2research center for brain and cognitive sciences 385

Unformatted text preview: on-face images with varying amounts of noise were used in a face tegorization task. b, Timing of events in each categorization trial. One of e four possible microstimulation conditions shown was applied randomly each trial. ehran, 19395, Iran. 2Research Center for Brain and Cognitive Sciences, 385, Iran. Afraz, Kiani, Esteky The visual system has to solve a hard problem: object recognition invariant to change Position Size Pose/Background We do not know how this is solved (we cannot build a machine that does it) We have some hypotheses about how it might work The ventral visual pathway: selectivity and invariance V2 Macaque V4 V1 pIT IT LGN retina Selectivity Invariance Receptive fields (Tolerance) get bigger retina V1 V4 IT Position separabil P “Invariant” Clutter -1 0 0.25 B 0 15 A Firing rate Response 370 (spikes /s) Position FIG. 3 Fraction of neurons Invariance -0.5 V1, mean: 0.02 IT, mean: 0.68 0 60 V1 simulated ORTICAL NEURONS COPE WITH CLUTTER? 0 IT Neurons in IT are not “Invariant”; they are “Tolerant” 7. Summary of the goodness of d f...
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