object recognition (2)

• Challenges to the FFA module hypothesis


  • Expertise-related activation in FFA
  • Activation in other brain regions to faces
  • Developmental prosopagnosia
  • Distributed patterns of activation to different object categories in ventral visual cortex
• Gauthier et al. (1999) trained subjects to recognise novel objects ('Greebles')


  Found activation in FFA in greeble experts but not in greeble novices
• Gauthier et al. (2000)


  1. Showed bird experts and car experts pictures of birds, cars and faces

  2. Stronger FFA activation to birds in bird experts and to cars in car experts
• Evidence for increased FFA activation for 'expertise' is weak and inconsistent – increases are small and several studies have failed to replicate findings
• Greeble experiment confounded by similarity of stimuli to faces
• Part/whole behavioural effects are observed for faces but not for other 'expertise' objects e.g. dog experts
• Univariate fMRI


  Looks for 'peaks' of activation
• MVPA fMRI


  Looks for patterns of activation
• Haxby et al (2001) findings:

  • Within-category correlations = higher than between category correlations for all voxels across the ventral visual cortex
  • This pattern = same even when they removed voxels that showed higher activation to each category
  • Shows we can predict what category of object someone is looking at.
• TMS during a discrimination task involving faces, objects or bodies

  1. TMS to OFA impairs face discrimination

  2. TMS to EBA impairs body discrimination

  3. TMS to LOC impairs object discrimination
• Neurosurgical patient implanted with electrodes along fusiform gyri


  1. Electrocorticographic responses showed selectivity to faces

  2. Electrical stimulation in region of FFA produced illusory experience of seeing a face ("facephene")
• Visual form agnosia

  • Cannot recognise even simple shapes
• Karnaths findings suggest lesion to:

  • parietal cortex
• Associative agnosia symptoms:

  • Identifying objects
  • Naming objects
  • Linking functions to objects
• In fMRI adaptation, a reduced neuronal response to different objects with the same function means that:

  • neuron is sensitive to function
• Area LOC should show a higher response to a picture of a real object relative to a picture of a novel, plausible object. True or false?

  • False