The human somatosensory system: From perception to decision making Burkhard Pleger a,b, *, Arno Villringer a,b,c a Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany b Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany c Berlin School of Mind & Brain and Mind & Brain Institute, Humboldt-University Berlin, Berlin, Germany Contents 1. From sensory input to perception and perceptual decision making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 2. Somatosensory perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 2.1. Electroencephalography for the identification of sensory and cognitive brain generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 2.2. Cerebral processing of subliminal versus supraliminal somatosensory stimuli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 2.3. How the state of the sensory system influences sensory perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 2.4. Computational modelling of somatosensory perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 2.5. Computational modelling of integrative processes for controlling movements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 2.6. Computational modelling of recurrent neural processing for somatosensory awareness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 2.7. The genetics of touch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 2.8. Summary on somatosensory perception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3. Perceptual decision making. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3.2. How does sensory information transfer from sensory input to motor output regions? Evidence from the visual domain. . . . . . . . . . 84 3.2.1. Perceptual decision making and cognitive contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.2.2. Evidence for a recurrent flow of decision-relevant information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 3.2.3. Summary on sensory-motor integration processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Progress in Neurobiology 103 (2013) 76–97 A R T I C L E I N F O Article history: Received 28 February 2012 Received in revised form 17 August 2012 Accepted 24 October 2012 Available online 2 November 2012 Keywords: Somatosensory perception Somatosensory decision making Social touch A B S T R A C T Pioneering human and animal research has yielded a better understanding of the brain networks involved in somatosensory perception and decision making. New methodical achievements in combination with computational formalization allow research questions to be addressed which increasingly reflect not only the complex sensory demands of real environments, but also the cognitive ones. Here, we review the latest research on somatosensory perception and decision making with a special focus on the recruitment of supplementary brain networks which are dependent on the situation- associated sensory and cognitive demands. We also refer to literature on sensory-motor integration processes during visual decision making to delineate the complexity and dynamics of how sensory information is relayed to the motor output system. Finally, we review the latest literature which provides novel evidence that other everyday life situations, such as semantic decision making or social interactions, appear to depend on tactile experiences; suggesting that the sense of touch, being the first sense to develop ontogenetically, may essentially support later development of other conceptual knowledge. ß 2012 Elsevier Ltd. All rights reserved. Abbreviations: ACC, anterior cingulate cortex; A1, primary auditory cortex; BA, brodmann area; BOLD, blood-oxygen-level-dependent; DLPFC, dorsolateral prefrontal cortex; DCM, dynamic causal modeling; EMG, electromyography; EEG, electroencephalography; ERP, event-related potentials; FEF, frontal eye fields; fMRI, functional magnetic resonance imaging; IFG, inferior frontal gyrus; IPL, inferior parietal lobe; IPS, intraparietal cortex; LIP, lateral intraparietal area; M1, primary motor cortex; MedFG, medial frontal gyrus; MFG, middle frontal gyrus; MLE, maximum likelihood estimation; MT, motion area; MEG, magnetoencephalography; OFC, orbitofrontal cortex; PET, positron emission tomography; PMC, premotor cortex; rTMS, repetitive transcranial magnetic stimulation; SI/1, primary somatosensory cortex; SII/2, secondary somatosensory cortex; SMA, supplementary motor area; SFG, superior frontal gyrus; SPL, superior parietal lobe; VMPFC, ventral medial prefrontal cortex. * Corresponding author at: Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstraße 1a, 04103 Leipzig, Germany. Tel.: +49 341 9940 135; fax: +49 341 9940 2221. E-mail address: bpleger@cbs.mpg.de (B. Pleger). Contents lists available at SciVerse ScienceDirect Progress in Neurobiology jo u rn al ho m epag e: ww w.els evier .c om /lo cat e/pn eu ro b io 0301-0082/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.pneurobio.2012.10.002