One study reveals that bad experiences with food, such as a dodgy curry that makes us sick for days, cause a change in the brain that means we never want to eat it again.
Researchers in the UK have been able to replicate the effect of a negative experience on eating behavior, using sugar-loving snails as models in the laboratory.
They used an “aversive workout,” which consisted of touching the screws on the head when sugar appeared, as a substitute for food poisoning in humans, while filming.
Aversive training triggered a switch to suppress appetite which meant the snails refused to feed on sugar, even with hunger.
Experts think something similar is happening, leading to a specific “persistent physiological change” of a certain food for the rest of our lives.
This tikka masala chicken sprinkled four years ago may make us never want to eat the dish, and researchers think they know why
“Indeed, a switch has been activated in the brain, which means that the snail no longer eats sugar when it is presented to it, because now the sugar suppresses instead of activating the food,” said the author of the study, Dr.
Snails like sugar and usually start feeding on it as soon as it is introduced to them, just like humans when they see sugary sweets in the kitchen.
“The screws provide us with a similar but exceptionally basic model of how human brains work,” said Professor George Kemenes, also of the University of Sussex.
“In our research, the negative experience the snail had with sugar could be compared to eating a bad curry to take away, which leaves us out of this dish in the future.”
Despite their primitive appearance and reputation, there is a snail brain that prevents them from eating too much.
One study reveals that bad experiences with food, like a splashed curry that makes us sick for days, cause a change in the brain that means we never want to eat it again.
This appetite suppressant switch (ASS) is controlled by a neuron, a highly excitable cell type that transmits information to parts of the body through electrical signals.
“There is a neuron in the snail’s brain that normally suppresses the feeding circuit,” Dr. Ildiko Kemenes said.
“This is important because the network is prone to activating spontaneously, even in the absence of food.”
“By suppressing the power circuit, you make sure the screw doesn’t just eat anything and everything.”
Researchers think something similar is happening to the human brain, which is believed to be a natural tactic to protect us from obesity (although some appetite suppressant switches are likely to work better than others).
Normally, when there is food, this neuron in the brain of the snails is inhibited so that feeding can begin.
After the aversive training of the hungry snails, the researchers found that this neuron reversed its electrical response to sugar and became excited instead of inhibiting it.
This increase in the activity of the excited neuron essentially caused the ASS, suppressing the appetite of the snails.
While important, this effect was only seen in sugar, which is why researchers have compared it to the lasting psychological effects of humans eating a specific food that makes them sick.
Researchers placed screws on Petri dishes and exposed them to sugar and “strong tactile stimuli in the head.”
When investigators presented the trained snails with a piece of cucumber, they found that the animal was still happy to eat it.
This showed that gentle head taps during aversive training were associated only with the particular type of food that was there at the time.
“We believe that in a human brain a similar change could occur in which particular groups of neurons reverse their activity in line with the negative association of a particular food,” said Professor George Kemenes. .
The research also revealed that when the neuron was completely removed from the trained snails, they ate sugar again.
“This suggests that the neuron is necessary for the expression of learned behavior and to alter the response to sugar,” said Dr. Ildiko Kemenes.
“However, we can’t rule out that the sugar-activated sensory pathway is also undergoing some changes, so we don’t make the assumption that this is all that’s going on in the brain.”
The study has been published in Current Biology.