Bristle sensilla

Bristle sensilla are a class of mechanoreceptors found in insects and other arthropods that respond to mechanical stimuli generated by the external world.

Bristle sensilla can be divided into two main types, macrochaete and microchaete, based on their size and physiology.

This induces mechanotransduction channels to open, producing an electrical signal that is carried along an axon to the central nervous system.

[8] It is thought that in both the SEZ and the VNC that the spatial organization of these axons represents a somatotopic map of different body segments.

These hairs tend to be longer with a distinct curve to their shape, they also contain a pore at the very tip that is used to sense various chemical signals.

[10] It is thought that this spatial difference in behavior was due to wing stimulation mimicking the invading presence of mites.

This has been characterized previously with extracellular recordings of individual bristle neurons in the fly in response to mechanical and optogenetic stimulation.

[13][14] On the other hand, only slow adapting bristles have been observed in flies with an exceedingly low threshold of only 1 degree.

Schematic cross-section of an insect bristle sensillum. Each bristle is composed of a hair with its base fixed to the dendrite of a sensory neuron. The hair acts as a lever that exerts force on the dendrite, inducing mechanotransduction channels to open and producing electrical currents.
Bristle sensilla on the edge of a fruit fly wing. Green fluorescent labeling shows where sensory neurons innervate the bristles. In this image, some of the neurons are mechanosensory and some are gustatory.