 Source Estimator may be used for discrete or distributed dipole source
analysis from EEG or MEG data which has been provided by the
Data Editor module. Three shell
spherical models or realistic head models (using data from the
Image Processor module) may be used for
field calculations. Source estimates may be output to
MR Viewer for MRI overlay.
Functionality
Source Models
- Spatiotemporal
dipole modeling. Fit one or more dipoles to the data. By interacting with
the data, the operator may use up to 32 dipoles to create source models. The
dipoles are subject to a variety of user-controlled constraints (including
free or fixed locations and/or orientations, mirror pairs, and maximal power
constraints). Multiple dipole time series may be estimated using minimum norm
techniques. Confidence intervals may be estimated.
- Dipole modeling in
Frequency and Time-Frequency domains. Dipoles may be fit directly in the
complex domain to Fourier transformed data, permitting the estimation of
generators of oscillatory activity directly. Source Estimation using wavelets
is a powerful tool for both time and frequency domains.
- Seeded Dipoles.
Dipole locations may be obtained from fMRI or PET hotspots (using
MR VIEWER) and transferred to SOURCE ESTIMATOR for
constrained dipole time series analysis.
- Beamformers and
other local estimators. Local estimators reveal spatially constrained
source activity.
- Distributed source
models. Source estimates are obtained from instantaneous data samples
using maximum likelihood and Laplacian smoothing (LORETA) or covariance
statistics (PRoMS) for a set of dipole current sources fixed to a lattice.
Related options include minimum norm and MUSIC algorithm. The resulting
analysis may be viewed as a tomographic display, either for a single time
slice, or for a sequence of time slices (4D analysis)
- Cortical surface
restriction*. Distributed source estimates may be restricted to the
cortical surface, obtained from the IMAGE
PROCESSOR module.
Head Models
- 3 shell sphere.
Digitized electrode locations (e.g. from LOCATOR)
may be used to determine a best-fit sphere origin. Measured electrode
locations are then used to calculate field potentials.
- 1 shell sphere.
External headshape data (e.g. from LOCATOR) may be
used to determine a best-fit sphere origin for MEG source estimation. 1 shell
sphere models may also be used for source analysis from ECoG data.
- Realistic headshape*.
Using segmented image data obtained from the IMAGE PROCESSOR* module, boundary element modeling calculates field
potentials, based on skull, scalp, and brain geometry (assuming homogeneous,
isotropic compartments).
Display
- Dynamic linkage
of graphical display windows permits selections in one window to update others
automatically.
- Discrete dipole
location, orientation, and confidence intervals are represented in
diagrammatic display (3 orthogonal planes).
- Tomographic
displays are available for distributed source estimates. 6D displays
optionally include position and moment for each lattice point.
- 3D rendering and
animation of cortical surface source estimates is available through
VISUALIZER.
Input/Output
- User Interface.
A conventional Microsoft Windows style graphical user interface is used
throughout. Dynamic linking of graphical display windows permits selections in
one window to update others automatically.
- Number of channels.
Up to a total of 256 channels (EEG and MEG) are supported s is available
through VISUALIZER.
Inter-module
Communication
File I/O
Other I/O
- Graphics
may be transferred to clipboard for use by other graphics programs or for
insertion into word processors.
Documentation
- Printed.
User manual, including file formats.
- On-line.
User manual and tutorial available as context sensitive hypertext.
| Requirements |
minimum required |
recommended |
| CPU |
Pentium |
|
| RAM |
32 Mbyte |
64+ Mbyte
recommended for >32 channels |
| Hard drive |
2 Mbyte
for executable |
64 Mbyte
swap space + additional data storage requirements |
| Operating
System |
Win
95/98/ME/NT/2000/XP |
|
| Display |
SVGA |
|
| Installation medium |
CD-ROM |
|
| Input
modules |
Data Editor |
|
Copyright ©
Source Signal Imaging, Inc. |
