Reading the mind with machines
By Marla Broadfoot
Researchers are developing brain-computer interfaces that would enable communication for people with locked-in syndrome and other conditions that render them unable to speak
In Alexandre Dumas ’ s classic novel The Count of Monte- Cristo , a character named Monsieur Noirtier de Villefort suffers a terrible stroke that leaves him paralyzed . Though he remains awake and aware , he is no longer able to move or speak , relying on his granddaughter Valentine to recite the alphabet and flip through a dictionary to find the letters and words he requires . With this rudimentary form of communication , the determined old man manages to save Valentine from being poisoned by her stepmother and thwart his son ’ s attempts to marry her off against her will .
Dumas ’ s portrayal of this catastrophic condition — where , as he puts it , “ the soul is trapped in a body that no longer obeys its commands ” — is one of the earliest descriptions of locked-in syndrome . This form of profound paralysis occurs when the brain stem is damaged , usually because of a stroke but also as the result of tumors , traumatic brain injury , snakebite , substance abuse , infection or neurodegenerative diseases like amyotrophic lateral sclerosis ( ALS ).
The condition is thought to be rare , though just how rare is hard to say . Many lockedin patients can communicate through purposeful eye movements and blinking , but others can become completely immobile , losing their ability even to move their eyeballs or eyelids , rendering the command “ blink twice if you understand me ” moot . As a result , patients can spend an average of 79 days imprisoned in a motionless body , conscious but unable to communicate , before they are properly diagnosed .
The advent of brain-machine interfaces has fostered hopes of restoring communication to people in this locked-in state , enabling them to reconnect
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