We propose a new measure (phase-slope index) to estimate the direction of information flux in multivariate time series. This measure (a) is insensitive to mixtures of independent sources, (b) gives meaningful results even if the phase spectrum is not linear, and (c) properly weights contributions from different frequencies. These properties are shown in extended simulations and contrasted to Granger causality which yields highly significant false detections for mixtures of independent sources. An application to electroencephalography data (eyes-closed condition) reveals a clear front-to-back information flow.

/pdf/robustly-estimating-the-flow-direction-of-information-in-3zsye6d41j.pdf

Robustly estimating the flow direction of information in complex physical systems.

http://ilabs.washington.edu/meltzoff/pdf/11MarshallMeltzoff_Mirroring_DCN.pdf

Neural Mirroring Systems: Exploring the EEG Mu Rhythm in Human Infancy

Human brain mapping: hemodynamic response and electrophysiology.

This study explores the possibility of noninvasively inducing long-term changes in human corticomotor excitability by means of a brain–computer interface, which enables users to exert internal control over the cortical rhythms recorded from the scalp. We demonstrate that self-regulation of electroencephalogram rhythms in quietly sitting, naive humans significantly affects the subsequent corticomotor response to transcranial magnetic stimulation, producing durable and correlated changes in neurotransmission. Specifically, we show that the intrinsic suppression of alpha cortical rhythms can in itself produce robust increases in corticospinal excitability and decreases in intracortical inhibition of up to 150%, which last for at least 20 min. Our observations may have important implications for therapies of brain disorders associated with abnormal cortical rhythms, and support the use of electroencephalogram-based neurofeedback as a noninvasive tool for establishing a causal link between rhythmic cortical activities and their functions.

/pdf/endogenous-control-of-waking-brain-rhythms-induces-21qoo74idm.pdf

Endogenous control of waking brain rhythms induces neuroplasticity in humans

The clinical use of mirror visual feedback (MVF) was initially introduced to alleviate phantom pain, and has since been applied to the improvement of hemiparesis following stroke. However, it is not known whether MVF can restore motor function by producing plastic changes in the human primary motor cortex (M1). Here, we used transcranial magnetic stimulation to test whether M1 plasticity is a physiological substrate of MVF-induced motor behavioral improvement. MVF intervention in normal volunteers using a mirror box improved motor behavior and enhanced excitatory functions of the M1. Moreover, behavioral and physiological measures of MVF-induced changes were positively correlated with each other. Improved motor performance occurred after observation of a simple action, but not after repetitive motor training of the nontarget hand without MVF, suggesting the crucial importance of visual feedback. The beneficial effects of MVF were disrupted by continuous theta burst stimulation (cTBS) over the M1, but not the control site in the occipital cortex. However, MVF following cTBS could further improve the motor functions. Our findings indicate that M1 plasticity, especially in its excitatory connections, is an essential component of MVF-based therapies.

https://www.jneurosci.org/content/jneuro/32/4/1293.full.pdf

T. Hiraoka

Papers

Neural correlates of regional EEG power change