Dogs have a habit of shaking themselves when they get wet, but this instinctive behavior is not unique to canines. Many mammals do the same, including mice, cats and even lions. US research, published in the journal Science, investigates the neurological mechanism that explains why animals shake themselves vigorously to dry off.
Researchers at Harvard Medical School's Howard Hughes Medical Institute set out to understand why some furry animals shake themselves when wet. The neurobiologists used genetics, physiology and optogenetics to determine which type of neuron and which neural circuit were responsible for so-called "wet dog" shaking in mice.
The neurons in question are low-threshold C mechanoreceptors (C-LTMRs). These ultra-sensitive tactile receptors are mainly located around hair follicles. They are also found in humans, although they do not play the same role as in mice. In humans, C-LTMRs respond to soft, pleasant sensations such as strokes and cuddles. In mice, they play a protective role, triggering an immediate reaction to the presence of something on the skin.
The authors of this study found evidence of this after dropping drops of sunflower seed oil onto the skin of the backs or necks of these small, hairy mammals. Within 10 seconds, the rodents were vigorously shaking their bodies to get rid of the droplets. The researchers took the experiment a step further by genetically suppressing the majority of C-LTMRs in certain mice. As a result, the ablation of these sensory neurons reduced the shaking normally provoked by the application of oil drops by about half.
To determine the signal pathways of the C-LTMRs in the brains of the rodents, the scientists used optogenetics, a technique for controlling the activity of neurons with light. They found that C-LTMRs made contact with neurons located in the brain's parabrachial nucleus, an area of the brain stem involved in the processing of various sensations such as pain, temperature and touch.
These discoveries shed light on the nature of the neurons and neural circuitry involved in "wet dog" shaking, an animal behavior observed in many species. These findings could help us to better understand our furry friends and their behavior. – AFP Relaxnews
