An *.ert file stores extended ROI time-course information in Turbo-BrainVoyager. It is a plain text log file that is written incrementally while data are processed.
Unlike .btc files, which store ROI-level beta estimates, an .ert file stores voxel-level ROI signal values for each logged time point, together with the average value for each ROI.
When is an ERT file created?
An ERT file is created when logging of ROI voxel time courses is enabled in TBV, for example via the option:
Log ROI Voxel Time Courses (ERT)
The file is typically saved in the target/output directory using the current run name, followed by:
_plots.ert
Example:
Run01_plots.ert
General structure
An .ert file starts with a short header:
FileVersion: 1
After the header, the file contains repeated blocks, one block per logged time point.
Example:
TimePoint: 1 NrOfROIs: 2 ROI: 1 NrOfVoxels: 3 12 34 5 985.00 13 34 5 992.00 12 35 5 997.00 AvgValue: 991.333333333 ROI: 2 NrOfVoxels: 2 20 28 6 1012.00 21 28 6 1008.00 AvgValue: 1010.000000000
A later time point is appended as another block:
TimePoint: 2 NrOfROIs: 2 ROI: 1 NrOfVoxels: 3 12 34 5 988.00 13 34 5 995.00 12 35 5 1001.00 AvgValue: 994.666666667 ROI: 2 NrOfVoxels: 2 20 28 6 1015.00 21 28 6 1011.00 AvgValue: 1013.000000000
Field descriptions
| Field | Description |
|---|---|
FileVersion | File format version. |
TimePoint | Logged time point. Time points are written as 1-based values. |
NrOfROIs | Number of ROIs available for the current time point. |
ROI | Index of the ROI in the current TBV session. |
NrOfVoxels | Number of voxels in the ROI. |
| Voxel rows | Each row contains the voxel coordinate and the signal value for the current time point. |
AvgValue | Average ROI time-course value for the current time point. |
Voxel row format
Each voxel row has the following structure:
x y z signal_value
Example:
12 34 5 985.00
This means that, for the current time point, the voxel at coordinate 12 34 5 had a signal value of 985.00.
The coordinates refer to the voxel coordinates used by the ROI in the current TBV data set.
Interpreting an ERT file
The ERT file is organized by time point first, then by ROI.
For each time point, TBV writes:
TimePoint NrOfROIs ROI 1 Voxel values for ROI 1 Average value for ROI 1 ROI 2 Voxel values for ROI 2 Average value for ROI 2 ...
This makes the file useful for inspecting how individual ROI voxels and ROI averages change over time during real-time processing.
Important notes
An .ert file stores voxel-level ROI signal values over time. It should not be confused with .btc files, which store ROI-level beta estimates.
The number of voxel rows in each ROI block should match NrOfVoxels.
If an ROI contains no voxels, the ROI block may contain no voxel rows.
The AvgValue line provides the average time-course value for the ROI at the current time point.
Because the file is written incrementally during processing, it can be inspected while a run is ongoing, but it is safest to analyze the complete file after the run has finished.
Use a plain text editor when opening or editing .ert files manually. Do not edit the file in a word processor, because hidden formatting characters can make the file unreadable by TBV.