Vadim V. Nikulin

Learn More
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(More)
Transcranial magnetic stimulation (TMS) was applied to motor areas in the left language-dominant hemisphere while right-handed human subjects made lexical decisions on words related to actions. Response times to words referring to leg actions (e.g. kick) were compared with those to words referring to movements involving the arms and hands (e.g. pick). TMS(More)
Transcranial magnetic stimulation (TMS) and multichannel electroencephalography (EEG) were used for the investigation of cortical excitability preceding voluntary movement in human subjects. The study showed the practical value of the combined TMS-EEG approach in differentiating between cortical and spinal-cord mechanisms, which is difficult with(More)
The presence of various ongoing oscillations in the brain is correlated with behavioral states such as restful wakefulness or drowsiness. However, even when subjects aim to maintain a high level of vigilance, ongoing oscillations exhibit large amplitude variability on time scales of hundreds of milliseconds to seconds, suggesting that the functional state(More)
Recent years of research have shown that the complex temporal structure of ongoing oscillations is scale-free and characterized by long-range temporal correlations. Detrended fluctuation analysis (DFA) has proven particularly useful, revealing that genetic variation, normal development, or disease can lead to differences in the scale-free amplitude(More)
We introduce Focal Vector Field Reconstruction (FVR), a novel technique for the inverse imaging of vector fields. The method was designed to simultaneously achieve two goals: a) invariance with respect to the orientation of the coordinate system, and b) a preference for sparsity of the solutions and their spatial derivatives. This was achieved by defining(More)
Brain-Computer Interfaces can suffer from a large variance of the subject conditions within and across sessions. For example vigilance fluctuations in the individual, variable task involvement, workload etc. alter the characteristics of EEG signals and thus challenge a stable BCI operation. In the present work we aim to define features based on a variant of(More)
Information flow between brain areas is difficult to estimate from EEG measurements due to the presence of noise as well as due to volume conduction. We here test the ability of popular measures of effective connectivity to detect an underlying neuronal interaction from simulated EEG data, as well as the ability of commonly used inverse source(More)
Presence of long-range temporal correlations in neuronal oscillations is thought to be beneficial for a reliable transfer of information in neuronal networks. In the present study long-range temporal correlations in electroencephalographic (EEG) neuronal oscillations were characterized with respect to their topography, frequency-band specificity (alpha and(More)
OBJECTIVE The aim of the present study was to evaluate test-retest reliability and condition sensitivity of long-range temporal correlations in the amplitude dynamics of electroencephalographic alpha and beta oscillations. METHODS Twelve normal subjects were measured two times with a test-retest interval of several days. Open- and closed-eyes conditions(More)