Sensory manipulation results in increased dorsolateral prefrontal cortex activation during static postural balance in sedentary older adults: An fNIRS study

Motor Cortex Activation Patterns in Both Hemispheres Induced by Motor Imagery in Patients With Right- and Left-Sided Cerebral Infarction: An fNIRS Study

This study aimed to explore the neuroimaging basis of motor imagery (MI) in stroke rehabilitation, particularly focusing on the brain activation patterns during MI tasks. Additionally, this study may provide insights into clinical rehabilitation strategies. A total of 40 right-handed stroke patients from Zhejiang Rehabilitation Medical Center were assigned to either the right-sided or left-sided cerebral infarction group. They were right-handed and recruited from Zhejiang Rehabilitation Medical Center. A portable near-infrared brain function imaging system was used to detect changes in oxyhemoglobin concentration in the bilateral sensorimotor cortex, premotor cortex, and supplementary motor area during the MI task. Activated channels and intensity changes in brain regions under the MI state were observed and analyzed. In patients with right-sided cerebral infarction, brain activation was left-lateralized during both left- and right-limb MI. Patients with left-sided cerebral infarction exhibited left lateralization during right-limb MI and right lateralization during left-limb MI. Functional near-infrared spectroscopy was utilized to investigate the activation of motor-related brain regions during MI after stroke. These regions of interest were associated with hand motor tasks and were successfully activated during the MI task. Following infarction, the activation of the MI cortex was asymmetric. When imagining movements on the dominant-hand side, MI becomes more vivid and activates bilateral motor cortex areas.

Dual-Task Effect on Center of Pressure Oscillations and Prefrontal Cortex Activation Between Young and Older Adults

Purpose: This study aimed to investigate the dual-task effect on conventional center of pressure (CoP) outcomes, CoP oscillations, and prefrontal cortex (PFC) activation between young and older adults. Methods: Fourteen healthy older adults (age: 66.25 ± 3.43 years) and another fourteen gender-matched young adults (age: 19.80 ± 0.75 years) participated in this study. Participants completed single-task and dual-task standing trials in a fixed order. The displacement of CoP and PFC activation were recorded using a Force plate and a functional near-infrared spectroscopy system, respectively. Two-way MANOVAs were used to examine the group and task effects. Additionally, the Pearson correlation analyses were used to investigate the relationship between CoP oscillations and PFC activation. Results: Our results showed a worse balance performance, greater CoP oscillations of 0-0.1 (11.03 ± 8.24 vs. 23.20 ± 12.54 cm2) and 0.1-0.5 (13.62 ± 9.30 vs. 30.00 ± 23.12 cm2) Hz in the medial-lateral direction and higher right (dorsomedial: -0.0003 ± 0.021 vs. 0.021 ± 0.021 & ventrolateral: 0.0087 ± 0.047 vs. 0.025 ± 0.045 mol/ml) and left (dorsomedial: 0.0033 ± 0.024 vs. 0.020 ± 0.025 & ventrolateral: 0.0060 ± 0.037 vs. 0.034 ± 0.037 mol/ml) PFC activation in response to a secondary cognitive task in older adults (p < .05). Older adults also showed significant positive correlations between CoP oscillations in the anterior-posterior direction and PFC activation under the single-task standing. Conclusion: These results suggest that older adults presented a loss of postural automaticity contributing to cognitive dysfunction. Moreover, heightened CoP oscillations at 0-0.5 Hz in response to a secondary cognitive task could provide evidence of a loss of automaticity, which might be associated with a greater reliance on the sensory inputs.

Changes in cerebral cortex activation during upright standing tasks in individuals with chronic neck pain: an fNIRS study

Introduction

Studies show that individuals with chronic neck pain (CNP) exhibit postural control deficits, potentially contributing to persistent and recurrent pain. However, the neural mechanisms underlying these deficits in CNP remain unexplored despite their importance for developing effective rehabilitation strategies. Therefore, this study aimed to investigate the neural activity during postural control using functional near-infrared spectroscopy (fNIRS), providing insights into the central mechanism underlying postural control deficits in individuals with CNP.

Methods

In this cross-sectional study, 10 individuals with CNP (CNP group) and 10 healthy controls (HC group) were assessed under three conditions: Task 1, standing on a force plate with eyes open and both feet; Task 2, standing on a force plate with eyes closed and both feet; Task 3, standing on a force plate with eyes closed and one foot. Cerebral cortex hemodynamic reactions, including bilateral prefrontal cortex (PFC), dorsolateral prefrontal cortex (DLPFC), pre-motor cortex and supplementary motor area (PMC/SMA), primary motor cortex (M1), and primary somatosensory cortex (S1) were measured using fNIRS. Balance parameters, including the sway area, total sway length, mean velocity, and center of pressure (COP) amplitude in the anterior-posterior (AP) and medial-lateral (ML) directions, were measured using a force plate.

Results

In Tasks 1 and 2, no differences were observed between both groups in balance parameters. However, the CNP group exhibited significantly higher activation in the left PMC/SMA (F = 4.788, p = 0.042) and M1 (F = 9.598, p = 0.006) in Task 1 and lower activation in the left (F = 4.952, p = 0.039) and right (F = 6.035, p = 0.024) PFC in Task 2 compared to that of the HC group. In Task 3, the CNP group exhibited a significantly larger COP amplitude in the AP direction (F = 7.057, p = 0.016) compared to that of the HC group. Additionally, activation in the right M1 (F = 7.873, p = 0.012) was significantly higher than in the HC group. Correlation analysis in Task 3 revealed stronger associations between the parameters in the CNP group.

Conclusion

Our findings suggest that individuals with CNP exhibit distinct patterns of cerebral cortex activities and postural control deficits. The PFC, M1, and PMC/SMA were involved in maintaining upright standing balance, and cerebral cortex changes associated with upright standing balance provide a more sensitive indicator of postural control deficits than peripheral balance parameters in individuals with CNP.

The effect of sensory manipulation on the static balance control and prefrontal cortex activation in older adults with mild cognitive impairment: a functional near-infrared spectroscopy (fNIRS) study

BACKGROUND

This study aimed to investigate the modulatory role of prefrontal cortex (PFC) activity in older adults with mild cognitive impairment (MCI) when sensory cues were removed or presented inaccurately (i.e., increased sensory complexity) during sensory manipulation of a balance task. The research sheds light on the neural regulatory mechanisms of the brain related to balance control in individuals with MCI.

METHODS

21 older adults with MCI (male/female: 9/12, age: 71.19 ± 3.36 years) were recruited as the experimental group and 19 healthy older adults (male/female: 10/9, age: 70.16 ± 4.54 years) as the control group. Participants were required to perform balance tests under four standing conditions: standing on a solid surface with eyes open, standing on a foam surface with eyes open, standing on a solid surface with eyes closed, and standing on a foam surface with eyes closed. Functional Near-Infrared Spectroscopy (fNIRS) and force measuring platform are used to collect hemodynamic signals of the PFC and center of pressure (COP) data during the balance task, respectively.

RESULTS

Under the eyes open condition, significant Group*Surface interaction effects were found in the mean velocity of the COP (MVELO), the mean velocity in the medial-lateral (ML) direction (MVELOml) and the 95% confidence ellipse area of the COP (95%AREA-CE). Additionally, significant Group*Surface interaction effect was found in the left orbitofrontal cortex (L-OFC). The significant group effects were detected for three ROI regions, namely the left ventrolateral prefrontal cortex (L-VLPFC), the left dorsolateral prefrontal cortex (L-DLPFC), the right dorsolateral prefrontal cortex (R-DLPFC). Under the eyes closed condition, the significant Group*Surface interaction effects were found in root mean square (RMS), the RMS in the ML direction (RMSml) and the 95%AREA-CE. Additionally, significant group effects were detected for five ROI regions, namely R-VLPFC, the left frontopolar cortex (L-FPC), L-DLPFC, R-DLPFC and R-OFC.

CONCLUSION

Our study emphasizes the role of the PFC in maintaining standing balance control among older adults with MCI, particularly during complex sensory conditions, and provides direct evidence for the role of the PFC during balance control of a clinically relevant measure of balance.

TRIAL REGISTRATION

ChiCTR2100044221, 12/03/2021.

Theta oscillations in observers' temporal cortex index postural instability of point-light displays

This study investigates whether postural equilibration follows the same principles of motor resonance as goal-oriented actions, namely, whether an individual activates the same neuronal substrates when experiencing postural perturbation as when observing another individual in this condition. To address this question, we examined electroencephalographic dynamics while subjects observed point-light displays featuring an unstable human display, a stable human display, and their respective scrambled counterparts lacking shape information and biological motion. We focused on theta band (4-7 Hz), which is a fundamental frequency for modulating brain activity during challenging balance tasks and reflects postural stability monitoring. Rather than mirroring activity, our findings suggest an inhibitory response to postural instability. Theta event-related synchronization in the left temporal cortex was dampened for the unstable display as compared to its scramble counterpart and to the stable display. This low theta response coincided with an increase in left temporal-prefrontal connectivity, compatible with top-down inhibitory mechanisms. By contrast, the stronger theta response to the stable display as compared to the unstable one could be due to the difficulty of recognizing low-motion biological stimuli, or alternatively, to a facilitation of stimulus processing and strengthening of the mirroring response. The response facilitation for stable posture, coupled with a diminished response to the unstable display, could contribute to a broader mechanism mitigating postural threats and ensuring stable balance. Future investigations should leverage these findings to explore how posture-related responses correlate with perceptual and motor expertise, and to more clearly define these mechanisms during dynamic social interactions.

Neuronal Control of Posture in Blind Individuals

The control of posture is guided by the integration of sensory information. Because blind individuals cannot apply visual information to control posture as sighted individuals do they must compensate by the remaining senses. We therefore hypothesize that blind individuals alter their brain activation in the sensorimotor cortex during postural control to compensate for balance control without vision by the increased integration of somatosensory information. Ten blind and ten sighted (matched) individuals controlled posture during conditions with (I) eyes closed / open, and (II) stable / unstable surface conditions. Postural sway was recorded by applying a pressure distribution measuring plate. Brain activation was collected by functional Near InfraRed Spectroscopy (fNIRS) above motor-sensory cortices of the right and left hemispheres. Blind individuals showed significantly increased postural sway when balancing with open eyes on an unstable surface and when compared to sighted individuals. Whereas blind individuals showed significantly increased brain activation when balancing with open eyes on stable and unstable surface conditions, sighted individuals increased their brain oxygenation only during closed eyes and unstable surface conditions. Overall conditions, blind individuals presented significantly increased brain activation in two channels of the left and right hemispheric motor-sensory cortex when compared to sighted individuals. We therefore conclude that sighted individuals increase their brain oxygenation in the sensorimotor cortex during postural control tasks that demand sensory integration processes. Blind individuals are characterized by increased brain activation overall conditions indicating additional sensory integration during postural control. Thus, the sensorimotor cortex of blind individuals adapts to control posture without vision.

The relationship between postural control and cognitive functioning following Zumba dancing in middle-aged women: A randomized clinical trial

This study aimed to investigate the effect of 12-week Zumba dancing on postural control and cognitive parameters and the correlations between these parameters in middle-aged women. Thirty-eight women, aged between 50 and 60 years, were randomly allocated to a Zumba group (ZG) or control group. Postural control and cognitive functions [working memory (WM) and reaction time (RT)] were assessed before and after 12 weeks of a Zumba dancing program using a stabilometric force platform, Corsi Block-Tapping Task and Simple RT tests, respectively. The results indicate that ZG showed significantly (p<.01) better balance performances when standing on a stable surface in both visual conditions [firm surface with eyes opened (EO) (20,9%) and eyes closed (EC) (12.3%)]. However, when standing on an unstable surface in both visual conditions (foam surface with EO/EC), the ZG showed no significant improvement in postural control. It seems that the benefits of Zumba on postural control depend on the sensory condition. Besides, 12-week Zumba dancing was not sufficient to significantly enhance cognitive performances (RT/WM) performances. These cognitive performances were related to postural control in challenging conditions and can be considered an effective tool for monitoring postural performances following an intervention program. Clinicians should, therefore, focus on interventions that boost cognitive functions in middle-aged women to achieve optimal postural control, mainly in challenging conditions, in order to prevent the risk and fear of falls as well as the incidence of falling.

Perceived cognitive fatigue has only marginal effects on static balance control in healthy young adults

We examined the influence of perceived cognitive fatigue on static balance control in healthy young adults to gain greater clarity about this issue than provided in previous research. Based on the prevailing assumption in pertinent literature, we hypothesized that the influence of cognitive fatigue on balance control depends on the attentional effort required by the balance tasks being performed. To test this hypothesis, 44 young adults (24 women and 20 men) were alternately assigned to either the experimental group that was cognitively fatigued (using the 16-min TloadDback-task with individualized settings) or the control group (who watched a documentary). Before and after the intervention, the participants performed six balance tasks that differed in (attentional) control requirements, while recording the center of pressure (COP). From these time series, sway variability, mean speed, and sample entropy were calculated and analyzed statistically. Additionally, perceived cognitive fatigue was assessed using VAS scales. Statistical analyses confirmed that the balance tasks differed in control characteristics and that cognitive fatigue was elevated in the experimental group, but not in the control group. Nevertheless, no significant main effects of cognitive fatigue were found on any of the COP measures of interest, except for some non-robust interaction effects related primarily to sample entropy. These results suggest that, in young adults, postural control in static balance tasks is largely automatic and unaffected by task-induced state fatigue.

Effect of dual-task interaction combining postural and visual perturbations on cortical activity and postural control ability

Previous studies have suggested cortical involvement in postural control in humans by measuring cortical activities and conducting dual-task paradigms. In dual-task paradigms, task performance deteriorates and can be facilitated in specific dual-task settings. Theoretical frameworks explaining these dual-task interactions have been proposed and debated for decades. Therefore, we investigated postural control performance under different visual conditions using a virtual reality system, simultaneously measuring cortical activities with a functional near-infrared spectroscopy system. Twenty-four healthy participants were included in this study. Postural stability and cortical activities after perturbations were measured under several conditions consisting of postural and visual perturbations. The results showed that concurrent visual and postural perturbations could facilitate cortical activities in the supplementary motor area and superior parietal lobe. Additionally, visual distractors deteriorated postural control ability and cortical activation of the supplementary motor area. These findings supported the theoretical framework of the "Cross talk model", in which concurrent tasks using similar neural domains can facilitate these task performances. Furthermore, it indicated that the cortical resource capacity and domains activated for information processing should be considered in experiments involving dual-task paradigms and training.

Treadmill Walking Maintains Dual-task Gait Performance and Reduces Frontopolar Cortex Activation in Healthy Adults

Studies examining dual-task gait (DTG) have used varying conditions such as overground or treadmill walking, however it is not known whether brain activation patterns differ during these conditions. Therefore, this study compared oxyhaemoglobin (O2Hb) responses of the prefrontal cortex (PFC) during overground and treadmill walking. A total of 30 participants (14M/16F) were recruited in a randomized crossover study comparing overground and treadmill walking under single- and dual-task (STG and DTG) conditions. The DTG consisted of performing walking and cognitive (serial subtraction by 7's) tasks concurrently. A portable 24-channel functional near-infrared spectroscopy system was placed over the PFC, corresponding the left and right dorsolateral PFC and frontopolar cortices (DLPFC and FPC) during overground and treadmill STG and DTG. Results showed a reduction in gait speed during DTG compared to STG on overground but not treadmill walking, while cognitive performance was maintained during DTG on both overground and treadmill walking. A reduction in O2Hb was seen in the FPC during DTG compared to a cognitive task only, and on the treadmill compared to overground walking. Increased activation was seen in the left and right DLPFC during DTG but did not differ between treadmill and overground walking. Our results support the concept of improved gait efficiency during treadmill walking, indicated by the lack of change in STG and DTG performance and concomitant with a reduction in FPC activation. These findings suggest different neural strategies underpinning treadmill and overground walking, which should be considered when designing gait assessment and rehabilitation interventions.

The immediate effects of iTBS on the muscle activation pattern under challenging balance conditions in the patients with chronic low back pain: A preliminary study

Background

The patients with chronic low back pain (CLBP) showed impaired postural control, especially in challenging postural task. The dorsolateral prefrontal cortex (DLPFC) is reported to involve in the complex balance task, which required considerable attentional control. The effect of intermittent theta burst stimulation (iTBS) over the DLPFC to the capacity of postural control of CLBP patients is still unknown.

Methods

Participants diagnosed with CLBP received a single-session iTBS over the left DLPFC. All the participants completed the postural control tasks of single-leg (left/right) standing before and after iTBS. The activation changes of the DLPFC and M1 before and after iTBS were recorded by functional near-infrared spectroscopy (fNIRS). The activation pattern of the trunk [transversus abdominis (TrA), superficial lumbar multifidus (SLM)] and leg [tibialis anterior (TA), gastrocnemius medialis (GM)] muscles including root mean square (RMS) and co-contraction index (CCI) during single-leg standing were measured by surface electromyography (sEMG) before and after the intervention. The paired t-test was used to test the difference before and after iTBS. Pearson correlation analyses were performed to test the relationship between the oxyhemoglobin concentration and sEMG outcome variables (RMS and CCI).

Results

Overall, 20 participants were recruited. In the right-leg standing condition, compared with before iTBS, the CCI of the right TrA/SLM was significantly decreased (t = −2.172, p = 0.043), and the RMS of the right GM was significantly increased (t = 4.024, p = 0.001) after iTBS. The activation of the left DLPFC (t = 2.783, p = 0.012) and left M1 (t = 2.752, p = 0.013) were significantly decreased and the relationship between the left DLPFC and M1 was significant after iTBS (r = 0.575, p = 0.014). Correlation analysis showed the hemoglobin concentration of M1 was negatively correlated with the RMS of the right GM (r = −0.659, p = 0.03) and positively correlated between CCI of the right TrA/SLM (r = 0.503, p = 0.047) after iTBS. There was no significant difference in the brain or muscle activation change in the left leg-standing condition between before and after iTBS.

Conclusion

Intermittent theta burst stimulation over the left DLPFC seems to be able to improve the muscle activation pattern during postural control ability in challenging postural task, which would provide a new approach to the treatment of CLBP.

Effect of transcranial magnetic stimulation on postural control of individuals with major depressive disorder: A case report

Accidental falls and major depressive disorder (MDD) are two common conditions associated with aging. Initial treatment of MDD often starts with administering antidepressants, followed by transcranial magnetic stimulation (TMS) for treatment-resistant individuals. The purpose of this case study was to determine the effect of repetitive TMS (rTMS) on postural control of an individual with MDD. A 44-year-old male with recurrent severe MDD was assessed for postural balance during eyes closed and eyes open conditions, pre and post three consecutive sessions receiving high-frequency rTMS (NeuroStar). Total excursion and velocity of sway significantly decreased following rTMS treatment when eyes were closed (p < 0.05). Power of the sway changed, but the changes were not statistically significant. The fractal dimension confidence circle area decreased significantly in eyes closed trials (p < 0.05). It appears that rTMS application can potentially impact postural steadiness in individuals with MDD. Our results warrant further studies with larger study samples.

Changes in cortical activation during upright stance in individuals with chronic low back pain: An fNIRS study

Introduction

Postural control deficits are a potential cause of persistent and recurrent pain in patients with chronic low back pain (CLBP). Although some studies have confirmed that the dorsolateral prefrontal cortex (DLPFC) contributes to pain regulation in CLBP, its role in the postural control of patients with CLBP remains unclear. Therefore, this study aimed to investigate the DLPFC activation of patients with CLBP and healthy controls under different upright stance task conditions.

Methods

Twenty patients with CLBP (26.50 ± 2.48 years) and 20 healthy controls (25.75 ± 3.57 years) performed upright stance tasks under three conditions: Task-1 was static balance with eyes open; Task-2 was static balance with eyes closed; Task-3 involved dynamic balance on an unstable surface with eyes open. A wireless functional near-infrared spectroscopy (fNIRS) system measured cortical activity, including the bilateral DLPFC, pre-motor cortex (PMC) and supplementary motor area (SMA), the primary motor cortex (M1), the primary somatosensory cortex (S1), and a force platform measured balance parameters during upright stance.

Results

The two-way repeated measures ANOVA results showed significant interaction in bilateral PMC/SMA activation. Moreover, patients with CLBP had significantly increased right DLPFC activation and higher sway 32 area and velocity than healthy controls during upright stance.

Discussion

Our results imply that PMC/SMA and DLPFC maintain standing balance. The patients with CLBP have higher cortical activity and upright stance control deficits, which may indicate that the patients with CLBP have low neural efficiency and need more motor resources to maintain balance.

The acute effects of mental fatigue on balance performance in healthy young and older adults - A systematic review and meta-analysis

Cognitive resources contribute to balance control. There is evidence that mental fatigue reduces cognitive resources and impairs balance performance, particularly in older adults and when balance tasks are complex, for example when trying to walk or stand while concurrently performing a secondary cognitive task. We conducted a systematic literature search in PubMed (MEDLINE), Web of Science and Google Scholar to identify eligible studies and performed a random effects meta-analysis to quantify the effects of experimentally induced mental fatigue on balance performance in healthy adults. Subgroup analyses were computed for age (healthy young vs. healthy older adults) and balance task complexity (balance tasks with high complexity vs. balance tasks with low complexity) to examine the moderating effects of these factors on fatigue-mediated balance performance. We identified 7 eligible studies with 9 study groups and 206 participants. Analysis revealed that performing a prolonged cognitive task had a small but significant effect (SMDwm = -0.38) on subsequent balance performance in healthy young and older adults. However, age- and task-related differences in balance responses to fatigue could not be confirmed statistically. Overall, aggregation of the available literature indicates that mental fatigue generally reduces balance in healthy adults. However, interactions between cognitive resource reduction, aging and balance task complexity remain elusive.

Brain Activation During Active Balancing and Its Behavioral Relevance in Younger and Older Adults: A Functional Near-Infrared Spectroscopy (fNIRS) Study

Age-related deterioration of balance control is widely regarded as an important phenomenon influencing quality of life and longevity, such that a more comprehensive understanding of the neural mechanisms underlying this process is warranted. Specifically, previous studies have reported that older adults typically show higher neural activity during balancing as compared to younger counterparts, but the implications of this finding on balance performance remain largely unclear. Using functional near-infrared spectroscopy (fNIRS), differences in the cortical control of balance between healthy younger (n = 27) and older (n = 35) adults were explored. More specifically, the association between cortical functional activity and balance performance across and within age groups was investigated. To this end, we measured hemodynamic responses (i.e., changes in oxygenated and deoxygenated hemoglobin) while participants balanced on an unstable device. As criterion variables for brain-behavior-correlations, we also assessed postural sway while standing on a free-swinging platform and while balancing on wobble boards with different levels of difficulty. We found that older compared to younger participants had higher activity in prefrontal and lower activity in postcentral regions. Subsequent robust regression analyses revealed that lower prefrontal brain activity was related to improved balance performance across age groups, indicating that higher activity of the prefrontal cortex during balancing reflects neural inefficiency. We also present evidence supporting that age serves as a moderator in the relationship between brain activity and balance, i.e., cortical hemodynamics generally appears to be a more important predictor of balance performance in the older than in the younger. Strikingly, we found that age differences in balance performance are mediated by balancing-induced activation of the superior frontal gyrus, thus suggesting that differential activation of this region reflects a mechanism involved in the aging process of the neural control of balance. Our study suggests that differences in functional brain activity between age groups are not a mere by-product of aging, but instead of direct behavioral relevance for balance performance. Potential implications of these findings in terms of early detection of fall-prone individuals and intervention strategies targeting balance and healthy aging are discussed.

Vision, cognition, and walking stability in young adults

Downward gazing is often observed when walking requires guidance. This gaze behavior is thought to promote walking stability through anticipatory stepping control. This study is part of an ongoing effort to investigate whether downward gazing also serves to enhance postural control, which can promote walking stability through a feedback/reactive mechanism. Since gaze behavior alone gives no indication as to what information is gathered and the functions it serves, we aimed to investigate the cognitive demands associated with downward gazing, as they are likely to differ between anticipatory and feedback use of visual input. To do so, we used a novel methodology to compromise walking stability in a manner that could not be resolved through modulation of stepping. Then, using interference methodology and neuroimaging, we tested for (1) interference related to dual tasking, and (2) changes in prefrontal activity. The novel methodology resulted in an increase in the time spent looking at the walking surface. Further, while some dual-task interference was observed, indicating that this gaze behavior is cognitively demanding, several gaze parameters pertaining to downward gazing and prefrontal activity correlated. These correlations revealed that a greater tendency to gaze onto the walking surface was associated with lower PFC activity, as is expected when sensory information is used through highly automatic, and useful, neural circuitry. These results, while not conclusive, do suggest that gazing onto the walking surface can be used for purposes other than anticipatory stepping control, bearing important motor-control and clinical implications.

Characteristics associated with decrements in objective measures of physical function in older patients with cancer during chemotherapy

PURPOSE

Study purposes were to evaluate for inter-individual variability in the trajectories of three objective measures of physical function (PF) in older patients receiving chemotherapy (n = 112) and determine which characteristics were associated with worse PF.

METHODS

Balance, gait speed, and chair-stand test were evaluated at initiation and 1, 3, 6, 9, and 12 months following chemotherapy. Hierarchical linear modeling was used to assess inter-individual variability in the trajectories of the three tests. Demographic, clinical, and symptom characteristics, and levels of cognitive function associated with initial levels and changes over time in each of the tests were determined.

RESULTS

Gait speed and chair-stand tests improved over time. Balance declined until month 6, then increased. Characteristics associated with decreases in balance scores at initiation of chemotherapy were lower level of education and lower Karnofsky Performance Status (KPS) score. For initial levels of poorer gait speed, older age, poorer Trail Making Test B (TMTB), and worse Attentional Function Index scores were the associated characteristics. Lower KPS scores, higher body mass index, and poorer TMTB scores were associated with poorer chair-stand times at initiation of chemotherapy. Worse trajectories of chair-stand times were associated with poorer chair-stand time at enrollment. Characteristic associated with lower initial levels and improved trajectories of balance was older age at enrollment.

CONCLUSIONS

Determination of characteristics associated with decrements in balance, gait speed, and chair-stand can assist clinicians to identify older oncology patients at risk for decrements in PF. Interventions to maintain and improve PF need to be implemented with higher risk patients.

The Immediate Effects of Intermittent Theta Burst Stimulation of the Cerebellar Vermis on Cerebral Cortical Excitability During a Balance Task in Healthy Individuals: A Pilot Study

Objective: This pilot study aimed to investigate the immediate effects of single-session intermittent theta-burst stimulation (iTBS) on the cerebellar vermis during a balance task, which could unveil the changes of cerebral cortical excitability in healthy individuals.

Subjects: A total of seven right-handed healthy subjects (26.86 ± 5.30 years) were included in this study.

Interventions: Each subject received single-session iTBS on cerebellar vermis in a sitting position.

Main Measures: Before and after the intervention, all subjects were asked to repeat the balance task of standing on the left leg three times. Each task consisted of 15 s of standing and 20 s of resting. Real-time changes in cerebral cortex oxygen concentrations were monitored with functional near-infrared spectroscopy (fNIRS). During the task, changes in blood oxygen concentration were recorded and converted into the mean HbO₂ for statistical analysis.

Results: After stimulation, the mean HbO₂ in the left SMA (P = 0.029) and right SMA (P = 0.043) significantly increased compared with baseline. However, no significant changes of mean HbO₂ were found in the bilateral dorsolateral prefrontal lobe (P > 0.05).

Conclusion: Single-session iTBS on the cerebellar vermis in healthy adults can increase the excitability of the cerebral cortex in the bilateral supplementary motor areas during balance tasks.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [ChiCTR2100048915].

Brain connectivity during simulated balance in older adults with and without Parkinson's disease

Individuals with Parkinson's disease often experience postural instability, a debilitating and largely treatment-resistant symptom. A better understanding of the neural substrates contributing to postural instability could lead to more effective treatments. Constraints of current functional neuroimaging techniques, such as the horizontal orientation of most MRI scanners (forcing participants to lie supine), complicates investigating cortical and subcortical activation patterns and connectivity networks involved in healthy and parkinsonian balance control. In this cross-sectional study, we utilized a newly-validated MRI-compatible balance simulator (based on an inverted pendulum) that enabled participants to perform balance-relevant tasks while supine in the scanner. We utilized functional MRI to explore effective connectivity underlying static and dynamic balance control in healthy older adults (n = 17) and individuals with Parkinson's disease while on medication (n = 17). Participants performed four tasks within the scanner with eyes closed: resting, proprioceptive tracking of passive ankle movement, static balancing of the simulator, and dynamic responses to random perturbations of the simulator. All analyses were done in the participant's native space without spatial transformation to a common template. Effective connectivity between 57 regions of interest was computed using a Bayesian Network learning approach with false discovery rate set to 5%. The first 12 principal components of the connection weights, binomial logistic regression, and cross-validation were used to create 4 separate models: contrasting static balancing vs {rest, proprioception} and dynamic balancing vs {rest, proprioception} for both controls and individuals with Parkinson's disease. In order to directly compare relevant connections between controls and individuals with Parkinson's disease, we used connections relevant for predicting a task in either controls or individuals with Parkinson's disease in logistic regression with Least Absolute Shrinkage and Selection Operator regularization. During dynamic balancing, we observed decreased connectivity between different motor areas and increased connectivity from the brainstem to several cortical and subcortical areas in controls, while individuals with Parkinson's disease showed increased connectivity associated with motor and parietal areas, and decreased connectivity from brainstem to other subcortical areas. No significant models were found for static balancing in either group. Our results support the notion that dynamic balance control in individuals with Parkinson's disease relies more on cortical motor areas compared to healthy older adults, who show a preference of subcortical control during dynamic balancing.

Functional Near-infrared Spectroscopy Reveals the Compensatory Potential of Pre-frontal Cortical Activity for Standing Balance in Young and Older Adults

Recent evidence suggests increased activity of the pre-frontal cortex (PFC) is associated with sensorimotor disturbances of standing balance. Here we manipulate sensorimotor inputs and concurrently load cognitive resources in order to investigate the functional role of PFC activity during standing balance, and how this changes with healthy ageing. Healthy younger (n = 24; mean age = 20.8 years) and older (n = 25; mean age = 70.6 years) adults maintained balance while sensorimotor inputs were manipulated by removing vision, reducing the base of support, and reducing proprioceptive feedback. To load cognitive resources, each balance condition was undertaken alone or simultaneously with a cognitive task (dual-task). Functional near infrared spectroscopy (fNIRS) measured PFC activity and a force-plate measured postural sway. When comparing dual-tasks relative to single balance tasks (dual-task effect), at lower levels of balance task demand, the older adults exhibited increased PFC activity and similar levels of postural sway. However, at higher levels of balance task demand, a limit to PFC activity was observed and postural sway became more unstable in older adults. In contrast, for younger adults at higher levels of balance task demand, the dual-task effect resulted in an increase in PFC activity and postural sway was not unduly affected. These results suggest that PFC activity is compensating for sensorimotor deficits to maintain stability, and that a cognitive resource limit is reached for easier balance tasks in older people compared to younger people. These results suggest that increasing cortical capacity in older people may improve their balance.

A consensus guide to using functional near-infrared spectroscopy in posture and gait research

BACKGROUND

Functional near-infrared spectroscopy (fNIRS) is increasingly used in the field of posture and gait to investigate patterns of cortical brain activation while people move freely. fNIRS methods, analysis and reporting of data vary greatly across studies which in turn can limit the replication of research, interpretation of findings and comparison across works.

RESEARCH QUESTION AND METHODS

Considering these issues, we propose a set of practical recommendations for the conduct and reporting of fNIRS studies in posture and gait, acknowledging specific challenges related to clinical groups with posture and gait disorders.

RESULTS

Our paper is organized around three main sections: 1) hardware set up and study protocols, 2) artefact removal and data processing and, 3) outcome measures, validity and reliability; it is supplemented with a detailed checklist.

SIGNIFICANCE

This paper was written by a core group of members of the International Society for Posture and Gait Research and posture and gait researchers, all experienced in fNIRS research, with the intent of assisting the research community to lead innovative and impactful fNIRS studies in the field of posture and gait, whilst ensuring standardization of research.

Altered prefrontal cortex responses in older adults with subjective memory complaints and dementia during dual-task gait: An fNIRS study

People with cognitive impairments show deficits during physical performances such as gait, in particular during cognitively challenging conditions (i.e. dual-task gait [DTG]). However, it is unclear if people at risk of dementia, such as those with subjective memory complaints (SMC), also display gait and central deficits associated with DTG. In this study, we investigated the effects of single- and dual-task gait (STG and DTG), on left prefrontal cortex (PFC) activation in elderly people with subjective memory complaints (SMC) and Dementia. A total of 58 older adults (aged 65-94 years; 26 Healthy; 23 SMC; 9 Dementia) were recruited. Gait spatiotemporal characteristics (i.e. stride velocity and length) were assessed using an instrumented walkway during STG and DTG. Single-channel functional near-infrared spectroscopy over the left PFC was used to measure changes in oxyhaemoglobin (O₂ Hb) during gait. Stride velocity and length during STG (all p < .05) and DTG (all p < .000) were significantly impaired in people with Dementia compared to Healthy and SMC individuals. No differences were observed between Healthy and SMC. For STG, a greater increase in O₂ Hb (p < .05) was observed in those with Dementia compared to the Healthy and SMC, while no differences were observed between Healthy and SMC. A significant increase and decline in O₂ Hb was observed during DTG in the SMC and Dementia groups, respectively, compared to Healthy. Our findings indicate an altered pattern of cerebral haemodynamic response of the left PFC in DTG in people with SMC and Dementia, which may suggest that central changes precede functional impairments in people with SMC.

A Systematic Review of the Application of Functional Near-Infrared Spectroscopy to the Study of Cerebral Hemodynamics in Healthy Aging

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies have shown that healthy aging is associated with functional brain deterioration that preferentially affects the prefrontal cortex. This article reviews the application of an alternative method, functional near-infrared spectroscopy (fNIRS), to the study of age-related changes in cerebral hemodynamics and factors that influence cerebral hemodynamics in the elderly population. We conducted literature searches in PudMed and PsycINFO, and selected only English original research articles that used fNIRS to study healthy individuals with a mean age of ≥ 55 years. All articles were published in peer-reviewed journals between 1977 and May 2019. We synthesized 114 fNIRS studies examining hemodynamic changes that occurred in the resting state and during the tasks of sensation and perception, motor control, semantic processing, word retrieval, attentional shifting, inhibitory control, memory, and emotion and motivation in healthy older adults. This review, which was not registered in a registry, reveals an age-related reduction in resting-state cerebral oxygenation and connectivity in the prefrontal cortex. It also shows that aging is associated with a reduction in functional hemispheric asymmetry and increased compensatory activity in the frontal lobe across multiple task domains. In addition, this article describes the beneficial effects of healthy lifestyles and the detrimental effects of cardiovascular disease risk factors on brain functioning among nondemented older adults. Limitations of this review include exclusion of gray and non-English literature and lack of meta-analysis. Altogether, the fNIRS literature provides some support for various neurocognitive aging theories derived from task-based PET and fMRI studies. Because fNIRS is relatively motion-tolerant and environmentally unconstrained, it is a promising tool for fostering the development of aging biomarkers and antiaging interventions.

Sensory manipulation results in increased dorsolateral prefrontal cortex activation during static postural balance in sedentary older adults: An fNIRS study

BACKGROUND

The dorsolateral prefrontal cortex (DLPFC) is involved with allocating attentional resources to maintain postural control. However, it is unknown whether age-related structural and functional declines of the DLPFC may impair postural control during sensory manipulation. In this study, we aim to understand the effects of aging on the DLPFC when sensory cues were removed or presented inaccurately (i.e., increased sensory complexity) during the sensory orientation test (SOT).

METHODS

Twenty young (18-25 years) and 18 older (66-73 years) healthy adults were recruited to undertake the SOT, which consisted of six conditions aimed at removing or disrupting the visual, vestibular, and proprioceptive senses. During these six SOT conditions, functional near-infrared spectroscopy (fNIRS), consisting of eight transmitter-receiver optode pairs (four channels over the left and right DLPFC), was used to measure hemodynamic responses (i.e., changes in oxy- [O₂ Hb] and deoxyhemoglobin [HHb]) from the bilateral DLPFC.

RESULTS

Our results show an increase in bilateral DLPFC activation (i.e., increase in O₂ Hb and concomitant smaller decrease in HHb) with increasing sensory complexity in both young and older adults. The increase in left and right DLPFC activation during more complex sensory conditions was greater, which was concomitant with reduced balance performance in older adults compared to younger adults. Furthermore, we observed a right lateralized DLPFC activation in younger adults. Finally, a significant positive association was observed between balance performance and increased bilateral DLPFC activation particularly for SOT conditions with greater sensory disruptions.

CONCLUSION

Our findings highlight the involvement of the DLPFC in maintaining postural control, particularly during complex sensory tasks, and provide direct evidence for the role of the DLPFC during postural control of a clinically relevant measure of balance.