Vision After Early-Onset Lesions of the Occipital Cortex:II. Physiological Studies

Abstract

SUMMARYIn one of two patients (MS and

Visual recovery after perinatal stroke evidenced by functional and diffusion MRI: case report

“…transcallosal, major forceps, or commissural tracts) [47,52]. Such interhemispheric connections may play major roles during visual recovery, particularly after early-onset unilateral lesions, as documented previously in animal studies [53].…”

“…These more laterally located activation could be part of extrastriate cortex, mainly in V2 area, as defined retinotopically in the adult visual cortex [43,44] and recently shown in children [45]. Although some studies have suggested that activation of the striate cortex was a major sign of visual recovery [46,47], activations limited to extrastriate areas have been reported in patients with brain lesions. Thus, in patients with occipital lobe epilepsy, extrastriate visual responses to full-field visual stimulation were observed with fMRI [48].…”

“…In a child with cortical dysplasia fMRI, showed that the activity in the malformed hemisphere was different from that in the intact hemisphere [9], and visual function was related to activations in parieto-temporal regions. In two patients with lesions in striate and prestriate cortex, visual recovery was observed, particularly in the patient with early-onset lesion [49], and correlated to weak fMRI activation of isolated foci in the striate cortex [47]. In addition, it was observed that the stimulation of the scotomatous field in a patient with abnormal striate cortex yielded significant activation in extrastriate areas [50], suggesting important roles of the extrastriate cortex in the process of visual recovery.…”

Vision After Early-Onset Lesions of the Occipital Cortex:I. Neuropsychological and Psychophysical Studies

“…The differences, on the other hand, might be useful for understanding the pathogenesis of the deficit and the possible mechanisms of functional recovery (Knyazeva et al, 2002).…”

“Roadblocks” revisited: Neural change, stuttering treatment, and recovery from stuttering

“…Known as neural plasticity, this process is considered a fundamental feature of all brain tissue. Initially demonstrated in animals (for review see Destexhe & Marder, 2004), in humans it has been documented most clearly within the motor cortices during the acquisition and practice of motor skills (Pascual-Leone et al, 1995;Ungerleider, Doyon, & Karni, 2002) and in the visual system after lesions to the occipital cortex (Kiper, Zesiger, Maeder, Deonna, & Innocenti, 2002;Knyazeva, Maeder, Kiper, Deonna, & Innocenti, 2002;Rahi et al, 2002). Human neural plasticity research began with the assumption that the phenomenon is most common in young children (Chugani, Muller, & Chugani, 1996), but even the adult cortex is now thought to undergo continual plastic remodeling (Paulsen & Sejnowski, 2000).…”