Several studies have reported that positive interactions with a dog reduced all parameters associated with stress, such as blood pressure, heart rate and cortisol levels. At the same time, contact with this animal increases the secretion of hormones associated with attachment (β-endorphin, oxytocin and prolactin). In contrast, research on the neurological correlates of human-animal interaction is more sparse. The few studies that address the topic are based on images of animals and not on interactions with real animals. However, some studies have made it possible to compare the effects caused by interaction with live and artificial animals (pictures, stuffed animals, robots). A team from the University of Basel recently took an interest in the question. She managed to highlight the effects of contact with a real dog on prefrontal brain activity.
The effects of dogs on brain oxygenation
Several studies have identified the prefrontal cortex as a key region for various aspects of social cognitive processing. In fact, it is involved in social and emotional interactions. The activity of the prefrontal cortex is therefore important. It makes it possible to study the underlying mechanisms of human-animal interactions. At least it is; what the authors of the study explain.
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The team compared the effects of different types of interaction with a dog and different types of interaction with a stuffed animal. Based on previous studies, they expected that increasing closeness in contact with the dog or stuffed animal would correlate with increased stimulation and thus increased activity. They also hypothesized that participants would show higher brain activity when in contact with a real dog rather than the stuffed animal.
About twenty adults, without allergies or fear of dogs, participated in this study. Each benefited from three sessions in contact with a real dog and three sessions in contact with a stuffed animal. These were then used as control sessions. The researchers monitored the activity of their prefrontal cortex using functional near-infrared spectroscopic imaging (ISPIf). It is a non-invasive technique. It consists in measuring the oxygenation of an area of the brain in order to derive its activity. Hemoglobin molecules absorb more or less infrared radiation depending on whether they carry oxygen or not.
More interactions with a dog lead to more brain activity
The sessions took place as follows. In a first phase, the participant looked directly at a white wall. This is the “neutral 1” phase. In the next phase, he had to observe a dog (or stuffed animal) located one meter away. This is the “see” phase. Then the dog lay down next to the participant on the sofa or the stuffed animal was placed on his thigh. The participant could then passively smell the animal, but was not yet allowed to touch it. This is the “feeling” phase. Then the participant could stroke the dog or stuffed animal. This is the “caress” phase. Finally, the session ended with another neutral phase where the participant looked at the white wall again while the dog/goblin was out of sight. This was the “neutral 2” phase.
The dogs used in the study were accustomed to human contact. They were trained to work with patients in a hospital. There was a female Jack Russel, a female Goldendoodle and a female Golden Retriever. The stuffed animal, about fifty centimeters, represented a lion, and its body contained a thermos filled with hot water. This not only mimicked the feel of the dog’s soft fur, but also its body temperature and weight.
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To conduct its analyses, the team retained 108 sessions (of which 53 were conducted with a real dog). The results showed that the more participants were able to interact with the animal or stuffed animal, the more their prefrontal activity increased. ” With increasing stimulation, oxygenated hemoglobin (O2Hb) in the prefrontal lobe increased significantly by 2.78 μmol/L from neutral phase 1 to caress phase “, the researchers report in PLOS One.
An approach to patients with socio-emotional deficits
At the same time, deoxygenated hemoglobin showed an opposite trend. It dropped significantly from the neutral phase 1 to the caressing phase. After the withdrawal of the stimulation (neutral phase 2), the O2Hb remained constant and still significantly higher compared to the neutral phase 1. This means that brain activity remains increased even after the dog’s departure.
As expected, and consistent with the results of previous studies, brain activity was found to be higher in the presence of the dog than in the presence of the stuffed animal (O2Hb was 0.80 μmol/L higher). This difference was the most important for the petting phase. ” This indicates that interactions with a dog may activate more attentional processes and elicit stronger emotional arousal than comparable nonliving stimuli. “, the researchers explain. Note that this increased brain activity could also be caused by a greater cognitive load. In fact, a dog is a more complex stimulus than a stuffed animal.
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Another important difference was that prefrontal brain activity increased whenever people interacted with the real dog. A trend that the researchers did not observe in the case of plush. This suggests that the response could be related to familiarity or social connection.
It thus appears from the study that particularly close and active physical contact with a familiar dog could promote social attention in humans. ” This is particularly relevant for patients with deficits in motivation, attention and social-emotional functioning. », underlines the team. Integrating animals into therapeutic interventions could therefore be a promising approach to improve emotional involvement and attention.