Typically Developed Controls Research Articles

Slips of the tongue in patients with Gilles de la Tourette syndrome

BackgroundMotor and vocal tics are the main symptom of Gilles de la Tourette-syndrome (GTS). A particular complex vocal tic comprises the utterance of swear words, termed coprolalia. Since taboo words are socially inappropriate, they are normally suppressed by people, which implies cognitive control processes.MethodTo investigate the control of the unintentional pronunciation of taboo words and the associated processes of conflict monitoring, we used the “Spoonerisms of Laboratory Induced Predisposition” (SLIP) paradigm. Participants read multiple inductor word pairs with the same phonemes, followed by pronouncing a target pair with inverse phonemes. This led to a conflict between two competing speech plans: the correct word pair and the word pair with inverted phonemes. Latter speech error, a spoonerism, could result in a neutral or taboo word. We investigated 19 patients with GTS and 23 typically developed controls (TDC) and measured participants’ electroencephalography (EEG) during the SLIP task.ResultsAt the behavioral level less taboo than neutral word spoonerisms occurred in both groups without significant differences. Event-related brain potentials (ERP) revealed a difference between taboo and neutral word conditions in the GTS group at the midline electrodes in a time range of 250–400 ms after the speech prompt, which was not found in the TDC group. The extent of this effect depended on the number of inductor word pairs, suggesting an increasing level of cognitive control in the GTS group.ConclusionThe differences between taboo and neutral word conditions in patients with GTS compared to TDC suggest an altered recruitment of cognitive control processes in GTS, likely enlisted to suppress taboo words.

Abnormal individualized peak functional connectivity toward potential repetitive transcranial magnetic stimulation treatment of autism spectrum disorder.

Functional connectivity (FC) derived from resting-state functional magnetic resonance imaging has been widely applied to guide precise repetitive transcranial magnetic stimulation (rTMS). The left, right, and bilateral dorsolateral prefrontal cortices (DLPFC) have been used as rTMS treatment target regions for autism spectrum disorder (ASD), albeit with moderate efficacy. Thus, we aimed to develop an individualized localization method for rTMS treatment of ASD. We included 266 male ASDs and 297 male typically-developed controls (TDCs) from the Autism Brain Imaging Data Exchange Dataset. The nucleus accumbens (NAc) was regarded as a promising effective region, which was used as a seed and individualized peak FC strength in the DLPFC was compared between ASD and TDC. Correlation analysis was conducted between individualized peak FC strength and symptoms in ASD. We also investigated the spatial distribution of individualized peak FC locations in the DLPFC and conducted voxel-wise analysis to compare NAc-based FC between the two groups. ASD showed stronger peak FC in the right DLPFC related to TDC (Cohen's d = -.19, 95% CI: -0.36 to -0.03, t = -2.30, p = .02). Moreover, negative correlation was found between the peak FC strength in the right DLPFC and Autism Diagnostic Observation Schedule (ADOS) scores, which assessed both the social communication and interaction (r = -.147, p = .04, uncorrected significant), and stereotyped behaviors and restricted interests (r = -.198, p = .02, corrected significant). Peak FC locations varied substantially across participants. No significant differences in NAc-based FC in the DLPFC were found in the voxel-wise comparison. Our study supports the use of individualized peak FC-guided precise rTMS treatment of male ASD. Moreover, stimulating the right DLPFC might alleviate core symptoms of ASD.

Global-Local Processing in ADHD Is Not Limited to the Visuospatial Domain: Novel Evidence From the Auditory Domain

Objective: Global-local visuospatial processing has been widely investigated in both healthy and clinical populations. Recent studies indicated that individuals with ADHD lack a global processing bias. However, the extant literature regarding global-local processing style focuses solely on the visual modality. Methods: ADHD (N = 21) and typically developed (TD) controls (N = 24) underwent an auditory global-local task, in which they had to decide whether the melody is ascending or descending in global or local conditions. Results: TD controls exhibited a classic global processing bias in the auditory task. The ADHD group exhibited no global processing bias, indicating similar processing for global and local dimensions, implying that individuals with ADHD are distracted by incongruent information in global and local conditions similarly, in both visual and auditory tasks. Conclusion: A lack of global processing bias in ADHD is not limited to the visuospatial modality and likely reflects a broader and more general processing style.

Assessment of foot deformities in individuals with cerebral palsy using weight-bearing CT.

The aims of this study were to visualize and quantify relative bone positions in the feet of individuals with cerebral palsy (CP) with a foot deformity and compare bone positions with those of typically developed (TD) controls. Weight-bearing CT images of 14 individuals with CP scheduled for tendon transfer and/or bony surgery and of 20 TD controls were acquired on a Planmed Verity WBCT scanner. Centroids of the navicular and calcaneus with respect to the talus were used to quantify foot deformities. All taluses were aligned and the size and dimensions of the individuals' talus were scaled to correct for differences in bone sizes. In order to visualize and quantify variations in relative bone positions, 95% CI ellipsoids and standard deviations in its principle X-, Y-, and Z-directions were determined. In individuals with CP (age 11-17), a large variation in centroid positions was observed compared to data of TD controls. Radiuses of the ellipsoids, representing the standard deviations of the 95% CI in the principle X-, Y-, and Z-directions, were larger in individuals with CP compared to TD controls for both the calcaneus (3.16 vs 1.86mm, 4.26 vs 2.60mm, 9.19 vs 3.60mm) and navicular (4.63 vs 1.55mm, 5.18 vs 2.10mm, 16.07 vs 4.16mm). By determining centroids of the calcaneus and navicular with respect to the talus on WBCT images, normal and abnormal relative bone positions can be visualized and quantified in individuals with CP with various foot deformities.

Temporal preparation in adults with autistic spectrum disorder: The variable foreperiod effect.

Research suggested the possibility that temporal cognition may be different in autistic spectrum disorder (ASD). Although there are some empirical studies examining timing ability in these individuals, to our knowledge, no one directly assessed the ability to predict when an event will occur. Here, we report a study on implicit temporal preparation in individuals with ASD as indexed by the variable foreperiod (FP) effect. We compared a group of adult ASD participants to a group of typically-developed (TD) controls, for their respective abilities to utilize implicit temporal information in a simple detection task with three different preparatory intervals (FP, short, middle and long). Participants were given a warning tone to signal an imminent stimulus, and asked to press a key as quickly as they could upon detection of the stimulus. Both groups were able to use implicit temporal information, as revealed by both the variable-FP effect (i.e., faster response for targets appearing after a long FP) and asymmetric sequential effects (i.e., slower response in short-FP trials following a previous long-FP trial). The TD group exhibited a faster response in a long-FP trial that was preceded by short-FP one, whereas the ASD group did not, as reflected in their higher percentage of response omissions for a target that appeared later than in the previous trial. The reduced ability of ASD participants to modulate their responses under these conditions might reflect a difficulty in time-based monitoring of stimulus occurrence. LAY SUMMARY: Time-processing may be different in autistic spectrum disorder (ASD). This study addressed the ability to anticipate a relevant stimulus's onset according to predictable interstimulus intervals comparing adults with ASD and typically developed controls. We found that ASD participants did not benefit from temporal preparation when stimulus appeared later than previously attended. This suggests a reduced ability in detecting implicit temporal regularities between events.

Keep it simple: Identification of basic versus complex emotions in spoken language in individuals with autism spectrum disorder without intellectual disability: A meta-analysis study.

Daily functioning involves identifying emotions in spoken language, a fundamental aspect of social interactions. To date, there is inconsistent evidence in the literature on whether individuals with autism spectrum disorder without intellectual disability (ASD-without-ID) experience difficulties in identification of spoken emotions. We conducted a meta-analysis (literature search following the PRISMA guidelines), with 26 data sets (taken from 23 peer-reviewed journal articles) comparing individuals with ASD-without-ID (N= 614) and typically-developed (TD) controls (N= 640), from nine countries and in seven languages (published until February 2020). In our analyses there was no sufficient evidence to suggest that individuals with HF-ASD differ from matched controls in the identification of simple prosodic emotions (e.g., sadness, happiness). However, individuals with ASD-without-ID were found to perform significantly worse than controls in identification of complex prosodic emotions (e.g., envy and boredom). The level of the semantic content of the stimuli presented (e.g., sentences vs. strings of digits) was not found to have an impact on the results. In conclusion, the difference in findings between simple and complex emotions calls for a new-look on emotion processing in ASD-without-ID. Intervention programs may rely on the intact abilities of individuals with ASD-without-ID to process simple emotions and target improved performance with complex emotions. LAY SUMMARY: Individuals with autism spectrum disorder without intellectual disability (ASD-without-ID) do not differ from matched controls in the identification of simple prosodic emotions (e.g., sadness, happiness). However, they were found to perform significantly worse than controls in the identification of complex prosodic emotions (e.g., envy, boredom). This was found in a meta-analysis of 26 data sets with 1254 participants from nine countries and in seven languages. Intervention programs may rely on the intact abilities of individuals with ASD-without-ID to process simple emotions.

Stronger proprioceptive BOLD-responses in the somatosensory cortices reflect worse sensorimotor function in adolescents with and without cerebral palsy

Cerebral palsy (CP) is a motor disorder where the motor defects are partly due to impaired proprioception. We studied cortical proprioceptive responses and sensorimotor performance in adolescents with CP and their typically-developed (TD) peers. Passive joint movements were used to stimulate proprioceptors during functional magnetic resonance imaging (fMRI) session to quantify the proprioceptive responses whose associations to behavioral sensorimotor performance were also examined.Twenty-three TD (15 females, age: mean ± standard deviation 14.2 ± 2.4 years) and 18 CP (12 females, age: mean ± standard deviation, 13.8 ± 2.3 years; 12 hemiplegic, 6 diplegic) participants were included in this study. Participants’ index fingers and ankles were separately stimulated at 3 Hz and 1 Hz respectively with pneumatic movement actuators. Regions-of-interest were used to quantify BOLD-responses from the primary sensorimotor (SM1) and secondary (SII) somatosensory cortices and were compared across the groups. Associations between responses strengths and sensorimotor performance measures were also examined.Proprioceptive responses were stronger for the individuals with CP compared to their TD peers in SM1 (p < 0.001) and SII (p < 0.05) cortices contralateral to their more affected index finger. The ankle responses yielded no significant differences between the groups. The CP group had worse sensorimotor performance for hands and feet (p < 0.001). Stronger responses to finger stimulation in the dominant SM1 (p < 0.001) and both dominant and non-dominant SII (p < 0.01, p < 0.001) cortices were associated with the worse hand sensorimotor performance across all participants.Worse hand function was associated with stronger cortical activation to the proprioceptive stimulation. This association was evident both in adolescents with CP and their typically-developed controls, thus it likely reflects both clinical factors and normal variation in the sensorimotor function. The specific mechanisms need to be clarified in future studies.

Fourth finger dependence of high-functioning autism spectrum disorder in multi-digit force coordination

A number of studies have reported that the digit ratio 2D:4D (length of the second finger divided by length of the fourth finger) is smaller (longer fourth digit) in autism spectrum disorder (ASD) than in typically developed (TD) controls. Because form and function are closely related in biological systems, we hypothesized that the 4D dominance occurs in not only finger morphology but also physical performance in ASD. Individuals with ASD and TD controls participated in a multi-digit force-producing task. Individuals with ASD showed a significant 4D dependence compared to TD controls in the task. We found a significant correlation between 4D dependence and scores of the standard diagnostic instrument across individuals with ASD. Our analysis of functional connectivity in resting-state functional MRI suggests that connectivity between the visual cortex and the cerebellum contributes to the 4D dependence. Collectively, these results extend the 2D:4D ratio beyond being a morphological marker to being involved in motor functions in the form of 4D dependence in a multi-digit force task.

Adrenoleukodystrophy linked to Chromosome X with Neuropsychiatric Symptoms and Frontal Involvement: Case Report

Objective: To compare the cardiac autonomic system at rest and its response to a submaximal aerobic test in children with cerebral palsy (CP) and typically developed (TD) controls. Design: Twenty-five children with CP aged 6-11 and 20 age and gender matched TD controls participated in the study. RR intervals were monitored at rest, while performing the sub-maximal treadmill test, and during the recovery period. The square-root of the mean of successive differences between adjacent RR intervals (RMSSD) was calculated. Results: The median level of the submaximal treadmill test stage was 3 for children with CP (95% CI 0.75-3.25), 16/20 TD children completed all test stages. The Log- Rank statistic (χ2 1=30.4) was highly significant (p<0.001). At rest the RMSSD values in children with CP were significantly lower as compared to children TD, and changed less due to the submaximal test and recovery stages (interaction-effect, F2;86=9, p<0.01). Conclusion: Children with CP show lower RMSSD at rest, and less adaptive to exercise as compared to TD children. Performing physical activity is highly recommended for children with CP, re-educating the cardiac autonomic system is one of its main goals. Assessing the autonomic response to different exercise protocols is the next step needed.

The Cardiac Autonomic Control System Response to Submaximal Exercise Test in Children with Cerebral Palsy Compared to Typical Peer

Objective: To compare the cardiac autonomic system at rest and its response to a submaximal aerobic test in children with cerebral palsy (CP) and typically developed (TD) controls. Design: Twenty-five children with CP aged 6-11 and 20 age and gender matched TD controls participated in the study. RR intervals were monitored at rest, while performing the sub-maximal treadmill test, and during the recovery period. The square-root of the mean of successive differences between adjacent RR intervals (RMSSD) was calculated. Results: The median level of the submaximal treadmill test stage was 3 for children with CP (95% CI 0.75-3.25), 16/20 TD children completed all test stages. The Log- Rank statistic (χ2 1=30.4) was highly significant (p<0.001). At rest the RMSSD values in children with CP were significantly lower as compared to children TD, and changed less due to the submaximal test and recovery stages (interaction-effect, F2;86=9, p<0.01). Conclusion: Children with CP show lower RMSSD at rest, and less adaptive to exercise as compared to TD children. Performing physical activity is highly recommended for children with CP, re-educating the cardiac autonomic system is one of its main goals. Assessing the autonomic response to different exercise protocols is the next step needed.

Executive function in high-functioning autism: Decision-making consistency as a characteristic gambling behaviour

Restricted and repetitive patterns of behaviours, interests, or activities are a critical diagnostic criterion for autism spectrum disorder (ASD). Previous studies using gambling paradigms with ASD populations have identified that, unlike typically developed control participants, people with a diagnosis of ASD tend to maintain particular response patterns regardless of the magnitude of potential outcomes to uncertain gains or losses. Here we designed a gambling test that permitted calculation of the response consistency in gambling choices in situations that presented varying expected outcomes in terms of gains or losses. The task was administered to 33 adults with a diagnosis of ASDs and compared to a group of 47 typically-developed (TD) control participants who were matched for age and IQ. When presented with choices where participants could either make a risky gamble or a safe choice in terms of gains or losses (e.g., 20% chance of winning £5 vs. 100% chance of winning £1), the ASD participants did not differ from the TDs in their overall risk-taking behaviour. However, they were more consistent in their individual choices from trial to trial. Furthermore, the proportion of participants who either implemented an invariate response strategy (e.g., either always choosing the most risky or most “safe” option) was significantly higher in the ASD group compared with the controls. Additionally, while the ASD group were slower to make their responses in the win frame and the first half of the lose frame, by the end of the task their decision times were the same as the TD controls. These findings suggest that the ASD tendency towards repetitive behaviour may demonstrate itself even in high-level decision-making tasks, which needs to be understood if we are to be sure what such tasks are measuring.

The Characteristics and Age Effects of Emotional Lability in ADHD Children With and Without Oppositional Defiant Disorder

Objective: This study evaluated the concurrent validity of emotional lability (EL) in children with ADHD. Method: A total of 2,015 children with ADHD and 745 typically developed controls (TDCs) were assessed and compared on EL. Results: ADHD participants expressed higher EL scores than TDCs, not influenced by gender or IQ. Higher levels of EL symptoms were found in children with comorbid oppositional defiant disorder (ODD) and with ADHD-combined subtype. Receiver operating characteristic (ROC) analyses showed a strong screening efficacy of EL symptoms on ADHD. The effect of developmental age on EL showed a desisting pattern in TDCs, as opposed to a persisting pattern in ADHD (not influenced by ODD comorbid status). ODD symptoms in ADHD showed an ascending pattern. Conclusion: EL can potentially serve as a sentinel index for the presence of ADHD, especially when the ADHD presentation is atypical. ODD may embody a developmental entity distinct from EL.

P300 amplitude and latency in autism spectrum disorder: a meta-analysis.

Autism spectrum disorder (ASD) is an early onset neurodevelopmental disorder. Evidence suggests that ASD patients have abnormalities in information processing. Event-related potential (ERP) technique can directly record brain neural activity in real time. P300 is a positive ERP component which can measure the neuroelectrophysiological characteristics of human beings and has the potential to discover the pathological mechanism of ASD. However, P300 studies on ASD patients are incongruent and the disparities may be caused by several factors. By searching PubMed, Embase and Cochrane Library databases, a meta-analysis of P300 component difference between ASD group and typically developed (TD) control group was conducted. Results of amplitude and latency of P3b and P3a from included studies were synthesized. Random effect model was chosen and standardized mean difference (SMD) was calculated. Subgroup analysis was used to identify the source of heterogeneity and to test the effect of different experiment factors. A total of 407 ASD patients and 457 TD controls from 32 studies were included in this analysis. Reduced amplitude of P3b was found in ASD group (SMD=-0.505, 95% CI -0.873, -0.138) compared with TD group, but no difference of P3b latency, P3a amplitude, or P3a latency was found between groups. Subgroup analysis showed that oddball paradigm elicited attenuated P3b amplitude in Pz electrode among ASD subjects. This meta-analysis suggests ASD patients have abnormalities in P300 component, which may represent for deficits in cognition, attention orientation and working memory processing, particularly in the decision-making processing condition.

Impaired neural reward processing in children and adolescents with reactive attachment disorder: A pilot study.

Reactive attachment disorder (RAD) is characterized by markedly disturbed and developmentally inappropriate social relatedness due to parental maltreatment. RAD patients often display a high number of comorbid attention deficit/hyperactivity disorder (ADHD) symptoms, and certain RAD symptoms are difficult to discriminate from ADHD. One of the core characteristics of ADHD is a decrease in neural reward processing due to dopamine dysfunction. The aim of the present study was to determine whether the brain activity involved in reward processing in RAD patients is impaired in comparison with ADHD patients and typically developed controls. Five RAD patients, 17 typically developed (TD) controls and 17 ADHD patients aged 10-16 years performed tasks with high and low monetary reward while undergoing functional magnetic resonance imaging. ADHD patients were tested before and after 3 months treatment with osmotic release oral system-methylphenidate. Before treatment, ADHD patients showed that striatal and thalamus activities only in the tasks with low monetary reward were lower than TD controls. RAD patients showed decrease in activity of the caudate, putamen and thalamus during both the high and low monetary reward conditions in comparison with all the other groups. In RAD patients, the activity of the putamen was associated with the severity of posttraumatic stress and overt dissociation. Reward sensitivity was markedly decreased in children and adolescents with RAD, as evidenced by a diminished neural response during reward perception. This suggests that dopaminergic dysfunction exists in these patients, and may inform future dopaminergic treatment strategies for RAD.

P8. Social brain network and autism spectrum disorder: Reduced connectivity to the frontal cortex

Subjects with autism spectrum disorder (ASD) consistently present with difficulties in social interaction. We presumed that in subjects with ASD social impairments might be associated with decreased activation and coupling of specific brain regions. We examined ASD-related differences in the activation and connectivity of brain areas involved in the processing of facial, vocal and audiovisual social signals (i.e. fusiform face area (FFA), temporal voice area (TVA), and amygdala; Refs. (Bruck et al., 2011; Wicker et al., 2008)). 10 adult subjects with ASD and 20 typically developed (TD) control subjects took part in the study. Data was obtained using a 3T scanner (Siemens TRIO, BOLD-fMRI, 2D-EPI sequence: TR=1700ms, TE=30ms, 30 slices, 4mm thickness+1mm gap). Three functional blocked-design localizers were used to define brain areas involved in the processing of facial, vocal, and audiovisual social signals (Refs. Kreifelts et al., 2010; Kreifelts et al., 2009). Data was analyzed using SPM8. Differences between TD controls and ASD subjects were explored by comparing activation pattern between groups (ASD vs. TD). Different psychophysiological interaction (PPI) analyses aimed at identifying brain regions showing altered connectivity with the FFA, the TVA, and the amygdala were used to infer group differences in the connectivity. Statistical thresholds were set at a height threshold of p ⩽0.01 and a cluster-wise significance level of p PPI Faces (Fig. 1). (a) Group comparison: ASD subjects vs. TD controls. PPI analysis showed a decreased connectivity between the right amygdala and the left inferior frontal cortex in the group of ASD subjects ( x =−39, y =41, z =8). (b) Correlation analysis with AQ scores: Connectivity was negatively correlated with AQ scores between the right amygdala and the left inferior frontal and the left frontoorbital cortex, respectively ( x =−38, y =41, z =3). PPI Voices (Fig. 2). (a) Group comparison: ASD subjects vs. TD controls. Highlighted areas in the medial frontal cortex indicate regions with decreased connectivity to the right TVA in ASD subjects ( x =2, y =−16, z =16). (b) Correlation analysis with AQ scores: Connectivity between the left TVA and the right frontal superior cortex was inversely correlated with AQ scores ( x =20, y =16, z =23). In ASD patients we found reduced connectivity of the amygdala and TVA with frontal brain areas known to be involved in social cognitive processes such as evaluating social information. Future research should aim to clarify whether the decreased cerebral connectivity should rather be considered the cause or the consequence of impaired social interactions in ASD.

Effect of concurrent cognitive tasks on temporo-spatial parameters of gait among children with cerebral palsy and typically developed controls

Objective: To assess the influence of different concurrent cognitive tasks on gait characteristics in children with cerebral palsy (CP) and typically developed (TD) controls.Methods: Eleven children with CP and eleven TD controls walked under three conditions: at a self-selected speed, at a self-selected speed while memorizing and recalling a series of three random numbers, at a self-selected speed while listening and identifying commonly experienced sounds. Gait parameters were measured with the GAITRite® system.Results: Children with CP walked slower in both assignments as compared to baseline walking; TD controls reduce walking velocity only during the sounds assignment. Step length was constantly reduced and step time and length variability were constantly increased among children with CP as compared to TD controls, throughout assignments.Conclusion: It might be advisable for clinicians when assessing walking performance in children with CP, to assess it during both single and dual-task conditions.

Recognition of Facial Expressions and Prosodic Cues with Graded Emotional Intensities in Adults with Asperger Syndrome

This study investigated the ability of adults with Asperger syndrome to recognize emotional categories of facial expressions and emotional prosodies with graded emotional intensities. The individuals with Asperger syndrome showed poorer recognition performance for angry and sad expressions from both facial and vocal information. The group difference in facial expression recognition was prominent for stimuli with low or intermediate emotional intensities. In contrast to this, the individuals with Asperger syndrome exhibited lower recognition accuracy than typically-developed controls mainly for emotional prosody with high emotional intensity. In facial expression recognition, Asperger and control groups showed an inversion effect for all categories. The magnitude of this effect was less in the Asperger group for angry and sad expressions, presumably attributable to reduced recruitment of the configural mode of face processing. The individuals with Asperger syndrome outperformed the control participants in recognizing inverted sad expressions, indicating enhanced processing of local facial information representing sad emotion. These results suggest that the adults with Asperger syndrome rely on modality-specific strategies in emotion recognition from facial expression and prosodic information.

Is There a "Hidden" Effect of Treadmill Walking on Step Characteristics, in Children With Cerebral Palsy and Typically Developed Controls?

Background: To examine the immediate effect of treadmill walking, on gait variability among children with cerebral palsy (CP) and typically developed (TD) age matched controls. Methods : Eleven children with CP and sixteen TD controls participated in this study. Ages were 7 - 13 years. Step time and length variability were assessed by an electronic walkway prior to and after treadmill walking for six minutes. Results : When walking on level ground prior to the treadmill session children with CP walked with significantly increased step time and step time and length variability and significant reduced step length compared to the TD subjects. Treadmill walking reduced walking velocity, increased step time and decreased step length variability significantly among children with CP. Conclusions: Walking on a treadmill at a fixed gait velocity impact gait characteristics among children with CP, with possible advantageous effect on step length variability. doi: http://dx.doi.org/10.4021/jnr132w

The effect of variable gait modes on walking parameters among children post severe traumatic brain injury and typically developed controls

The goal of the present study was to assess the effect of various walking modes on dynamic gait characteristics and to evaluate the possible differences in the adaptation reactions between children post severe traumatic brain injury (TBI) and typically developed (TD) controls. Thirteen children post severe TBI, mean of 3.5 years post trauma, independent walkers, with a walking velocity > 1.1 m/sec, and 15 TD controls participated in this study. Ages were 7-13 years. Gait speed, step time and length and step time and length variability were assessed by an electronic walkway. The children completed three cycles on the walkway for each of the following situations: comfortable walking, walking as fast as possible, as slow as possible and walking on a straight line. Despite a similar walking performance while walking at a "regular" speed, children post severe TBI exhibit a significantly reduced range of walking speeds (73-154 cm/sec), about half, as compared to TD children (54-193 cm/sec) across the study assignments. In addition, while "walking on a straight line" children post TBI walk slower, with increased step variability as compared to their peers. Children post severe traumatic brain injury may achieve independent walking at a comparable rate to typically developed controls; however their impairments will be exacerbated as the demands increase. Since a variety of walking speeds is crucial for independent daily living at any age and for children in particular, and since adequate balance is an inherent element of walking, these issues need repeated assessments and the children should receive appropriate treatment.

Effect of concurrent cognitive tasks on gait features among children post-severe traumatic brain injury and typically-developed controls

Aim: To investigate and compare the influence of concurrent cognitive tasks on gait characteristics in children post-traumatic brain injury (TBI) and typically-developed (TD) controls.Methods: Fifteen children post-TBI (aged 9.5 ± 2.2 years) and 15 TD controls (aged 9.9 ± 1.3 years) were included in the study. The children were asked to walk under three conditions: (1) walking at a self-selected speed, (2) walking at a self-selected speed while memorizing and recalling a series of three random numbers and (3) walking at a self-selected speed while listening and identifying commonly experienced sounds. Gait parameters include walking speed, step time and length and step time and length variability as measured with the GAITRite® system.Results: Introduction of a concurrent task led to decreased walking speed and step length and increased step time and step length variability in both groups, but with a significantly prominent effect in children post-TBI. The results also showed that the effect of a concurrent cognitive task on walking depended on the complexity level of the task.Conclusion: When children were asked to perform an additional task while they were walking, this had a negative effect on their gait. One may deduce from these results that control of the rhythmic stepping mechanism at a self-selected walking speed in children is dependant to an extent on their ability to focus attention on their gait. In children post-TBI who usually have an attention deficit anyway, this ability is severely disturbed.