Neural Mechanisms of Prism Adaptation in Healthy Adults and Individuals with Spatial Neglect after Unilateral Stroke: A Review of fMRI Studies.

Olga Boukrina,Peii Chen

doi:10.3390/brainsci11111468

Olga Boukrina, Peii Chen

Open Access

https://doi.org/10.3390/brainsci11111468

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Abstract

Functional disability due to spatial neglect hinders recovery in up to 30% of stroke survivors. Prism adaptation treatment (PAT) may alleviate the disabling consequences of spatial neglect, but we do not yet know why some individuals show much better outcomes following PAT than others. The goal of this scoping review and meta-analysis was to investigate the neural mechanisms underlying prism adaptation (PA). We conducted both quantitative and qualitative analyses across fMRI studies investigating brain activity before, during, and after PA, in healthy individuals and patients with right or left brain damage (RBD or LBD) due to stroke. In healthy adults, PA was linked with activity in posterior parietal and cerebellar clusters, reduced bilateral parieto-frontal connectivity, and increased fronto-limbic and sensorimotor network connectivity. In contrast, RBD individuals with spatial neglect relied on different circuits, including an activity cluster in the intact left occipital cortex. This finding is consistent with a shift in hemispheric dominance in spatial processing to the left hemisphere. However, more studies are needed to clarify the contribution of lesion location and load on the circuits involved in PA after unilateral brain damage. Future studies are also needed to clarify the relationship of decreasing resting state functional connectivity (rsFC) to visuomotor function.

Highlights

Among stroke survivors in the acute and subacute inpatient settings, approximately 30% have spatial neglect, which is more common after right than left brain damage (RBD and LBD, respectively) [1]
prism adaptation (PA) effects evaluated in a factorial model of whole brain activation
Summary: Reduction of left neglect after PA associated with bilateral increases in SPL, middle frontal gyrus (MFG), occipital lobe

Summary

Introduction

Among stroke survivors in the acute and subacute inpatient settings, approximately 30% have spatial neglect, which is more common after right than left brain damage (RBD and LBD, respectively) [1]. Spatial neglect is a neuropsychological syndrome that results from damage to the neural networks critical to the processing of spatial information and the control of attention [5,6]. The results of randomized sham-controlled trials in stroke patients are mixed with respect to unequivocal benefits of this treatment for all stroke patients [19,20,21,22,23]. It is unknown what determines the short-term beneficial effects and long-term therapeutic effects of PAT. We reviewed theoretical accounts for PAT mechanisms, conducted a series of

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