The OpenBCI boards can be used for different proposes and research is one of them. This document covers command to use for the OpenBCI 32bit boards to execute the experiment done by Irene Vigue and distinguish motor imagery versus motor execution while using two external buttons connected to the board.
Overview
Motor imagery has become the newest trend in BCI research since imagination of movements appears to recruit neural mechanisms in the brain, which are similar – or the same – to those used to perform the same movements. However, the question of whether similar functional connectivity patterns among recruited brain areas associated with both real and imagined movements exist has been less addressed in the BCI frame.
For a better understanding of brain correlates of real and imagined movements, in the present work, we investigated the spatio-temporal EEG brain activity during a real and an imaginary rhythmic finger-tapping task. Repetitive finger movements externally paced by auditory or visual cues have been studied to investigate cortical connectivity, sensorimotor coordination. Moreover, in the frame of BCI research, repetitive finger and hand movements, real and imagined one, where used to extract characteristic features that serve as inputs for the detection of the intention of movement. These features include lateralized patterns of power decrease and an increase in the alpha and beta frequency bands.
It is widely accepted that while brain processes certain events, the ongoing brain rhythmical activity can be blocked or desynchronized. These types of changes are better detected by frequency analysis because they represent frequency-specific changes of the ongoing EEG activity. They consist, in general of a power decrease (event-related desynchronization, ERD) and/or of a power enhancement (event-related synchronization, ERS) of certain frequency bands. This is considered to be due to a decrease or an increase in synchrony of the underlying neuronal populations, respectively.
The evolution of ERD and ERS patterns for both actual and imagined movements is calculated by averaging the energy distributions of single EEG trials at each time instant in the time-frequency domain. We focused on the detection of beta rhythms and associated ERD/ERS patterns, previously described to occur with initiation and execution of motor actions as well as with motor imagination. Discrimination of short time activations during motor imagery based on the frequency content may improve decision-making and enhance the performance of a BCI system.
Methodology
The aim of the present study is to investigate the cortical activation and connectivity sub-serving real and imaginary rhythmic finger tapping, from the analysis of multi-channel electroencephalogram (EEG) scalp recordings.
Methods: Only one subject participated in the experiment involving two tasks of simple limb motor imagery (left hand, right hand). Simultaneous imagination of different limbs contributes to the activation of larger cortical areas as well as two estimated sources located at corresponding motor areas within beta rhythm.
Every trial is 10 seconds time long and it’s composed with different status:
- Ready: The first second of each trial command shows up an alarm
- Focus: The following three seconds are based on a countdown before the cue, just to let the subject prepare himself for what is coming.
- Cue: It’s only four seconds long and it shows the cue that has to be done in the trial. In each trial the cue is different. This is the non-random version, which means that the cues appear in the following order: Move right finger – Move left finger – Imagine moving right finger – Imagine moving left finger.
- Rest: The subject has two seconds to rest between trails.
Equipment
OpenBCI Headset
Despite the instructions well explained in OpenBCI Learning Headware page I’ve improved the way nodes can be assembled and adjusted to the scalp without twisting the cables. I reused jumpers from other cables to attached to the electrode. So, the cable from the electrode to the OpenBCI 32 bit board has completly angles of freedom.
Electrodes position
Two external buttons
Connection (Two buttons)
Connection (OpenBCI 32bit Board)
Edit OpenBCI GUI
On the top-right of the image the Playground tab appears showing the time of each trial, the number of trial you are, and all the commands related with start/stop experiment.
Upload new code to OpenBCI board
Results
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