Brain activity in response to the touch of a hand on the center of the back

Abstract

The aim of this study was to validate the possibility of using functional Near-Infrared Spectroscopy (fNIRS) to measure changes in cerebral blood flow in response to a hand being placed on a participant’s back, and to identify the areas of enhanced activity in the brain. Nineteen female adult volunteers participated in the study. An experienced school nurse touched the center of the participant’s back between the shoulder blades with the palm of her hand. Cerebral blood volume dynamics were measured with a 52-channel fNIRS system. Significantly higher oxygenated hemoglobin (oxy-Hb) concentration levels were recorded by channels 11, 14, 21, 22, 24, 32, 35, 45, 46, and 49 during the touching period than during the resting period. These channels indicated enhanced activity in the supramarginal gyrus, the middle frontal gyrus, the superior temporal gyrus, and the inferior frontal gyrus. The ability to detect changes in cerebral blood flow using this method indicates the possibility of measuring changes in cerebral blood flow using fNIRS when a person is touched on the back. fNIRS has been shown to be useful for studying the effects of touch.

The Effects of Social Touch on Prefrontal Cortex Activity, Physiological Activity and Emotion Recognition.

“…Evidently, one obvious explanation to this may be simply due to the small sample size of the study lacking statistical power. Morita et al (2018) showed that touch to the back increased oxygenated haemoglobin in the dorsolateral prefrontal cortex. However, data from the present study does show that in comparison to baseline, the right dorsolateral prefrontal cortex does show a mean increase in haemodynamic activity during touch.…”

“…Moreover, this study is one of few that have investigated social touch using fNIRS (Bennett et al, 2014;Morita et al, 2018) whilst majority of studies have used fMRI.…”

“…Despite the exciting implications that fNIRS had in the study of emotion, no studies have used the method of fNIRS to investigate how social touch affects emotional recognition. As it has been shown that social touch activates the dlPFC (Bennett et al, 2017;Morita et al, 2018), a frontal area involved in emotional processing, how social touch would then affect overall emotional processing accuracy is unknown and would thus necessitate investigation.…”

The effect of a spinal thrust manipulation’s audible pop on brain wave activity: a quasi-experimental repeated measure design

“…Touch has been previously shown to improve one’s subjective assessment of physical and psychological function. Physical contact by itself can provide a placebo benefit to patients for reducing both anxiety and pain ( Morita et al, 2018 ). Morita et al.…”

Phasic and repetitive self-touch differ in hemodynamic response in the prefrontal cortex–An fNIRS study

“…Repeated activation of CT afferents is associated with better health by reducing sympathetic nervous system activity, increasing parasympathetic nervous system activity, and reducing stress, pain, and anxiety via oxytocin (Heinrichs and Domes, 2008 ; Ishak et al, 2011 ; Quirin et al, 2011 ; Love, 2014 ; Pfeifer et al, 2016 ; Walker et al, 2017 ; Hurlemann and Grinevich, 2018 ; Field, 2019 ; Uvnäs-Moberg et al, 2020 ; Uvnäs-Moberg and Petersson, 2022 ). At the neural level, correlates of social touch are found with the cortical brain regions in the dorsolateral prefrontal cortex (dlPFC) and the OFC, which are also associated with oxytocin projections (Rolls et al, 2003 ; Croy et al, 2016 ; Morita et al, 2018 ; Boehme et al, 2019 ; Field, 2019 ; Chen et al, 2020 ; Uvnäs-Moberg et al, 2020 ). Motor aspects of touch (discriminative touch) significantly predict the activation in the sensorimotor cortex (Rolls et al, 2003 ; Case et al, 2016 ).…”