Neuroscientists have made a brain implant that restored decision-making ability in laboratory monkeys whose faculties had been experimentally addled by cocaine. Eventually, researchers hope, such prostheses could boost cognitive abilities of brain-damaged patients.
In this experiment, five rhesus monkeys were wired up with an implant that tapped into two areas of the prefrontal cortex, the part of the brain credited with such functions as thinking and planning, that communicate during decision making. First, the researchers used the implant to record electrical signals that those neurons sent when the monkey was making a correct match, sort of like tapping a phone conversation. Next, they gave the monkeys cocaine, which impaired their performance on the matching task. But the researchers were able to override the effect of the drug by sending the neurons involved in the task the “correct” signals—based on the ones recorded earlier—through the implant. With this prosthetic boost, the monkeys performed as well as they had before taking cocaine. (The stimulation also improved performance in sober monkeys, the researchers found, making them better at the task than they were from training alone.)
When communication between two cortical areas was impaired by cocaine, the brain implant compensated by sending signals directly to their final destination. “The whole idea is that the device would generate an output pattern that bypasses the damaged area, providing an alternative connection,” neuroscientist Sam A. Deadwyler, one of the study authors, told the New York Times. In the future, such implants might be able to circumvent brain damage in a more familiar primate: humans.
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