Cortical activity modulations underlying age‑related performance differences during posture–cognition dual tasking (original) (raw)
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Age-related neural correlates of cognitive task performance under increased postural load
AGE, 2013
Behavioral studies suggest that postural control requires increased cognitive control and visuospatial processing with aging. Consequently, performance can decline when concurrently performing a postural and a demanding cognitive task. We aimed to identify the neural substrate underlying this effect. A demanding cognitive task, requiring visuospatial transformations, was performed with varying postural loads. More specifically, old and young subjects performed mental rotations of abstract figures in a seated position and when standing on a force platform. Additionally, functional magnetic resonance imaging (fMRI) was used to identify brain regions associated with mental rotation performance. Old as compared to young subjects showed increased blood oxygenation leveldependent (BOLD) responses in a frontoparietal network as well as activations in additional areas. Despite this overall increased activation, they could still modulate BOLD responses with increasing task complexity. Importantly, activity in left lingual gyrus was highly predictive (r=−0.83, adjusted R 2 =0.65) of the older subjects' degree of success in mental rotation performance when shifting from a sitting to a standing position. More specifically, increased activation in this area was associated with better performance, once postural load increased.
In older adults, cognitive resources play a key role in maintaining postural stability. In the present study, we evaluated whether increasing postural instability using sway referencing induces changes in resource allocation in dual-task performance leading older adults to prioritize the more age-salient posture task over a cognitive task. Young and older adults participated in the study which comprised two sessions. In the first session, three posture tasks (stable, sway reference visual, sway reference somatosensory) and a working memory task (n-back) were examined. In the second session, single-and dual-task performance of posture and memory were assessed. Postural stability improved with session. Participants were more unstable in the sway reference conditions, and pronounced age differences were observed in the somatosensory sway reference condition. In dual-task performance on the stable surface, older adults showed an almost 40% increase in instability compared to single-task. However, in the sway reference somatosensory condition, stability was the same in single-and dual-task performance, whereas pronounced (15%) costs emerged for cognition. These results show that during dual-tasking while standing on a stable surface, older adults have the flexibility to allow an increase in instability to accommodate cognitive task performance. However, when instability increases by means of compromising somatosensory information, levels of postural control are kept similar in single-and dual-task, by utilizing resources otherwise allocated to the cognitive task. This evidence emphasizes the flexible nature of resource allocation, developed over the life-span to compensate for age-related decline in sensorimotor and cognitive processing.
Experimental Brain Research, 2008
In older adults, cognitive resources play a key role in maintaining postural stability. In the present study, we evaluated whether increasing postural instability using sway referencing induces changes in resource allocation in dual-task performance leading older adults to prioritize the more age-salient posture task over a cognitive task. Young and older adults participated in the study which comprised two sessions. In the first session, three posture tasks (stable, sway reference visual, sway reference somatosensory) and a working memory task (n-back) were examined. In the second session, single-and dual-task performance of posture and memory were assessed. Postural stability improved with session. Participants were more unstable in the sway reference conditions, and pronounced age differences were observed in the somatosensory sway reference condition. In dual-task performance on the stable surface, older adults showed an almost 40% increase in instability compared to single-task. However, in the sway reference somatosensory condition, stability was the same in single-and dual-task performance, whereas pronounced (15%) costs emerged for cognition. These results show that during dual-tasking while standing on a stable surface, older adults have the flexibility to allow an increase in instability to accommodate cognitive task performance. However, when instability increases by means of compromising somatosensory information, levels of postural control are kept similar in single-and dual-task, by utilizing resources otherwise allocated to the cognitive task. This evidence emphasizes the flexible nature of resource allocation, developed over the life-span to compensate for age-related decline in sensorimotor and cognitive processing.
Neuroscience & Biobehavioral Reviews, 2013
Dual-task designs have been used widely to study the degree of automatic and controlled processing involved in postural stability of young and older adults. However, several unexplained discrepancies in the results weaken this literature. To resolve this problem, a careful selection of dual-task studies that met certain methodological criteria are considered with respect to reported interactions of age (young vs. older adults) × task (single task vs. dual task) in stable and unstable postural conditions. Our review shows that older adults are able to perform a postural dual task as well as younger adults in stable conditions. However, when the complexity of the postural task is increased by dynamic conditions (surface and surround), performance in postural, concurrent, or both tasks is more affected in older relative to young adults. In light of neuroimaging studies and new conceptual frameworks, these results demonstrate an age-related increase of controlled processing of standing associated with greater intermittent adjustments.
Gait & Posture, 2007
The aim of this work was to determine the effects of ageing on the possible mobilisation of cognitive processes in orthostatic postural balance. Seventy-nine individuals of three different age groups were placed in dual-task situations that combined standing postural control with three different cognitive tasks. Two of these three tasks, auditory-verbal and visual-verbal ones, required external information acquisition whereas the third, a mental counting task, did not require such information. The results showed contrasting variations in postural control performances that are an improvement in young subjects during cognitive tasks which required external information acquisition and a deterioration in elderly subjects during cognitive tasks which did not involve external information acquisition. The middle-aged subjects tended to develop these two types of variations simultaneously. These results confirm that cognitive processes could have a role that increases with age in ensuring postural control. The contrasting results observed between the young and old populations highlight that the allocation of cognitive resources to postural control could, on the one hand, contribute to improving postural performance in subjects with mainly automated control and, on the other, perturb this performance in subjects with mainly cognitive control. #
Brain Research Bulletin, 2006
Postural control in everyday life is generally accompanied by posture-unrelated cognitive activity. Thus, mild forms of dual-tasking postural control are the norm rather than the exception. Based on this consideration and available evidence, we propose and empirically examined, in young and old adults, a non-monotonic, U-shaped relation between the efficacy of postural control and concurrent cognitive demands that reflect opposing trends of the effects of attention focus and attentional resource competition. When instructed to perform an easy cognitive task that presumably shifted the focus of attention away from posture control, the center of body pressure (COP) excursions decreased both in young and older adults relative to a single-task baseline where the focus of attention was explicitly directed towards the postural control task itself. However, when performing more demanding cognitive tasks, older adults showed increased COP displacements, in line with the predicted Ushape function, whereas young adults did not. We outline mechanisms linking postural control to cognitive demand and suggest routes for future investigation.
Cortical correlates in upright dynamic and static balance in the elderly
Scientific Reports, 2021
Falls are the second most frequent cause of injury in the elderly. Physiological processes associated with aging affect the elderly's ability to respond to unexpected balance perturbations, leading to increased fall risk. Every year, approximately 30% of adults, 65 years and older, experiences at least one fall. Investigating the neurophysiological mechanisms underlying the control of static and dynamic balance in the elderly is an emerging research area. The study aimed to identify cortical and muscular correlates during static and dynamic balance tests in a cohort of young and old healthy adults. We recorded cortical and muscular activity in nine elderly and eight younger healthy participants during an upright stance task in static and dynamic (core board) conditions. To simulate real-life dual-task postural control conditions, the second set of experiments incorporated an oddball visual task. We observed higher electroencephalographic (EEG) delta rhythm over the anterior cortex in the elderly and more diffused fast rhythms (i.e., alpha, beta, gamma) in younger participants during the static balance tests. When adding a visual oddball, the elderly displayed an increase in theta activation over the sensorimotor and occipital cortices. During the dynamic balance tests, the elderly showed the recruitment of sensorimotor areas and increased muscle activity level, suggesting a preferential motor strategy for postural control. This strategy was even more prominent during the oddball task. Younger participants showed reduced cortical and muscular activity compared to the elderly, with the noteworthy difference of a preferential activation of occipital areas that increased during the oddball task. These results support the hypothesis that different strategies are used by the elderly compared to younger adults during postural tasks, particularly when postural and cognitive tasks are combined. The knowledge gained in this study could inform the development of age-specific rehabilitative and assistive interventions.
Posture and cognition interfere in later adulthood even without concurrent response production
Human Movement Science, 2010
We investigated adult age differences in dual-task costs in cognitive-sensorimotor settings without concurrent response production and with individually adjusted resource demands for the cognitive task. Twenty-four young adults (M = 25.42 years, SD = 3.55) and 23 older adults (M = 68 years, SD = 4.46) performed a cognitive task and two postural control tasks (standing on a stable and moving platform) both separately (single-task context) and concurrently (dual-task context). The cognitive task did not require response production during posture data collection and its difficulty was individually adjusted to 80% correct performance under single-task conditions. Results showed pronounced age differences in postural control in the moving platform condition, which increased further under dual-task conditions. Our findings support the assumption of increased cognitive resource demands for postural control in older adults. They extend existing work by taking two shortcomings of previous studies into account. We discuss cognitive and posture task constraints in this and previous studies as factors determining multi-tasking and its changes in later adulthood.
2014
Maintaining upright posture is seemingly an automatic task in younger adults, but it may require additional resources in late adulthood due to decreases in sensorimotor and cognitive functions. The thesis used a dual-task paradigm to investigate age-related changes in relation to the secondary task and context-dependent factors attributes to postural control. The postural task involved visuomotor tracking. Successfully performing the visuomotor task necessitated proper sensory feedback, motor response, and sensorimotor integration. Moreover, we used silent counting as a cognitive task to investigate attentional demands on postural control and age-related difference in cognitive processing. We first investigated the relative contributions of visual feedback delay and cognitive task load on postural dynamics as well as age-related difference in this effect. Our results supported distinct timescale mechanisms for postural control. Moment-to-moment center of pressure fluctuations are dependent on cognitive performance during delayed visual feedback postural control. Also, we demonstrated the increased role of vision with age in postural control. Next, we investigated whether postural control improved when performing a cognitive task with an internal focus of attention. We found that devoting less attention internally by performing a cognitive dual-task enhanced postural control in young adults. Yet, the age-related iv declines diminish the attentional allocation ability. Lastly, we investigated how older and younger adults differ in employing sensorimotor strategies in a dual-task situation. Our results suggested that age-related changes in postural control may degrade the flexible coordination of the sensory feedback and motor execution. Furthermore, diminished cognitive and attentional capacities may alter postural performance in dual-task conditions. This thesis adds to the current understanding of the role of sensorimotor processing, attentional influence and age in the control of posture. Our data provide convergent evidence that deterioration of peripheral sensorimotor systems and reduced flexibility in central information processing are responsible for the age-related differences in postural control. v
Attentional demands for postural control: the effects of aging and sensory reintegration
Gait & Posture, 2001
The aim of this experiment was to examine if, with aging, the task of reintegrating sensory information perturbs balance and requires additional attentional demand. Young adults and the elderly were asked to maintain a stable upright posture while standing on a force platform. Visual and ankle proprioceptive information were removed or perturbed and suddenly reinserted. Subjects also had to respond vocally as quickly as possible to an unpredictable auditory stimulus presented before or following a sensory reintegration and in control conditions. Reaction times to the auditory stimuli were used as an index of the attentional demands necessary for calibrating the postural system. Reintegration of proprioception in absence of vision and under vision yielded a faster center of pressure velocity for both groups. This effect, however, was more important for the elderly than the young adults. An increased attentional demand was observed for both groups when proprioceptive information had to be reintegrated in absence of vision. Altogether, these results propose that, for the elderly persons, postural contexts requiring a reweighting of sensory inputs could lead to increased risk for loss of balance and falls if insufficient attentional resources are allocated to the postural task.