Researchers have taken a key step towards recovering specific brain functions in sufferers of brain disease and injuries by successfully restoring the decision-making processes in monkeys.
By placing a neural device onto the front part of the monkeys' brains, the researchers, from Wake Forest Baptist Medical Centre, University of Kentucky and University of Southern California, were able to recover, and even improve, the monkeys' ability to make decisions when their normal cognitive functioning was disrupted.
The study, which has been published today, 14 September, in IOP Publishing's Journal of Neural Engineering, involved the use of a neural prosthesis, which consisted of an array of electrodes measuring the signals from neurons in the brain to calculate how the monkeys' ability to perform a memory task could be restored.
In the delayed match-to-sample task an image was flashed onto a screen and, after a delay, the monkeys were prompted to select the same image on the screen from a sampling which included 1-7 other images. Five monkeys (all rhesus, Macaca mulatta) were involved in the experiment and were trained for two years to perform to a 70-75 per cent proficiency in the task.
The movement of the monkeys' arms were tracked with a camera and translated to movements of the cursor on the screen; they were awarded with a drop of juice when they correctly matched an image.
The prosthesis was placed into two cortical layers L2/3 and L5 of the brain and recorded brain activity within structures known as minicolumns in the prefrontal cortex area.
Once it was confirmed that minicolumn communication between layers L2/3 and L5 was involved in decision making, it was supressed by administering the dopamine-modifying drug, cocaine, to the monkeys. The task was performed again but this time the researchers deployed a 'multi-input multi-output nonlinear' (MIMO) model to stimulate the neurons that were used i
|Contact: Michael Bishop|
Institute of Physics