Journal
NEUROPSYCHOLOGIA
Volume 158, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.neuropsychologia.2021.107913
Keywords
Prism adaptation; Intraparietal cortex; Spatial updating; Sensory-motor realignment; Hemispatial neglect
Funding
- British Federation of Women Graduates
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The study suggests that shifts in proprioceptive spatial representations induced by prism adaptation are more significant in patients with intraparietal cortex lesions, indicating the potential key role of this brain region in visual realignment.
Reaching toward a target viewed through laterally refracting prisms results in adaptation of both visual and (limb) proprioceptive spatial representations. Common ways to measure adaptation after-effect are to ask a person to point straight ahead with their eyes closed (manual straight ahead, MSA), or to a seen target using their unseen hand (open-loop pointing, OLP). MSA measures changes in proprioception only, whereas OLP measures the combined visual and proprioceptive shift. The behavioural and neurological mechanisms of prism adaptation have come under scrutiny following reports of reduced hemispatial neglect in patients following this procedure. We present evidence suggesting that shifts in proprioceptive spatial representations induced by prism adaptation are larger following lesions to the intraparietal cortex - a brain region that integrates retinotopic visual signals with signals of eye position in the orbit and that is activated during prism adaptation. Six healthy participants and six patients with unilateral intraparietal cortex lesions underwent prism adaptation. Aftereffects were measured with OLP and MSA. After-effects of control participants were larger when measured with OLP than with MSA, consistent with previous research and with the additional contribution of visual shift to OLP after-effects. However, patients' OLP shifts were not significantly different to their MSA shifts. We conclude that, for the patients, correction of pointing errors during prism adaptation involved proportionally more changes to arm proprioception than for controls. Since lesions to intraparietal cortex led to enhanced realignment of arm proprioceptive representations, our results indirectly suggest that the intraparietal cortex could be key for visual realignment.
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