FMost furry creatures, from the largest tiger to the smallest mouse, have a common problem: how to dry themselves without a bath towel. Many people have developed similar strategies. It’s a vigorous, whole-body shaking motion that researchers call a “wet dog shake.” Although it seems somewhat silly, this behavior can be important in the following cases: survivalcan help animals dry quickly, saving body heat and precious calories.1
Currently, a research team led by a neurobiologist at Harvard University is david ginty identified the somatosensory mechanisms that mediate this behavior. in study Published today (November 7th) scienceGinty and his team discovered that a type of mechanoreceptor called C-fiber low-threshold mechanoreceptors (C-LTMRs) helps trigger this behavior in response to a variety of stimuli.2 This discovery reveals a new feature of C-LTMR. emotional touch and pain regulation Both mice and humans.3,4
The researchers found that different types of stimuli caused wet dog tremors in mice. The rats performed this behavior when wet, but they also responded to small irritants, such as a drop of oil or a puff of air applied to the back of their necks. To support the suspicion that wet dogs’ shivering is mediated by mechanosensation, as opposed to the mild cold sensation also induced by wetness and air puffs, the researchers piezo 2 This gene encodes an ion channel important for sensing touch. As they predicted, piezo 2 We have essentially eliminated the shaking motion in response to water or oil droplets.
Mice and humans have different types of mechanosensory neurons, each responding to different types of touch. The researchers measured how these neuronal populations responded to the application of oil droplets and found that three types of low-threshold mechanoreceptors were the most responsive. Of these, only C-LTMR consistently produced tremors in wet dogs when subjected to optogenetic stimulation. Conversely, when the researchers removed most of the C-LTMR, the oil droplet-induced shivering behavior was significantly reduced, but the mice otherwise maintained normal locomotor behavior.
Finally, the researchers traced the pathway that carries these sensory signals from the skin to the brain. Previous anatomical studies have demonstrated that C-LTMR collects contact information from the skin and transmits it to the other end of cells located in the dorsal horn of the spinal cord (in a cross-section of the spinal cord). There are butterflies). A gray matter-shaped region composed mostly of cell bodies. The dorsal horn is the upper wing of the butterfly. From there, the researchers traced the signal through synapses to spinal parabrachial neurons. The spinal parabrachial nucleus (PBN) carried the signal up the spinal cord to the parabrachial nucleus (PBN), a brainstem region responsible for transmitting sensory information to the rest of the brain. When the researchers suppressed the ability of spinal neurons to communicate with the PBN, or silenced the PBN itself, trembling behavior was reduced, confirming the importance of the spinal parabrachial pathway in mediating tremors in wet dogs. .
Humans have access to bath towels so we don’t have to shake them dry, but humans have a similar type of mechanoreceptor. In humans, these C mechanoreceptors are thought to encode: pleasant feel;they may be helpful regulate pain is likely to play a role in the evaluation of social touch.5～7 Therefore, understanding the function of these mechanoreceptors may lead to new insights into both pleasure and pain.
