Breaking the Lock for Locked-in Syndrome: A new Brain Computer Interface

    10/01/2015

    A short while ago I watched The Diving Bell and the Butterfly, an extraordinary film based on the true story of Jean Dominique Bauby, the French ELLE magazine executive who suffered a stroke at the age of 43, leaving him almost completely paralyzed and a sufferer of Locked-in Syndrome. Locked-in Syndrome is caused by a brain stem stroke that cuts off blood supply to the medulla often resulting in severe quadruplegia and an inability to speak. However, parts of the brain involving cognitive function, proprioception and sometimes extraocular muscles are left intact which means patients can still sense their surroundings, can see and hear people and can sometimes communicate by moving their eyes. Depending on the severity of the stroke and which brain regions are damaged, the resulting levels of paralysis vary greatly in different people - from total Locked-in syndrome, where patients cannot respond to anything and lie in a "sleep paralysis" state, to partial Locked-in syndrome, where patients retain some voluntary control of their head and neck. Jean Dominique Bauby had to rely on Partner Assisted Scanning, a system where a person would recite the alphabet slowly and he would respond by moving his eyes in order to communicate each word he wanted to speak. You can imagine the tedious and laborious process it took for him to communicate on a daily basis, not to mention the process of writing his memoire that inspired the film.

    A recent clinical trial study brings us a step closer to alleviating the suffering of Locked-in patients. A collaboration set up between Harvard and Brown University scientists directly connected paralyzed patients with a computer processor in a system called BrainGate Neural Interface System. This study began 5 years ago when two patients who had suffered brain stem strokes were connected by neurosurgery using intracortical microelectrodes implanted to the arm area of the motor cortex. The electrodes were connected to a 96 channel recording cable that fed into a a decoder for the neural interface computer. The computer was connected to two robotic arm systems which could move in response to the patient's thoughts (the decoder responds to spikes in action potential firing). After nearly 2000 days of training and assessement on the neural interface system, one patient was able to successfully use the robotic arm to lift up a cup of coffee, drink from it and place it down. This was the first time after 14 years the patient drank (almost) unassisted:

     

    In the latest paper, the medical team report that the patient can successfully augment the point-and-click movements of a computer mouse as well as the efficient use of an on-screen keyboard to express words and sentences. They were even able to conduct limited internet Google Chat using the system. The patient was able to do this after 1900 days of training by imagining the physical movement of the mouse, while connected to the BrainGate system. The key to speeding up the typing process was to use an ingenious radial keyboard rather than the traditional QWERTY keyboard:

    The implications of this brain-computer interface are that it solves the problem of slow, laborious communications between the paralyzed patient and the outside world. Such a device could be used to help not only people who suffer from Locked-in Syndrome but also those with spinal cord injuries, amyotrophic lateral sclerosis and any other disorders which cause quadruplegia.

    The ongoing clinical trial, named BrainGate2, can be found here at clinicaltrials.gov.