Auditory Stroop Task Research Articles

Determinants of voice recognition in monolingual and bilingual listeners

AbstractRecent findings demonstrate a bilingual advantage for voice processing in children, but the mechanism supporting this advantage is unknown. Here we examined whether a bilingual advantage for voice processing is observed in adults and, if so, if it reflects enhanced pitch perception or inhibitory control. Voice processing was assessed for monolingual and bilingual adults using an associative learning identification task and a discrimination task in English (a familiar language) and French (an unfamiliar language). Participants also completed pitch perception, flanker, and auditory Stroop tasks. Voice processing was improved for the familiar compared to the unfamiliar language and reflected individual differences in pitch perception (both tasks) and inhibitory control (identification task). However, no bilingual advantage was observed for either voice task, suggesting that the bilingual advantage for voice processing becomes attenuated during maturation, with performance in adulthood reflecting knowledge of linguistic structure in addition to general auditory and inhibitory control abilities.

Effects of Aging and Task Prioritization on Split-Belt Gait Adaptation.

Background: Age-related changes in the sensorimotor system and cognition affect gait adaptation, especially when locomotion is combined with a cognitive task. Performing a dual-task can shift the focus of attention and thus require task prioritization, especially in older adults. To gain a better understanding of the age-related changes in the sensorimotor system, we examined how age and dual-tasking affect adaptive gait and task prioritization while walking on a split-belt treadmill.Methods: Young (21.5 ± 1.0 years, n = 10) and older adults (67.8 ± 5.8 years, n = 12) walked on a split-belt treadmill with a 2:1 belt speed ratio, with and without a cognitive Auditory Stroop task. Symmetry in step length, limb excursion, and double support time, and strategy variables swing time and swing speed were compared between the tied-belt baseline (BL), early (EA) and late split-belt adaptation (LA), and early tied-belt post-adaptation (EP).Results: Both age groups adapted to split-belt walking by re-establishing symmetry in step length and double support time. However, young and older adults differed on adaptation strategy. Older vs. young adults increased swing speed of the fast leg more during EA and LA (0.10–0.13 m/s), while young vs. older adults increased swing time of the fast leg more (2%). Dual-tasking affected limb excursion symmetry during EP. Cognitive task performance was 5–6% lower during EA compared to BL and LA in both age groups. Older vs. young adults had a lower cognitive task performance (max. 11% during EA).Conclusion: Healthy older adults retain the ability to adapt to split-belt perturbations, but interestingly age affects adaptation strategy during split-belt walking. This age-related change in adaptation strategy possibly reflects a need to increase gait stability to prevent falling. The decline in cognitive task performance during early adaptation suggests task prioritization, especially in older adults. Thus, a challenging motor task, like split-belt adaptation, requires prioritization between the motor and cognitive task to prevent adverse outcomes. This suggests that task prioritization and adaptation strategy should be a focus in fall prevention interventions.

Determinants of Dual-Task Training Effect Size in Parkinson Disease: Who Will Benefit Most?

Dual-task interventions show positive effects in people with Parkinson disease (PD), but it remains unclear which factors determine the size of these benefits. As a secondary analysis of the DUALITY trial, the aim of this study was to assess the determinants of the effect size after 2 types of dual-task practice. We randomly allocated 121 participants with PD to receive either integrated or consecutive dual-task training. Dual-task walking performance was assessed during (i) a backward digit span task (digit), (ii) an auditory Stroop task (Stroop), and (iii) a functional mobile phone task. Baseline descriptive, motor, and cognitive variables were correlated with the change in dual-task gait velocity after the intervention. Factors correlated with the change in dual-task gait velocity postintervention (P < 0.20) were entered into a stepwise forward multiple linear regression model. Lower dual-task gait velocity and higher cognitive capacity (Scales for Outcomes in Parkinson's Disease-Cognition [ScopaCog]) at baseline were related to larger improvements in dual-task gait velocity after both integrated and consecutive dual-task training for all 3 tasks (β[gait] = -0.45, β[ScopaCog] = 0.34, R = 0.23, P < 0.001, for digit; β[gait] = -0.52, β[ScopaCog] = 0.29, R = 0.26, P < 0.001, for Stroop; and β[gait] = -0.40, β[ScopaCog] = 0.30, R = 0.18, P < 0.001, for mobile phone task). Participants with PD who showed a slow dual-task gait velocity and good cognitive functioning at baseline benefited most from the dual-task training, irrespective of the type of training and type of dual-task outcome.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A242).

Explanation of Cognitive Load on Brain Activity during Auditory Stroop Task using LRP

Explanation of Cognitive Load on Brain Activity during Auditory Stroop Task using LRP

Loneliness increases attention to negative vocal tone in an auditory Stroop task

Lonely individuals are sensitive to negative social information. Past evidence for this finding comes mostly from research on visual cues (e.g., facial expression); less is known whether a parallel pattern occurs for auditory cues (e.g., voice). Using a vocal emotional Stroop task, we examined whether loneliness heightens attention to other's vocal tone. Compared to less lonely individuals, lonely participants' reaction time during the Stroop task was significantly slower when a positive (vs. negative) semantic word was presented via a negative vocal tone. It appears that lonely individuals, compared to others, are more distracted by the negative emotionality of a voice tone, which might signal social threats. This attentional bias remained when controlling for neuroticism, and was more pronounced when social, rather than nonsocial words were presented.

Regional specialization of visual cortex in congenital blindness reveals takeover by multiple distinct top-down fronto-parietal inputs

Recent evidence suggests that, in blindness, visual cortices become responsive to higher-cognitive information, including language and number. We hypothesize that this plasticity is mediated by takeover of visual cortex by multiple fronto-parietal networks that typically provide top-down feedback to vision. To test this hypothesis, we asked whether a) visual cortices participate in executive functions, which are also supported by fronto-parietal networks and b) whether executive functioning, numerical reasoning and linguistic processing colonize distinct "visual" regions. Congenitally blind and sighted control participants took part in three fMRI experiments. In a sentence comprehension experiment, participants either listened to spoken sentences or lists of non-words. In a math calculation experiment, participants solved math equations or processed sentences. Finally, we measured executive conflict using an auditory STROOP task. Participants judged whether the voice of a speaker was male or female. On congruent (C) trials, a female speaker said "female" or a male speaker said "male" and vice versa on incongruent (I) trials. On neutral (N) trials male and female speakers said gender-neutral words. In congenitally blind but not sighted individuals, parts of primary visual cortex (V1) were more active during incongruent than congruent trials (F(1,18)=4.63, p< 0.05; group interaction: F(1,26)=5.45, p=0.03). Different occipital regions, within and outside of V1, responded to language (sentence>nonwords; lateral and ventral occipito-temporal cortices (LO & VOT)) and numerical information (math>language; middle occipital gyrus (MOG)). Math- and language-responsive visual regions don't show a congruency effect (MOG: I&C>N F(1,18)=0.01, p=0.94, I>C F(1,18)=1.96, p=0.18; LO: I&C>N F(1,18)=0.28, p=0.60, I>C F(1,18)=0.27, p=0.61; VOT: I&C>N F(1,18)=1.46, p=0.24, I>C F(1,18)=0.02, p=0.88). We conclude that, in congenital blindness, "visual" cortex becomes sub-specialized for multiple distinct higher cognitive functions, including domain general executive conflict, language and numerical processing. We hypothesize that this plasticity is related to the intrinsic long-range top-down connectivity to the visual system from fronto-parietal networks. Meeting abstract presented at VSS 2018

Increased Postural Demand Is Associated With Greater Cognitive Workload in Healthy Young Adults: A Pupillometry Study.

Introduction: Balance tasks require cognitive resources to ensure postural stability. Pupillometry has been used to quantify cognitive workload of various cognitive tasks, but has not been studied in postural control. The current investigation utilized pupillometry to quantify the cognitive workload of postural control in healthy young adults. We hypothesized that cognitive workload, indexed by pupil size, will increase with challenging postural control conditions including visual occlusion and cognitive dual tasking.Methods: Twenty-one young healthy adults (mean ± standard error of the mean), (age = 23.2 ± 0.49 years; 12 females) were recruited for this study. Participants completed four tasks: (1) standing with eyes open; (2) standing with eyes occluded (3) standing with eyes open while performing an auditory Stroop task; and (4) standing with eyes occluded while performing an auditory Stroop task. Participants wore eye tracking glasses while standing on a force platform. The eye tracking glasses recorded changes in pupil size that in turn were converted into the Index of Cognitive Activity (ICA). ICA values were averaged for each eye and condition. A two-way Analysis of Variance with post-hoc Sidak correction for pairwise comparisons was run to examine the effect of visual occlusion and dual tasking on ICA values as well on Center of Pressure (CoP) sway velocity in anterior–posterior (AP) and medio-lateral (ML) directions. A Pearson’s correlation coefficient was utilized to determine the relationship between ICA values and CoP sway velocity.Results: Significant within-condition effect was observed with visual occlusion for the right eye ICA values (p = 0.008). Right eye ICA increased from eyes open to eyes occluded conditions (p = 0.008). In addition, a significant inverse correlation was observed between right eye ICA values and CoP sway velocity in the ML direction across all the conditions (r = -0.25, p = 0.02).Conclusion: This study demonstrated support for increased cognitive workload, measured by pupillometry, as a result of changes in postural control in healthy young adults. Further research is warranted to investigate the clinical application of pupillometry in balance assessment.

Attention demands of postural control in non-specific chronic low back pain subjects with low and high pain-related anxiety.

Impaired postural control in chronic low back pain (CLBP) has been attributed to deficits in sensory and motor functions. However, it is not known if pain-related anxiety affects motor and cognitive function of postural control. The aim of this study was to compare the interactive effects of postural and cognitive function in CLBP patients with high and low pain-related anxiety and healthy subjects. Thirty-eight patients with nonspecific CLBP (19 with low and 19 with high pain-related anxiety levels) and 20 asymptomatic subjects participated. Postural control was assessed by center of pressure (COP) parameters including mean total sway velocity, area, anterior-posterior (A-P), and medial-lateral (Med-Lat) range. Postural task was assessed during four conditions (eyes open with and without ankle vibration-eyes closed with and without ankle vibrations). Participants performed the postural task with or without auditory Stroop task. Average reaction time and error ratio of auditory Stroop test were calculated as measures of the cognitive task performance. Significantly reduced sway area was observed in CLBP patients with high pain-related anxiety and control subjects during the dual-task condition as compared with the single task. In addition, A-P range was significantly reduced in CLBP patients with high pain-related anxiety during dual tasking when eyes were closed with ankle vibration. In addition, only the CLBP subjects with high pain-related anxiety showed significantly longer reaction times by increasing the difficulty of standing postural task. Pain-related anxiety may influence the postural cognitive interactions in CLBP patients. Furthermore, it may be considered as a contributing factor for postural strategies adopted by CLBP patients.

Do perturbation-evoked responses result in higher reaction time costs depending on the direction and magnitude of perturbation?

To date, little work has focused on whether cognitive-task interference during postural response execution is influenced by the direction and/or magnitude of the perturbation applied. Hypothetically, the increased difficulty associated with a backward loss of balance could necessitate increased allocation of cognitive resources to counteract destabilizing forces. The current study investigated these relationships using a paradigm in which individuals performed a cognitive task (auditory Stroop task during quiet stance; baseline condition). In certain trials, a translation of the support surface was concurrently evoked (magnitude: small or large; direction: forward or backward) which required a postural response to maintain balance. Ten healthy young adults completed four blocks of these experimental trials (26 randomized trials/block). Postural stability during balance recovery was evaluated using the margin of stability (MoS), while Stroop task performance was based onreaction time cost (RTC)and differences between experimental conditions. Results showed no effect of perturbation direction onRTC, but there was an observed MoS increase at peak extrapolated center of mass excursion following a small perturbation evoked concurrently with the cognitive task. No effect of cognitive-task performance was detected for MoS during stepping strategies (followed large perturbations). Instead, increasedRTC were observed relative to the fixed base of support responses. In general, young adults adopted a "posture-first" strategy, regardless of perturbation direction, reinforcing the importance of cognition in the maintenance of upright balance.

Tunes and Tones: Music, Language, and Inhibitory Control

Abstract A debate is underway regarding the perceptual and cognitive benefits of bilingualism and musical experience. This study contributes to the debate by investigating auditory inhibitory control in English-speaking monolingual musicians, non-musicians, tone language bilinguals, and non-tone language bilinguals. We predicted that musicians and tone language bilinguals would demonstrate enhanced processing relative to monolinguals and other bilinguals. Groups of monolinguals (N = 22), monolingual musicians (N = 19), non-tone language bilinguals (N = 20) and tone language bilinguals (N = 18) were compared on auditory Stroop tasks to assess domain-transferable processing benefits (e.g. auditory inhibitory control) resulting from potentially shared underlying cognitive mechanisms (Patel, 2003; Bialystok &amp; DePape, 2009). In one task, participants heard the words “high” and “low” presented in high or low pitches, and responded regarding the pitch of the stimuli as quickly as possible. In another task, participants heard the words “rise” or “fall” presented in rising or falling pitch contours, and responded regarding the contour of the stimuli as quickly as possible. Results suggest transferable auditory inhibitory control benefits for musicians across pitch and contour processing, but any possible enhanced processing for speakers of tone languages may be task-dependent, as lexical tone activation may interfere with pitch contour processing.

Examining Transfer Effects of Dual-Task Training Protocols for a Complex Locomotor Task

ABSTRACTTraining protocols designed to improve dual-task performance of an obstacle crossing and auditory Stroop task (OBS+Stroop) were tested. In Experiment 1, following baseline collection of OBS+Stroop trials, proximally related walking training was performed, and participants were then retested on the OBS+Stroop test. After training, participants adopted a more cautious obstacle crossing strategy, indicating a potentially safer navigation strategy. Transfer effects from distally related training were then examined (Experiment 2); a computer game training paradigm was examined using the same testing protocol as Experiment 1. Computer training demonstrated improved dual-task performance on some measures, but did not induce a more cautious stepping strategy. Results indicate that dual-task training needs to be similar to targeted tasks to yield reliable, positive training outcomes.

Accounting for verbal and spatial working memory load in an auditory Stroop task

The Stroop task (Stroop, 1935) has been used extensively in cognitive psychology research for the study of selective attention and processing speed and accuracy. A recent experiment in our lab used an auditory-spatial Stroop task where participants were required to determine the spatial location of congruent and incongruent directional words. Results of that experiment showed that incongruent trials had a significant effect on performance, but only in the vertical plane. Special load theory (Park, Kim, &amp; Chun, 2007) states that distractibility is a function of the relationship between working memory (WM) load and the targets/distractors of the task. The auditory-spatial Stroop task was modified by using WM loads intended to interfere specifically with the semantic or spatial aspects of the task. Given that targets in the task are the spatial locations of the words, special load theory predicts that a spatial WM load results in decreased performance (increased interference) while a verbal WM load predicts increased performance (decreased interference). Data presented will illuminate whether spatial or verbal WM load has a greater impact on performance in an auditory-spatial Stroop task.

Reliability of kinematic measures in subjects with anterior cruciate ligament deficiency during dual-task walking

ObjectiveTo define the throughout within- and between-day reliability of gait parameters in single - and dual-task conditions in subjects with and without anterior cruciate ligament deficiency (ACLD). MethodsFourteen subjects with ACLD and 14 healthy subjects completed a walking task on a treadmill with three levels of velocity (self-selected, high and low), with or without performing an auditory Stroop task over two sessions each 3–5 days apart. The gait kinematic parameters, including maximum and minimum hip flexion, total hip range of motion, maximum and minimum knee flexion and total knee range of motion were recorded using a motion analysis system. The intraclass correlation coefficient (ICC), the standard error of measurement (SEM), and the coefficient of variation (CV) were used to determine inter- and intrasession reliability of kinematic and cognitive measures. ResultsICCs for ACLD group in dual-task and single task conditions ranged between 0.50 to 0.93 and 0.53 to 0.93, respectively. ICC values for healthy groups in dual-task and single task conditions ranged between 0.36 to 0.90 and 0.39 to 0.87, respectively. When comparing relative reliability across kinematic variables in different velocities, ICC values were generally identical in all three levels of velocity. ConclusionThe findings suggest that dual-tasking could also be applied reliably for the assessment of functional activities in subjects with and without ACLD.

Measuring the effects of a visual or auditory Stroop task on dual-task costs during obstacle crossing

Successful planning and execution of motor strategies while concurrently performing a cognitive task has been previously examined, but unfortunately the varied and numerous cognitive tasks studied has limited our fundamental understanding of how the central nervous system successfully integrates and executes these tasks simultaneously. To gain a better understanding of these mechanisms we used a set of cognitive tasks requiring similar central executive function processes and response outputs but requiring different perceptual mechanisms to perform the motor task. Thirteen healthy young adults (20.6±1.6years old) were instrumented with kinematic markers (60Hz) and completed 5 practice, 10 single-task obstacle walking trials and two 40 trial experimental blocks. Each block contained 20 trials of seated (single-task) trials followed by 20 cognitive and obstacle (30% lower leg length) crossing trials (dual-task). Blocks were randomly presented and included either an auditory Stroop task (AST; central interference only) or a visual Stroop task (VST; combined central and structural interference). Higher accuracy rates and shorter response times were observed for the VST versus AST single-task trials (p<0.05). Conversely, for the obstacle stepping performance, larger dual task costs were observed for the VST as compared to the AST for clearance measures (the VST induced larger clearance values for both the leading and trailing feet), indicating VST tasks caused greater interference for obstacle crossing (p<0.05). These results supported the hypothesis that structural interference has a larger effect on motor performance in a dual-task situation compared to cognitive tasks that pose interference at only the central processing stage.

Dual-Tasking Effects on Dynamic Postural Stability in Athletes With and Without Anterior Cruciate Ligament Reconstruction.

To compare the effect of dual tasking on postural stability between patients with anterior cruciate ligament reconstruction (ACL-R) and healthy controls. Single-limb postural stability was assessed in 17 athletes with ACL-R and 17 healthy matched athletes while standing on a Biodex Balance System platform in 4 conditions: stability level of 8 (ie, more-stable support surface) with eyes open, stability level of 8 with eyes closed, stability level of 6 (ie, less-stable support surface) with eyes open, and stability level of 6 with eyes closed. Postural-stability tasks were performed with and without auditory Stroop task. The anteroposterior stability index (APSI), mediolateral stability index (MLSI), and overall stability index (OSI) as measures of postural performance, as well as reaction time and error ratio as measures of cognitive performance, were recorded. Dual-tasking effect on postural stability was not significantly different between the groups in 3 postural conditions. Only in level 6 with eyes open, for APSI and OSI, patients with ACL-R showed lower postural stability under the dual-task condition. However, patients showed poorer performance on both reaction time and error ratio in all postural conditions. The patients with ACL-R appeared to sacrifice their cognitive performance to optimize their performance on postural stability. This posture-first strategy was reflected by a more pronounced effect of dual tasking on the auditory Stroop task than the postural-stability task. In situations where maintenance of posture is challenging, giving priority to the postural task at the expense of cognitive performance can ensure safety from balance loss.

EP 123. Impaired conflict processing in patients with hippocampal sclerosis

Introduction Hippocampal sclerosis (HS) frequently underlies temporal lobe epilepsy. Patients often suffer from refractory epileptic seizures, but episodic memory deficits, depressive syndromes or impaired special navigation are also common symptoms. Much less is known about the role of the hippocampus for conflict processing. Patients with impaired conflict processing show specific behavioral deficits. They lack goal-directed behavior, are more distractible or have personality characteristics such as unsteadiness, emotional instability, with frequent and rapid mood changes. Early evidence for a hippocampal role in conflict processing comes from Gray’s 1982 model of anxiety, which suggests that the hippocampus supports avoidance behavior during approach-avoidance-conflicts. In addition, the hippocampus is thought to be important for inhibitory learning, a fundamental process that might modulate higher cognitive functions like memory or even conflict processing ( Chan et al., 2001 ). A recent fMRI-EEG study confirmed a role of the human hippocampus for conflict processing by showing hippocampal activity during cognitive conflicts in an auditory stroop task ( Oehrn et al., 2015 ). Here we investigate how hippocampal damage relates to deficits in conflict processing. Methods Patients with temporal lobe epilepsy and HS, patients with TLE and a temporolateral lesion and 27 healthy controls perform the auditory stroop task. Subjects listen to the words “high”, “low” and “good” (semantic aspect) in a low or high pitch (phonetic aspect). Semantic and phonetic aspects either matched (congruent condition) or contradicted (incongruent condition). Results So far, we collected data from two patients with HS and 27 healthy controls. Patients show higher conflict-related slowing of response time (166 ms ± 94) than healthy controls (68 ms ± 53). Patients also show less correct responses during conflict (61% ± 51) compared to non-conflict condition (86% ± 19). However, healthy controls responded correctly in most trials during incongruent (99% ± 1) and congruent condition (95% ± 8). Conclusions The preliminary descriptive data indicate conflict-related slowing of information processing in patients with hippocampal damage. The findings can further our understanding of the role of the hippocampus for conflict processing. It may also help to explain psychiatric comorbidities in patients with temporal lobe epilepsy.

Decoding of task-relevant and task-irrelevant intracranial EEG representations

Natural stimuli consist of multiple properties. However, not all of these properties are equally relevant in a given situation. In this study, we applied multivariate classification algorithms to intracranial electroencephalography data of human epilepsy patients performing an auditory Stroop task. This allowed us to identify neuronal representations of task-relevant and irrelevant pitch and semantic information of spoken words in a subset of patients. When properties were relevant, representations could be detected after about 350ms after stimulus onset. When irrelevant, the association with gamma power differed for these properties. Patients with more reliable representations of irrelevant pitch showed increased gamma band activity (35–64Hz), suggesting that attentional resources allow an increase in gamma power in some but not all patients. This effect was not observed for irrelevant semantics, possibly because the more automatic processing of this property allowed for less variation in free resources. Processing of different properties of the same stimulus seems therefore to be dependent on the characteristics of the property.

Test-Retest Reliability of Dual-Task Outcome Measures in People With Parkinson Disease.

Dual-task (DT) training is gaining ground as a physical therapy intervention in people with Parkinson disease (PD). Future studies evaluating the effect of such interventions need reliable outcome measures. To date, the test-retest reliability of DT measures in patients with PD remains largely unknown. The purpose of this study was to assess the reliability of DT outcome measures in patients with PD. A repeated-measures design was used. Patients with PD ("on" medication, Mini-Mental State Examination score ≥24) performed 2 cognitive tasks (ie, backward digit span task and auditory Stroop task) and 1 functional task (ie, mobile phone task) in combination with walking. Tasks were assessed at 2 time points (same hour) with an interval of 6 weeks. Test-retest reliability was assessed for gait while performing each secondary task (DT gait) for both cognitive tasks while walking (DT cognitive) and for the functional task while walking (DT functional). Sixty-two patients with PD (age=39-89 years, Hoehn and Yahr stages II-III) were included in the study. Intraclass correlation coefficients (ICCs) showed excellent reliability for DT gait measures, ranging between .86 and .95 when combined with the digit span task, between .86 and .95 when combined with the auditory Stroop task, and between .72 and .90 when combined with the mobile phone task. The standard error of measurements for DT gait speed varied between 0.06 and 0.08 m/s, leading to minimal detectable changes between 0.16 and 0.22 m/s. With regard to DT cognitive measures, reaction times showed good-to-excellent reliability (digit span task: ICC=.75; auditory Stroop task: ICC=.82). The results cannot be generalized to patients with advanced disease or to other DT measures. In people with PD, DT measures proved to be reliable for use in clinical studies and look promising for use in clinical practice to assess improvements after DT training. Large effects, however, are needed to obtain meaningful effect sizes.

Balance recovery reactions in individuals with recurrent nonspecific low back pain: Effect of attention

People who suffer from Low Back Pain (LBP) demonstrate impaired postural control. Deficits in sensory-motor systems have been proposed to be related to these changes. Considering higher cognitive process contribution to postural control, the aim of this study was to investigate the effects of cognitive load on balance control of patients with LBP. Twenty subjects with recurrent non-specific LBP and 20 healthy controls participated. They stood on a moveable platform with each foot placed on a separate force plate. They were asked to maintain their balance (a) while expecting translations of the support surface at two sizes of perturbation (b) with and without performing a cognitive (auditory Stroop) task. The outcomes included reaction time (RT), latency, initial velocity and amplitude of center of pressure response for balance, and RT for cognitive performance. Compared to the healthy group, LBP group demonstrated delayed RT and latency, and reduced initial velocity (P<0.05). Moreover, they had slower Stroop RT (F=70.88, P<0.001). Concurrent performance of tasks resulted in increased Stroop RT (F=3.42, P=0.03) and adaptation in initial velocity (F=6.70, P=0.01). At the smaller size of perturbation, cognitive load increased velocity in LBP group but decreased this variable in the healthy group. When the cognitive load was added at the larger size of perturbation, velocity of response decreased in LBP group (P<0.05). These findings imply altered cognitive regulation of dynamic balance in patients with LBP and suggest that the adopted strategy might alter depending upon the characteristics of the postural challenge.

Are factors related to dual-task performance in people with Parkinson's disease dependent on the type of dual task?

BackgroundImpaired dual-task performance significantly impacts upon functional mobility in people with Parkinson's disease (PD). The aim of this study was to identify determinants of dual-task performance in people with PD in three different dual tasks to assess their possible task-dependency. MethodsWe recruited 121 home-dwelling patients with PD (mean age 65.93 years; mean disease duration 8.67 years) whom we subjected to regular walking (control condition) and to three dual-task conditions: walking combined with a backwards Digit Span task, an auditory Stroop task and a Mobile Phone task. We measured dual-task gait velocity using the GAITRite mat and dual-task reaction times and errors on the concurrent tasks as outcomes. Motor, cognitive and descriptive variables which correlated to dual-task performance (p < 0.20) were entered into a stepwise forward multiple linear regression model. ResultsSingle-task gait velocity and executive function, tested by the alternating intake test, was significantly associated with gait velocity during the Digit Span (R2 = 0.65; p < 0.001), the Stroop (R2 = 0.73; p < 0.001) and the Mobile Phone task (R2 = 0.62; p < 0.001). In addition, disease severity proved correlated to gait velocity during the Stroop task. Age was a surplus determinant of gait velocity while using a mobile phone. ConclusionSingle-task gait velocity and executive function as measured by a verbal fluency switching task were independent determinants of dual-task gait performance in people with PD. In contrast to expectation, these factors were the same across different tasks, supporting the robustness of the findings. Future study needs to determine whether these factors predict dual-task abnormalities prospectively.