor cortex can be non-invasively detected in healthy subjects using EEG, opening a new perspective for investigating the role of high gamma range neuronal activity both in function and dysfunction of the human cortical sensorimotor network.

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Available from: Tonio Ball
    • "In this study, we focused on HGA, because it represents a proxy of local cortical processing. In particular, HGA can be used for functional mapping of cognitive processes using intracranial EGG [Brovelli et al., 2005;Cheyne and Ferrari, 2013;Crone et al., 2006;Jerbi et al., 2009;Ko et al., 2013;Lachaux et al., 2012], noninvasive[Ball et al., 2008;Darvas et al., 2010;Vidal et al., 2006]and multimodal neu- rophysiologicaltechniques. In addition, modulations in HGA correlates with BOLD responses in animals [Goense and Logothetis, 2008;Logothetis et al., 2001;Niessing et al., 2005]and humans[Hermes et al., 2012;Lachaux et al., 2007;Nir et al., 2007;Ojemann et al., 2013;Scheeringa et al., 2011]. Therefore, we suggest that the use of HGA in combination with the MarsAtlas could provide an appropriate framework for combining information from multiple functional modalities such as MEG, SEEG and fMRI. "
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    • "In fact, the rapidly growing interest in ECoG is mostly due to its improved signal characteristics relative to the artifact prone EEG. Compared with EEG, ECoG has finer spatial resolution (mesoscale (millimeters) versus macroscale (centimeters)) [89–91], broader spectral range (0–500 Hz versus 0–40 Hz) [92], higher amplitude (i.e., 50–100 μV versus 10–20 μV) [93], and less vulnerability to movement artifacts [5, 93, 94]. Moreover, ECoG electrode grids, which are typically platinum electrodes 4 mm (2.3 mm exposed) in diameter and are configured in either a grid (e.g., 8 × 8 electrodes) or strip (e.g., 4 or 6 electrodes) configuration with an interelectrode distance of usually 10 mm, are far more likely to yield long-term functional stability [95–99] than intracortical electrodes, which induce complex histological responses that may impair neuronal recordings [100–102]. "
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    • "We can appreciate that there is more significant and localized discriminability (around electrode C3) during the first seconds, i.e. pre-movement, and movement, while the discriminant activity starts to become more scattered by the end of the task, i.e. post-movement and rest. This suggests that brain activity is being decoded and used for discrimination and also agrees with the results shown in [19] regarding high-γ activity over the motor cortex at movement onset. "
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