Tag: amygdala

Scientists may have Found the Specific Neurons Behind Anorexia Nervosa

Anorexia nervosa, a mental health disorder in which people dangerously restrict their eating or purge their stomachs soon after a meal, is one of the deadliest psychological diseases. Yet, the neural mechanisms behind this have remained unclear, and therapies are limited.

Scientists have been tailing a lead for years, though. They’ve known that the disorder is often associated with anxiety and depression, hinting that the biological basis for anorexia could be regulated by neurons somewhere in the brain region that controls emotion – the amygdala.

That’s exactly where Haijiang Cai, a University of Arizona associate professor in the Department of Neuroscience and BIO5 Institute member, and his team found it: Anorexia is caused by a combination of two subregions in the amygdala, according to new research published in Cell Reports.

One knot of neurons in the central nucleus of the amygdala curbs appetite when a person gets full, feels nauseous or tastes something bitter. The other is in the oval region of the bed nucleus of the stria terminalis, which also halts eating due to inflammation and sickness.

Cai and his research team found that when they destroyed a certain type of brain cell, called PKC-delta neurons, in both of these regions, they could prevent anorexia development.

They also found that PKC-delta neurons become more active in response to eating during the anorexia development. What’s more, when they artificially activated these neurons, they caused a suppression in eating habits and increased exercise.

“This study suggests two important insights to treat anorexia,” Cai said. “One is that we need to target multiple brain regions to develop therapies. We also need to treat multiple conditions. For example, maybe one drug will target nausea and another drug target will target inflammation, and you have to combine them, like a cocktail therapy, to have better therapeutic effects.”

The team relied on mice models for their research.

“There’s no animal model that can mimic human disease completely, but this is as close as we can get,” Cai said. “For example, there are multiple common features, including a warped body image, a very low body weight, limited food intake and excessive exercise. We can’t know if an animal has a warped body image, but we can measure the other three features.”

One future step – since researchers cannot destroy neurons for human treatment – is to develop a method to silence the neurons temporarily, using drugs or some other method to test if that can prevent anorexia development or speed up recovery for people who have already developed the disorder.

Source: University of Arizona

Amygdala Enlargement in Kids with ASD Starts Early

Source: Pixabay

The amygdala, which is enlarged in two-year-old children with autism spectrum disorder (ASD), begins its accelerated growth between 6 and 12 months of age, suggests a study appearing in the American Journal of Psychiatry. The findings indicate that therapies to reduce the symptoms of ASD might have the greatest chance of success if they begin in the first year of life, before the amygdala begins its accelerated growth.

The amygdala, which is involved in processing emotions, such as interpreting facial expression in typically developing children increases substantially in volume from 7.5 to 18.5 years of age. The amygdala in children with autism is initially larger, but does not undergo the age-related increase observed in typically developing children.

The study included 408 infants, 270 of whom with an increased ASD risk from having an older sibling with ASD, 109 typically developing infants, and 29 infants with Fragile X syndrome. The researchers conducted MRI scans of the children at 6, 12 and 24 months of age. They found that the 58 infants who went on to develop ASD had a normal-sized amygdala at 6 months, but an enlarged amygdala at 12 months and 24 months. Moreover, the faster the rate of amygdala overgrowth, the greater the severity of ASD symptoms at 24 months. The infants with Fragile X syndrome had no differences in amygdala growth but enlargement of the caudate, which was linked to increased repetitive behaviours.

The researchers suggested that difficulty in processing sensory information during infancy may stress the amygdala, leading to its overgrowth.

Source: NIH