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

MA 076 Swaroop

Clever hack!

• Representational

dissimilarity matrix (RDM)

• It is based on stimuli , not

the modality of

measurement!

MA 076 Swaroop

MA 076 Swaroop

Results

MA 076 Swaroop

MA 076 Swaroop

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

Questions?

Thank you