Files & Formats
Neuroelectrics devices generate a series of files:
- The ".easy" data format (ASCII) - The ".info" file (ASCII) - The ".edf" (EFF+) and ".nedf" data formats (binary) - The ".stim" file (ASCII) - The .sdeeg SD card data format
Stimulation generated files
Neuroelectrics stimulation StarStim class devices generate stimulation specific files as well as EEG data. Here we describe the former (for EEG see the EEG data section).
the .stim file
This ASCII file contains a record of the currents at each electrode. There is a row per time sample. The last column contains the time stamp.
the .info file associated with a stimulation session
Here is an example of the ASCII data file associated to a stimulation session. The name of the file would be something like 20130220112635_Patient01.stim:
StartDate (first EEG timestamp): 1361377909087 Device class: StarStim Device Mac: 00:07:80:58:9C:1A NIC version: v1.1.9 Firmware version: 699 Line filter status: OFF Additional channel status:OFF Number of records of Stimulation: 46 (1 second/record) Total number of channels: 8 Number of EEG channels: 6 Number of stimulation channels: 1 Stimulation sampling rate: 500 Samples/second Stimulation units: uA Ramp up duration (s): 15 Ramp down duration (s): 15 Shamp ramp duration (s): OFF Stimulation duration (s): 1200 Type of stimulation: tACS+ Stimulation parameters: Channel 1: Position: C3 Type: EEG Recording Channel 2: Position: C4 Type: Stimulation Anodal Amplitude (uA): 100 Offset (uA): 0 Frequency (Hz): 10 Channel 3: Position: Ch3 Type: EEG Recording Channel 4: Position: Ch4 Type: Return Percentage return: 100% Channel 5: Position: Ch5 Type: EEG Recording Channel 6: Position: Ch6 Type: EEG Recording Channel 7: Position: Ch7 Type: EEG Recording Channel 8: Position: Ch8 Type: EEG Recording Trigger information: Code Description 1 Subject moved 2 Eyes opened 3 Eyes closed 4 sleeping 5 EEG signals are noisy 6 7 8 9
EEG data files and formats
The .easy data format (ASCII)
ABOUT THE NE ASCII DATA FORMAT (July 2012): NE ASCII files contain one line per time sample. Each line contains first the EEG data (8 or 20 channels, depending on the device, with units in nV), followed by three acceleration channels (aX,aY,aZ in mm/s^2- millimeters per second squared), an *optional* external input channel, a trigger flag (int32) and, finally, a timestamp in Unix time (ms from Jan 1 1970): Ch1(nV) ... Ch8or20(nV) aX(mg) aY(mg) aZ(mg) AddSensor Flags(uint32) TimeStamp (ms) Therefore Enobio8/StarStim will have a minimum of 8+2 (10) columns, or 8+3=11 if no accelerometer or >= 8+4 (with accelerometer). In summary: Enobio8/20 10 Columns: no AddSensor, no accelerometer data: 11 Comumns: no accelerometer, but there is AddSensor 13 Columns: there is accelerometer, but no Addsensor 14 Comumns: there is accelerometer, AddSensor. Enobio 20 will have >= 22 and >=24 columns if acc. data present: 22 Columns: no AddSensor, no accelerometer 23 Comumns: no accelerometer, but there is AddSensor 25 Columns: there is accelerometer, no AddSensor 26 Comumns: there is accelerometer, AddSensor. Enobio 32 will have >=34 adn >=36 if acc data is present 34 Columns: no AddSensor, no accelerometer 35 Comumns: no accelerometer, but there is AddSensor 37 Columns: there is accelerometer, no AddSensor 38 Comumns: there is accelerometer, AddSensor.
The .edf (binary, EDF+) data format
This is the standard | EDF data format. Files in this format can be opened from EDF data readers.
The .nedf (binary) data format
This is Neuroelectrics proprietary data format. It is lossless (full 24 bit) binary. It can be opened by NIC Offline.