2023 年 19 巻 1 号 p. 117-123
Introduction: Prism adaptation (PA) is a promising treatment to improve unilateral spatial neglect (USN). Egocentric neglect and allocentric neglect are the two types of USN in terms of spatial reference frames, but no study was reported the PA affects allocentric frame selectively. This study therefore aimed to investigate whether the PA effect could be observed only on allocentric frame in healthy participants.
Method: Thirty right-handed participants (12 females and 18 males, mean age 22.6 years), wore the right wedged prismatic glasses that created an optical shift of 5.7° to the left. They were asked to reach two visual targets with the right index finger 100 times alternately. Outcomes were measured through the line bisection task where lines of two different lengths (200 mm and 50 mm) were presented one by one in front of or on the left or right side of the participants.
Results: The subjective midpoint on the 200-mm line shifted significantly to the right after the PA, but not on the 50-mm line. Additionally, the degree of rightward deviation was not affected by the position of the presented line regardless of its length.
Discussion: These results indicate that the PA task induced allocentric neglect-like behavior. Hence, PA affected only the allocentric frame among healthy participants. The results of this study may contribute to the evaluation and treatment of allocentric neglect.
