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BACKGROUND Patients with homonymous hemianopia often have some residual sensitivity for visual stimuli in their blind hemifield. Previous imaging studies suggest an important role for extrastriate cortical areas in such residual vision, but results of training to improve vision in patients with hemianopia are conflicting. OBJECTIVE To show that intensive(More)
Human medial occipital cortex comprises multiple visual areas, each with a distinct retinotopic representation of visual environment. We measured spatial frequency (SF) tuning curves with functional magnetic resonance imaging (fMRI) and found consistent differences between these areas. Areas V1, V2, VP, V3, V4v, and V3A were all band-pass tuned, with(More)
Multifocal functional magnetic resonance imaging has recently been introduced as an alternative method for retinotopic mapping, and it enables effective functional localization of multiple regions-of-interest in the visual cortex. In this study we characterized interactions in V1 with spatially and temporally identical stimuli presented alone, or as a part(More)
An image patch can be locally decomposed into sinusoidal waves of different orientations, spatial frequencies, amplitudes, and phases. The local phase information is essential for perception, because important visual features like edges emerge at locations of maximal local phase coherence. Detection of phase coherence requires integration of spatial(More)
People are embedded in social interaction that shapes their brains throughout lifetime. Instead of emerging from lower-level cognitive functions, social interaction could be the default mode via which humans communicate with their environment. Should this hypothesis be true, it would have profound implications on how we think about brain functions and how(More)
In non-human primates at least three anatomically and functionally distinct channels convey signals from the retina to the primary visual cortex (V1). Two of these channels, the parvocellular and the koniocellular, are sensitive to chromatic contrasts and form the basis of color vision. In humans, common phylogenetic history with other primates and(More)
BACKGROUND Mental disorders are known to be as prevalent in Ethiopia as in other countries. Only 26 psychiatrists are working in the country with close to 80 million inhabitants. To this should be added clinics run by psychiatric nurses in most of the general hospitals. This means that still most of the mentally ill in the country are trected and cared for(More)
The localization of visual areas in the human cortex is typically based on mapping the retinotopic organization with functional magnetic resonance imaging (fMRI). The most common approach is to encode the response phase for a slowly moving visual stimulus and to present the result on an individual's reconstructed cortical surface. The main aims of this(More)
It has been suggested that unconscious visual processing of some stimulus features might occur without the contribution of early visual cortex (V1/V2). In the present study, the causal role of V1/V2 in unconscious processing of simple shapes in intact human brain was studied by applying transcranial magnetic stimulation (TMS) on early visual cortex or(More)