Several studies have reported that positive interactions with a dog reduced all parameters associated with stress, such as blood pressure, heart rate and cortisol level. 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 scarcer. The few studies that deal with the subject are based on images of animals and not on interactions with real animals. Some research has, however, 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 different aspects of social cognitive processing. Indeed, 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. It is, in any case; what the authors of the study explain.
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The team compared the effects of different forms of interaction with a dog and different forms 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 therefore, increased activity. cerebral. They also hypothesized that participants would exhibit higher brain activity when in contact with a real dog rather than the stuffed animal.
About twenty adults, without allergies or fears towards dogs, took part 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 deduce its activity. Hemoglobin molecules absorb more or less infrared radiation depending on whether or not they carry oxygen.
More interactions with a dog leads to more brain activity
The sessions took place as follows. In a first phase, the participant looked straight 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 “look” 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 the stuffed animal. This is the “caresses” phase. Finally, the session ended with a second neutral phase where the participant looked at the white wall again, while the dog/cuddly toy 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 setting. 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 hot water bottle filled with warm water. This mimicked not only the feel of the dog’s soft fur, but also its body temperature and weight.
Effects of different forms of interaction with a dog and a stuffed animal on the concentration of oxygenated hemoglobin (A), deoxyhemoglobin (B), total hemoglobin (C) and on oxygen saturation (D). Credits: R. Marti et al., PLOS One (2022)
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To carry out its analyses, the team retained 108 sessions (including 53 carried out with a real dog). The results showed that the more participants could 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 caresses phase “, report the researchers in PLOS One.
An approach for patients with socio-emotional deficit
At the same time, deoxygenated hemoglobin showed an opposite trend. It decreased significantly from the neutral phase 1 to the caressing phase. Following 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 the brain activity remains increased, even after the departure of the dog.
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 might activate more attentional processes and elicit stronger emotional arousal than comparable non-living stimuli. “, explain the researchers. Note that this increased brain activity could also have been caused by a greater cognitive load. Indeed, a dog is a more complex stimulus than a stuffed animal.
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Another key difference was that prefrontal brain activity increased each time people interacted with the real dog. A trend that scientists did not observe in the case of plush. This suggests that the answer could be related to familiarity or social connection.
Thus, it 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 improving emotional involvement and attention.
