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TRANSCRIPT
Matching categorical object representation in the
inferior temporal cortex of man and monkey
Kriegeskorte et al.
Neuron 2008
Presented by
Swaroop Guntupalli
Why bother?
• Brain is a massive complex adaptive network (neurons are agents)
– 50-100 billion of these with 100 trillion synapses which change every second!
• So the problem is how to observe and understand its dynamics?
– Simple, just poke into it and record.
– Can’t do that on humans (since using torture on humans is only allowed for – Can’t do that on humans (since using torture on humans is only allowed for
homeland security but not for scientific understanding)
– fMRI (BOLD is alias of neural activity) in humans
– Do monkeys see the world like we do?
– How to compare activity of a few neurons to combined activity alias of a
cortical cube of side 2mm (which has tens of thousands of these units)
MA 076 Swaroop
Clever hack!
• Representational
dissimilarity matrix (RDM)
• It is based on stimuli , not
the modality of
measurement!
MA 076 Swaroop
So what?
• Response patterns in brain cluster according to same categorical structure in
monkey and man
• Stayed even if the regions that are specialized in processing faces and places are
removed! (Information representation is distributed)
• This categorization is absent in early visual processing areas (Visual cortex)
• Heirarchical category structure is inherent to IT• Heirarchical category structure is inherent to IT
• A low and intermediate level computer models did not produce such
categorization
• We and monkeys have a common code! (which is determined by yet another
complex network called gene regulatory network)
MA 076 Swaroop