Behzad Mansouri

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PURPOSE Strabismic amblyopia is typically associated with several visual deficits, including loss of contrast sensitivity in the amblyopic eye and abnormal binocular vision. Binocular summation ratios (BSRs) are usually assessed by comparing contrast sensitivity for binocular stimuli (sens(BIN)) with that measured in the good eye alone (sens(GOOD)), giving(More)
Previously, we have shown that humans with amblyopia exhibit deficits for global motion discrimination that cannot be simply ascribed to a reduction in visibility or contrast sensitivity. Deficits exist in the processing of global motion in the fronto-parallel plane that suggest reduced extra-striate function (i.e., MT) in amblyopia. Here, we ask whether(More)
Some studies have reported deficits in amblyopia for global form and motion integration, whereas other studies have shown global integration of form and motion information to be normal in amblyopia. Here, we attempt to resolve this discrepancy by showing that amblyopes only exhibit selective performance deficits on global tasks that contain noise as well as(More)
It has been established that in amblyopia, information from the amblyopic eye (AME) is not combined with that from the fellow fixing eye (FFE) under conditions of binocular viewing. However, recent evidence suggests that mechanisms that combine information between the eyes are intact in amblyopia. The lack of binocular function is most likely due to the(More)
To better understand the nature of the cortical deficit in amblyopia we undertook a systematic investigation of second-order processing in 8 amblyopic and 8 normal observers. We investigated local detection, discrimination and global integration. Our local stimulus consisted of a Gaussian patch of fractal noise multiplied by a 1-d sinusoidal modulator. Our(More)
This study investigates four key issues concerning the binocular properties of the mechanisms that encode global motion in human vision: (1) the extent of any binocular advantage; (2) the possible site of this binocular summation; (3) whether or not purely monocular inputs exist for global motion perception; (4) the extent of any dichoptic interaction.(More)
The problem of how visual information such as orientation is combined across space bears on key visual abiities, such as texture perception. Orientation signals can be derived from both luminance and contrast, but it is not well understood how such information is pooled or how these different orientation signals interact in the integration process. We(More)
PURPOSE We developed a binocular treatment for amblyopia based on antisuppression therapy. METHODS A novel procedure is outlined for measuring the extent to which the fixing eye suppresses the fellow amblyopic eye. We hypothesize that suppression renders a structurally binocular system, functionally monocular. RESULTS We demonstrate using three(More)
PURPOSE The understanding of the site and nature of the cortical processing deficit in human amblyopia awaits the resolution of three fundamental questions about which there is, at present, much controversy: First, is area V1 affected as the present animal models would predict, but some imaging studies argue against? Second, how extensive is the loss of(More)
Amblyopia is a cortically based visual disorder caused by disruption of vision during a critical early developmental period. It is often thought to be a largely intractable problem in adult patients because of a lack of neuronal plasticity after this critical period [1]; however, recent advances have suggested that plasticity is still present in the adult(More)