Neurophysiological Examination of the Effects of Behavioral Antecedents on Physical Balance in Older Individuals

Research Article

Phys Med Rehabil Int. 2022; 9(2): 1202.

Neurophysiological Examination of the Effects of Behavioral Antecedents on Physical Balance in Older Individuals

Kodama T¹*, Abiko T¹, Matsuo N¹ and Yamaguchi H²

1Department of Physical Therapy, Kyoto Tachibana University, Japan

2Department of Advanced Development, AISIN Co., Ltd., Japan

*Corresponding author: Takayuki Kodama, Department of Physical Therapy, Faculty of Health Sciences, Kyoto Tachibana University, 34 Yamada-cho, Oyake, Yamashina-ku, Kyoto 607-8175, Japan

Received: June 30, 2022; Accepted: July 22, 2022; Published: July 29, 2022


Falls in older individuals can be caused by balance disorders, influenced by predictive factors based on self-efficacy and outcome expectation. This study investigated the relationship between predictive factors related to regional neural functional activity and postural control. We included 16 older men (average age, 76.4±5.8 years) and evaluated their balancing ability and fall-related selfefficacy using the Japanese version of Mini-Balance Evaluation Systems Test (J-Mini-BESTest) and the Japanese version of the Falls Efficacy Scale (JFES), respectively. We performed an electroencephalogram before, during, and after postural perturbations. The cortical activity in the right Inferior Parietal Lobe (IPL) and Supplementary Motor Area (SMA) was analyzed using current density in the specific regions of interest. Foot Response Values (FRV) were used to evaluate physical responses during postural perturbations. The neural activity values in the IPL after postural perturbations indicated a significant positive correlation with JFES and J-Mini-BESTest scores when prior information was provided to participants. The neural activity values in the SMA before postural perturbations showed a significant positive correlation with J-Mini-BESTest score and a significant negative correlation with FRV. Furthermore, during postural perturbations, subjects with prior information exhibited significant positive neural correlations with neural activity between the SMA and IPL. These results suggest that neural activity in these brain regions influence balancing ability and predictive factors. Prior knowledge of a postural perturbation’s timing could be a compensatory factor promoting the activation of predictive factors.

Keywords: Postural balance; Fall-related self-efficacy; Mini-BESTest; Electroencephalography; Sense of agency; Supplementary motor area


Quality of life in older individuals is affected by falls that occur during daily activities [1], which are more likely to happen than in younger people due to functional decline [2]. Moreover, these falls cause fractures that are significantly associated with increased mortality in this population [3]. In particular, older individuals have a high incidence of hip fractures [4], which may result in impaired activities of daily living due to limited movements like standing and walking, and a decline in functions necessary for independent living [5]. In addition, approximately half the individuals who have fallen once experience repeated falls, and 10–20% of these individuals experience a second fall in the same year [6]. Accordingly, falls in this population are considered to be a public health and social problem that may cause increased disability, morbidity, and mortality.

Balance disorders have been reported as one of the primary causes of falls in older individuals [7,8]. Indicated that self-efficacy is one of the factors that influence balance disorders caused by aging. Self-efficacy, a cognitive control system leading to self-confidence in performing a specific task [9], can be regarded as the amount of confidence an individual has in their ability to perform an action [8]. In addition, the degree of fall-related self-efficacy, which is “the degree of daily life that can be achieved without falling,” is a predictor of the fear of falling that affects posture balance [11]; however, no study has reported an association between these two factors [12]. This demonstrates that there is no unified view on the fact that fallrelated self-efficacy is a predictor of the fear of falling. Nevertheless, predictive factors that determine movements in an individual are important clues in understanding the relationship between selfefficacy and balancing ability [10].

Predictive factors consist of self-efficacy and outcome expectation, which combined, predict one’s ability to perform actions. Outcome expectations predict the outcomes of one’s own actions; [13] showed that this behavioral prediction is an important factor in balancing ability, arguing that such anticipatory mechanism helps in postural adjustment. Furthermore, the authors indicated that when a postural perturbation is experienced by the body, an anticipatory mechanism recognizes the environment and recalls a strategy to avoid falling, followed by the predictive adjustment of posture based on the recalled strategy and the actual movement. This anticipatory mechanism collects information on the environment and changes in advance, interprets how these changes affect stability based on experience, and determines an avoidance strategy. Thus, this mechanism can be viewed as “brain simulation of possible movements prior to actual movements” and has been termed prediction of behavior—the ability to collect information about the environment and to imagine possible future movements. Imagining movements does not lead to the generation of motion parameters necessary for execution (e.g., muscle recruiting and direction of movement). Rather, it refers to the ability to simulate kinesthetic sensations needed and expected for a concrete image of a movement program that can be controlled in response to a perturbation [14]. Moreover, the ability to mentally represent motor action declines with age [15-17] stated that the ability to mentally represent actions gradually decreases with age due to deterioration of motor imagery quality (i.e., isochrony between executed and imagined movements). In contrast, as a predictive factor, self-efficacy is necessary for the development of a sense of agency [18]. This development requires an active sensation (e.g., self-efficacy) of being able to act on the environment and to take a purposeful action independently to achieve an ideal or desired state [19]; a sense of agency develops when these are matched [20]. Moreover, changes in the sense of agency occur with age and are associated with changes in physical functions [21]. These findings suggest that self-efficacy may affect the physical and mental functioning in older people, and predictive factors may be closely associated with balance. If the expected outcome and self-efficacy are regarded as an image of the movement [22] and the perception of a sense of agency [23,24], respectively, the basis of brain function in creating a predictive factor of behavior that may affect balancing ability includes the neural activity of the right Inferior Parietal Lobe (IPL) and the Supplementary Motor Area (SMA). It is possible that predictive factors are established by cooperative activity between these brain regions via a neural connection.

Older individuals often experience near-falls, even if they have no experience of actual falls, due to age-related decline in sensory functioning, such as sight and hearing [25]. A decrease in attention also affects their ability to respond appropriately to changes in the environment, therefore, it is difficult for older individuals to appropriately integrate internal information such as behavioral predictive factors, and external information from the environment. To prevent falls, older individuals must act by predicting the risk of falls caused by declines in sensory function. Thus, we propose that prior knowledge of a disturbance helps compensate deteriorating sensory functions in older subjects and hypothesize that balancing ability may change if predictive factors are activated by supplying information on the timing of a perturbation in advance. This hypothesis is supported by Shinya et al, [26]. That described that one of the important issues in the function of the central nervous system associated with postural control was “to cope with the uncertainty and unpredictability of real-world perturbations.” They examined posture control upon perturbation of the supporting surface using a splitbelt treadmill and investigated how prior knowledge of perturbation affects latent muscle reflex. Reflexive muscle activity is a part of the automatic postural response and is a complex and sophisticated pattern of muscle activity to cope with various disturbance stimuli. Thus, the activity of the gastrocnemius and soleus muscles of the right lower limb decreased and that of the tibialis anterior muscle increased when the prediction of acceleration was provided. Moreover, latency activity shortened and reaction after a disturbance was faster when prior knowledge of the timing of acceleration and deceleration was provided. These results suggest that prior knowledge may enhance the posture control system like balancing ability through the activity of the lower thigh muscles. However, while many reports have examined muscle activity and evaluated behavior with or without prior knowledge, there have been no reports on the association between neural activity of the brain regions and predictive factors such as self-efficacy or actual balancing ability when a postural perturbation is applied.

In this study, we aim to examine how the body’s balancing ability and fall-related self-efficacy in older subjects are related to the brain regions that may control predictive factors during a postural perturbation, and how prior knowledge in advance of a postural perturbation affects these relationships. The present study is the first to examine whether prior knowledge has a compensatory effect on the brain functions that create predictive factors in older individuals. Clarifying these relationships may help to create an approach for fall prevention.

Materials and Methods

Study participants

During the convenience sampling process, we recruited 30 older men living in the community. Those with orthopedic, neurological, mental, movement, or sensory disorders were excluded from the study. Those who had experienced falls were also excluded because it affects fall-related self-efficacy [27]. As a result, 17older men (average age of 76.4 ± 5.8 years) were included in the study (Table 1). The methodology and purpose of this study were explained to the subjects, both in writing and verbally, prior to obtaining their written consent to participate. This study was approved by the Kyoto Tachibana University (approval number: 19-08). Owing to its Crosssectional study, this study was conducted in line with the STROBE guidelines.