title: The brain's response to pleasant touch: an EEG investigation of tactile caressing.
abstract: Somatosensation as a proximal sense can have a strong impact on our attitude toward physical objects and other human beings. However, relatively little is known about how hedonic valence of touch is processed at the cortical level. Here we investigated the electrophysiological correlates of affective tactile sensation during caressing of the right forearm with pleasant and unpleasant textile fabrics. We show dissociation between more physically driven differential brain responses to the different fabrics in early somatosensory cortex - the well-known mu-suppression (10-20 Hz) - and a beta-band response (25-30 Hz) in presumably higher-order somatosensory areas in the right hemisphere that correlated well with the subjective valence of tactile caressing. Importantly, when using single trial classification techniques, beta-power significantly distinguished between pleasant and unpleasant stimulation on a single trial basis with high accuracy. Our results therefore suggest a dissociation of the sensory and affective aspects of touch in the somatosensory system and may provide features that may be used for single trial decoding of affective mental states from simple electroencephalographic measurements.
authors.affiliation: UCL Interaction Centre, University College London London, UK ; School of Engineering and Design, Brunel University London, UK ; Department of Medical Physics and Bioengineering, University College London London, UK.
authors.forename: Harsimrat
authors.initials: H
authors.lastname: Singh
authors.affiliation: School of Psychology, University of Nottingham Nottingham, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Bauer
authors.affiliation: UCL Interaction Centre, University College London London, UK.
authors.forename: Wojtek
authors.initials: W
authors.lastname: Chowanski
authors.affiliation: UCL Interaction Centre, University College London London, UK.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sui
authors.affiliation: London College of Fashion, University of the Arts London London, UK.
authors.forename: Douglas
authors.initials: D
authors.lastname: Atkinson
authors.affiliation: School of Engineering and Design, Brunel University London, UK.
authors.forename: Sharon
authors.initials: S
authors.lastname: Baurley
authors.affiliation: Department of Medical Physics and Bioengineering, University College London London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Fry
authors.affiliation: Department of Medical Physics and Bioengineering, University College London London, UK.
authors.forename: Joe
authors.initials: J
authors.lastname: Evans
authors.affiliation: UCL Interaction Centre, University College London London, UK.
authors.forename: Nadia
authors.initials: N
authors.lastname: Bianchi-Berthouze
keywords: affective touch; beta band; electroencephalogram (EEG); somatosensation; somatosensory; tactile