Bad food experiences, such as a dodgy curry that makes us sick for days, trigger an interruption in our brain, which means we never want to eat again, a study shows.
Researchers in the UK have been able to replicate the effect of a negative experience on eating behavior, using sugar-loving snails as laboratory models.
They used “aversive training”, which involved touching snails on the head when sugar appeared, as a proxy for food poisoning in humans while they were being filmed.
The aversive workout threw out an appetite suppressant switch, which meant the snails refused to feed on sugar, even when they were hungry.
Experts believe that something similar is happening, leading to “persistent physiological changes” specific to a particular food for the rest of our lives.
That the Tikka masala chicken from four years ago can make us never want to eat the dish again – and researchers think they know why
“Actually, a switch has been overturned in the brain, which means that the snail no longer eats sugar when it is presented, because sugar suppresses rather than activates feeding,” said study author Dr. Ildiko Kemenes of the University of Sussex. .
Snails like sugar and usually start feeding on it as soon as it is introduced to them, just like people when they see sweet food in the kitchen.
“Snails give us a similar, but exceptionally simple, pattern of how the human brain works,” said Professor George Kemenes, also at the University of Sussex.
“In our research, the negative experience that the snail had with sugar could be likened to eating a bad curry to eat, which then takes us out of that dish in the future.”
Despite their primitive appearance and reputation, there is a change in the snail’s brain that prevents them from eating too much.
Bad food experiences, such as a dodgy curry that makes us sick for days, trigger an interruption in our brain, which means we never want to eat again, a study shows
This appetite suppression switch (ASS) is controlled by a neuron – an extremely excitable cell type that transmits information to parts of the body through electrical signals.
“There is a neuron in the brain of the snail that normally suppresses the feeding circuit,” said Dr. Ildiko Kemenes.
“This is important because the network is prone to spontaneous activation, even in the absence of any food.”
“By suppressing the feeding circuit, it is ensured that the snail does not eat everything and everything.”
Researchers believe that something similar is happening in the human brain, considered a natural tactic to protect us against obesity (although it is likely that switches that suppress the appetite of some people work better than others).
Usually, when there is food, this neuron in the brain of the snail is inhibited, so that the food begins.
After aversive training of hungry snails, the researchers found that this neuron reversed its electrical response to sugar and became excited instead of being inhibited by it.
This increased activity from the excited neuron essentially threw away the ASS, suppressing the lust for the snail.
Importantly, this effect was observed only for sugar – which is why researchers compared it with the lasting psychological effects of people who consume a specific mass that makes them sick.
Researchers placed snails in Petri dishes and exposed them to sugar and “strong tactile stimuli to the head”
When the researchers presented the trained snails with a piece of cucumber, they found that the animal was still happy to eat it.
This showed that slight headaches during aversive training were associated only with the special type of food that was present at that time.
“We believe that in a human brain, a similar exchange could occur if certain groups of neurons reverse their activity according to 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 returned to sugar consumption again.
“This suggests that the neuron is needed to express learned behavior and to change the response to sugar,” said Dr. Ildiko Kemenes.
However, we cannot rule out that the sugar-activated sensory pathway also undergoes some changes, so we do not assume that this is all that happens in the brain.
The study was published in Current Biology.