Question to the brain
Why is it soothing to pet Animals?
Published: 08.12.2024
Many people find petting an animal soothing. Is there a neurobiological explanation for this?
The editor's reply is:
Dr. Rahel Marti, Institute for Interdisciplinary Research on Human-Animal Relationships, Allschwil, Switzerland:There are many different attempts to explain this question. One prominent explanation is that Cortisol levels in the body decrease when we pet animals. Cortisol is also known as the stress Hormone and is released in situations that trigger anxiety, for example. Researchers have proven that contact with animals lowers the concentration of cortisol in the blood, causing humans to relax.
In addition, the parasympathetic hypothesis is well known: according to this hypothesis, the parasympathetic nervous system, i.e., the autonomic nervous system, is activated by touching animals, which causes the heart rate to slow down, for example. The body switches from activity mode to relaxation mode.
It is also known that touching animals releases the cuddle hormone oxytocin. This hormone is important for building trust and social bonds, for example between mothers and their children. Studies have shown that stroking animals also increases the concentration of oxytocin in saliva.
When children play in the sand, it also has a calming effect on them. The same is true of stroking. Tactile engagement can also convey a feeling of security and comfort. This probably also works via the neurological aspects of cortisol, the parasympathetic nervous system, and oxytocin.
We approached the topic a little differently by measuring the brain activity in the Frontal lobe of test subjects while they interacted with a dog or stuffed animal. Many executive, planning, and problem-solving processes take place in the frontal lobe. However, it is also a hub for certain emotional processes and is very well connected to other areas of the brain.
Since it is hardly possible to have a person lying in an MRI scanner stroke an animal and measure brain activity at the same time, we used near-infrared spectroscopy for the measurement. This involves measuring the oxygen content of the blood non-invasively using a head cap with electrodes. This cap allowed participants to move and interact with the animal or stuffed animal normally. In addition, the device makes no noise, so the dogs were not stressed. Since increased brain activity is associated with increased oxygen demand, it is possible to measure whether brain activity changes due to external influences, such as petting an animal.
In our study, all volunteers came to our laboratory six times. Three times they had contact with a dog and three times with a stuffed animal. In each session, they first looked at a white wall, then at the animal or stuffed animal. Then the animal or stuffed animal came a little closer and they could also feel it on their thigh. Finally, the participants were allowed to pet the animal or stuffed animal. At the end, there was another neutral phase in which they looked at the white wall. Each of these phases lasted 2 minutes.
It was found that the participants' brain activity was higher with the real animal than with the stuffed animal. The closer the animal or stuffed animal was to the participant, the higher the activation of the measured brain area. We explained the differences between a dog and a stuffed animal by the fact that the dog is the more complex object. In addition, a dog is a much more emotional stimulus than a stuffed animal, which means that the participants are more interested in the dog. Our study also showed that brain activity increased over the course of the three sessions with the dog, but decreased with the stuffed animal. In most cases, each participant was presented with the same dog in all three sessions, but in some cases a different dog was used. The result can perhaps be explained by a higher level of interest in the dog. It could also be related to a minimal Neural representation of a relationship with the dog; after all, it is possible to interact with a dog, which is not possible with a stuffed animal. However, further studies will be needed to confirm the results and better understand why this brain activation occurs.
Recorded by Stefanie Flunkert
Cortisol
A hormone produced by the adrenal cortex that is primarily an important stress hormone. It belongs to the group of glucocorticoids and influences carbohydrate and protein metabolism in the body, suppresses the immune system, and acts directly on certain neurons in the central nervous system.
Hormone
Hormones are chemical messengers in the body. They serve to transmit information between organs and cells, usually slowly, e.g., to regulate blood sugar levels. Many hormones are produced in glandular cells and released into the blood. At their destination, e.g., an organ, they dock at binding sites and trigger processes inside the cell. Hormones have a broader effect than neurotransmitters; they can influence various functions in many cells of the body.
oxytocin
Oxytocin
Oxytocin is a hormone produced in the paraventricular nucleus and supraoptic nucleus of the hypothalamus and released into the blood via the posterior lobe of the pituitary gland. It initiates contractions during childbirth and supports the milk ejection reflex during breastfeeding. It is also released during orgasm. Oxytocin can promote trust and strengthen pair bonding, but recent findings show that its effects are more complex and, in certain contexts, can also promote separation from out-groups.
frontal
An anatomical position designation – frontal means "towards the forehead," i.e., at the front.
Frontal lobe
Lobus frontalis
The frontal cortex is the largest of the four lobes of the cerebral cortex and its functions are correspondingly comprehensive. The front area, known as the prefrontal cortex, is responsible for complex action planning (known as executive functions), which also shapes our personality. Its development (myelination) takes up to 30 years and even then is not yet complete. Other important components of the frontal cortex are Broca's area, which controls our ability to express ourselves linguistically, and the primary motor cortex, which sends movement impulses throughout the body.
stroke
Cerebral apoplexy
In a stroke, the brain or parts of it are no longer supplied with sufficient blood, which impairs the supply of oxygen and glucose. The most common cause is a blockage in an artery (ischemic stroke), less commonly a hemorrhage (hemorrhagic stroke). Typical symptoms include sudden visual disturbances, dizziness, paralysis, speech or sensory disturbances. Long-term consequences can include various sensory, motor, and cognitive impairments.
Neural representation
Various parts of the brain contain representations not only of the sensory systems, but also of objects such as faces. For example, so-called place cells in the hippocampus appear to play an important role in the representation of space. Each place cell represents a specific location in the environment and becomes active when its owner is at that location. Another group of neurons, grid cells, fire in a regular hexagonal pattern that is interpreted as a metric grid of the environment. This grid provides a kind of coordinate system that place cells can use for location coding.