AUTHOR=von Au Sabrina , Helmich Ingo , Kieffer Simon , Lausberg Hedda 

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

JOURNAL=Frontiers in Neuroergonomics

VOLUME=4

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroergonomics/articles/10.3389/fnrgo.2023.1266439

DOI=10.3389/fnrgo.2023.1266439

ISSN=2673-6195

ABSTRACT=<sec><title>Introduction</title><p>Each individual touches the own body several 100 times a day. While some researchers propose a self-regulatory function of self-touch, others report that self-touching increases nervousness. This controversy appears to be caused by the fact that researchers did not define the kind of self-touch they examined and actually, referred to different types of self-touch. Thus, kinematically defining different types of self-touch, such as <italic>phasic</italic> (discrete), <italic>repetitive</italic>, and <italic>irregular</italic>, and exploring the neural correlates of the different types will provide insight into the neuropsychological function of self-touching behavior.</p></sec><sec><title>Methods</title><p>To this aim, we assessed hemodynamic responses in prefrontal brain areas using functional near-infrared spectroscopy (fNIRS) and behavioral responses with NEUROGES®. Fifty-two participants were recorded during three specific kinematically types of self-touch (<italic>phasic, irregular, repetitive</italic>) that were to be performed on command. The recently developed toolbox Satori was used for the visualization of neuronal processes.</p></sec><sec><title>Results</title><p>Behaviorally, the participants did not perform <italic>irregular</italic> self-touch reliably. Neurally, the comparison of <italic>phasic, irregular</italic> and <italic>repetitive</italic> self-touch revealed different activation patterns. <italic>Repetitive</italic> self-touch is associated with stronger hemodynamic responses in the left Orbitofrontal Cortex and the Dorsolateral Prefrontal Cortex than <italic>phasic</italic> self-touch.</p></sec><sec><title>Discussion</title><p>These brain areas have been reported to be associated with self-regulatory processes. Furthermore, <italic>irregular</italic> self-touch appears to be primarily generated by implicit neural control. Thus, by distinguishing kinematically different types of self-touch, our findings shed light on the controverse discussion on the neuropsychological function of self-touch.</p></sec>