A Brain Chemical Helps Neurons Know When to Start a Movement

By washing through the brain, you can control the excitability of a large region of the brain more or less in the same way.

Many human diseases and mood disorders can be caused by abnormal levels of chemicals in the brain. Within their optimal levels, neuromodulators are like secret puppeteers holding the strings of the brain, constantly shaping circuits and shifting activity patterns into whatever may be the most adaptive for the organisms, moment by moment.

Mac Shine is a neurobiologist at the University of Sydney.

The brain states are shifting.

A burst of technological advances has paved the way for neuroscientists to look across the whole brain in real time. They have been made possible by a new generation of sensors that modify the metabotropic neuronal receptors, making them light up when a specific neuromodulator lands on them.

The lab of Yulong Li at Peking University in Beijing has developed many of these sensors. The team is taking advantage of the fact that the receptors have already evolved to detect these molecules, said Li.

There is going to be an enormous wave of people using all of those tools, according to Jessica Cardin, a neuroscientist at Yale University.

In a paper posted in 2020 on the preprint server bioarxiv.org, Cardin and her colleagues became the first to use Li's sensor to measure acetylcholine across the entire cortex in mice. Acetylcholine regulates attention and brain states related to arousal. It was thought that chyln made neurons more independent of the activity in their circuits, increasing their ability to be alert. The team found this to be true in small circuits. In networks with billions of neurons, higher levels of acetylcholine lead to more synchronized activity. The picture that does not have uniform effects everywhere depends on the region of the brain and the arousal level.

A study published in Current Biology last November upended long-held notions about the neuromodulator. Norepinephrine is part of a monitoring system. Since the 1970s, it has been thought that norepinephrine is not involved in this system during certain stages of sleep. In the new study, the University of Lausanne in Switzerland and her colleagues used new techniques to show for the first time that norepinephrine doesn't shut down during all stages of sleep.