Effects of prism adaptation on motor-intentional spatial bias in neglect

Abstract

Prism adaptation may alleviate some symptoms of spatial neglect. However, the mechanism through which this technique works is still unclear. This study investigated whether prism adaptation differentially affects dysfunction in perceptual-attentional 'where' bias versus motor-intentional 'aiming' bias. Five neglect patients performed a line bisection task in which lines were viewed under both normal and right-left reversed viewing conditions, allowing for the fractionation of 'where' and 'aiming' spatial bias components. After two consecutive days of prism adaptation, participants demonstrated a significant improvement in 'aiming' spatial bias, with no effect on 'where' spatial bias. These findings suggest that prism adaptation may primarily affect motor-intentional 'aiming' bias in poststroke spatial neglect patients.

Figure 1

Lesion mapping in five right-hemisphere-damaged patients, and lesion overlay plots (bottom row: frequency of overlapping lesions, from violet, N= 1, to yellow, N=5).

Figure 2

a: Motor-intentional “aiming” bias and b: perceptual-attentional “where” bias. “Where” and “aiming” biases were derived from the fragmentation of the Natural and Reversed line bisection errors (mm, positive/negative scores indicate rightward/leftward errors, error bars indicate SEM). Results refers to the group of five subjects and the average of the group; before (grey column) and after (black column) two days of prism adaptation training.