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How the brain discerns between like and dislike

Valence is a term used to describe the good and bad feelings that neurons assign to different experiences, tastes, or sensations in the amygdala part of the brain.

Valence helps us discern bad smells and bitter tastes from good ones by assigning emotions to them. But how does the brain define good and bad tastes and experiences?

Now, new study examines exactly how valence assignment occurs in the amygdala and the neural circuitry involved.

The study was conducted by researchers from the Picower Institute for Learning and Memory and published in the journal Cell Reports.

The researchers focused on the basolateral amygdala and were able to show which neurons were involved in the valence processing circuitry, how the neurons interacted, and where the neural response was located and projected to in the brain.

For the study, the researchers gave trained lab mice sucrose and quinine drops to activate bitter and sweet tastes.

The two tastes were given a different sound tone so the mice learned to associate the tastes with sound. After playing the tones, the researchers identified which neurons responded and mapped its corresponding valence assignment.

Once the key neurons involved in valence assignment were identified, the researchers were able to make them responsive to pulses of light, which showed how the different neurons interacted in the basolateral amygdala and brain.

The results showed that positive valence was associated with the nucleus accumbens region of the brain and negative valence assignment was connected to the central amygdala.

The inner workings of valence assignment could help with treatments and therapies for mental health disorders.

“Perturbations of emotional valence processing is at the core of many mental health disorders,” said Kay Tye, the leader of the study. “Anxiety and addiction, for example, may be an imbalance or a misassignment of positive or negative valence with different stimuli.”

By Kay Vandette, Staff Writer

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