Researchers at Washington University School of Medicine, St. Louis identified a neural circuit and a neuropeptide that transmits the sensation of pleasant touch from the skin to the brain. The study is published in the journal Science.
The researchers divided the sense of touch into two categories. The first was ‘discriminative touch’ which allowed the one being touched to detect the touch and identify its force and location. The second was an affectionate sensation of ‘pleasant touch’ with an attached emotional value.
Then, they bred mice without the neuropeptide called prokinecticin 2 (PROK2) or the spinal cord neural circuit expressing its receptor (PROKR2)—the neural mechanisms that convey the pleasant touch sensation to the brain. They further observed how the mice behaved, as individuals and in groups.
The results showed that mice lacking the neural mechanisms displayed greater social avoidance and signs of stress than normal mice. They also avoided activities such as grooming and petting.
However, when the researchers put the engineered mice in a controlled environment where they were pleasantly brushed in a ‘petting gesture’, it was seen that the mice preferred the pleasant touch sensation. This is because the pleasant brushing activated the neural pathways (PROK2 in sensory neurons and PROKR2 in the spinal cord) that exclusively transmitted pleasant touch signals to the brain.
The researchers are enthusiastic that the study can help develop evidence-based interventions and treatment plans for neurological disorders characterized by impaired social development, touch avoidance, and hormonal imbalances.
In the words of one of the lead researchers, Zhou-Feng Chen, with the study findings, “it may be possible to enhance pleasant touch signals without interfering with other circuits, which is crucial because pleasant touch boosts several hormones in the brain that are essential for social interactions and mental health.”
To Know More Please Refer To
Liu, B., Qiao, L., Liu, K., Liu, J., Piccinni-Ash, T. J., & Chen, Z. F. (2022). Molecular and neural basis of pleasant touch sensation. Science (New York, N.Y.), 376(6592), 483–491. https://doi.org/10.1126/science.abn2479