title: Differential frontal involvement in shifts of internal and perceptual attention.
abstract: BACKGROUND
  Perceptual attention enhances the processing of items in the environment, whereas internal attention enhances processing of items encoded in visual working memory. In perceptual and internal attention cueing paradigms, cues indicate the to-be-probed item before (pre-cueing) or after (retro-cueing) the memory display, respectively. Pre- and retro-cues confer similar behavioral accuracy benefits (pre-: 14-19%, retro-: 11-17%) and neuroimaging data show that they activate overlapping frontoparietal networks. Yet reports of behavioral and neuroimaging differences suggest that pre- and retro-cueing differentially recruit frontal and parietal cortices (Lepsien and Nobre, 2006).
  
  
  OBJECTIVE
  This study examined whether perceptual and internal attention are equally disrupted by neurostimulation to frontal and parietal cortices. We hypothesized that neurostimulation applied to frontal cortex would disrupt internal attention to a greater extent than perceptual attention.
  
  
  METHODS
  Cathodal transcranial direct current stimulation (tDCS) was applied to frontal or parietal cortices. After stimulation, participants completed a change detection task coupled with either pre- or retro-cues.
  
  
  RESULTS
  Cathodal tDCS across site (frontal, parietal) hindered performance. However, frontal tDCS had a greater negative impact on the retro-cued trials demonstrating greater frontal involvement during shifts of internal attention.
  
  
  CONCLUSIONS
  These results complement the neuroimaging data and provide further evidence suggesting that perceptual and internal attention are not identical processes. We conclude that although internal and perceptual attention are mediated by similar frontoparietal networks, the weight of contribution of these structures differs, with internal attention relying more heavily on the frontal cortex.
authors.affiliation: Department of Psychology, University of Nevada, 1664 N. Virginia Street, Reno, NV 89557, USA.
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Tanoue
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Jones
authors.forename: Dwight J
authors.initials: DJ
authors.lastname: Peterson
authors.forename: Marian E
authors.initials: ME
authors.lastname: Berryhill
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D003463:Cues; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D014796:Visual Perception / Q000502:physiology