Novel neural pathway for odour tracking
A new neural pathway that regulates the sensitivity of the olfactory system to odour concentrations has been found by researchers from the MRC Centre for Developmental Neurobiology (CDN) at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN). The results have been published in the Journal of Neuroscience.
To survive, animals constantly respond to sensory stimuli from their surrounding environment and many species need to detect odour concentration in the air, as an increase in concentration is likely to signal greater proximity to an odour’s source and so may indicate the direction of movement for the animal. The researchers used Drosophila larvae in the study because they move towards food in response to odour, and found the neurons responsible for odour detection in the larvae brain by silencing them, which caused the larvae’s ability to navigate towards the food in low odour concentrations to diminish. In addition, when they increased the excitability of the target neurons, the larvae found the food quicker.
“These neurons boost odour input when odour concentrations are low allowing the brain to decipher small changes in odour concentration,” said Dr Camilla Larsen from the MRC Centre for Developmental Neurobiology and senior author of the study. “The larvae can therefore recognize small changes in odour concentration and navigate towards the odour source.”
The mechanism by which odour stimuli are decoded by the brain is similar between different animal species and discoveries made in even simple organisms like Drosophila are applicable to mammals and humans. Odour sensitivity is important for typical activities other than food finding including avoiding predators and responding to potential mating partners, and so discovering more about how the brain translates odour intensity is a step to better understanding how it is able to evaluate the sensory input and react to it.
“We have discovered a novel set of neurons in fruit flies that help the brain understand different concentrations of an odour, such as the odour coming from food, but there are still a lot of questions regarding how the neural circuitry translates odours into behavioural responses,” Dr Larsen concluded.
This work was funded by a Wellcome Trust Research Fellowship
Paper reference: Slater G., Levy P., Chan K.L., Larsen C. ‘A central neural pathway controlling odor tracking in Drosophila’ published in Journal of Neuroscience DOI: 10.1523/JNEUROSCI.2331-14.2015
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