When Thought Becomes Action
A report from the Lyon Neuroscience Research Center (CRNL). Here, researchers from the Brain Dynamics and Cognition (Dycog) team are tackling development of the brain-computer interface.
At the Lyon Neuroscience Research Center (CRNL)*, strange headgear is in fashion. Made from fabric studded with a series of electrodes, this cap is used to perform human electroencephalography (EEG). Or, in other words, to measure the electrical activity of the brain. On paper, this activity is just a succession of peaks and troughs but for researchers from the Brain Dynamics and Cognition (Dycog) team, it is a way to… access your thoughts! "When you're focused on something, such as a game, it's possible to measure a characteristic brain signal using the cap’s sensors", explains Jérémie Mattout, Inserm Research Associate at the CRNL and head of the Brain-computer interaction: control and learning project
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Emmanuel Maby, Inserm Research Engineer, fits the EEG cap onto today’s guinea pig, student Jordan Alves. When placed in contact with his scalp, the electrodes record the electrical activity of his neurons. A gel is applied to the base of each electrode using a syringe to promote the conduction of a very mild current.
© Inserm/Guénet, François -
Emmanuel Maby (left) and Jérémie Mattout (right) develop the experiments performed at the laboratory and are interested in various disorders or pathological states such as ADD/H, coma, locked-in syndrome, etc.
© Inserm/Guénet, François -
The 16 electrodes fitted to the cap are used to record brain activity. The signals captured come from the entire cortex and are limited to low frequencies, unlike the signals measured using invasive electrodes, which are implanted directly in the targeted regions of the cortex. However, its ease of use and non-invasive nature open the EEG up to many applications.
© Inserm/Guénet, François -
Video games have been developed by Parisian company Black Sheep Studio for the needs of Mind Your Brain, which began in February 2017 and is devoted to children with ADD/H. To play, no joystick is required – just thoughts! On the checkerboard of this naval battle, squares flash intermittently. The aim is to count the number of times that the square we want to play lights up, which in turn intensifies our focus on it. A specific brain signal, known as a marker of attention, will then appear just after the chosen square flashes – something which does not occur with the other squares. Recorded using an EEG, the signal is transmitted to the computer which will then "play" that particular square.
© Inserm/Guénet, François -
Video games have been developed by Parisian company Black Sheep Studio for the needs of Mind Your Brain, which began in February 2017 and is devoted to children with ADD/H. To play, no joystick is required – just thoughts! On the checkerboard of this naval battle, squares flash intermittently. The aim is to count the number of times that the square we want to play lights up, which in turn intensifies our focus on it. A specific brain signal, known as a marker of attention, will then appear just after the chosen square flashes – something which does not occur with the other squares. Recorded using an EEG, the signal is transmitted to the computer which will then "play" that particular square.
© Inserm/Guénet, François -
This marker has a name: wave P300, identified by the arrow and named as such because it appears approximately 300 ms after the expected event (in our case, when the square we want to play lights up). Before being applied to games, the use of this wave was developed in patients with locked-in syndrome, who are shown letters of the alphabet and select them by thought in order to communicate.
© Inserm/Guénet, François -
Thanks to this trial, Jérémie Mattout (right) and Emmanuel Maby (center) test an alternative to the medicines prescribed to children with ADD/H: neurofeedback. The idea is to record neural activity and enable the brain to correct it in real time if there is a disorder, such as a lack of attention. Here it is impossible to play correctly if the player is inattentive: the machine will not understand where the attention is being focused and so will select a square at random from the fluctuating EEG signal. By playing, the child will gradually be able to learn how to take control of his or her attention.
© Inserm/Guénet, François -
The EEG of student Maxime Gaudet-Trafit is being recorded while he performs an exercise test on a bike. Objective of the Meegaperf trial: in the same way as for the P300 wave, which signifies attention, it involves distinguishing from the brain activity a marker that characterizes the imminent onset of a dip in performance while the athlete pedals at his maximum strength.
© Inserm/Guénet, François -
To ensure that the cyclist reaches his maximum strength, and the accompanying physical exhaustion, he is equipped with sensors to measure various physiological parameters, such as gas exchange – a reflection of the level of oxygenation during exercise, or cardiac activity, recorded by electrocardiography.
© Inserm/Guénet, François -
The marker developed by Physip, the SMB sponsoring the project, can be translated as an index of prediction of physical or mental performance. When this moves into the "red zone" (see left-hand screen), there is a major risk of impaired performance. This marker could therefore be used in situations in which such an impairment could have serious consequences: air traffic control, piloting a plane, and more. The French Directorate General of Armaments is already interested and is funding this project in partnership with the CRNL, Telecom Paris Tech and the Inter-University Laboratory of Human Movement Biology.
© Inserm/Guénet, François
Following computer analysis, the data are transformed into commands intended for a machine, such as a computer, prosthetic or artificial voice. Commands through which thought directly becomes action, circumventing the peripheral nerves and muscles usually required to move our limbs and jaws! The potential clinical applications are many. Tetraplegic patients could enjoy new autonomy using an exoskeleton directed by their thoughts, the victims of locked-in syndrome could regain the ability to communicate with the aid of a computer, amputees could control a neuroprosthetic, etc. These are all applications that perfectly illustrate two projects conducted by the Dycog team: Mind Your Brain, a clinical trial devoted to children suffering from Attention Deficit Disorder with and without Hyperactivity (ADD/H) and Meegaperf, which is dedicated to detecting mental or physical fatigue.
*Inserm/CNRS/Université Saint Etienne-Jean Monnet/Université Claude Bernard Lyon 1 Unit 1028
Find the report in issue 35 of Science&Santé magazine (in French)