Memory-guided saccade processing in visual form agnosia (patient DF)

Rossit, Stéphanie; Szymanek, Larissa; Butler, Stephen H.; Harvey, Monika

doi:10.1007/s00221-009-2074-0

Cited by 15 publications

(16 citation statements)

References 41 publications

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“…D.F. also showed a comparable dissociation when she was asked to make saccadic eye movements to a target location, either directly or after a delay when the target was no longer there (Milner et al 1999; Rossit et al 2010). In the latter case her accuracy dropped precipitously.…”

Section: Evidence For Ventral-to-dorsal Trafficmentioning

confidence: 99%

How do the two visual streams interact with each other?

2017

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The current consensus divides primate cortical visual processing into two broad networks or “streams” composed of highly interconnected areas (Milner and Goodale 2006, 2008; Goodale 2014). The ventral stream, passing from primary visual cortex (V1) through to inferior parts of the temporal lobe, is considered to mediate the transformation of the contents of the visual signal into the mental furniture that guides memory, recognition and conscious perception. In contrast the dorsal stream, passing from V1 through to various areas in the posterior parietal lobe, is generally considered to mediate the visual guidance of action, primarily in real time. The brain, however, does not work through mutually insulated subsystems, and indeed there are well-documented interconnections between the two streams. Evidence for contributions from ventral stream systems to the dorsal stream comes from human neuropsychological and neuroimaging research, and indicates a crucial role in mediating complex and flexible visuomotor skills. Complementary evidence points to a role for posterior dorsal-stream visual analysis in certain aspects of 3-D perceptual function in the ventral stream. A series of studies of a patient with visual form agnosia has been instrumental in shaping our knowledge of what each stream can achieve in isolation; but it has also helped us to tease apart the relative dependence of parietal visuomotor systems on direct bottom-up visual inputs versus inputs redirected via perceptual systems within the ventral stream.

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Section: Evidence For Ventral-to-dorsal Trafficmentioning

confidence: 99%

How do the two visual streams interact with each other?

2017

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“…Neuropsychology has revealed a double dissociation between the ability to perform immediate vs. delayed actions. Specifically, a patient, DF, with visual form agnosia and bilateral lesions within LOC [6] was far more impaired in performing delayed than immediate actions [7], [8]. Conversely, another patient, IG, with optic ataxia and a lesion to posterior parietal cortex, performed better for delayed than immediate actions [9].…”

Section: Introductionmentioning

confidence: 95%

Human fMRI Reveals That Delayed Action Re-Recruits Visual Perception

et al. 2013

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Behavioral and neuropsychological research suggests that delayed actions rely on different neural substrates than immediate actions; however, the specific brain areas implicated in the two types of actions remain unknown. We used functional magnetic resonance imaging (fMRI) to measure human brain activation during delayed grasping and reaching. Specifically, we examined activation during visual stimulation and action execution separated by a 18-s delay interval in which subjects had to remember an intended action toward the remembered object. The long delay interval enabled us to unambiguously distinguish visual, memory-related, and action responses. Most strikingly, we observed reactivation of the lateral occipital complex (LOC), a ventral-stream area implicated in visual object recognition, and early visual cortex (EVC) at the time of action. Importantly this reactivation was observed even though participants remained in complete darkness with no visual stimulation at the time of the action. Moreover, within EVC, higher activation was observed for grasping than reaching during both vision and action execution. Areas in the dorsal visual stream were activated during action execution as expected and, for some, also during vision. Several areas, including the anterior intraparietal sulcus (aIPS), dorsal premotor cortex (PMd), primary motor cortex (M1) and the supplementary motor area (SMA), showed sustained activation during the delay phase. We propose that during delayed actions, dorsal-stream areas plan and maintain coarse action goals; however, at the time of execution, motor programming requires re-recruitment of detailed visual information about the object through reactivation of (1) ventral-stream areas involved in object perception and (2) early visual areas that contain richly detailed visual representations, particularly for grasping.

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“…Those regions connect with each other through specific neural pathways of information flow. The saccade generation process relies on the dorsal visual stream, the circuit responsible for visuospatial processing (Goodale and Milner, 1992;Milner and Goodale, 2008;Rossit et al, 2010;Valyear et al, 2006). A recent review by Kravitz et al (2011) revealed three distinct pathways that emerge from the dorsal visual stream.…”

Section: Introductionmentioning

confidence: 98%