The collection of data streams from fMRI, MEG, EEG, and extracellular recordings is only the first step of the experimental process engaged by neuroinvestigators at the Brain Sciences Center.  The data streams themselves are very abstract, and virtually meaningless without multiple stages of comprehensive data processing.  After the data streams are initially collected, the real work of Center scientists begins as they embark on months, and even years, of painstakingly-thorough analyses of these data sets.

     Such analyses require sophisticated computer software packages, along with the most advanced computers available today.  The majority of this work utilizes one of the six data processing workstations within the Brain Sciences Center.  Each of these workstations is equipped with dual Pentium processors, dual monitors, and over 4 GB of RAM.  Each workstation also includes over 150 GB of hard disk space, and DVD burners for backing-up the massive amounts of raw and fully processed brain data.  Each of the six workstations is outfitted with a variety of discipline-specific software packages, such as BESA and BrainVoyager, which allows Center researchers to employ the most advanced data processing procedures currently available, as well as providing the capacity to create novel approaches to the processing and interpretation of the multi-dimensional data streams generated by instruments available in the Center.

   BrainVoyager is a highly versatile software package that can be used to visualize 2D or 3D MRI/fMRI images from virtually any native format.  The software features a high degree of customizability, which provides researchers the capacity to perform detailed region-of-interest analyses, as well as test many different models of the hemodynamic response function.  BrainVoyager is also a ‘complete’ software package that is capable of performing all aspects of the data analyses.  Using only BrainVoyager, researchers can proceed directly from the raw slice sequences, initially acquired by the MRI/fMRI instrument, to the final stages of an analysis (e.g., testing the reliability of main experiment effects through statistical comparisons).  The software also features a novel collection of user-friendly and time saving tools, such as those used for automatic brain segmentation (i.e., parcellating the gray/white matter boundary), cortical surface reconstruction, cortex inflation, and even brain surface flattening (which allows the 3D brain to be visualized in a more simple and interpretable 2D space).

     BESA (Brain Electric Source Analysis) is another software package used by researchers at the Center.  Like BrainVoyager, BESA is highly versatile and recognizes EEG and MEG data streams from a variety of instruments (i.e., data in many different native formats).  BESA is also a complete package for all aspects of EEG or MEG data processing.  For example, the BESA base module provides the necessary functionality for all aspects of data preprocessing.  A few of the data processing tools available in the BESA base module include:

(1) digital paging functions for quickly reviewing raw, continuously recorded data streams

(2) automatic artifact rejection routines

(3) artifact correction algorithms

(4) a Boolean averaging wizard for quick and seamless processing of complicated multi-condition cognitive experiments

(5) a variety of data filters for reducing the bandwidth of the recording to only the interesting frequencies

(6) quick and simple routines for voltage (EEG) and flux (MEG) mapping on a standardized head template. 

      Along with the base module, BESA also includes a source coherence module and a source analysis module.  The source coherence module provides several tools useful for calculating the frequency composition of the neural data as a function of time (i.e., time-frequency analysis), computing event-related synchronizations and event-related desynchronizations (ERS/ERD) for each brain region of interest, and even figuring coherence estimates for neural sources that are spatially distinct but overlapping in time.  Finally, BESA’s source analysis module provides Center researchers with the tools for localizing the neural generators of MEG and EEG signals.  The source analysis module is equipped with many different source localization algorithms (e.g., RAP-MUSIC, Genetic Algorithm, and several Optimization algorithms), which can be used in the construction of single and/or multi-dipole models.  This module also has the capacity for distributed-source modeling techniques, such as the Minimum-Norm Estimation.

     A unique feature of the BESA/BrainVoyager software packages is that they can be linked together in real time.  When combined, the two programs provide a venue for visualizing single and multi-dipole models (constructed from EEG or MEG recordings in BESA) in the most insightful context; that is, the high-resolution MRI of the participant’s individual brain (constructed in BrainVoyager).  Visualizing source models in this way allows Center researchers to identify the precise location of the neural generators that produced the MEG or EEG signals in individual participants, and facilitates recognition of differential neural processing that may coincide with health or disease. 

     Linking the BESA/BrainVoyager software packages also allows the results of fMRI experiments to inform those of MEG or EEG experiments (and vice-versa).  For example, the same experiment can be carried-out on the same participants by Center researchers specializing fMRI, and those specializing in MEG.  After data collection, the high spatial accuracy provided by fMRI data can be combined with the precise temporal information provided by MEG.  The end result of such collaborative efforts, between Center researchers, is a more representative and accurate portrait of the neural regions active during the cognitive task of interest, and their associated time course of activity.