Since leptin is released by fat cells, scientists believe its presence in the blood is likely to signal to the brain that the animal is in an environment where food is ample and there’s no need to conserve energy. According to new research, low levels leptin may alert the brain that there is malnutrition in the body. This could cause the brain’s switch to low-power mode.
“These results are unusually satisfying,” said Julia HarrisA neuroscientist at London’s Francis Crick Institute, Dr. “It is not so common to obtain such a beautiful finding that is so in line with the existing understanding,”
Are you distorting Neuroscience?
One important implication of these new findings is that many of our knowledge about brains and neuron function may have been gleaned from brains that researchers accidentally put in low-power mode. In neuroscience studies, it is very common to limit food availability to mice and other experimental animals weeks in advance to encourage them to complete tasks in exchange for food rewards. (Alternatively, animals may prefer to just sit there.)
“One really profound impact is that it clearly shows that food restriction does impact brain function,” said Rochefort. Because they are dependent on specific changes at synapses, the observed changes in charge ions flow could be particularly significant for memory and learning, she suggested.
“We have to think really carefully about how we design experiments and how we interpret experiments if we want to ask questions about the sensitivity of an animal’s perception, or the sensitivity of neurons,” Glickfeld said.
These results raise new questions about how hormone signals and other physiological states could impact the brain. It is also possible that individuals might see the world differently if they have different levels of hormones.
Rune Nguyen RasmussenA neuroscientist from the University of Copenhagen noted that individuals have different metabolic profiles and levels of leptin. “Does that mean, then, that even our visual perception—although we might not be aware of it—is actually different between humans?” he said.
Rasmussen warns against provocative questions that leave few clues as to their answers. It seems likely that the conscious visual perceptions of the mice were affected by food deprivation because there were changes in the neuronal representations of those perceptions and in the animals’ behaviors. We can’t know for sure, however, “since this would require that the animals could describe to us their qualitative visual experience, and obviously they cannot do this,” he said.
But so far there also aren’t any reasons to think that the low-power mode enacted by the visual cortical neurons in mice, and its impact on perception, won’t be the same in humans and other mammals.
“These are mechanisms that I think are really fundamental to neurons,” Glickfeld said.
Editor’s note: Nathalie Rochefort is a member of the board of the Simons Initiative for the Developing Brain, which is funded by the Simons Foundation, the sponsor of This independent editorial magazine. Maria Geffen is a member the advisory board Quanta.
Original story Reprinted with permission of Quanta Magazine, An independent editorial publication of The Simons Foundation The mission of this website is to increase public understanding of science through the coverage of research developments and trends in mathematics, the physical and life sciences.