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You have a test next week!

You have a test next week!. Review Session Monday next week 4 – 5 Room Th 173. Parallel pathways in the visual system. Dorsal and Ventral Pathways. recall some details about visual pathways. Dorsal and Ventral Pathways.

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You have a test next week!

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  1. You have a test next week! Review Session Monday next week 4 – 5 Room Th 173

  2. Parallel pathways in the visual system

  3. Dorsal and Ventral Pathways • recall some details about visual pathways

  4. Dorsal and Ventral Pathways • Different visual cortex regions contain cells with different tuning properties represent different features in the visual field • PET study by Zeki et al. • Double dissociation of lesions • V5/MT is selectively responsive to motion • V4 is selectively responsive to color

  5. What are the different roles of these pathways? • Ventral Stream • Object identification • Awareness? • Dorsal stream • Spatial representations

  6. Dorsal and Ventral Pathways • V4 and V5 are key parts of two larger functional pathways: • Dorsal or “Where” pathway • Ventral or “What” pathway • Ungerleider and Mishkin (1982) • Magno and Parvo dichotomy arose at the retina and gives rise to two distinct cortical pathways

  7. FusiformGyrus: Specialized for perception of complex objects • Ventral pathway has specialized regions for complex object identification: • Faces – Fusiform Face Area (FFA) • Word Form – Visual Word Form Area (VWFA)

  8. Visual Word Form Area • fMRI contrasting words with pictures • Left inferior temporal lobe Deheane et al. (2009) NeuroImage

  9. Visual Word Form Area • Exhibits invariance to surface structure of words • Table, TABLE, tAblE are equivalent Deheane et al. (2009) NeuroImage

  10. Visual Word Form Area • Possibly mediates the critical skill of overcoming mirror invariance for objects during learning Deheane et al. (2009) NeuroImage

  11. Visual Word Form Area • Lesions cause Pure Alexia • Inability to read visual input efficiently • Letter-by-letter strategies are intact but S – L – O – W • Words traced on the skin can be read!? Deheane et al. (2009) NeuroImage

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