title: The attentive homunculus: ERP evidence for somatotopic allocation of attention in tactile search.
abstract: Our brain constantly receives tactile information from the body's surface. We often only become aware of this information when directing our attention towards the body. Here, we report a study investigating the behavioural and neural response when selecting a target amongst distractor vibrations presented simultaneously to several locations either across the hands or body. Comparable visual search studies have revealed the N2pc as the neural correlate of visual selective attention. Analogously, we describe an enhanced negativity contralateral to the tactile target side. This effect is strongest over somatosensory areas and lasts approximately 200ms from the onset of the somatosensory N140 ERP component. Based on these characteristics we named this electrophysiological signature of attentional tactile target selection during tactile search the N140-central-contralateral (N140cc). Furthermore, we present supporting evince that the N140cc reflects attentional enhancement of target rather than suppression of distractor locations; the component was not reliably altered by distractor but rather by target location changes. Taken together, our findings present a novel electrophysiological marker of tactile search and show how attentional selection of touch operates by mainly enhancing task relevant locations within the somatosensory homunculus.
authors.affiliation: Department of Psychology, Cognitive Neuroscience Research Unit, City University London, London, UK. Electronic address: b.forster@city.ac.uk.
authors.forename: Bettina
authors.initials: B
authors.lastname: Forster
authors.affiliation: Institute of Brain, Behaviour and Mental Health, University of Manchester, Manchester, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Tziraki
authors.affiliation: Department of Psychology, Middlesex University, London, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010812:Physical Stimulation / Q000379:methods; D014034:Toes / Q000502:physiology; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
keywords: Attentional selection; Body; Somatosensory system; Tactile attention; Tactile search