title: Temporal dynamics of brain activation during 40 minutes of pleasant touch.
abstract: BACKGROUND
  Touch is important for individuals' subjective well-being, is typically rewarding, and is one of few sensory stimuli which are experienced as pleasant for a rather long time. This study tracked brain activation during slow stroking stimulation of the arm that was applied continuously for 40min - a much longer time than what previous studies have investigated.
  
  
  METHODS
  25 subjects were stroked for 40min with a soft brush while they were scanned with functional Magnetic Resonance Imaging, and rated the perceived pleasantness of the brush stroking. Two resting baselines were included. Whole brain-based analyses investigated the neural response to long-lasting stroking.
  
  
  RESULTS
  Stroking was perceived as pleasant throughout scanning and activated areas that were previously found to be involved in the processing of pleasant touch. Activation in primary somatosensory cortex (S1) and S2, subdivision OP1, decreased over time, whereas activation in orbito-frontal gyrus (OFC) and putamen strongly increased until reaching a plateau after approximately 20min. Similarly, functional connectivity of posterior insula with middle cingulate and striatal regions increased over time.
  
  
  CONCLUSIONS
  Long-lasting stroking was processed in similar areas as shorter-lasting stroking. The decreased activation in somatosensory cortices over time may represent stimulus habituation, whereas increased activation in OFC and putamen may relate to the stimulation's subjective reward value. This involvement of reward-related brain circuits can facilitate maintenance of long-lasting social touch interactions.
authors.affiliation: Dept. of Psychology, University of Gothenburg, Gothenburg, Sweden; Faculty of Medicine, Institute of Basic Medical Sciences, Dept. of Behavioural Sciences in Medicine, University of Oslo, Oslo, Norway. Electronic address: uta.sailer@medisin.uio.no.
authors.forename: Uta
authors.initials: U
authors.lastname: Sailer
authors.affiliation: Dept. of Psychology, University of Gothenburg, Gothenburg, Sweden; Dept. of Clinical Neurophysiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Chantal
authors.initials: C
authors.lastname: Triscoli
authors.affiliation: Dept. of Pedagogical, Curricular and Professional Studies, University of Gothenburg, Sweden.
authors.forename: Gisela
authors.initials: G
authors.lastname: Häggblad
authors.affiliation: Center for Social and Affective Neuroscience, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Paul
authors.initials: P
authors.lastname: Hamilton
authors.affiliation: Dept. of Clinical Neurophysiology, Sahlgrenska University Hospital, Gothenburg, Sweden; Center for Social and Affective Neuroscience, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Olausson
authors.affiliation: Center for Social and Affective Neuroscience, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; Clinic for Psychosomatic Medicine, Technical University of Dresden, Germany.
authors.forename: Ilona
authors.initials: I
authors.lastname: Croy
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010812:Physical Stimulation; D012201:Reward; D013997:Time Factors; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
keywords: Inferior frontal gyrus; Putamen; Reward; Secondary somatosensory cortex; Stroking; Touch