A Sexy New Implant

Researchers have developed the first memory prosthetic device—a neural implant that, in rats, restored lost brain function and improved short-term memory retention, evidence that the brain’s complex neural code can be both interpreted and reproduced to aid memory conversion from short-term to  long-term storage.

 

Neurophysiologist Samuel Deadwyler of Wake Forest University 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 two sets of tiny 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. Another set of electrodes—eight on the right, eight on the left—monitored signals being sent from neurons in the CA3 layer area of the hippocampus and another 16 monitored the outgoing signals received by neurons in the CA1 layer.

Biomedical engineer/neuroscientist Theodore Berger (U. of So. Cal.) and Deadwyler decoded the neuron’s activity during a correct sequence, hinting at the formation of a real short-term memory. They then stimulated the nerves with the implant in the same pattern and retested the rats. This time, the animals made fewer mistakes and could remember which lever to press even after long delays. The researchers blocked memory formation with  drugs, and found that the rats could still remember which lever to press if they were juiced with the correct neural impulse pattern—nice proof of concept.

The chip (and its set of electrodes) holds an program that deciphers and the reproduces the neural messages that the CA3 layer of the brain sends to CA1. Its creators believe that an implant built on the same principles with gnarlier hardware could improve memory in people with brain damage.  And, of course, there’s the Jeopardy! show.

Berger and Deadwyler plan to move their research into nonhuman primates.