TB6 (L1) – Object processing in the ventral stream
Classic hierarchical model of object processing
- Info Retina LGN Primary visual cortex
- Assume that information flows in a “feed-forward” fashion along a cortical hierarchy of
regions (Travels in a forward motion) where assumed it gets more complex along the
hierarchy (Fellemann & Van Essen, 1992)
Two visual streams (systems)
Dorsal Stream (Where?) Ventral stream (What?) found in V2, V4,
inferotemporal cortex
Occipital lobe Parietal lobe Occipital lobe Temporal lobe
Object-guided action Object recognition/ discrimination
Location & movement (catching a ball) Object quality
- Mishikin et al., 1983 – Removing monkey brain parts and found such association (Associate
shape with reward, remove inferior temporal cortex from ventral stream cannot
associate shapes) (Learn spatial location, remove parietal cortex from dorsal stream
Cannot locate item)
- Goodale et al., 1991 – Lateral Occipital area (Lights up when object processing in normal
people) lesions in patient D.F. (Cannot tilt & match orientation of an object, but can act on it)
(Cannot match perceptual qualities but vision reaction is unaffected)
Response properties in the ventral stream
- Different properties in different regions but generally, all visual regions have preference for
the contralateral visual field
- Regions earlier in the hierarchy have more fine-grained receptive fields, vice versa e.g. V1
smaller but more, V4 larger but fewer
- Larger RFs are more useful for object information and meaning evaluation (e.g., V1 registers
local and smaller patches and fine details (Hair, cheekbone, edge of smile), V4 registers more
global and general information (Eye, mouth, entire nose…)
Early visual region neurons Driven by simple visual features (do not allow
meaningful object recognition)
Intermediate region neurons Exhibit preference to complex feature conjunctions
(focus on contrasting and combinations) e.g. shape
combination or colours
Later stage neurons Start to respond to presence of meaningful objects
Anterior temporal cortex neurons Seem to only respond to meaningful stimuli that are
encountered before, e.g. familiar people
- Grandmother Neurons – Remember all features of ‘grandma’ when see these features then
will activate specific neuron (Could activate when seen in different dimensons)
Classic hierarchical model of object processing
- Info Retina LGN Primary visual cortex
- Assume that information flows in a “feed-forward” fashion along a cortical hierarchy of
regions (Travels in a forward motion) where assumed it gets more complex along the
hierarchy (Fellemann & Van Essen, 1992)
Two visual streams (systems)
Dorsal Stream (Where?) Ventral stream (What?) found in V2, V4,
inferotemporal cortex
Occipital lobe Parietal lobe Occipital lobe Temporal lobe
Object-guided action Object recognition/ discrimination
Location & movement (catching a ball) Object quality
- Mishikin et al., 1983 – Removing monkey brain parts and found such association (Associate
shape with reward, remove inferior temporal cortex from ventral stream cannot
associate shapes) (Learn spatial location, remove parietal cortex from dorsal stream
Cannot locate item)
- Goodale et al., 1991 – Lateral Occipital area (Lights up when object processing in normal
people) lesions in patient D.F. (Cannot tilt & match orientation of an object, but can act on it)
(Cannot match perceptual qualities but vision reaction is unaffected)
Response properties in the ventral stream
- Different properties in different regions but generally, all visual regions have preference for
the contralateral visual field
- Regions earlier in the hierarchy have more fine-grained receptive fields, vice versa e.g. V1
smaller but more, V4 larger but fewer
- Larger RFs are more useful for object information and meaning evaluation (e.g., V1 registers
local and smaller patches and fine details (Hair, cheekbone, edge of smile), V4 registers more
global and general information (Eye, mouth, entire nose…)
Early visual region neurons Driven by simple visual features (do not allow
meaningful object recognition)
Intermediate region neurons Exhibit preference to complex feature conjunctions
(focus on contrasting and combinations) e.g. shape
combination or colours
Later stage neurons Start to respond to presence of meaningful objects
Anterior temporal cortex neurons Seem to only respond to meaningful stimuli that are
encountered before, e.g. familiar people
- Grandmother Neurons – Remember all features of ‘grandma’ when see these features then
will activate specific neuron (Could activate when seen in different dimensons)
