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In a new study, researchers attached electrodes to individual neurons in monkeys’ brains and then rerouted those neuronal signals through a brain-machine interface, which converted them into electrical signals that controlled the monkeys’ own paralyzed muscles. Researchers say this roundabout feat of bioengineering could eventually lead to new treatments and prosthetics for paralyzed people.

The implant exploits the fact that even when the neural connection between a brain region and the muscles it controls is severed or damaged by, say, a stroke or spinal injury, the controlling neurons remain active. For example, people living with quadriplegia who try to move their arm still generate arm-movement signals in the motor cortex of their brain, even after several years of paralysis [New Scientist]. The new study is the first to send the signals back to the user’s own muscles, as opposed to related research in which the signals are fed into electronic devices.

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A small study has found that the brains of men and women are wired differently in a region that is related to speech, memory, and hearing. Researchers studied the brain tissue from four men and four women who were all having a small portion of their brains excised as a treatment for epilepsy. They found that in the brain region called the temporal neocortex, men have a higher density of synapses, which are the connection points between brain cells.

For many years, scientists have searched for structural variations between men’s and women’s brains to explain psychological studies showing that, overall, the sexes think and act differently. Past studies found differences in brain mass and neuron density, but “they were hyped and untrustworthy,” [neuroscientist Edward] Jones says. This study is meticulously detailed, he notes. It is the first to show gender differences on such a fine scale — at the synapse [Science News].

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Researchers have gotten an amazingly close look at the human brain’s methods of short-term memory formation and recollection. A new study has examined the activity of individual brain cells, and found that the same neurons that fire when a person gets their first look at something fire again when they recall it.

Scientists at the University of California, Los Angeles, (U.C.L.A.) showed 13 volunteers—epilepsy patients with therapeutic electrodes implanted in their brains—several five- to 10-second clips from videos such as The Simpsons. The researchers found that a small sample comprising some 50 neurons in the hippocampus and entorhinal cortex (memory centers in the brain) fired in distinctive repeatable patterns that differed for each clip [Scientific American]. A few minutes later, when researchers asked the volunteers to think back to the film clips and say what came to mind, the neurons fired in the same distinct patterns when they mentioned each clip.

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Researchers have built a “biological brain” for a robot using a dish full of rat neurons, and have harnessed the neurons’ electric signals to navigate the robot around a pen. Researchers say the experiment should add to their understanding of how brain cells function, and could provide insight into what goes wrong in neurons affected by diseases like Alzheimer’s and Parkinson’s.

The robot’s controller nestles inside a small pot containing a pink broth of nutrients and antibiotics. Inside that pot, some 300,000 rat neurons have made - and continue to make - connections with each other. As they do so, the disembodied neurons are communicating, sending electrical signals to one another just as they do in a living creature [New Scientist]. The neurons’ automatic drive to connect and communicate may be an indication of how sturdy brain cells are; researcher Steve Potter, who has been involved in similar experiments, says that brain cells have “evolved to reconnect under almost any circumstance that doesn’t kill them” [Telegraph].

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