Voyko Kavcic

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The goal of the current investigation was to detect clinically important axonal damage in cerebral white matter after mild traumatic brain injury (TBI) using diffusion tensor imaging (DTI). To this end, we evaluated a prospective, pilot study of six subjects with isolated mild TBI and six matched orthopedic controls. All subjects underwent DTI scanning,(More)
BACKGROUND Patients with Alzheimer's disease (AD) and many older adults become lost even in familiar surroundings. This is commonly attributed to memory impairment, but it may reflect impaired spatial cognition. METHODS The authors examined the role of memory, perceptual, and cognitive mechanisms in spatial disorientation by comparing the performance of(More)
Visuospatial disorientation forces Alzheimer's disease patients to abandon independent activities. We found previously that limitations of ambulatory and vehicular navigation are linked to impaired visual motion processing in Alzheimer's disease. We now hypothesize that these perceptual impairments reflect temporal constraints on visual attention. We(More)
Partial cortical blindness is a visual deficit caused by unilateral damage to the primary visual cortex, a condition previously considered beyond hopes of rehabilitation. However, recent data demonstrate that patients may recover both simple and global motion discrimination following intensive training in their blind field. The present experiments(More)
BACKGROUND AND PURPOSE The effects of a number of diffusion-encoding gradient directions (NDGD) on diffusion tensor imaging (DTI) indices have been studied previously with theoretic analysis and numeric simulations. In this study, we made in vivo measurements in the human brain to compare different clinical scan protocols and to evaluate their effects on(More)
Understanding the effects of increased and decreased gravity on central nervous system is essential for developing proper physical and cognitive countermeasures to assure safe and effective space missions and human survival in space. This short review covers the available literature on the brain electrocortical activity effects of decreased and increased(More)
Aging and Alzheimer's disease (AD) are associated with declines in the visual perception of self-movement that undermine navigation and independent living. We studied 214 subjects' heading direction and speed discrimination using the radial patterns of visual motion in optic flow. Young (YA), middle-aged (MA), and older normal (ON) subjects, and AD patients(More)
OBJECTIVE We developed visual motion evoked potential (EP) measures related to navigational impairment in Alzheimer disease (AD) and have now applied these methods to explore the role of elementary perceptual and attentional mechanisms mediating these effects. METHODS Older adult (OA) control subjects and AD patients underwent visual motion perceptual(More)
We assessed visual processing related to navigational impairment in Alzheimer's disease hypothesizing that visual motion evoked responses to optic flow simulating observer self-movement would be linked to navigational performance. Mild Alzheimer's disease and older adult control subjects underwent open-field navigational testing, visual motion perceptual(More)
BACKGROUND Alzheimer's disease (AD) is associated with changes in cerebral white matter (WM), but the functional significance of such findings is not yet established. We hypothesized that diffusion tensor imaging (DTI) might reveal links between regional WM changes and specific neuropsychologically and psychophysically defined impairments in early AD. (More)