Visual cognition in normal and brain-damaged humans.
Despite the fact that visual scenes often contain multiple objects and people, humans can recognize the different objects and individuals with ease and accuracy. Research in my laboratory focuses on studying how this is achieved - what are the necessary psychological processes and representations that underlie abilities such as object segmentation and recognition, face recognition, mental imagery, reading and writing and spatial attention? Although these questions are asked within the framework of information-processing models used in cognitive psychology, I am also interested in identifying the neural mechanisms, which are responsible for these complex abilities.
The major approach I use to address these questions is to study the behavior of human adults who have sustained brain damage (usually through stroke or head injury) which selectively affects their ability to carry out these processes. For example, some patients are impaired at recognizing faces (prosopagnosia), some are impaired at recognizing objects (visual object agnosia) and some are unable to represent visuospatial information (hemispatial neglect). By examining patterns of associations and dissociations among abilities after brain damage, one can make inferences about the functional and structural organization of the brain. This neuropsychological approach is combined with several other methods: experiments from traditional cognitive psychology paradigms (analyzing the response latencies and accuracies of normal subjects); studies of the acquisition of these skills in children; simulations of artificial neural networks which may be used to model these processes and their breakdown following brain-damage; and functional neuroimaging studies which examine the biological substrate of high-level vision.
A final thread to my research is to conduct rehabilitation studies with the brain damaged subjects in order to treat the observed deficit. Carefully planned rehabilitation studies provide valuable information that can shed light on the mechanisms underlying visual cognition.
Dinstein, I., Thomas, C., Humphreys, K., Minshew, N., Behrmann, M. and Heeger, D. Normal movement selectivity in autism, Neuron, 13;66(3): 461-9, 2010. (NIHMS195210)
Behrmann, M. and Nishimura, M. Agnosia, WIREs: Cognitive Science. 1, 203-213, 2010.
Scherf, S., Luna, B., Minshew, N. and Behrmann, M. Location, location, location: alterations in the functional topography of face- but not object- or place-related cortex in adolescents with autism, Frontiers in Human Neuroscience, doi: 10.3389/fnhum.2010.00026, 2010.
Avidan, G. and Behrmann, M. Functional MRI reveals compromised neural integrity of the face processing network in congenital prosopagnosia, Current Biology, 19, 13, 1146-1150, 2009. (NIHMS)
Thomas, C., Avidan, G., Humphreys, K., Jung, K. J. , Gao, F. and Behrmann, M. Reduced structural connectivity in ventral visual cortex in congenital prosopagnosia, Nature Neuroscience, 12, 1, 29-31, 2009.