A study, published in the journal Science, shows that brain transplants in a key area of mice brains is more repairable than was widely believed. No development in this area was bigger than an implant designed to record and replay memories.
In this study, neuronal transplants have repaired brain circuitry and normalized function in mice with a brain disorder, being unable to respond to leptin, a hormone that regulates metabolism and controls body weight.
These mutant mice usually become morbidly obese, but the neuron transplants repaired defective brain circuits, letting them to respond to leptin and gain much less weight.
Performing a memory task that trained a group of implant rats to get a drink of water by touching one lever in a cage, then—after a distraction—touching another. In order to know which lever to push the second time, they had to remember which one they’d already pushed. Electrodes in the implants recorded signals between two areas of their brains involved in storing new information in long-term memory. Researchers gave the rats a drug that kept those brain areas from communicating.
The rats still knew they had to press one lever then the other to get water, but couldn’t remember which lever they’d already pressed. When researchers played back the neural signals they’d recorded earlier via the implants, the rats again remembered which lever they had hit, and pressed the other one. When researchers played back the signals in rats not on the drug (thus amplifying their normal memory) the rats made fewer mistakes and remembered which lever they’d pressed even longer.
The study found that newly developed neurons from embryonic cells are efficient at integrating with the native neuronal circuitry. They communicated to recipient neurons through normal synaptic contacts, and that the brain, in turn, signaled back. Responding to leptin, insulin and glucose, these neurons had effectively joined the brain’s network and rewired the damaged circuitry.
This ground-breaking research shows that neural signals involved in memory can be recorded and replayed, suggesting the possibility of new therapeutic approaches to conditions such as spinal cord injury, autism, epilepsy, ALS (Lou Gehrig’s disease), Parkinson’s disease, Huntington’s disease and dementias such as Alzheimer’s disease.
