moabb.datasets.MAMEM2#

class moabb.datasets.MAMEM2[source]#

SSVEP MAMEM 2 dataset.

Dataset summary

Name

#Subj

#Chan

#Classes

#Trials / class

Trials length

Sampling rate

#Sessions

MAMEM2

10

256

5

20-30

3s

250Hz

1

Dataset from [1].

EEG signals with 256 channels captured from 11 subjects executing a SSVEP-based experimental protocol. Five different frequencies (6.66, 7.50, 8.57, 10.00 and 12.00 Hz) have been used for the visual stimulation,and the EGI 300 Geodesic EEG System, using a stimulation, HydroCel Geodesic Sensor Net (HCGSN) and a sampling rate of 250 Hz has been used for capturing the signals.

Subjects were exposed to flickering lights from five violet boxes with frequencies [6.66Hz, 7.5Hz, 8.57Hz, 10Hz, and 12Hz] simultaneously. Prior to and during each flicking window, one of the boxes is marked by a yellow arrow indicating the box to be focused on by the subject. 256 channel EEG recordings were captured.

From [2], each subject underwent a single adaptation period before the first of their 5 sessions (unlike experiment 1 in which each session began with its own adaptation period). In the adaptation period, the subject is exposed to ten 5-second flickering windows from the five boxes simultaneously, with the target frequencies specified in the FREQUENCIES2.txt file under ‘adaptation’. The flickering windows are separated by 5 seconds of rest, and the 100s adaptation period precedes the first session by 30 seconds.

Each session consisted of the following: For the series of frequencies specified in the FREQUENCIES2.txt file under ‘sessions’: A 5 second window with all boxes flickering and the subject focusing on the specified frequency’s marked box, followed by 5 seconds of rest. This gives a total of 25 flickering windows for each session (not including the first adaptation period). Five minutes of rest before the next session (not including the 5th session).

The order of chosen frequencies is the same for each session, although there are small-moderate variations in the actual frequencies of each individual window. Note: Each ‘session’ in experiment 1 includes an adaptation period, unlike experiment 2 and 3 where each subject undergoes only one adaptation period before their first ‘session’.

Waveforms and Annotations File names are in the form T0NNn, where NN is the subject number and n is a - e for the session letter or x for the adaptation period. Each session lasts in the order of several minutes and is sampled at 250Hz. Each session and adaptation period has the following files: A waveform file of the EEG signals (.dat) along with its header file (.hea). If the channel corresponds to an international 10-20 channel then it is labeled as such. Otherwise, it is just labeled ‘EEG’. An annotation file (.flash) containing the locations of each individual flash. An annotation file (.win) containing the locations of the beginning and end of each 5 second flickering window. The annotations are labeled as ‘(’ for start and ‘)’ for stop, along with auxiliary strings indicating the focal frequency of the flashing windows.

The FREQUENCIES2.txt file indicates the approximate marked frequencies of the flickering windows, equal for each session, adaptation, and subject. These values are equal to those contained in the .win annotations.

Observed artifacts: During the stimulus presentation to subject S007 the research stuff noted that the subject had a tendency to eye blink. As a result the interference, in matters of artifacts, on the recorded signal is expected to be high.

References

[1]

MAMEM Steady State Visually Evoked Potential EEG Database https://archive.physionet.org/physiobank/database/mssvepdb/