Neuropsychological Profile in Children with Posterior Fossa Tumors with or Without Postoperative Cerebellar Mutism Syndrome (CMS)

Cerebellar mutism syndrome (CMS) is a common surgical sequela in children following posterior fossa tumor (PFT) resection. Here, we analyze the neuropsychological features associated with PFT in children, focusing particularly on the differential profiles associated with the presence or absence of CMS after surgery. We further examine the effect of post-resection treatments, tumor type, and presence/absence of hydrocephalus on surgical outcome. Thirty-six patients diagnosed with PFT (19 with and 17 without CMS) and 34 age- and gender-matched healthy controls (HCs) were recruited. A comprehensive neuropsychological evaluation was conducted in all patients postoperatively and in HCs, including an assessment of general cognitive ability, motor skills, perception, language, memory, attention, executive functions, and academic competence. CMS was found to be a clinical marker of lower neuropsychological profile scores across all cognitive domains except auditory-verbal processing and visual memory tasks. PFT patients not presenting CMS exhibited milder impairment in intellectual functioning, motor tasks, reasoning, language, verbal learning and recall, attention, cognitive executive functions, and academic competence. High-grade tumors were associated with slower processing speed and verbal delayed recall as well as alterations in selective and sustained attention. Hydrocephalus was detrimental to motor functioning and nonverbal reasoning. Patients who had undergone surgery, chemotherapy, and radiotherapy presented impaired processing speed, verbal learning, and reading. In addition to the deleterious effects of PFT, post-resection PFT treatments have a negative cognitive impact. These undesired consequences and the associated tumor-related damage can be assessed using standardized, long-term neuropsychological evaluation when planning rehabilitation.     

Memory consolidation in children with specific language impairment: Delayed gains and susceptibility to interference in implicit sequence learning

In this study, the time course of the procedural learning of a visuomotor sequence skill was followed over a 24-hour and a 1-week time period in children with and without specific language impairment (SLI). Two aspects of memory consolidation in implicit sequence learning were examined: the evolution of post-training gains in sequence knowledge (Experiment 1) and the susceptibility to interference (Experiment 2). In the first experiment, 18 children with SLI and 17 control children matched for sex, age, and nonverbal intelligence completed a serial reaction-time (SRT) task and were tested 24 hours and 1 week after practicing. The two groups of children attained an equal level of sequence knowledge in the training session, but the children with SLI lacked the consolidation gains displayed by the control children in the two post-training sessions. Working with a new group of children, 17 with SLI and 17 control peers, Experiment 2 examined resistance to interference by introducing a second sequence 15 min after the first training session. Similar results were obtained for the performance of both groups in the training session. However, although the performance of the control group improved in the post-training sessions, the performance of the SLI group deteriorated significantly during the consolidation phase due to the interfering sequence. These findings suggest that the consolidation phase of sequence learning is impaired in children with SLI.     

Dissociation in performance of children with ADHD and high-functioning autism on a task of sustained attention

Attention deficit hyperactivity disorder (ADHD) and autism are two neurodevelopmental disorders associated with prominent executive dysfunction, which may be underpinned by disruption within fronto-striatal and fronto-parietal circuits. We probed executive function in these disorders using a sustained attention task with a validated brain-behaviour basis. Twenty-three children with ADHD, 21 children with high-functioning autism (HFA) and 18 control children were tested on the Sustained Attention to Response Task (SART). In a fixed sequence version of the task, children were required to withhold their response to a predictably occurring no-go target (3) in a 1-9 digit sequence; in the random version the sequence was unpredictable. The ADHD group showed clear deficits in response inhibition and sustained attention, through higher errors of commission and omission on both SART versions. The HFA group showed no sustained attention deficits, through a normal number of omission errors on both SART versions. The HFA group showed dissociation in response inhibition performance, as indexed by commission errors. On the Fixed SART, a normal number of errors was made, however when the stimuli were randomised, the HFA group made as many commission errors as the ADHD group. Greater slow-frequency variability in response time and a slowing in mean response time by the ADHD group suggested impaired arousal processes. The ADHD group showed greater fast-frequency variability in response time, indicative of impaired top-down control, relative to the HFA and control groups. These data imply involvement of fronto-parietal attentional networks and sub-cortical arousal systems in the pathology of ADHD and prefrontal cortex dysfunction in children with HFA.     

Procedural learning is impaired in Huntington's disease: evidence from the serial reaction time task.

The purpose of the study was to test the hypothesis that Huntington's disease (HD) is associated with impairment of procedural learning. We identified 13 patients with mild to moderate HD whose manual performance was still sufficiently intact to assess learning on the serial reaction time (SRT) task. Twelve age-matched neurologically normal control subjects were studied as well. The SRT task was a four-choice reaction time task in which the stimuli followed a sequence (10 items in length) which repeated itself 10 times during each of the first four blocks of trials. During the fifth block of trials, the stimuli were random. Learning was manifested by a reduction in response latency over the first four blocks and an increase in response latency in the fifth (random) block. Learning in this task has been demonstrated in other amnesics of other etiologies. The HD patients were significantly impaired on sequence-specific learning, using the log-transformed reaction time data (P less than 0.004). In addition, in an individual-by-individual analysis, five of the HD patients and none of the control subjects failed to show sequence-specific learning, a difference in proportions that was significant (P less than 0.04). No feature of the standard cognitive or motor assessment of the HD patients was associated with efficacy of procedural learning. HD, including patients with mild disease, was associated with a deficit in procedural learning, consistent with the hypothesis that the striatum plays a critical role in supporting procedural learning.     

Effects of methylphenidate in auditory processing evaluation of children and adolescents with attention deficit hyperactivity disorder

PURPOSE: To compare the performance of a group of children and adolescents diagnosed with attention deficit hyperactivity disorder (ADHD) pre and post-methylphenidate use in a behavioral auditory processing test battery (AP). METHOD: Twenty-nine subjects, male and female, ranging from 7 to 15 years old have undergone different behavioral auditory processing tests. A control group composed of 29 subjects with and without learning disabilities was also evaluated. RESULTS: The group with ADHD had a performance similar to the control group without learning disabilities which improved after medication. The group with learning disabilities and without ADHD had the worst performance in tests while the group without learning disabilities and without ADHD exhibited the best ones. CONCLUSION: The AP battery was unable to distinguish ADHD patients from paired controls; the use of methylphenidate improved the performance on AP tests of ADHD group in the post-medication evaluation.     

Serial order short-term memory capacities and specific language impairment: No evidence for a causal association

This study re-explored the nature of verbal short-term memory (STM) deficits in children with specific language impairment (SLI), by distinguishing item and serial order STM processes. Recent studies have shown serial order STM capacity to be a critical determinant of language development, relative to item STM. In Experiment 1, 12 children with SLI, 12 age-matched children and 12 language-matched children were administered serial order recognition and reconstruction tasks. Experiment 2 assessed implicit serial learning abilities via a Hebb learning task. The SLI group showed impaired performance for the serial order reconstruction and recognition tasks, relative to language-matched and/or age-matched control groups. However, normal serial position effects were observed in all SLI children in the serial order reconstruction task, suggesting normal coding of serial position information. Similarly, performance on the Hebb serial learning task was at chronological age appropriate levels. Experiment 3 showed that the group differences observed for the serial order STM tasks in Experiment 1 disappeared when the SLI group was compared to a mental age-matched control group. Experiment 4 showed similar performance levels in the SLI group and the mental age-matched control group for a nonword recognition task assessing item STM capacities. This study shows that children with SLI have no specific impairments for serial order and item STM components but that poorer general cognitive efficiency is related to functional limitations in verbal STM tasks. The data are in line with limited information processing accounts of SLI.     

Cross-Modal Attention-Switching is Impaired in Autism Spectrum Disorders

This investigation aimed to determine if children with ASD are impaired in their ability to switch attention between different tasks, and whether performance is further impaired when required to switch across two separate modalities (visual and auditory). Eighteen children with ASD (9–13?years old) were compared with 18 typically-developing children matched with the ASD group for mental age, and also with 18 subjects with learning difficulties matched with the ASD group for mental and chronological age. Individuals alternated between two different visual tasks, and between a different visual task and an auditory task. Children with ASD performed worse than both comparison groups at both switching tasks. Moreover, children with ASD had greater difficulty when different modalities were required than where only one modality was required in the switching task in comparison with participants matched in terms of mental and chronological age.     

Neural substrates of contextual interference during motor learning support a model of active preparation

When individuals acquire new skills, initial performance is typically better and tasks are judged to be easier when the tasks are segregated and practiced by block, compared to when different tasks are randomly intermixed in practice. However, subsequent skill retention is better for a randomly practiced group, an effect known as contextual interference (CI). The present study examined the neural substrates of CI using functional magnetic resonance imaging (fMRI). Individuals learned a set of three 4-element sequences with the left hand according to a block or random practice schedule. Behavioral retest for skill retention confirmed the presence of a typical CI effect with the random group outperforming the block group. Using a go/no-go fMRI paradigm, sequence preparation during the premovement study period was separated from movement execution. Imaging data for the two groups were compared for the first 1/3 and final 1/3 of training trials. Toward the end of training, behavioral performance between the two groups was similar, although the random group would later display a performance advantage on retention testing. During study time, the random group showed greater activity in sensorimotor and premotor regions compared to the block group. These areas are associated with motor preparation, sequencing, and response selection. This pattern of recruitment is consistent with the hypothesis that CI benefits in a sequencing task are due to improved capacity to actively prepare motor responses.     

Dissociation between online and offline learning in developmental dyslexia

Most studies investigating procedural learning in developmental dyslexia (DD) have focused on the acquisition stage, ignoring later stages involved in the process of skill learning. The current study examined sequence learning among DD and control groups in two sessions. Both groups completed a sequence-learning task over a first session (online learning) and a second session 24 hours later (offline learning). While both groups showed improvements in performance during offline learning, only the control group showed improvements in performance during online learning. Moreover, the DD group differed from the control group in their ability to recover from the introduction of a different sequence.     

Declarative and nondeclarative sequence learning tasks: closed-head injured patients versus control participants

Patients who sustained closed-head injury (CHI) have been shown to have impaired memory for temporal order when measured under intentional, but not incidental, retrieval conditions. A group of 26 patients who sustained CHI and a matched control group of 26 individuals were tested on a declarative sequence learning task--"Chain Making" (CM), and a nondeclarative sequence learning task--Tower of Hanoi puzzle (TOHP). The TOHP is a problem solving task that requires planning and a strategic approach. The latter are cognitive processes known to be impaired following frontal lobe damage, as has been frequently documented in CHI patients. The goal of the present study was to test whether CHI patients' nondeclarative learning as measured by the TOHP task is preserved, as seen in amnesic patients, or impaired, as would be predicted following frontal lobe damage. Half of the participants in each group underwent active training, and the other half went through passive training of the tasks. The results demonstrate that the control group outperformed the CHI group (in most measures) in both declarative and nondeclarative sequence learning tasks. The effect of type of training differed for the two tasks: while performance of the control group on the TOHP was better under passive training (CHI patients did not improve on either one of the training modes), performance on the CM task was better under active training for both groups. The results are discussed in light of the role of the frontal lobes in memory generally, and in sequence learning particularly.     

Incidence of mutism, dysarthria and dysphagia associated with childhood posterior fossa tumour

Purpose  

Dysarthria and dysphagia are known complications following posterior fossa tumour (PFT) surgery. Outcome studies for these disorders, however, have focused on a select sub-group of children with mutism. Little is known regarding the incidence or features of these impairments in a consecutively admitted sample of children with PFT. This study describes the incidence and features of mutism, dysarthria and dysphagia during the acute post-surgical phase in a consecutive sample of children with PFT, unselected for the presence of mutism.     

Declarative and Nondeclarative Sequence Learning Tasks: Closed-Head Injured Patients Versus Control Participants

Patients who sustained closed-head injury (CHI) have been shown to have impaired memory for temporal order when measured under intentional, but not incidental, retrieval conditions. A group of 26 patients who sustained CHI and a matched control group of 26 individuals were tested on a declarative sequence learning task - Chain Making (CM), and a nondeclarative sequence learning - Tower of Hanoi puzzle (TOHP). The TOHP is a problem solving task that requires planning and a strategic approach. The latter are cognitive processes known to be impaired following frontal lobe damage, as has been frequently documented in CHI patients. The goal of the present study was to test whether CHI patients nondeclarative learning as measured by the TOHP task is preserved, as seen in amnesic patients, or impaired, as would be predicted following frontal lobe damage. Half of the participants in each group underwent active training, and the other half went through passive training of the tasks. The results demonstrate that the control group outperformed the CHI group (in most measures) in both declarative and nondeclarative sequence learning tasks. The effect of type of training differed for the two tasks: while performance of the control group on the TOHP was better under passive training (CHI patients did not improve on either one of the training modes), performance on the CM task was better under active training for both groups. The results are discussed in light of the role of the frontal lobes in memory generally, and in sequence learning particularly.     

Intact procedural motor sequence learning in developmental coordination disorder

The purpose of the present study was to explore the possibility of a procedural learning deficit among children with developmental coordination disorder (DCD). We tested 34 children aged 6–12 years with and without DCD using the serial reaction time task, in which the standard keyboard was replaced by a touch screen in order to minimize the impact of perceptuomotor coordination difficulties that characterize this disorder. The results showed that children with DCD succeed as well as control children at the procedural sequence learning task. These findings challenge the hypothesis that a procedural learning impairment underlies the difficulties of DCD children in acquiring and automatizing daily activities. We suggest that the previously reported impairment of children with DCD on the serial reaction time task is not due to a sequence learning deficit per se, but rather due to methodological factors such as the response mode used in these studies.     

Is learning by observation impaired in children with dyslexia?

Numerous studies have shown that imitating observed actions belongs to the same category of processes involved in planning and executing actions. New competencies may be acquired by actually executing a task or by executing a task after having seen how to do it. The performance of thirty dyslexic children was compared with that of an age- and gender-matched group of thirty normally reading children on tasks of learning a visuo-motor sequence by observation or by trial and error. The children observed an actor detecting a visuo-motor sequence and then performed the task reproducing either the previously observed sequence or a new one (Learning by Observation), or detected a sequence by trial and error (Learning by Doing), or first performed the task by trial and error and then performed it after an observational training (Learning by Observation after Doing). Results demonstrate that the dyslexic children were severely impaired in learning a sequence by observation, were able to detect a sequence by trial and error, and became as efficient as normal readers in reproducing an observed sequence after a task of learning by doing. Thus, the impaired ability to learn by observation could be reversed by agentive experience that supplied dyslexic children with a powerful learning mechanism, which enabled them to efficiently transfer action information across modalities. The beneficial effect of practice on the ability to learn by observation could provide dyslexic children a useful chance to acquire new cognitive abilities through more tuned teaching approach.     

Eye-movement disorders and visual-perceptual impairment in diplegia children born preterm: a clinical evaluation

The visual-motor behaviour of 15 preterm diplegic children and 50 control children (age range 4 to 7 years) was recorded on video as they performed a visual-perceptual task (an adaptation of the Animal House subtest of the Wechsler Preschool Primary Scale of Intelligence). The following parameters were analysed and scored: time to perform task; omissions; figure-colour association; sequence direction; sequential scanning order; accuracy of fitting target; and number of anticipatory saccadic movements to next target. The ability of the control children to perform the task improved significantly with age, as measured by performance time, mistakes in sequence direction and scanning order, accuracy of target fitting, and number of anticipatory saccadic movements. The scores of children with diplegia were not related to age and were poorer overall than those of the control group. Children with diplegia made significantly more mistakes of sequence direction and scanning order, and significantly fewer anticipatory saccadic movements than the control group. These results indicate that visual-perceptual impairment in diplegic children born preterm is not attributable only to sensory visual loss and to fine manipulation difficulties but is also related to difficulties in eye movements and in using anticipatory control to process information.     

Aggression bei Migräne und chronischem Rückenschmerz – eine Querschnittsstudie

Whether chronic pain is associated more with inwardly or outwardly directed aggression is a matter of discussion. In the present investigation, female patients with migraines, as well as female patients with chronic back pain, were studied with respect to their potential for aggression. The results from female inpatients with migraines (N = 40) and chronic back pain (N = 40) were compared with the results from a healthy control group (N = 40). The study was carried out with two standardized questionnaires, the Symptom Checklist (SCL-90-R) and the State-Trait Anger Expression Inventory (STAXI), as well as with a projective prospective procedure, the Rosenzweig Picture Frustration Test (PFT). Female patients with migraines, as well as those with back pain, showed significantly higher values for aggression/hostility (SCL-90-R) than the control group. Both groups of patients had significantly higher scores on the Anger-In scale (STAXI), and on the Aggression-Expression-Index (PFT) than the control group, which, however, could not be replicated on the PFT scale for intropunitiveness. The superego pattern E-E of the PFT, as a measure of outward aggression, resulted in a significant difference only between the migraine patients and control group. The results of this study suggest that female patients with migraines, as well as female patients with chronic back pain, have strong perceptions of aggression. These perceptions might be clearly directed inwardly. The unambiguousness of this statement is, however, limited by the very specific random sample and the non-validated PFT measurement.     

Short-term and serial memory in autistic,retarded, and normal children

Experimental data on memory ability of autistic children is scarce and contradictory. It is suggested that this may in part be the result of failure to control for acquisition of the correct response before memory is tested. In the first experiment reported, acquisition was controlled in a delayed-response visual discrimination task. The performance of autistic children was compared with MA matched normal and retarded controls. Recall deteriorated with increasing delay interval in each group. There were no significant group differences. The second experiment was designed to measure the effects of interference on memory using a serial memory task. No differences were found among groups in rate of learning, although the autistic children improved significantly on the second and longer series. There was no relationship between performance on the STM and the serial memory tasks over the same time intervals for any group. The results are interpreted as supporting the view that when MA and response acquisition level are equated with normal and retarded children in a memory task, autistic children do not show any specific memory deficits.     

Implicit procedural learning in fragile X and Down syndrome

Background Procedural learning refers to rule‐based motor skill learning and storage. It involves the cerebellum, striatum and motor areas of the frontal lobe network. Fragile X syndrome, which has been linked with anatomical abnormalities within the striatum, may result in implicit procedural learning deficit. Methods To address this issue, a serial reaction time (RT) task including six blocks of trials was performed by 14 individuals with fragile X syndrome, 12 individuals with Down syndrome and 12 mental age‐matched control subjects. The first (B1) and fifth (B5) blocks were random whereas the others (B2, B3, B4 and B6) consisted of a repeated 10‐step sequence. Results were analysed by Kruskal–Wallis one‐way analysis of variance and Wilcoxon signed‐rank test. Results For patients with fragile X syndrome, the RT was highly suggestive of preserved implicit learning as a significant difference was observed between blocks B5 and B6 (P = 0.009). However, the difference of RT between B4 and B5 did not reach significance, possibly due to a subgroup of individuals who did not learn. In contrast, in the Down syndrome group, RT decreased significantly between B4 and B5 (W = 2; P = 0.003) but not between the last ordered block (B6) and the last random block (B5), suggesting a weakness in procedural learning which was sensitive to the interfering random block. Conclusion implicit learning is variable in genetic syndromes and therefore relatively independent of general intellectual capacities. The results are discussed together with previous reports.     

Deficit in implicit motor sequence learning among children and adolescents with spastic Cerebral Palsy

Skill learning (SL) is learning as a result of repeated exposure and practice, which encompasses independent explicit (response to instructions) and implicit (response to hidden regularities) processes. Little is known about the effects of developmental disorders, such as Cerebral Palsy (CP), on the ability to acquire new skills. We compared performance of CP and typically developing (TD) children and adolescents in completing the serial reaction time (SRT) task, which is a motor sequence learning task, and examined the impact of various factors on this performance as indicative of the ability to acquire motor skills. While both groups improved in performance, participants with CP were significantly slower than TD controls and did not learn the implicit sequence. Our results indicate that SL in children and adolescents with CP is qualitatively and quantitatively different than that of their peers. Understanding the unique aspects of SL in children and adolescents with CP might help plan appropriate and efficient interventions.     

Implicit motor learning deficits in dyslexic adults

Children with developmental dyslexia fail to develop age-appropriate reading skills despite adequate intelligence and education. It has been suggested that dyslexics' various literacy, sensory and motor difficulties may be related to impaired cerebellar function. As the cerebellum is involved in motor learning, we measured serial reaction time performance in 40 adults (21 controls, 19 dyslexics). Dyslexic subjects performed comparably to controls during the randomly-ordered reaction time blocks, indicating that the dyslexics were as able as controls to make appropriate stimulus-response associations. However, the dyslexics failed to show the reaction time reduction that the control group showed during the repeated sequences (p = 0.018) and there was a significant group by condition effect when comparing the last two blocks of the sequence condition with the first two blocks of the final random condition (p = 0.008). Furthermore, there was a significant difference between good and poor readers on the degree of learning during the task (p = 0.015). This suggests that some dyslexics may suffer from an implicit motor learning deficit, which could generalize to non-motor learning.