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Shining lasers into the brain could control hunger, a breakthrough study has found.Researchers from North Carolina University made the discovery while working with genetically modified mice whose brain cells had been tweaked to respond to light.
By pinpointing the cells that send hunger messages to and from the brains of the mice, the neuroscientists were able to 'fire' or activate these neurons by shining lasers directly onto them.
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Researchers from North Carolina genetically modified mice so their brain cells responded to light. By shining a laser onto a specific group of cells, pictured, the neurons became active and the mice began eating. They continued to eat until the scientists switched the laser off
WHAT IS THE HYPOTHALAMUS?
The hypothalamus is the part of the brain that sends and receives messages for various bodily functions.
It controls metabolism and other nervous system activities, as well as releases certain hormones.
The specific cells that control hunger and thirst are in the lateral hypothalamus.
By activating the BNST neurons, the researchers from North Carolina effectively shut down the neurons in the lateral hypothalamus.
This meant the mice were unable to establish whether they were hungry or full and caused the rodents to carry on eating.
This suggest the neurons in the lateral hypothalamus are the ones responsible for telling a mice, and potentially a person, when to stop eating.
This contradicts previous research that hinted that these neurons encouraged eating.
'This is a really important missing piece of the puzzle,' neuroscientist Seth Blackshaw told Science News. 'These are cell types that weren’t even predicted to exist.'
The scientists were led by Joshua Jennings and Garret Stuber from the university.
They genetically modified the mice so that a specific group of neurons in their brains, in a region called the bed nucleus of the stria terminalis (BNST), would respond to light.
By shining lasers onto these neurons, the scientists discovered the cells would either 'fire' and become active, or remain silent.
Some of these neurons send messages directly to the 'lateral hypothalamus', the part of the brain that controls hunger and sends and receives messages to and from the stomach.
The researchers discovered that when the neurons were 'switched on' by the laser, the mice would eat non-stop, yet as soon as the neurons were silenced, or 'switched off', the mice would stop eating.
In experiments, even hungry mice shunned food when the neurons were deactivated. This technique is called optogenetics and each mice was in roughly 20-minute bursts.
By activating the BNST neurons, it shut down the neurons in the lateral hypothalamus. This meant the mice were unable to establish whether they were hungry or full and caused the rodents to carry on eating.
The researchers believe this means the neurons in the lateral hypothalamus are the ones responsible for telling a mice, and potentially a person, when to stop eating.
This contradicts previous research that hinted that these neurons encouraged eating. However, it is unsure whether the mice would continue to eat if the neurons remained stimulated, or if they would starve if they remained silent.
This discovery can now lead to better understanding of why and how people develop eating disorders, and how to treat them. The findings appear in the journal Science.
The researchers discovered that when the neurons were 'switched on' by the laser, the mice would eat non-stop, yet as soon as the neurons were silenced, or 'switched off', the mice would stop eating, pictured. In a separate experiment, hungry mice were found to shun food when the cells were left inactive.
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