Scientists have found a new type of brain cell that might explain why humans are wired differently from other animals.

A study by a team led by Ed Lein of Allen Institute for Brain Science and Gábor Tamás of the University of Szeged in Szeged identified a kind of brain cell found in people, but not mice. It was named "rosehip neuron" because it looked like a rose after the petals have fallen off.

The Rosehip Neuron

"We really don't understand what makes the human brain special," said Lein. "Studying the differences at the level of cells and circuits is a good place to start, and now we have new tools to do just that."

Rosehip neurons are inhibitory neurons that work like brakes to a car: they tell the flow of electrochemical information in the brain to slow down or stop. Researchers found the new brain cells while examining samples from two deceased males who in their 50s who donated their bodies to science. They took sections of the top layer of the cortex, the part of the brain responsible for consciousness, and compared them to mice.

"The neocortex, the outermost layer of cells, is greatly expanded in humans — about a thousandfold compared to mice," explained Trygve Bakken, co-author of the study. "From neurological studies, if you have a stroke in your neocortex for example, it really impacts your ability to do these sorts of high-order cognitive processing."

The study found that the same neuron is not present in brains of mice, which are often used to sample medicine and other laboratory experiments. Whether the newly discovered type of brain cells also exist in other species such as monkeys or chimps remain unknown.

Researchers plan to further look into whether the rosehip neurons are also present in other parts of the human brain.

The study was published in the journal Nature Neuroscience.

Game Changer

The findings of the ground-breaking study make major changes to future research surrounding the human brain. Lein said that the study "throws some doubt" on the use of mice to study human behavior and brain-related diseases.

The existence of the rosehip neurons in the human brain and not in mouse might also shed light on the mystery of why some experimental treatments for brain disorders work on mice, but not on people.

Joshua Gordon, National Institue of Mental Health director, hopes that the new discovery could provide clues to scientists who are studying diseases to understand disorders including autism, schizophrenia, and Alzheimer's.

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