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Laboratory of Neuropsychology

Research

Dr. Afraz's main research interest is object recognition in the brain. He combines conventional and interventional physiology with visual psychophysics to investigate the neural underpinnings of object recognition behavior. He uses neural and behavioral data to inform computational models of object recognition. On a broader horizon, he is interested in the brain mechanisms underlying visual perception.

Face and object processing in the brain

Spatial limits of face processing

The idea of “translational invariance” has been one of the tenets of the visual neuroscience for a long time; the visual system recognizes objects no matter where in the visual field they appear. In the classical literature, functional translational invariance has been explained by large receptive fields of higher cortical areas (like inferotemporal cortex). Using “face recognition” as a controlled and well-studied instance of general object recognition, in this line of research, Dr. Afraz is challenging the “large receptive field” theory, also the very basic notion of translational invariance. His goal here, is to formulate a new theoretical approach to the question of “translation invariance”.

Brain mechanisms underlying face and object processing

What are the neural underpinnings of face and object perception? How does the neural structures in the inferotemporal cortex represent and cause perception of faces and objects? How plastic are these representations and what happens in the cortex when we learn new visual objects? Studying the neural activity in the inferotemporal cortex with a neurophysiological approach, Dr. Afraz is currently trying to answer some of these questions.

Visual awareness

Split brain

Corpus callosum interconnects the two cerebral hemispheres and mediates inter-hemispheric interactions at multiple levels of information representation in the brain. Surgical removal of the “splenium” of the corpus callosum for treatment of epileptic attacks provided a unique opportunity for us to study inter-hemispheric visual interactions in the absence of low-level visual connection between the two hemispheres.

Visual dynamics in the absence of awareness

Using psychophysical tricks like “crowding effect” and “binocular rivalry”, it is possible to alter visual awareness without removing the visual stimulus from the retina. This opens the door for experimental approach to visual awareness and makes it possible to study the dynamics of vision in the absence of consciousness.