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Neurotransmitter that makes a memory positive or negative discovered



A new study has identified a neurotransmitter responsible for marking a memory positive or negative.

The discovery, published in Nature, paves the way for a better understanding on why some people are more likely to retain negative emotions than positive ones. This could treat disorders such as anxiety, depression or post-traumatic stress disorder (PTSD).

Kay Tye, one of the senior authors of the paper, said: “We’ve basically gotten a handle on the fundamental biological process of how you can remember if something is good or bas. This is something that’s core to our experience of life, and the notion that it can boil down to a single molecule is incredibly exciting.”

In 2016, Tye discovered that a group of neutrons in the brain’s basolateral amygdala (BLA) helps assign valence when mice are learning. One set of BLA neurone was activated with positive valence, as the animals learned to associate a tone with a sweet taste.

A separate set of BLA neurons was activated with negative valence, as the animals learned to associate a different tone with a bitter taste.

“We found these two pathways- analogous to railroad tracks – that were leading to positive and negative valence, but we still didn’t know what signal was acting as the switch operator to direct which track should be used at any given time,” said Tye.

The findings suggest that the brain’s default state is to have a bias toward fear – the neurons associated with negative valence are activated until neurottensin is releases, switching on the neurons associated with positive valence.

From an evolutionary perspective, Tye says, this makes sense because it helps people avoid potentially dangerous situations – and it probably resonates with people who tend to find the worst in a situation.

The researchers still have questions about whether levels of neurotensin can be modulated in people’s brains to treat anxiety or PTSD. They are also planning future studies to probe what other brain pathways and molecules are responsible for triggering the release of neurotensin. 


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