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Vincent Walsh - One of the best experts on this subject based on the ideXlab platform.

  • Double Dissociation of Format-Dependent and Number-Specific Neurons in Human Parietal Cortex
    Cerebral cortex (New York N.Y. : 1991), 2010
    Co-Authors: Roi Cohen Kadosh, Juha Silvanto, Neil G. Muggleton, Vincent Walsh
    Abstract:

    Based on neuroimaging methods, it is a commonly held view that numerical representation in the human parietal lobes is format independent. We used a transcranial magnetic stimulation adaptation paradigm to examine the existence of functionally segregated overlapping populations of neurons for different numerical formats and to reveal how numerical information is encoded and represented. Based on 2 experiments, we found that right parietal lobe stimulation showed a Dissociation between digits and verbal numbers, whereas the left parietal lobe showed a Double Dissociation between the different numerical formats. Further analysis and modeling also excluded pre- or postrepresentational components as the source of the current effects. These results demonstrate that both parietal lobes are equipped with format-dependent neurons that encode quantity.

  • Double Dissociation of v1 and v5 mt activity in visual awareness
    Cerebral Cortex, 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

  • Double Dissociation of V1 and V5/MT activity in Visual Awareness
    Cerebral cortex (New York N.Y. : 1991), 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

Juha Silvanto - One of the best experts on this subject based on the ideXlab platform.

  • Double Dissociation of Format-Dependent and Number-Specific Neurons in Human Parietal Cortex
    Cerebral cortex (New York N.Y. : 1991), 2010
    Co-Authors: Roi Cohen Kadosh, Juha Silvanto, Neil G. Muggleton, Vincent Walsh
    Abstract:

    Based on neuroimaging methods, it is a commonly held view that numerical representation in the human parietal lobes is format independent. We used a transcranial magnetic stimulation adaptation paradigm to examine the existence of functionally segregated overlapping populations of neurons for different numerical formats and to reveal how numerical information is encoded and represented. Based on 2 experiments, we found that right parietal lobe stimulation showed a Dissociation between digits and verbal numbers, whereas the left parietal lobe showed a Double Dissociation between the different numerical formats. Further analysis and modeling also excluded pre- or postrepresentational components as the source of the current effects. These results demonstrate that both parietal lobes are equipped with format-dependent neurons that encode quantity.

  • Double Dissociation of v1 and v5 mt activity in visual awareness
    Cerebral Cortex, 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

  • Double Dissociation of V1 and V5/MT activity in Visual Awareness
    Cerebral cortex (New York N.Y. : 1991), 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

Nilli Lavie - One of the best experts on this subject based on the ideXlab platform.

  • Double Dissociation of v1 and v5 mt activity in visual awareness
    Cerebral Cortex, 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

  • Double Dissociation of V1 and V5/MT activity in Visual Awareness
    Cerebral cortex (New York N.Y. : 1991), 2005
    Co-Authors: Juha Silvanto, Nilli Lavie, Vincent Walsh
    Abstract:

    The critical time windows of the contribution of V1 and V5/MT to visual awareness of moving visual stimuli were compared by administering transcranial magnetic stimulation (TMS) to V1 or V5/MT in various time intervals from stimulus offset during performance of a simple motion detection task. Our results show a Double Dissociation in which the critical period of V1 both predates and postdates that of V5/MT, and where stimulation of either V1 at V5/MT's critical period or V5/MT at V1's critical period does not impair performance. These findings demonstrate the importance of back-projections from V5/MT to V1 in awareness of real motion stimuli.

H. B. Coslett - One of the best experts on this subject based on the ideXlab platform.

  • Neglect in vision and visual imagery: a Double Dissociation.
    Brain, 1997
    Co-Authors: H. B. Coslett
    Abstract:

    We report two patients with right hemisphere lesions who demonstrate a Double Dissociation on visual imagery and visual perceptual tasks. One (M.N.) performed normally on a variety of standard tests for neglects as well as on measures of visual attention known to be sensitive to the presence of neglect, yet failed to report items from the left side of an imagined scene. In contrast, the other (C.I.) performed normally on tests of visual imagery but demonstrated substantial neglect on visual perceptual and visual attentional tasks. These data are not readily accommodated by accounts which attribute neglect to a single processing deficit, but suggest that the disorder is a heterogeneous syndrome attributable to disruptions of different aspects of spatial cognition.

John D E Gabrieli - One of the best experts on this subject based on the ideXlab platform.

  • Double Dissociation of memory capacities after bilateral occipital lobe or medial temporal lobe lesions
    Brain, 1995
    Co-Authors: Margaret M Keane, John D E Gabrieli, Heather C Mapstone, Keith A Johnson, Suzanne Corkin
    Abstract:

    Summary Memory for recently encountered information can be reflected in conscious recall and recognition of that material, or in facilitated reprocessing of that material, an effect known as repetition priming. Repetition priming may be perceptual (form-based) or conceptual (meaning-based). A patient with bilateral occipital-lobe lesions (L.H.) and a patient with bilateral medial-temporal lobe lesions (H.M.). L.H. showed a Double Dissociation between visuopercep-tual priming (impaired in L.H. and intact in H.M.) and visual recognition memory (intact in L.H. and impaired in H.M.). L.H. showed intact conceptual priming for visually presented words; his pattern of impaired visuoperceptual priming and intact conceptual priming is the reverse Dissociation to that observed in prior studies of patients with Alzheimer's disease, in whom occipital cortices are relatively spared. These Double Dissociations suggest that a memory system localized to the occipital lobe mediates visuoperceptual priming effects, and that this system is independent of neural circuits mediating conceptual priming effects, and independent of the limbic-diencephalic system supporting conscious recognition of recently encountered information.

  • Double Dissociation between memory systems underlying explicit and implicit memory in the human brain
    Psychological Science, 1995
    Co-Authors: Margaret M Keane, John D E Gabrieli, Debra A Fleischman, Sheryl L Reminger, Frank Morrell
    Abstract:

    Amnesic patients have impaired explicit memory that is evident in poor recall and recognition of words, yet can have intact implicit memory for words as measured by repetition priming, the enhanced efficiency for reprocessing those words The Dissociation between explicit and implicit memory for words is a fundamental characteristic of normal cognition that could reflect two different functional architectures of the human brain two separate processing systems or two levels of operation of a single system with implicit memory less demanding of that system We present a patient who has a lesion in the right occipital lobe and who showed intact explicit and impaired implicit memory for words The deficit was specific to visual priming The Double Dissociation between explicit and implicit visual memory for words indicates that separate processing systems mediate these two forms of memory, and that a memory system in right occipital cortex mediates implicit visual memory for words