Scientists have successfully restored and in some cases enhanced decision-making ability in brain-damaged monkeys on cocaine by connecting a prosthetic device to their brains. This breakthrough may one day help restore cognitive ability in people who have cognitive deficiencies due to brain disease or injury.
Researchers from the Wake Forest Baptist Medical Center explain that the electronic prosthetic system taps into the existing circuitry in the brain at the cellular level and records the firing patterns of multiple neurons in the prefrontal cortex, the portion of the brain responsible in decision-making.
The device then electrically stimulates the decision-based neural activity by playing the recording back to the same part of the brain.
The team found the device not only restored decision-making function, but in some cases even improved it, according to the study published in the Journal of Neural Engineering.
"The prosthetic device is like 'flipping a switch' to turn on a decision in real time," study author Sam Deadwyler, professor of physiology and pharmacology at Wake Forest Baptist said in a statement.
Researchers had trained five monkeys to match a variety of images on a computer screen until they were correct 70 percent to 75 percent of the time.
Researchers explained that the monkeys were trained to select, using a hand-controller cursor, an image that appeared on the screen. Afterwards the screen would go black for up to two minutes and the two to eight images would reappear including the initial one on the same screen.
Researchers said that when the monkeys correctly chose the image that was shown first, the electronic prosthetic device would record the pattern of neural pulses associated with their decision using a multi-input multi-output nonlinear (MIMO) mathematical model.
Afterwards, researchers administered cocaine, a drug known to disrupt cognitive ability, to the monkeys to simulate brain injury. Study results show that after the monkeys took cocaine, their scores for the "repeat the image-selection" tasks decreased by 13 percent form normal.
However, when the prosthetic device was turned on during these "drug sessions," the device detected when the monkeys were likely to choose the wrong image and played back the previously recorded "correct" neural patterns for the task.
The latest findings show that the MIMO device was effective in restoring the cocaine-impaired decision-making ability and even improve decision making by 10 percent above normal, even when the drug was still present and active.
"The basis for why the MIMO prosthesis was effective in improving performance was because we specifically programmed the model to recognize neural patterns that occurred when the animals correctly performed the behavioral task in real time, which is a unique feature of this particular device," lead author Robert Hampson, an associate professor of physiology and pharmacology at Wake Forest Baptist said in a statement.
"Based on the findings of this study, we hope in the future to develop an implantable neuroprosthesis that could help people recover from cognitive deficiencies due to brain injuries," he added.