Spatial Hyperschematia without Spatial Neglect after Insulo-Thalamic Disconnection

Abstract

Different spatial representations are not stored as a single multipurpose map in the brain. Right brain-damaged patients can show a distortion, a compression of peripersonal and extrapersonal space. Here we report the case of a patient with a right insulo-thalamic disconnection without spatial neglect. The patient, compared with 10 healthy control subjects, showed a constant and reliable increase of her peripersonal and extrapersonal egocentric space representations - that we named spatial hyperschematia - yet left her allocentric space representations intact. This striking dissociation shows that our interactions with the surrounding world are represented and processed modularly in the human brain, depending on their frame of reference.

Alice in Wonderland Syndrome: A Clinical and Pathophysiological Review

“…We know of a case of spatial hyperschematia, compatible with AIWS symptoms, in a patient with a lesion disconnecting the thalamus from right parietal and temporal cerebral cortices as well as the insula [38]. …”

“…A case of spatial hyperschematia without spatial neglect was described after an ischemic lesion causing a disconnection between the right insula and the posterior part/pulvinar of the thalamus [38]. In this subject, an extension of peripersonal and extrapersonal space, especially from the egocentric point of view, was observed.…”

A brief exposure to rightward prismatic adaptation changes resting-state network characteristics of the ventral attentional system

“…A similar change in VAN lateralization was shown to occur in neglect patients after right hemispheric lesions [30]. Second, tasks known to rely on DAN, such as line bisection or visual search, yielded greater activation within DAN after R-PA, as shown in patients with neglect [32]. Both types of changes in the organization of the attentional system occur very rapidly, over a few minutes, and reflect thus functional reorganization rather than structural changes [20].…”

“…alleviate neglect symptoms [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]64], predominantly in patients with anterior lesions in whom the posterior part of the corpus callosum and the right DAN are spared [50,65,66]. Activation studies have demonstrated that R-PA induces in neglect patients a shift of dominance by establishing ipsilateral spatial representation within VAN on the left side [30] and that it increases responsiveness of DAN [32]. Thus, there are similarities in R-PA induced effects between normal subjects and patients with neglect, but several aspects have not yet been investigated.…”

“…We made use of network science [48] to analyze the effects of prismatic adaptation on the configuration of the attentional system. Our working hypothesis was based on the observation that R-PA induces a rapid reorganization of the attentional system, including the emergence of ipsilateral spatial representation within the left VAN [30,49,50] and changes in responsiveness within DAN bilaterally [32]. Both phenomena are likely to rely on changes in functional connectivity, which appears to be modulated within DAN [33] as well as within VAN and DMN [35].…”