[MS6-3B-2] Neuromagnetic Differences of Multi-Frequency Brain Activities between Eyes-open and Eyes-closed
[Objective] The objective of the present study was to characterize the differences of endogenous brain actives from low to high frequency ranges between eyes-open and eyes-closed.
[Method] Twenty-four healthy adolescents were studied at eyes-open and eyes-closed resting states with a whole-head magnetoencephalography (MEG) system. MEG sources were localized with accumulated source imaging, a relatively new method optimized for localizing and quantifying spontaneous brain activity. Source activities were analyzed in nine frequency bands, which included delta (1–4 Hz), theta(4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), low-gamma(30–55 Hz), high-gamma (65–90 Hz), ripple (90–200 Hz), high-frequency oscillations (HFOs, 200–1,000 Hz) and very high-frequency oscillations (VHFOs, 1,000–2,000 Hz). The relative strength of brain activity was obtained by normalizing the strength of brain activity by total power.
[Result] In comparison with eyes-open, eyes-closed was associated with significant increases of alpha activities. There was no significant difference between eyes-closed and eyes-open in terms of beta, high-gamma activities and ripples. Interestingly, in comparison with eyes-open, eyes-closed was associated with significant decreases of delta, theta, low-gamma, HFOs and VHFOs.
[Conclusion] The results suggested that eyes closure or open would result in significant changes of brain activities in a wide frequency range. To our knowledge, this is the first report on the finding of the increases of high frequency brain activities during eyes-open as compared with eyes-closed, which may indicate an increase of visual processing or other brain functional activation.
[Method] Twenty-four healthy adolescents were studied at eyes-open and eyes-closed resting states with a whole-head magnetoencephalography (MEG) system. MEG sources were localized with accumulated source imaging, a relatively new method optimized for localizing and quantifying spontaneous brain activity. Source activities were analyzed in nine frequency bands, which included delta (1–4 Hz), theta(4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), low-gamma(30–55 Hz), high-gamma (65–90 Hz), ripple (90–200 Hz), high-frequency oscillations (HFOs, 200–1,000 Hz) and very high-frequency oscillations (VHFOs, 1,000–2,000 Hz). The relative strength of brain activity was obtained by normalizing the strength of brain activity by total power.
[Result] In comparison with eyes-open, eyes-closed was associated with significant increases of alpha activities. There was no significant difference between eyes-closed and eyes-open in terms of beta, high-gamma activities and ripples. Interestingly, in comparison with eyes-open, eyes-closed was associated with significant decreases of delta, theta, low-gamma, HFOs and VHFOs.
[Conclusion] The results suggested that eyes closure or open would result in significant changes of brain activities in a wide frequency range. To our knowledge, this is the first report on the finding of the increases of high frequency brain activities during eyes-open as compared with eyes-closed, which may indicate an increase of visual processing or other brain functional activation.