Data Editor
EMSE Suite DATA EDITOR module may be used as a stand-alone program to view, analyze, filter and transform EEG and MEG time series data, and to select intervals or events for further analysis, including topographic mapping, spatial components analysis and wavelet decomposition. In addition, the data are directly accessible to SOURCE ESTIMATOR module for source analysis, and to the VISUALIZER module for 3D rendering and animation. DATA EDITOR includes signal processing and statistical analysis tools. DATA EDITOR takes input in ASCII format or in native modes from many hardware vendors.

Functionality

Time Domain Analysis
 

• Time Series Display. Four modes are available to view time series data: chart recorder, superimposed, sensor position, and channel array. Multichannel overlays are available. Mouse cursor may be used to measure latencies or select an interval for further processing.
  

   

• Averaging. Data may be averaged on triggers selectively, with baseline correction and artifact rejection. Prestimulus and poststimulus interval are user selectable. The prestimulus baseline (or other interval) may be used optionally for linear detrending. Batch averaging as well as grand averaging are available.
   
• Event Review Mode. For datasets with events, such as those obtained from ERP studies, you may quickly scroll through the data on an event-by-event basis. Spatial components from PCA/ICA are synchronized with the events, enabling the user to view the component topographies associated with each event.
  
   
• Basic Statistics include Signal-to-Noise Ratio and Variance of averaged data, maximum, minimum, mean, and standard deviation for each channel.
• Advanced Statistics include permution tests and the generation of p-value maps exportable to the Visualizer module.
• Baseline correction/artifact rejection. Any user selected interval may be used for baseline correction and/or linear detrending. Artifacts are rejected when user selected level is exceeded.
• Filters. Time series filters include zero phase shift IIR (low pass, high pass, band pass, and notch), median, and Savitsky-Golay.
   
• Filter Pipeline consolidates all your filters in a simple interface. This allows you to save a collection of filters in the workspace, view and modify the properties of each filter, independently enabling/disabling filters and reverting to previous filter configurations.
  
   
• Waveform operations. Sum, difference, or grand average.
• Peak finder. Automated peak detection based on user selected peak identification criteria. Area under peak may be caluculated automatically.
   
• Principal components analysis. Principal components are calculated by singular value decomposition of interchannel covariance matrix. Components may be used to filter data or estimate number of independent sources, either by inspection of SVD spectrum, or by minimum descriptor length statistic.
  
   
• PCA Rotations. Varimax and Promax rotations are available for principal components.
• Independent Components Analysis. InfoMax and SOBI ICA algorithms are provided. Reconstruction of the data is possible with arbitrary user-selected components.
• Montages. Arbitrary reference montages may be created. Implicit reference, physical reference, average reference, Laplacian, and Hjorth are preprogrammed.
• Simulation. EEG and MEG time series data may be simulated, using up to 32 dipoles. Each dipole may be given an independent position and orientation. Time series types include exponential on/off ("PSP"), pseudorandom, square, and sine.

Frequency Domain Analysis

• Fourier transform. Discrete Fourier Transform (DFT/FFT) provides amplitude and phase spectra for a single sweep or user selected time series interval.
• Power spectrum analysis, with user selected averaging criteria, windowing, and overlapping.
• Steady state ERP. Harmonic analysis of steady state ERP may be used to extract signal with frequency components harmonic to the stimulation frequency.
• Frequency band selection filter may be created via inverse Fourier transform.

Time-Frequency Analysis

• Wavelet transform. Combined time frequency analysis may be accomplished using the Wavelet decomposition. The transform is displayed in a time-frequency-amplitude format, making it easy to distinguish power variations in different frequency domains over a given temporal interval. Extensions to time-frequency analysis are available, including coherence in signal or source space.
  

   

Topographic Mapping

• Pseudocolor topographic maps are available for electric or magnetic field data in the time or frequency domain as well as Hjorth, or Laplacian derivations.
• Modes. Maps may be viewed in 2 modes. In 'Instance' mode, the display is animated, and varies with the cursor location in the time series display window. In 'Sequence' mode, set of maps corresponding to a selected time series interval may be viewed in a window.

Filter Pipeline

• The Filter Pipeline includes both temporal (eg IIR) and spatial (eg Laplacian or Ocular Artifact Correction) filters for use with time series data. The pipeline allows you to turn filters on and off, change their properties and sequence of application, and save and restore the filter history, which is stored automatically along with the data.

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.

Intermodule Communication

• Input. LOCATOR module may be used for electrode locations.
• Output. VISUALIZER may be used for topographic mapping on realistic head surface.

File I/O

• Input Data time series: ASCII, ASTM (partial support), Biomagnetic Technologies, EGI, InstEP or Neuroscan, Biosemi
• Input Sensor location: LOCATOR, Neuroscan ASCII export, or ASCII.
• Output. ASCII files may be input to spreadsheet or other analysis programs

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.