Behavioral change and its neural correlates in visual agnosia after expertise training.

Behrmann M, Marotta J, Gauthier I, Tarr MJ, McKeeff TJ
J Cogn Neurosci. 2005 17 (4): 554-68

PMID: 15829077 · DOI:10.1162/0898929053467613

Agnosia, the impairment in object and face recognition despite intact vision and intelligence, is one of the most intriguing and debilitating neuropsychological deficits. The goal of this study was to determine whether S.M., an individual with longstanding visual agnosia and concomitant prosopagnosia, can be retrained to perform visual object recognition and, if so, what neural substrates mediate this reacquisition. Additionally, of interest is the extent to which training on one type of visual stimulus generalizes to other visual stimuli, as this informs our understanding of the organization of ventral visual cortex. Greebles were chosen as the stimuli for retraining given that, in neurologically normal individuals, these stimuli can engage the fusiform face area. Posttraining, S.M. showed significant improvement in recognizing Greebles, although he did not attain normal levels of performance. He was also able to recognize untrained Greebles and showed improvement in recognizing common objects. Surprisingly, his performance on face recognition, albeit poor initially, was even more impaired following training. A comparison of pre- and postintervention functional neuroimaging data mirrored the behavioral findings: Face-selective voxels in the fusiform gyrus prior to training were no longer so and were, in fact, more Greeble-selective. The findings indicate potential for experience-dependent dynamic reorganization in agnosia with the possibility that residual neural tissue, with limited capacity, will compete for representations.

MeSH Terms (14)

Adult Agnosia Brain Mapping Discrimination, Psychological Generalization, Psychological Humans Male Neuropsychological Tests Pattern Recognition, Visual Photic Stimulation Prosopagnosia Reaction Time Recognition, Psychology Time Factors

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