Balance and the brain: A review of structural brain correlates of postural balance and balance training in humans

Abstract

Background: Balance challenges are associated with not only the aging process but also a wide variety of psychiatric and neurological disorders. However, relatively little is known regarding the neural basis of balance and the effects of balance interventions on the brain.

Research question: This review synthesizes the existing literature to answer the question: What are the key brain structures associated with balance?

Methods: This review examined 37 studies that assessed brain structures in relation to balance assessment or intervention. These studies provided 234 findings implicating 71 brain structures. The frequency of implication for each structure was examined based upon specific methodological parameters, including study design (assessment/intervention), type of balance measured (static/dynamic), population (clinical/non-clinical), and imaging analysis technique (region of interest [ROI]/voxel-based morphometry [VBM]).

Results: Although a number of structures were associated with balance across the brain, the most frequently implicated structures included the cerebellum, basal ganglia, thalamus, hippocampus, inferior parietal cortex, and frontal lobe regions. Findings in the cerebellum and brainstem were most common in studies with clinical populations, studies that used an ROI approach, and studies that measured dynamic balance. Findings in the frontal, occipital, and parietal regions were also more common in studies that measured dynamic compared to static balance.

Significance: While balance appears to be a whole-brain phenomenon, a subset of structures appear to play a key role in balance and are likely implicated in balance disorders. Some of these structures (i.e., the cerebellum, basal ganglia and thalamus) have a well-appreciated role in balance, whereas other regions (i.e., hippocampus and inferior parietal cortex) are not commonly thought to be associated with balance and therefore may provide alternative explanations for the neural basis of balance. Key avenues for future research include understanding the roles of all regions involved in balance across the lifespan and in different clinical populations.

Keywords: Balance; Diffusion tensor imaging; MRI; Magnetic resonance imaging; Postural control.

Conflict of interest statement

Declaration of interests: None.

Copyright © 2019 Elsevier B.V. All rights reserved.

Figures

Figure 1.

Structural involvement in balance as indexed by total number of findings per region. A) Frequency of findings implicating each brain region in balance. B-G) Frequency of findings per structure within each region that had 15 or more total findings. Structures that contributed to 10% or more of that region’s total number of findings are reported. Remaining structures that contributed to less than 10% of the region’s total number of findings are not listed but can be found in Supplementary Table 1. GM, Gray Matter; WM, White Matter

Figure 2.

Frequency of specific parameters used to produce regional findings. A) Frequency of findings per region that used assessment versus intervention study designs. B) Frequency of findings per region that used ROI versus VBM analysis techniques. C) Frequency of findings per region that used static versus dynamic measures of balance. Studies that assessed balance using both static and dynamic metrics or a composite score of both static and dynamic balance are noted. D) Frequency of findings per region that looked at balance in clinical versus non-clinical populations. Studies that presented findings in both clinical and non-clinical populations are noted.