The attentive homunculus: ERP evidence for somatotopic allocation of attention in tactile search

• Published in: Neuropsychologia Vol. 84; pp. 158 - 166
• Main Authors: Forster, Bettina, Tziraki, Maria, Jones, Alexander
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2016
• Subjects: Adolescent; Adult; Attention - physiology; Attentional selection; Body; Brain - physiology; Brain Mapping; Electroencephalography; Evoked Potentials, Somatosensory; Female; Functional Laterality - physiology; Hand - physiology; Humans; Male; Neuropsychological Tests; Physical Stimulation - methods; Somatosensory system; Tactile attention; Tactile search; Toes - physiology; Touch Perception - physiology; Young Adult; Tactile attention; Tactile search; Somatosensory system; Body; Attentional selection
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2016.02.009

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. •We investigated the ERP signature of tactile search.•We identified the N140cc as a marker of tactile attentional selection.•The N140cc mainly reflects enhancement of target location.•The N140cc may serve to trace allocation of attention to different limbs.•We provide evidence for somototopically specific allocation of attention.