Induced activity: oscillatory activity occurring in a certain event-related time window with varying time lag and phase.Time-locked activity: event-related signal with similar wave shape over trials.Time-frequency analysis: analysis or display of the event-related time-locked or induced activity in the time-frequency domain.Source montage: the transformation of the on-going EEG into the estimated contributions or source waveforms of a set of brain regions.Source waveform: a time signal calculated for a specified brain region or cortical surface.Surface waveform: a time signal recorded from EEG-electrodes or MEG sensors.BESA Research introduces several tools for fast and user-friendly time-frequency analysis including source and scalp coherence.įirst, let us introduce some terminology in order to clarify the concepts: Recently, an increasing number of papers on oscillatory coupling between brain regions in animal studies and on time-frequency analysis of human EEG and MEG data has been published. Please also refer to our website at for the latest tutorial on source coherence and related topics. rectified EMG, can be included in the analysis.Ī highly optimized graphical user interaction enables fast testing of hypotheses, and quick focusing on the features of interest.įor an introduction and an outline of the underlying concepts of source coherence, please continue with the next topic, " Concepts of Source Coherence"įor more details check the following topics: Apart from source channels, intracranial channels, and scalp channels, also other polygraphic channels, e.g. Time-frequency transforms are obtained in a very fast implementation based on complex demodulation. Export of analysis results into ASCII text files.Probability plots transforming all time-frequency parameters into statistical p-values.Display of the inter-trial phase locking (ITPL).Computation and display of phase delay and latency difference between channels in a graphically defined time and frequency window.Coherence estimate between any combination of surface or source channels (coherence or phase coherence).Joint display of time-frequency or coherence plots with the evoked potential of individual channels.Separation of evoked and induced activity.Display of temporal-spectral evolution (TSE) in percent. Time-frequency diagrams based on brain source or surface channels.The Source Coherence Module provides a variety of tools for time-frequency based event-related data analysis. Transforming the scalp surface into the brain signals using source montages greatly enhances the spatial resolution and largely removes one of the major drawbacks of traditional coherence analysis, the widespread overlap at the scalp due to volume conduction. These are derived from multiple source models of the data. The Source Coherence Module provides new insights into the interaction between brain regions using brain source montages. 3 Layout of the Source Coherence Window.1 Source Coherence Module - Introduction.
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