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Unilateral vestibular loss impairs external space representation.

Borel L, Redon-Zouiteni C, Cauvin P, Dumitrescu M, Devèze A, Magnan J, Péruch P - PLoS ONE (2014)

Bottom Line: These individuals were also required to estimate their body pointing direction.Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently.These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université, Marseille, France ; CNRS, UMR 7260 Laboratoire de Neurosciences Intégratives et Adaptatives, Marseille, France.

ABSTRACT
The vestibular system is responsible for a wide range of postural and oculomotor functions and maintains an internal, updated representation of the position and movement of the head in space. In this study, we assessed whether unilateral vestibular loss affects external space representation. Patients with Menière's disease and healthy participants were instructed to point to memorized targets in near (peripersonal) and far (extrapersonal) spaces in the absence or presence of a visual background. These individuals were also required to estimate their body pointing direction. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (one week and one month after the operation), and healthy participants were tested at similar times. Unilateral vestibular loss impaired the representation of both the external space and the body pointing direction: in the dark, the configuration of perceived targets was shifted toward the lesioned side and compressed toward the contralesioned hemifield, with higher pointing error in the near space. Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently. These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

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Related in: MedlinePlus

Pointing error in near and far spaces.Average pointing error (degrees) for each group of participants in the near (bottom) and far (top) spaces. The white squares correspond to the actual target locations. The distribution of targets and of pointing errors is presented to scale as seen from the observer's position, while the distances between the observer and the two spaces are not to scale. Three sessions were plotted for each patient: one day before UVN (D−1), one week after UVN (D+7), and one month after UVN (D+30). For clarity, only the average value was plotted in controls, as their variations across sessions were non-significant. The values were computed by averaging the x- (left-right direction) and y- (fore-aft distance) error of each group of participants. The 95% confidence intervals are also shown. In both spaces, the shift between the black full lines linking the target locations and the red dotted lines linking the maximal observed pointing error in patients at D+7 shows the systematic deviation of the memorized targets. A global space distortion toward the right side (highlighted by the red arrows) with a small underestimation of the distances was observed. As a result, the represented space is slightly compressed in the contralesional hemifield.
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pone-0088576-g003: Pointing error in near and far spaces.Average pointing error (degrees) for each group of participants in the near (bottom) and far (top) spaces. The white squares correspond to the actual target locations. The distribution of targets and of pointing errors is presented to scale as seen from the observer's position, while the distances between the observer and the two spaces are not to scale. Three sessions were plotted for each patient: one day before UVN (D−1), one week after UVN (D+7), and one month after UVN (D+30). For clarity, only the average value was plotted in controls, as their variations across sessions were non-significant. The values were computed by averaging the x- (left-right direction) and y- (fore-aft distance) error of each group of participants. The 95% confidence intervals are also shown. In both spaces, the shift between the black full lines linking the target locations and the red dotted lines linking the maximal observed pointing error in patients at D+7 shows the systematic deviation of the memorized targets. A global space distortion toward the right side (highlighted by the red arrows) with a small underestimation of the distances was observed. As a result, the represented space is slightly compressed in the contralesional hemifield.

Mentions: Interestingly, in the dark, the pointing error at D+7 depended on the location of the target respective to the patient's midline (Figure 3). For patients with right vestibular loss, the pointing error was consistently to the right side. For both spaces, the more targets that appeared to the right, the lower the pointing error was. In the near space, the pointing error was higher for left area targets (4.9±1.8°) than for both central (2.9±1.1°) and right area (2.4±0.9°) targets (p = 0.0005 and p = 0.004, respectively); the pointing error did not significantly differ for the central and right area targets. In the far space, the pointing error was higher for left area targets (3.3±0.9°) than for both central (2.5±0.9°) and right area (1.9±0.7°) targets (p = 0.006 and p = 0.0001, respectively), with a higher value detected for the central area than for the right area targets (p = 0.01). Therefore, considering the configuration formed by all targets, the represented space is distorted during the early stages following unilateral vestibular loss; this distortion is characterized by a shift toward the lesioned side and compression in the contralesional hemifield.


Unilateral vestibular loss impairs external space representation.

Borel L, Redon-Zouiteni C, Cauvin P, Dumitrescu M, Devèze A, Magnan J, Péruch P - PLoS ONE (2014)

Pointing error in near and far spaces.Average pointing error (degrees) for each group of participants in the near (bottom) and far (top) spaces. The white squares correspond to the actual target locations. The distribution of targets and of pointing errors is presented to scale as seen from the observer's position, while the distances between the observer and the two spaces are not to scale. Three sessions were plotted for each patient: one day before UVN (D−1), one week after UVN (D+7), and one month after UVN (D+30). For clarity, only the average value was plotted in controls, as their variations across sessions were non-significant. The values were computed by averaging the x- (left-right direction) and y- (fore-aft distance) error of each group of participants. The 95% confidence intervals are also shown. In both spaces, the shift between the black full lines linking the target locations and the red dotted lines linking the maximal observed pointing error in patients at D+7 shows the systematic deviation of the memorized targets. A global space distortion toward the right side (highlighted by the red arrows) with a small underestimation of the distances was observed. As a result, the represented space is slightly compressed in the contralesional hemifield.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921214&req=5

pone-0088576-g003: Pointing error in near and far spaces.Average pointing error (degrees) for each group of participants in the near (bottom) and far (top) spaces. The white squares correspond to the actual target locations. The distribution of targets and of pointing errors is presented to scale as seen from the observer's position, while the distances between the observer and the two spaces are not to scale. Three sessions were plotted for each patient: one day before UVN (D−1), one week after UVN (D+7), and one month after UVN (D+30). For clarity, only the average value was plotted in controls, as their variations across sessions were non-significant. The values were computed by averaging the x- (left-right direction) and y- (fore-aft distance) error of each group of participants. The 95% confidence intervals are also shown. In both spaces, the shift between the black full lines linking the target locations and the red dotted lines linking the maximal observed pointing error in patients at D+7 shows the systematic deviation of the memorized targets. A global space distortion toward the right side (highlighted by the red arrows) with a small underestimation of the distances was observed. As a result, the represented space is slightly compressed in the contralesional hemifield.
Mentions: Interestingly, in the dark, the pointing error at D+7 depended on the location of the target respective to the patient's midline (Figure 3). For patients with right vestibular loss, the pointing error was consistently to the right side. For both spaces, the more targets that appeared to the right, the lower the pointing error was. In the near space, the pointing error was higher for left area targets (4.9±1.8°) than for both central (2.9±1.1°) and right area (2.4±0.9°) targets (p = 0.0005 and p = 0.004, respectively); the pointing error did not significantly differ for the central and right area targets. In the far space, the pointing error was higher for left area targets (3.3±0.9°) than for both central (2.5±0.9°) and right area (1.9±0.7°) targets (p = 0.006 and p = 0.0001, respectively), with a higher value detected for the central area than for the right area targets (p = 0.01). Therefore, considering the configuration formed by all targets, the represented space is distorted during the early stages following unilateral vestibular loss; this distortion is characterized by a shift toward the lesioned side and compression in the contralesional hemifield.

Bottom Line: These individuals were also required to estimate their body pointing direction.Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently.These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

View Article: PubMed Central - PubMed

Affiliation: Aix-Marseille Université, Marseille, France ; CNRS, UMR 7260 Laboratoire de Neurosciences Intégratives et Adaptatives, Marseille, France.

ABSTRACT
The vestibular system is responsible for a wide range of postural and oculomotor functions and maintains an internal, updated representation of the position and movement of the head in space. In this study, we assessed whether unilateral vestibular loss affects external space representation. Patients with Menière's disease and healthy participants were instructed to point to memorized targets in near (peripersonal) and far (extrapersonal) spaces in the absence or presence of a visual background. These individuals were also required to estimate their body pointing direction. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (one week and one month after the operation), and healthy participants were tested at similar times. Unilateral vestibular loss impaired the representation of both the external space and the body pointing direction: in the dark, the configuration of perceived targets was shifted toward the lesioned side and compressed toward the contralesioned hemifield, with higher pointing error in the near space. Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently. These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

Show MeSH
Related in: MedlinePlus