title: Dissociable effects of anodal and cathodal tDCS reveal distinct functional roles for right parietal cortex in the detection of single and competing stimuli.
abstract: Spatial attention can be used to direct neural processing resources to a subset of task-relevant or otherwise salient items within the environment. Such selective processes are particularly important for resolving competition between multiple stimuli. Deficits in processing single stimuli can arise after damage to parietal, frontal and temporal brain regions, as is typical in patients with contralesional spatial neglect. By contrast, deficits in processing multiple competing stimuli may arise specifically following lesions of the posterior parietal cortex (PPC), as occurs in the disorder of spatial extinction. It remains unclear, however, whether mechanisms involved in selecting single and competing stimuli reflect the same or dissociable neural operations within the PPC. To address this issue, in separate sessions, we applied transcranial direct current stimulation (tDCS) to the left or right PPC and measured the effect on detecting and discriminating single and competing visual stimulus events. Our results revealed reliable tDCS modulations of stimulus processing, specific to the right PPC, as well as a dissociation in the detection of single and competing stimuli. For the right PPC only, single stimuli presented to the left (contralateral) visual field were affected selectively by anodal tDCS, whereas competing stimuli across the two visual fields were affected by both anodal and cathodal tDCS. These contrasting effects of anodal and cathodal tDCS on perception of single and competing stimuli suggest dissociable neural coding properties within the right PPC.
authors: School of Psychology, The University of Queensland, McElwain Building, St Lucia, QLD 4072, Australia. Electronic address: h.l.filmer@gmail.com.
authors: Hannah L
authors: HL
authors: Filmer
authors: School of Psychology, The University of Queensland, McElwain Building, St Lucia, QLD 4072, Australia.
authors: Paul E
authors: PE
authors: Dux
authors: School of Psychology, The University of Queensland, McElwain Building, St Lucia, QLD 4072, Australia; Queensland Brain Institute, The University of Queensland, St Lucia, QLD 4072, Australia.
authors: Jason B
authors: JB
authors: Mattingley
mesh_terms: D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D001703:Biophysics; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D017603:Signal Detection, Psychological / Q000502:physiology*; D013997:Time Factors; D065908:Transcranial Direct Current Stimulation; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Parietal cortex; Right hemisphere; Spatial attention; Transcranial direct current stimulation; Visual competition