Transcript Visual categorization shapes feature selectivity in the primate

Visual categorization shapes
feature selectivity in the
primate temporal cortex
Interdisciplinary Program in Brain Science
Eye Movement & Vision Research LAB
Hwang, Jae Won
Inferior Temporal Cortex
• The inferior temporal cortex area has a critical role
in visual object recognition and responds to complex
stimuli.
• Activity in the human temporal cortex is thought to
be sensitive to the categorization level of the stimuli
and to depend on the expertise of the observer.
Stimuli and Categories
Feature Selectivity
•An example of a
neuron whose firing
rate discriminates
different values of
one diagnostic feature
of the eye height(EH)
stimuli.
Black : Responses of the neuron to
the best feature value
Grey : Responses to the worst
feature value
s.i.
: Selectivity Index
=
Max - Min
Max + Min
Population Average
• Population average
for all the neurons
tested with the face
stimuli.
Black : average responses to the
best feature value
Grey : average responses to the
worst feature value
Representation of the DF
Red circles : Neurons with statistically significant selectivity for diagnostic dimension only
Blue circles : Neurons with significant selectivity for diagnostic and non-diagnostic feature
Black triangles : Neurons with no significant selectivity
Red star : Example neuron depicted in previous figure
Conclusion
• Stimulus features important for categorization are
instantiated in the activity of single units in the primate
inferior temporal cortex.
• This neuronal fine-tuning may reflect the monkey’s
perceptual increase of sensitivity for the diagnostic
features.