Human brain mapping
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Human brain mapping · Jun 2013
Periods of rest in fMRI contain individual spontaneous events which are related to slowly fluctuating spontaneous activity.
fMRI studies of brain activity at rest study slow (<0.1 Hz) intrinsic fluctuations in the blood-oxygenation-level-dependent (BOLD) signal that are observed in a temporal scale of several minutes. The origin of these fluctuations is not clear but has previously been associated with slow changes in rhythmic neuronal activity resulting from changes in cortical excitability or neuronal synchronization. In this work, we show that individual spontaneous BOLD events occur during rest, in addition to slow fluctuations. ⋯ We showed that the correlation varied considerably over time, peaking at the time of spontaneous events in these networks. By regressing spontaneous events out of the fMRI signal, we showed that both the correlation strength and the power in spectral frequencies <0.1 Hz decreased, indicating that spontaneous activation events contribute to low-frequency fluctuations observed in resting state networks with fMRI. This work provides new insights into the origin of signals detected in fMRI studies of functional connectivity.
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Human brain mapping · Jun 2013
The organization of intrinsic brain activity differs between genders: a resting-state fMRI study in a large cohort of young healthy subjects.
To investigate, using resting state (RS) functional MRI (fMRI), gender-related differences of functional connectivity (FC) and functional network connectivity (FNC) of the human brain. ⋯ The organization of intrinsic FC and FNC differ between genders. The detected differences could contribute to the understanding of the known between-gender variation in task-related recruitments, and the patterns of abnormalities detected in neurologic and psychiatric diseases with a gender prevalence.