When it comes to the sense of touch, our bodies are capable of detecting the lightest brush of a feather against skin, or a haymaker thump to the gut. But how do our nerves detect and distinguish such forces? What’s behind this incredible range of sensory detection? Scientists are getting closer to answering these questions, at least in fruit flies. They have identified cells that respond to certain pain stimuli and more recently they have also discovered that the neurons [nerve cells] pictured (purple) are responsible for detecting gentle touch. These cells have masses of protrusions called sensory filopodia packed with specialized ion channels (white), which activate the cell in response to gentle mechanical forces. Disturbances in either the channels or the protrusions render fruit fly larvae incapable of reacting to being tickled with an eyelash – a standard albeit quirky method of testing touch in flies.
Written by Ruth Williams
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