Choose the best signal processing for your EEG and MEG data

BESA (Brain Electrical Source Analysis) is the most widely used software for source analysis and dipole localization in EEG and MEG research.

BESA has been developed on the basis of 20 years experience in human brain research by Michael Scherg, University of Heidelberg, and Patrick Berg, University of Konstanz.

BESA is a highly versatile and user-friendly Windows® program with optimized tools and scripts to preprocess raw or averaged data for source analysis.

All important aspects of source analysis are displayed in one window for immediate selection of a wide range of tools. BESA provides a variety of source analysis algorithms, a standardized realistic head model (FEM), and allows for fast and easy hypothesis testing and integration with MRI and fMRI when linked in with BrainVoyager™

Source coherence, a unique new feature for viewing brain activity

BESA transforms the surface signals into brain activity using source montages derived from multiple source models.
This allows to display ongoing EEG, single epochs, and averages with much higher spatial resolution.

The 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. Source coherence analysis
reveals the functional connectivity between brain regions by reducing the volume conduction effects seen in surface coherence.

More than just dipole source localization

BESA covers the whole range of signal processing and analysis from the acquired raw data to dynamic source images

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.

Source Montage and 3D Whole-Head Mapping

New montage editor

• Graphical editing of user montages for convenient data review 

• Virtual montages with standardized electrode locations 

• Combined montages of recorded, virtual, and source channels 

• 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 

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

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

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 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.

Integration with MRI and fMRI

For an easy superposition of the results of source analysis with individual MRI and fMRI data, BESA provides an interactive link to Rainer Goebel's BrainVoyager 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 with the BrainVoyager™ program

• Analysis of individual MRI and fMRI data in BrainVoyager™

• Separate license required for the BrainVoyager™ (BV) program.

• MRI and fMRI analysis in BrainVoyager™

• Visualization and processing of individual MRI and fMRI

• Automated rendering of scalp and cortical surfaces

• Expansion and flattening of the cortical surface

• Coregistration of EEG & MEG with MRI BrainVoyager™

• Coregistration of coordinate systems by fiducials and / or surface points 

• Direct projection of BESA source models into the individual MRI via interactive link with BrainVoyager™ 

• Projection of BESA source models into the individual MRI in BESA 

• Direct imaging of 3D source images in the individual MRI 

• Minimum norm current image based on individual gray/white matter boundary 

• Seeding of sources into BESA from anatomical 2D or 3D MR images or from fMRI BOLD clusters in BrainVoyager™ via interactive link

• Overlapped display of fMRI and EEG / MEG sources in BrainVoyager™

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 formats, e.g. 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

• Linear and non-linear correlation between scalp and source channels

• Spectral analysis: FFT, DSA, power and phase mapping 

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.)

• Pattern detection and averaging by spatio-temporal correlation

• Linear and non-linear correlation between scalp and source channels

• Spectral analysis: FFT, DSA, power and phase mapping

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

• 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 / apmlitude 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 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 and user-defined 3D imaging

• 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

• 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

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

• 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) channel

• 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

• 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)

System Requirements

• Pentium, 800 MHz or higher, 256 MB RAM (512 MB RAM with source coherence)

• Windows® 2000 or XP (Vista not supported yet)

• Graphics card supporting OpenGL 1.1 with 16 MB RAM or more 

Certification

BESA has CE Certification