Patient DF's visual brain in action: Visual feedforward control in visual form agnosia.
Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width...
| Publicado en: | Vision Research Vol. 110; no. Pt B; pp. 265 - 277 |
|---|---|
| Autores principales: | , , , , |
| Formato: | Journal Article |
| Publicado: |
Pergamon Press - An Imprint of Elsevier Science
2015 May
|
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=109728364&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 109728364 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 00426989 2FL jtl: Vision Research issn: 00426989 maglogo: N pubinfo: dt: 2015 May vid: 110 iid: Pt B pid: 2410 pub: Pergamon Press - An Imprint of Elsevier Science artinfo: ui: 109728364 NLM25199609 2012988616 10.1016/j.visres.2014.08.016 NLM25199609 109728364 ppf: 265 ppct: 12 formats: tig: atl: Patient DF's visual brain in action: Visual feedforward control in visual form agnosia. aug: au: Whitwell, Robert L Milner, A David Cavina-Pratesi, Cristiana Barat, Masihullah Goodale, Melvyn A sug: ab: Patient DF, who developed visual form agnosia following ventral-stream damage, is unable to discriminate the width of objects, performing at chance, for example, when asked to open her thumb and forefinger a matching amount. Remarkably, however, DF adjusts her hand aperture to accommodate the width of objects when reaching out to pick them up (grip scaling). While this spared ability to grasp objects is presumed to be mediated by visuomotor modules in her relatively intact dorsal stream, it is possible that it may rely abnormally on online visual or haptic feedback. We report here that DF's grip scaling remained intact when her vision was completely suppressed during grasp movements, and it still dissociated sharply from her poor perceptual estimates of target size. We then tested whether providing trial-by-trial haptic feedback after making such perceptual estimates might improve DF's performance, but found that they remained significantly impaired. In a final experiment, we re-examined whether DF's grip scaling depends on receiving veridical haptic feedback during grasping. In one condition, the haptic feedback was identical to the visual targets. In a second condition, the haptic feedback was of a constant intermediate width while the visual target varied trial by trial. Despite this incongruent feedback, DF still scaled her grip aperture to the visual widths of the target blocks, showing only normal adaptation to the false haptically-experienced width. Taken together, these results strengthen the view that DF's spared grasping relies on a normal mode of dorsal-stream functioning, based chiefly on visual feedforward processing. pubtype: Academic Journal doctype: Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
|---|