Drosophila larvae whiff and adapt to survive in a dynamically changing world. Credit: Mrunal Nagaraj Kulkarni (CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)

Researchers at the CSIR-Centre for Cellular and Molecular Biology in Hyderabad, India, have identified a transporter protein in the fruit fly brain that plays a vital role in habituation1.

Habituation, which is widespread from single-celled animals to humans, enhances attention to environmental stimuli that are essential for survival, such as food, mates and danger.

The protein, known as choline transporter, ferries choline – an essential nutrient – into neurons so that the cells can produce the neurotransmitter acetylcholine. This regulates habituation to smells by firing specific neurons.

The brain circuitry and molecular mechanisms involved in habituation are currently poorly understood. A team led by Runa Hamid set out to study the ability of fruit flies to distinguish essential from non-essential stimuli. They specifically investigated how fruit flies are able to disregard a specific scent.

The scientists found that flies with fewer choline transporters in certain parts of their brain did not become habituated to the scent. Instead, they became hypersensitive and overreacted to the scent.

The hypersensitivity and other changes observed in the flies with fewer choline transporters are similar to symptoms experienced by people with autism spectrum disorder. Previous research has linked variations in the choline transporter to attention deficit hyperactivity disorder.

The findings pave the way for future research to investigate the role of choline transporters in disorders related to habituation. The researchers say their work may lead to a better understanding of several neurological disorders.