A neural implant helps rats with
short-term recall.
(June 23, 2011) Researchers have developed the first memory
prosthetic device—a neural implant that, in rats, restored lost brain function
and improved short-term memory retention. While human testing is still a
distant goal, the implant provides evidence that the brain’s complex neural
code can be interpreted and reproduced to enhance cognitive function.
The device, which consists of a
tiny chip and a set of 32 electrodes, marries math and neuroscience. At its
heart is an algorithm that deciphers and replicates the neural code that one
layer of the brain sends to another. The function restored by the implant is
limited—rats were able to remember which of two levers they had pressed. But
its creators believe that a device on the same principle could one day be used
to improve recall in people suffering from stroke, dementia, or other brain
damage.
Wake Forest University
neurophysiologist Samuel Deadwyler first trained the rats to press two
different levers in succession. The animals learned to press one lever as it
was presented to them and then, after a delay, remember which they’d pressed
and choose the other one the second time around. While the rats performed the
task, two sets of minute electrodes recorded the activity of individual neurons
on the right and left sides of the hippocampus, an area of the brain that
consolidates short-term memory by processing information as it passes through
multiple layers. A set of 16 electrodes—eight on the right, eight on the
left—monitored signals being sent from neurons in an area of the hippocampus
called the CA3 layer, and another 16 monitored the processed signals received
by neurons in the CA1 layer.