Background
Declines in gait parameters are common with aging and more pronounced in tasks with increased executive demand. However, the neural correlates of age-related gait impairments are not fully ...understood yet.
Objectives
To investigate (a) the effects of aging on prefrontal cortex (PFC) activity and gait parameters during usual walking, obstacle crossing and dual-task walking and (b) the association between PFC activity and measures of gait and executive function.
Methods
Eighty-eight healthy individuals were distributed into 6 age-groups: 20-25 (G20), 30-35 (G30), 40-45 (G40), 50-55 (G50), 60-65 (G60), and 70-75 years (G70). Participants walked overground under 3 conditions: usual walking, obstacle crossing, and dual-task walking. Changes in oxygenated and deoxygenated hemoglobin in the PFC were recorded using functional near-infrared spectroscopy. Gait spatiotemporal parameters were assessed using an electronic walkway. Executive function was assessed through validated tests.
Results
Between-group differences on PFC activity were observed for all conditions. Multiple groups (ie, G30, G50, G60, and G70) showed increased PFC activity in at least one of the walking conditions. Young adults (G20 and G30) had the lowest levels of PFC activity while G60 had the highest levels. Only G70 showed reduced executive function and gait impairments (which were more pronounced during obstacle crossing and dual-task walking). PFC activity was related to gait and executive function.
Conclusions
Aging causes a gradual increase in PFC activity during walking. This compensatory mechanism may reach the resource ceiling in the 70s, when reduced executive function limits its efficiency and gait impairments are observed.
•CMi refers to the simultaneous performance of a cognitive and a motor task as DT.•CMi is assessed by various techniques able to measure the related brain activity.•FMRI studies showed ...additive/over-additive brain activity as multiple resources are needed.•Specific loci have been identified, although they may depend on the single components.
Cognitive-motor interference refers to dual-tasking (DT) interference (DTi) occurring when the simultaneous performance of a cognitive and a motor task leads to a percentage change in one or both tasks. Several theories exist to explain DTi in humans: the capacity-sharing, the bottleneck and the cross-talk theories. Numerous studies investigating whether a specific brain locus is associated with cognitive-motor DTi have been conducted, but not systematically reviewed. We aimed to review the evidences on brain activity associated with the cognitive-motor DT, in order to better understand the neurological basis of the CMi. Results were reported according to the technique used to assess brain activity. Twenty-three articles met the inclusion criteria. Out of them, nine studies used functional magnetic resonance imaging to show an additive, under-additive, over- additive, or a mixed activation pattern of the brain. Seven studies used near-infrared spectroscopy, and seven neurophysiological instruments. Yet a specific DT locus in the brain cannot be concluded from the overall current literature. Future studies are warranted to overcome the shortcomings identified.
Dual-task (DT) studies have demonstrated that performing a secondary cognitive task alters gait. However, the tasks employed in these studies are typically of low ecological relevance, and have not ...emphasized a possible impact of emotional processing on gait parameters.
The current work aim was to examine whether gait in old individuals is influenced by simultaneously preforming cognitive-emotional tasks of retrieving autobiographical memories (AM) or imagining future projections (FP), in a dual-task (DT) paradigm. Our working hypothesis was that similar to lab-based cognitive tasks, naturalistic, emotion-evoking processes may lead to alterations in gait execution.
Twenty-four old adults were instructed to recollect AM and FP, in response to cue words that were chosen in preliminary interviews to be personally relevant. A single-task condition (ST) served as baseline and a cognitive verbal fluency task (VF) as an active control.
Emotional responses to the tasks were subjectively rated using the Self-Assessment Manikin (SAM) scale, the autonomic-system activity was monitored using the MindWare Impedance Cardiograph, and gait was measured using the APDM's Mobility Lab™.
AM and FP increased emotional valence relative to ST (P<0.0001), while VF had diverse emotional responses. This effect was corroborated by increases in skin conductance, which were higher in the DT conditions relative to ST (P<0.0001). DT led to a decrease in gait speed and cadence and an increase in double-limb-support, primarily in the VF condition and with a similar trend in AM and FP. Increase in emotional valence led to increases in gait speed (P=0.05) and cadence (P=0.011).
The effect of AM and FP on walking characteristics in the elderly showed similar trends to that of VF. Walking was influenced by emotional aspects that accompanied the various tasks.
When simultaneously performing two tasks that share response properties, interference can occur. Besides general performance decrements, performance in the first task is worse when the second task ...requires a spatially incompatible response, known as the backward crosstalk effect (BCE). The size of this BCE, similar to congruency effects in conflict tasks, is subject to a sequential modulation, with a smaller BCE after incompatible compared to compatible trials. In the present study, we focus on a potential bidirectional interaction between crosstalk (and its resolution) at a lower level of task performance and higher-order processes of task organization. Two questions were of particular interest: First, do participants switch task order more frequently after a conflict-prone incompatible trial than after a compatible trial? Second, does changing task order influence the efficiency of conflict resolution, as indexed by the size of the sequential modulation of the BCE. Across four experiments, we only found marginal evidence for an influence of lower-level conflict on higher-order processes of task organization, with only one experiment revealing a tendency to repeat task order following conflict. Our results thus suggest practical independence between conflict and task-order control. When separating processes of task selection and task performance, the sequential modulation was generally diminished, suggesting that conflict resolution in dual-tasks can be disrupted by a deliberate decision about task order, or, alternatively, by a longer inter-trial interval. Finally, the study found a strong bias towards repeating the same task order across trials, suggesting that task-order sets not only impact task performance but also guide task selection.
We expand the usually cross-sectional perspective on dual-tasking performance to include both intra- and interpersonal variability, which should capture within-person dynamics and psychological ...processes better. Two simple tasks, first as single-, then as dual-tasks, were performed by 58 participants over 20 sessions. We found positive relationships between (1) single- and dual-tasking performance and (2) the dual-task component tasks both inter- and intrapersonally. Better single-taskers were better dual-taskers and better single-tasking sessions were better dual-tasking sessions. This implies shared capacities that covary both inter- and intraindividually. We conclude that taking intra- and interpersonal variability into account is a promising future perspective.
Recently, reliable interindividual differences were found for the way how individuals process multiple tasks (at a cognitive level) and how they organize their responses (at a response level). ...Previous studies have shown mixed results with respect to the flexibility of these preferences. On the one hand, individuals tend to adjust their preferred task processing mode to varying degrees of risk of crosstalk between tasks. On the other, response strategies were observed to be highly stable under varying between-resource competition. In the present study, we investigated whether the stability of response strategies also persists with increased risk of crosstalk or whether individuals adjust their choice of response strategy, similar to what has been found at the level of task processing modes. Besides, related differences in multitasking efficiency were assessed. For this purpose, 53 participants performed the
(FCDT) paradigm, which allows them to control their task scheduling and response organization. The participants completed the FCDT paradigm under two conditions including task pairs characterized by either low or high levels of risk of crosstalk. The free choice of task scheduling resulted in the previously found distinct response patterns, best described as
,
or
. Remarkably, we did not find any notable adjustments of strategies of response organization to the extent of crosstalk. However, we observed suspected performance decrements of a switching strategy in the condition of high risk of crosstalk. The results suggest that individual strategies of response organization are stable habits. Further, they illustrate disadvantages of switching vs. blocking strategies of response organization in case of high task similarity.
Working at altitudes, dual-tasking (DT), and lack of experience cause falls. This study aimed to investigate the impact of virtual heights, DT, and training on static postural stability. Twenty-eight ...volunteers' balance at seven virtual environments VE; ground (G), altitude 1 (A1), edge 1 (E1), altitude 2 (A2), edge 2 (E2), altitude 3 (A3), and edge 3 (E3) were recorded during single-tasking (ST) and DT over three days. Independent variables were analyzed using a 7 (VE) x 3 (DAY) x 2 (TASK) factorial repeated measures ANOVA. Greater postural sway was observed in A3 and E1, on DAY 1, and during DT. The study demonstrated static postural stability deteriorates at higher virtual altitudes and during DT and improves with training. The findings of the study suggest that virtual reality is a great altitude simulator, which could be used as a potential balance training tool in ergonomic settings.
•Static balance deteriorates at higher virtual altitudes and during dual-tasking.•A short, virtual reality (VR) based training improves static postural stability.•VR is a great tool due to its simulation capability and affordability.•VR could be used as a potential balance training tool in ergonomic settings.
▶ Gait control places demand on cognitive centres of the brain. ▶ Cognitive tasks that involve internal interfering factors disturb gait. ▶ Speed is a sensitive measure of gait performance under ...dual-task conditions.
Dual-task methodology has been increasingly used to assess cognitive motor interference while walking. However, whether the observed dual-task-related gait changes are systematically related to methodological variations remains unclear and researchers still lack knowledge of what cognitive task to use in different groups for clinical purposes or for research. We systematically reviewed experimental studies that measured gait performance with and without performing concurrent cognitive task. Our results suggest that cognitive tasks that involve internal interfering factors seem to disturb gait performance more than those involving external interfering factors. Meta-analysis results show that the overall effect of different cognitive tasks was prominent in gait speed. In healthy participants, meta-regression analysis suggests strong associations between age and speed reduction under dual-task conditions and between the level of cognitive state and speed reduction under dual-task conditions. Standardizing research methodologies, as well as improving their ecological validity, enables better understanding of dual-task-related gait changes in different populations and improves, in turn, our understanding of neural mechanisms and gait control in general in content.
Background. Gait is influenced by higher order cognitive and cortical control mechanisms. Functional near infrared spectroscopy (fNIRS) has been used to examine frontal activation during walking in ...healthy older adults, reporting increased oxygenated hemoglobin (HbO2) levels during dual task walking (DT), compared with usual walking. Objective. To investigate the role of the frontal lobe during DT and obstacle negotiation, in healthy older adults and patients with Parkinson’s disease (PD). Methods. Thirty-eight healthy older adults (mean age 70.4 ± 0.9 years) and 68 patients with PD (mean age 71.7 ± 1.1 years,) performed 3 walking tasks: (a) usual walking, (b) DT walking, and (c) obstacles negotiation, with fNIRS and accelerometers. Linear-mix models were used to detect changes between groups and within tasks. Results. Patients with PD had higher activation during usual walking (P < .030). During DT, HbO2 increased only in healthy older adults (P < .001). During obstacle negotiation, HbO2 increased in patients with PD (P = .001) and tended to increase in healthy older adults (P = .053). Higher DT and obstacle cost (P < .003) and worse cognitive performance were observed in patients with PD (P = .001). Conclusions. A different pattern of frontal activation during walking was observed between groups. The higher activation during usual walking in patients with PD suggests that the prefrontal cortex plays an important role already during simple walking. However, higher activation relative to baseline during obstacle negotiation and not during DT in the patients with PD demonstrates that prefrontal activation depends on the nature of the task. These findings may have important implications for rehabilitation of gait in patients with PD.
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