Since leptin is released by fat cells, scientists believe its presence in the blood has the potential to signal to the brain that the animal is in an environment with lots of food and doesn’t need to conserve energy. . New research shows that low leptin levels alert the brain to malnutrition, shifting the brain into a low-energy mode.
“These results are unusually satisfying,” says Julia Harris, a neuroscientist at the Francis Crick Institute in London. “It is not so common to get a stunning find that matches the existing understanding,”
Distorting neuroscience?
One important implication of the new finding is that much of what we know about how the brain and neurons work may have been learned from brains that the researchers inadvertently put into high energy mode. low quantity. It is extremely common to restrict food intake to rats and other laboratory animals for weeks before and during neuroscientific research to motivate them to perform tasks in exchange for food rewards. (Otherwise, animals often just want to sit around.)
“A really profound effect is that it clearly shows that food restriction affects brain function,” says Rochefort. The changes observed in the flow of charged ions may be particularly important for learning and memory, she suggests, because they are based on specific changes occurring at synapses.
“We have to think very hard about how we design experiments and how we interpret experiments if we want to question the sensitivity of animals’ perception or the sensitivity of cells,” says Glickfeld. nerve cells.
The results also open up entirely new questions about how other physiological states and hormone signals can affect the brain, and whether different levels of hormones in the blood can cause individuals to see the world slightly differently. or not.
Rune Nguyen Rasmussen, a neuroscientist at the University of Copenhagen, notes that people vary in their leptin and overall metabolic profiles. “So does that mean that even our visual perception – even though we may not be aware of it – actually differs from person to person?” he say.
Rasmussen cautions that the question is provocative, with few definite suggestions for an answer. It appears that the conscious visual perception of the rats was affected by food deprivation because there were changes in the neuronal representation of those perceptions and in the animals’ behaviour. However, we cannot know for sure, “because this requires the animals to describe to us their qualitative visual experience, and it is clear that they cannot do this,” he said. speak.
But so far there has not been any reason to think that the low-power mode activated by optic cortical neurons in mice, and its effects on cognition, would not be the same. humans and other mammals.
“These are the mechanisms that I think are really fundamental to neurons,” says Glickfeld.
Editor’s Note: Nathalie Rochefort is a member of the board of trustees of the Simons Initiative for Developing Brains, funded by the Simons Foundation, sponsor of the This editorially independent magazine. Maria Geffen is a member of the advisory board for Quantum.
Original story Reprinted with permission of Quanta magazine, an editorially independent publication of The Simons Organization whose mission is to advance public understanding of science by including research developments and trends in mathematics as well as the physical and life sciences.
