Right-hemispheric dominance for visual remapping in humans

Abstract

We review evidence showing a right-hemispheric dominance for visuo-spatial processing and representation in humans. Accordingly, visual disorganization symptoms (intuitively related to remapping impairments) are observed in both neglect and constructional apraxia. More specifically, we review findings from the intervening saccade paradigm in humans-and present additional original data-which suggest a specific role of the asymmetrical network at the temporo-parietal junction (TPJ) in the right hemisphere in visual remapping: following damage to the right dorsal posterior parietal cortex (PPC) as well as part of the corpus callosum connecting the PPC to the frontal lobes, patient OK in a double-step saccadic task exhibited an impairment when the second saccade had to be directed rightward. This singular and lateralized deficit cannot result solely from the patient's cortical lesion and, therefore, we propose that it is due to his callosal lesion that may specifically interrupt the interhemispheric transfer of information necessary to execute accurate rightward saccades towards a remapped target location. This suggests a specialized right-hemispheric network for visuo-spatial remapping that subsequently transfers target location information to downstream planning regions, which are symmetrically organized.

Position specificity of adaptation-related face aftereffects

“…Furthermore, it is interesting to note that similar ideas have been put forward regarding spatial selectivity for action as well: the right posterior parietal cortex represents space in both hemispheres, while other action-related areas, such as the frontal eye field, show contralateral selectivity [98,99]. The question remains to what extent the spatial invariance of object representations might play a role in the stability of the world across eye movements.…”

Visual stability

“…Reviews of studies with clinical patients [25] and with TMS [27] show how the use of well-designed behavioural tests can give insight into the mechanisms of visual stability. At the same time, the presence of redundant circuits [20] might mask the functional role of individual brain regions.…”

“…Regions in posterior parietal cortex (LIP, in monkey), the frontal eye fields and the superior colliculus work together in guiding eye movements and, not surprisingly, these areas show remapping of oculocentric receptive fields [20,21]. In humans, evidence from TMS and clinical studies (reviewed in [25,27]) suggests that the right posterior parietal cortex may play a special role in maintaining spatial constancy (see also [73]). Lesions to the thalamus can also lead to failures of visual stability, in which self-movement and external, object movement are confounded [74].…”

“…Finally, there are neurons the receptive fields of which seem to spatially expand or contract, or even split into multiple zones. An important question for future work is to understand whether the heterogeneous pattern of remapping reflects a single spatial-temporal transformation or, rather, multiple independent mechanisms that serve different aspects of visual stability (as suggested, for example, in this issue in the Discussion section of [25]). As reviewed by Hamker et al, different computational models of visual stability incorporate varying types of dynamic receptive fields.…”

Free-Drawing from Memory in Constructional Apraxia: A Case Series

“…Symbol Search has many of the features of a line-by-line reconstitution of the elements of a nonverbal design from one point on the page to another. The right superior parietal lobule has been shown to be essential for such visual remapping of spatial coordinates [67] and for participant 3A this brain region was severely damaged. Participant 3A's age scaled scores on Designs I and II were 9 and 4 respectively.…”