Modules

DATA REVIEW AND PROCESSING MODULE

This main BESA window provides many tools for reviewing and processing of your EEG or MEG data. Raw data are directly read using readers implemented for many EEG and MEG file formats. Data processing steps include digital filtering, artifact detection and correction, computation of correlation and spectral analysis. All these steps can be performed easily with a few mouse clicks. A variety of different display options allows for convenient review of your data

Data import and export

Direct readers for most EEG and MEG data file formats
Import of user-defined file formats using generic reader
Data import / export to ASCII and binary files
MATLAB interface for direct transfer of analysis results to MATLAB

Data processing

Superior digital filtering: high, low, and narrow band pass, notch
Interpolation from recorded to virtual and source channels
Automated EOG and EKG artifact detection and correction
Advanced user defined instantaneous artifact correction
Pattern detection and averaging by spatio-temporal correlation

Data review

Easy and fast review of digital EEG and MEG data files
Fast paging, tagging and selected viewing of epochs of interest
DSA and event displays for quick jump to relevant pages
Additional selected and virtual artifact channels (EOG etc.)
Linear and non-linear correlation between scalp and source channels
Spectral analysis: FFT, DSA, power and phase mapping

SOURCE MONTAGES AND 3D WHOLE-HEAD MAPPING

Montage editor

Graphical editing of user montages for convenient data review
Virtual montages with user-definable or standardized electrode locations
Computation of arbitrary arithmetic combinations of channels
Remontaging to arbitrary channel averages (e.g. ears, mastoids, user-defined)
Immediate resorting for regional and hemispheric comparison

Source montages

Transformation of surface EEG or MEG into brain source activity
Montages derived from multiple dipole or regional source models
Standardization for various brain regions or definition by the user
Additional channels to display PCA components and / or eye artifacts

BESA_SourceMontages_1

3D whole-head mapping

Whole-head spline interpolation for voltage and CSD mapping
3D or 2D view of maps, sensors, and head surface points
Mapping of FFT power, amplitude, and phase
MEG maps of flux and planar gradients at the scalp surface
Time series of maps with easy selection of viewpoint, number of maps, and epoch of interest

BESA_SourceMontages_2

ERP ANALYSIS AND AVERAGING

This module assists in extracting event-related potentials or fields from your raw data. It provides an easy-to use interactive tool for designing your own scripted paradigms with predefined trigger definitions, conditions and settings for averaging. Data Files can be scanned automatically for artifacts, and bad channels and samples can be easily identified and excluded using an advanced 2D selection tool. A variety of displays is at hand to view the event-related signals, including 3D whole head maps and event-related (de)synchronization

Handling of paradigms, events, and conditions

Scripted paradigms for fast definition of triggers, conditions, epochs, filter settings etc.
Import, export, and editing of event lists, triggers, and paradigms
Design of complex conditions by logical expressions
Creation of triggers from recorded signals, e.g. rectified EMG

Batch scripts for automated processing

Fast and automated analysis of group studies using batch scripts
Batches for MATLAB function calls and data transfer
Script functions for paradigm import
Automated artifact scan with 2D graphical rejection tool
Batch guided averaging within and across subjects
User-defined combination of conditions (e.g. difference, average)
Automated ERP peak detection and latency / amplitude output
Spatial and temporal data interpolation
Batch commands for most source analysis functions

ERP displays and tools

Topographic display and 3D whole-head mapping of averaged waveforms
User definable layout with postscript export
Overplot of multiple conditions
Display of additional channels (polygraphic,intracranial, source, EEG, MEG)
Event related (de)synchronisation: Display of ERD/ERS waveforms

SOURCE ANALYSIS AND IMAGING

BESA has a highly interactive and easy-to-use window for source analysis. All relevant information is available at one glance including data, PCA, source waveforms and source localization in 3D head schemes or standardized MRI. You can choose among a variety of state-of-the-art source modeling techniques and head models. 2D and 3D source imaging can be performed with projection onto a standardized MRI.

Source Localization

Highly interactive graphical user interface for fast hypothesis testing
Spatio-temporal multiple dipole and regional source modeling
Image-weighted source fitting
Tomographic source sensitivity display
Automated multiple source probe scan (MSPS) for model validation
(MSPS) for model validation
Automated source fitting: RAP-MUSIC, Genetic algorithm
PCA analysis with generation of spatial source components
Realistic standardized FEM and multi-shell ellipsoidal head models

Source imaging

3D imaging of oscillatory activity using the multiple source beamformer (MSBF)
Distributed volume images: LORETA, sLORETA, swLORETA, LAURA, SSLOFO
Iterative, focusing 3D imaging by CLARA (Classical LORETA Analysis Recursively Applied)
User-defined 3D imaging methods
Minimum norm images based on the individual brain surface
3D movie of maps and dipoles using source waveforms
Source activity projected onto standardized or individual MRI

Source import and export

Direct transfer of source models between subjects and conditions
Transfer of source models, waveforms, and 3D images to MATLAB
Export of source models and source waveforms in ASCII
Creation of source montages
Coordinate systems: Talairach / Head / Device / Unit Sphere
Batch commands for many source analysis functions

INTEGRATION WITH MRI AND fMRI

For an easy superposition of source analysis results with individual MRI data, BESA Research provides an interactive interface to BESA MRI. EEG / MEG data can be coregistered with individual MRI data using individually digitized electrode positions or standard electrodes. BESA MRI has CE certification

BESA MRI

Integrated workflow for all user-interactions
Automatic preprocessing with inhomogeneity correction
Automatic reconstruction of scalp and cortex
Coregistration using digitized electrodes / headshape points or 10-10 / 10-20 standard electrodes
Overlay of source reconstructions on the individual MRI
Separate license required for BESA MRI program
BESA Research also provides an interactive link to Rainer Goebel’s BrainVoyager™ (BV) program. The bidirectional connection of the two programs allows for source seeding from fMRI clusters with one mouse click.

BrainVoyager™

Direct and easy interactive user interface of BESA Research with BV
Analysis of individual MRI and fMRI data in BV
Visualization and processing of individual MRI and fMRI
Automated rendering of scalp and cortical surfaces
Expansion and flattening of the cortical surface
Minimum norm current image based on individual gray/white matter boundary
Seeding of sources into BESA Research from anatomical 2D or 3D MR images or from fMRI BOLD clusters in BV via interactive link
Overlapped display of fMRI and EEG / MEG sources in BV
Separate license required for the BrainVoyager™ program

SOURCE COHERENCE AND TIME-FREQUENCY DISPLAY

Source coherence analysis reveals the functional connectivity between brain regions. This is achieved by transforming the surface signals into brain activity using brain source montages derived from multiple source models. The new Source Coherence Module provides an extremely fast and user-friendly implementation of time-frequency analysis based on complex demodulation. Users can create event-related time-frequency displays of power, amplitude, or event-related (de)synchronization and coherence for the current montage using brain sources or surface channels. Induced and evoked activities can be separated.

Time-frequency analysis

Time-frequency diagrams based on surface or source channels
Display of absolute power or spectral amplitude
Display of event-related spectral perturbation (ERD / ERS) in percent
Temporal-spectral information optimized by complex demodulation
Visualization of inter-trial phase locking
Variable setting of time-frequency resolution
Separation of evoked and induced activity by subtraction of the averaged evoked activity from single trials
Direct comparison of two conditions
3D Imaging of oscillatory activity using the BESA Mulitple Source Beamformer (MSBF)

Source coherence

Oscillatory coupling between brain regions analyzed directly in brain source space using source montages
Calculation of cross-spectral matrices between any combination of source (and / or surface) channels
Event-related coherence displayed in time-frequency space
Coherence analysis based on power and phase locking
Computation and display of phase delay and latency difference between channels

Statistical analysis – BESA Statistics 1.0

Statistical probability maps based on resampling of the single trial data
Statistics available for all time-frequency displays (absolute amplitude, TSE, coherence, comparison of conditions)
Export of displayed data for offline statistics across subjects (e.g. in MATLAB)
Visualization of significant data clusters
Cross-subject statistics based on permutation tests
Preliminary statistics: for defining regions of interest
Intuitive Workflow