Summary: A recent study demonstrates how serotonin indicating in the brain is activated to foster social ties between people and animals. Researchers discovered that animals ‘ repeated teasing increased their noises, choice for human interaction, and VMHvl receptor expression.
The rats ‘ affinity-like behavior was reduced by blocking hormone signaling, which supports its crucial role in cross-species bond. These findings may aid in explaining the therapeutic value of contact and provide recommendations for social connection issues.
Important Information
- Oxytocin Link: Nice touch increases oxytocin signaling and strengthens bonds.
- Tickling Result: After repeated tickling, rats began to like human interaction.
- Medical Possible: Information about using animal-assisted contact could be used to inform treatments.
Okayama University Cause
In several animal species, particularly mammal, social interaction is fueled by pleasant sensory stimulation.
The infant-caregiver relationship is based on sensory stimulus, which frequently results in affinity-like conduct, which suggests the formation of social securities. Teenage juvenile rats frequently engage in rough-and-tumble play, which produces distinctive acoustic vocalizations.
These vocalizations, which are usually in the 50 m regularity range, are thought to be related to pleasant mental states. Teenager rats that tickle with human hands even produce 50 m acoustic vocalizations, which mimics typical rough-and-tumble play.
Additionally, repeated tickling causes these animals to have a strong attachment for humans.
Scientists discovered that repeated tickling of human hands increases the expression of estrogen receptors in a place of the rabbit’s brain known as the ventrolateral part of the ventromedial brain (VMHvl ), which was recently made available online on June 4, 2025, and was published in Volume 35 Matter 12 of the journal , Current Biology  on June 23, 2025. In the study, rats ‘ affinity-like conduct was lowered when they were touched by humans because oxytocin signaling was blocked in this region of the brain.
We discovered a portion of the neural circuit underlying why normally cautious animals attach to people. The lead author of the study, Dr. Himeka Hayashi of Okayama University, Japan, explains that the actions of estrogen in a certain mental area (VMHvl ) mediates the effects of pleasant sensory stimulation and controls the formation of social ties across species.
Along with Dr. Hayashi, the study also received significant contributions from Okayama University’s Professor Hirotaka Sakamoto, among other researchers.
Rats were given 10 days of tickling instruction, and researchers monitored their 50 kHz vocalizations during this time. The rats started producing these vocalizations in response to tickling on day five, though they only occasionally emitted 50 kHz vocalizations at first.
These vocalizations increased day 10 and suggested that repeated tickling gave rats pleasant sensations.
Rats were given a conditioned place preference test at the conclusion of the training period. The rats spent more time in the tickling room after the test than they did before, which indicated an affinity for repeated tickling.
” We have always been curious about how people and animals can form bonds despite not having a common language or way of life,” says Dr. Hayashi.
” We questioned whether the connection we felt with animals was genuine or was merely a product of our imagination. Through this study, we discovered that rats actually enjoy interacting with us, which was very positive for us.
The researchers conducted nerve fiber tracing studies to examine the neural connections of oxytocin receptor neurons in the VMHvI that are implicated in affinity-like behavior.
A subset of these neuronal fibers were discovered in tracing studies in the supraoptic nucleus region of the brain, which supports the magnocellular neuronal network’s role in controlling affinity-like behavior in rats.
The identification of specific neural mechanisms that underlie the development of affinity-like behavior provides important insights into social interactions between people and rats.
” The discovery that pleasant tactile stimulation promotes cross-species social bonding through oxytocin pathways may help to better understand the neural mechanisms underlying both social interaction issues and the therapeutic effects of physical contact with animal companions like cats and dogs.
This understanding may lead to the development of novel therapeutic and support strategies for those who struggle with social interactions, says Dr. Hayashi.
By identifying the neural basis for cross-species affinity, it opens the door to the development of therapeutic approaches that make use of physical contact to enhance social connection and emotional well-being.
About this research on bonding and tactile stimulation.
Author: Yuichi Iida
Source: Okayama University
Contact: Yuichi Iida – Okayama University
Image: The image is credited to Neuroscience News
Open access to original research.
Hirotaka Sakamoto et al.,” Oxytocin helps rats exhibit touch-induced play..” Current Biology
Abstract
Oxytocin helps rats exhibit touch-induced play.
Pleasant touch sensations are a key component of social bonding, but the neural mechanisms that underlie affinity-like behaviors are still poorly understood.
We show that juvenile-adolescent rats, who are naturally social playmates and exhibit rough-and-tumble interactions and 50 kHz ultrasonic vocalizations indicating pleasant sensations, have a strong affinity for human hands through repeated tickling with human hands.
We discovered that repeated tickling that mimicked rough-and-tumble play increased the ventrolateral part of the ventromedial hypothalamus (VMHvl ) and increased oxytocin receptor ( OTR ) expression in this rat with a high affinity for human hands and tickling-induced high affinity for humans. VMHvl’s inhibition of oxytocin signaling reduced affinity-like behaviors from rats to humans.
These findings support the hypothesis that OTR neurons in VMHvl play a significant role in the rise in the affinity for human hands brought on by the pleasant touch sensation and play behavior brought on by human touch.
We find that a subset of oxytocin fibers in the VMHvl are derived from the SON as the primary sources of oxytocin, supporting the hypothesis that magnocellular neurons may be involved in magnocellular neuronal signaling.
Together, this study advances our understanding of how oxytocin affects social behavior and may help us develop therapeutic strategies to promote positive social interactions.
