Neuroscience of Visual Processing
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Questions and Answers

What is the primary function of the ventral stream in visual processing?

  • Detecting lines, edges, and shapes
  • Identifying the object's location
  • Identifying an object (correct)
  • Synchronizing visual input with hand movements

    • Which area of the brain is primarily linked to the perception of color?

  • V1
  • FFA
  • V4 (correct)
  • V5

    • What characterizes optic ataxia as a visual disorder?

  • Challenges in coordinating visual input with hand movements (correct)
  • Problems identifying colors under different lighting
  • Inability to detect motion through vision
  • Difficulty in recognizing familiar faces

    • In the study of visual agnosia, which area of the brain is typically implicated?

    <p>Temporal lobe</p> Signup and view all the answers

    What phenomenon is demonstrated by patient LM in the context of akinetopsia?

    <p>Inability to perceive motion visually</p> Signup and view all the answers

    The Fusiform Face Area (FFA) is known to be more responsive to what type of stimuli?

    <p>Faces over other objects</p> Signup and view all the answers

    Which study demonstrated that training on non-face objects could enhance face perception abilities?

    <p>Gauthier et al. 1999</p> Signup and view all the answers

    What is a distinguishing characteristic of the Visual Word Form Area (VWFA)?

    <p>Responds to written words more than to non-words</p> Signup and view all the answers

    Which of the following is not a recognized outcome of lesions in the temporal lobe?

    <p>Inability to perceive color constancy</p> Signup and view all the answers

    The concept of color constancy primarily involves which brain area's processing ability?

    <p>V4</p> Signup and view all the answers

    What is primarily responsible for the functional specialization of the visual system?

    <p>Interconnectedness of task demands and visual systems</p> Signup and view all the answers

    Which of the following statements accurately describes object recognition?

    <p>It is invariant to location and size.</p> Signup and view all the answers

    What is the relationship between the ventral and dorsal streams regarding skilled object use?

    <p>They interact but focus on different visual tasks.</p> Signup and view all the answers

    Which system is specifically linked to the process of word recognition?

    <p>VWFA (Visual Word Form Area)</p> Signup and view all the answers

    How does the theory of 'task decomposition' relate to visual cognitive systems?

    <p>It indicates that specialized systems manage sub-tasks.</p> Signup and view all the answers

    What role does neuronal recycling play in visual processing?

    <p>It enhances the ability to learn visual tasks.</p> Signup and view all the answers

    Which aspect of visual demand does object localization depend on?

    <p>It is tied to specific location, size, and shape.</p> Signup and view all the answers

    In chimpanzees, how is tool use correlated to their brain structure?

    <p>It is correlated with grey matter volume in the ventral-dorsal stream.</p> Signup and view all the answers

    What is the primary function of the FFA (Fusiform Face Area)?

    <p>Recognition of faces.</p> Signup and view all the answers

    Which characteristic differentiates the dorsal stream from the ventral stream?

    <p>Involvement in spatial awareness and action.</p> Signup and view all the answers

    Study Notes

    Feature Detectors

    • Feature detectors are involved in identifying lines, edges, and shapes.
    • Visual illusions activate the same brain regions as non-illusory perceptions.

    Organisation of Visual Processing

    • Dorsal stream (Parietal cortex): Processes object location and visual-guided actions.
    • Ventral stream (Inferotemporal cortex): Identifies objects.
      • Category selectivity increases from anterior to posterior regions of the ventral stream.

    Double Dissociation

    • Lesion studies (humans) and ablation/single-unit recording studies (monkeys) show double dissociation.
    • Visual agnosia: Temporal lobe lesion; difficulty recognising shapes.
    • Optic ataxia: Parietal lobe lesion; difficulty coordinating visual input and hand movements.
      • Primarily affects upper visual field.
      • Reaching movements appear wide-open.

    PET study - Zeki et al. 1991

    • V4: Primarily involved in color perception (comparing coloured to grayscale images).
    • V5: Involved in motion perception (comparing moving and static dots).

    Patient LM - Zihl et al. 1983 (Akinetopsia)

    • Inability to perceive motion.
    • Difficulty in identifying moving and stationary objects.
    • Can perceive motion through other senses (hearing, touch).

    Retina vs. V4

    • Retina (cones): Detect different wavelengths of light.
    • V4: Accounts for variations in lighting conditions, preserving colour constancy.
      • V4 cells respond to the same surface color even under varying light sources.
      • V1 cells do not demonstrate colour constancy.

    De Renzi 1986

    • Patient failed to recognize family members; this ability was present with voice or clothes.
    • Could compare different views of faces and identify other objects.

    Fusiform Face Area (FFA)

    • Located in the right hemisphere.
    • Actively responds to faces more than other objects in functional imaging experiments (Kanwisher).
    • FFA activity might be linked to expertise in recognizing faces.
    • There is a relative difference in face vs object recognition in some cases.

    Expertise and FFA - Gauthier et al. 1999

    • Greeble recognition training demonstrates holistic face-like perception in recognising Greebles.
    • Greeble recognition shows similar behavioral patterns, following face recognition.
    • Increased ability to process Greebles after extensive training, sometimes at the cost of face recognition ability.

    Domain Specificity and Innateness

    • Difficulties in definitively proving domain specificity/innateness of face recognition mechanisms.

    Visual Word Form Area (VWFA)

    • Located in the left hemisphere.
    • Displays stronger response to written words than consonant strings.
    • Pure alexia: Difficulty in reading letters individually, showing a letter-by-letter reading pattern.
    • Recovery in reading abilities is possible over time, though full recovery is not guaranteed.

    VWFA vs. FFA

    • Differing locations in left and right hemispheres.
    • Word and face recognition have similar visual and computational demands.
    • Theory: Functional specialization is a consequence of task and visual system interactions.
    • Neuronal recycling: Reading may repurpose pre-existing object or face recognition neural networks (Dehaene et al. 2015).

    Emergent Specialisation

    • Distinct tasks within the visual system exist and have unique computational demands.
    • Object recognition (location, size invariant).
    • Object localisation (location, size, shape invariant).
    • Deconstruction of complex tasks into specialized cognitive systems (e.g., VWFA and FFA).

    Ventral-Dorsal Streams

    • Connections between dorsal and ventral streams exist.
    • Important for skilled object use.

    Tool Use in Chimpanzees

    • Tool use ability correlates with the grey matter volume in the ventral-dorsal stream.

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    Description

    Explore the intricate workings of feature detectors and the organisation of visual processing in the brain. This quiz covers topics including the dorsal and ventral streams, as well as conditions like visual agnosia and optic ataxia. Test your knowledge on key studies and concepts in visual perception.

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