Some of the classic characteristics of the autistic spectrum disorder (ASD) describe a state of sensory overload - colors are too bright, light too intense, sounds too vivid, touch too acute, and odors that overwhelm. A Harvard University research scientist recently presented the findings of a study she conducted that used very simple fruit fly brains to try to unlock the mystery of the sensory overstimulation experienced by autism patients.
The researcher, a neurobiologist named Rachel Wilson, felt that understanding the mechanisms of the extremely complex human brain would develop most effectively if less complex brains were studied one evolutionary step at a time. Her study, titled “Sensory Processing in Dropsophilia: Synapses, Circutis, and Computations,” was presented at the annual meeting of the Society for Neuroscience on November 11, 2013. Dropsophilia is the genus name of fruit flies.
Wilson discovered that fruit flies have a neurological control that she likens to a volume-control system on a stereo or TV or to the gas and accelerator pedals in an automobile. This control governs how fruit flies experience odors.
When a fruit fly detects a faint odor, it cranks up the volume to get a better whiff of whatever aroma has caught its attention. The fruit fly’s brain becomes much more sensitive to the odor, making it easier to detect, identify, and perhaps follow if the odor is something that promises to be good enough to eat. If the odor is strong and easily detected, the fruit fly brain tones down the sensitivity level of the olfactory process. It minimizes the impact of the powerful aroma to prevent the fruit fly’s olfactory system from being overwhelmed by aromatic intensity, just like a car’s brake pedal controls excess speed or a volume control reduces the sound of music.
Wilson expects to find similar neurological mechanisms in the more advanced brains of higher animals, including humans. It’s likely similar mechanisms control the vigor of other sensory input besides just the sense of smell.
When the “volume control” of the senses is not working properly, as might be the case in autism, everyday activities and environmental factors could easily overload the senses of a person with the disorder. In the case of sensory extremes - the scent of perfume, bright sunlight glinting off water or snow, school bells ringing between classes - an autistic person may experience the sensory input with frightening intensity.
If the people who study autism know to look for a control mechanism similar to the olfactory sensory control of the fruit fly, the key to unlocking the mystery of the disorder may be in sight, according to Wilson.
Source: Hamilton, Jon. “Can A Fruit Fly Help Explain Autism?” Shots / Morning Edition. NPR. Dec 27, 2013. Web. Dec 30, 2013.
