Diminished motor imagery capability in adults with motor impairment: An fMRI mental rotation study.

Recent research has demonstrated that adults with probable Developmental Coordination Disorder (pDCD) show similar behavioural deficits as those observed in children DCD when performing a motor imagery task. The aim of this study was to investigate whether the pattern of neural activation in adults with pDCD during motor imagery differed from adults without motor skill impairment. Twelve adults with pDCD (5 male; age M=24.5 yrs) and 11 adults without pDCD (6 male; age M=26.7 yrs) participated. The hand rotation task was used to assess motor imagery ability, while functional neural images were acquired using a 3T MR scanner. Performance on the hand task in both groups conformed to the biomechanical constraints of real movement, supporting the use of motor imagery to complete the task. Comparisons of response time and accuracy data showed no significant group differences. Comparison of the BOLD signal activation maps identified a significant parametric difference between groups. The% BOLD signal change for increasing angle of rotation showed greater activation in controls compared to the pDCD group in the occipito-parietal and parieto-frontal networks including the middle frontal gyrus bilaterally, the left superior parietal lobe as well as in the cerebellum (lobule VI). The pattern of reduced activation in adults with pDCD is consistent with recent studies of childhood DCD that suggest atypical activation in frontal, parietal and cerebellar areas, and supports the theory that this type of impairment may be associated with disruption of parieto-frontal and parieto-cerebellar networks.

Revealing hot executive function in children with motor coordination problems: What's the go?

Recent research suggests that children with Developmental Coordination Disorder (DCD) often show deficits in executive functioning (EF) and, more specifically, the ability to use inhibitory control in 'hot', emotionally rewarding contexts. This study optimized the assessment of sensitivity of children with DCD to emotionally significant stimuli by using easily discriminable emotional expressions in a go/no-go task. Thirty-six children (12 with DCD), aged 7-12years, completed an emotional go/no-go task in which neutral facial expressions were paired with either happy or sad ones. Each expression was used as both, a go and no-go target in different runs of the task. There were no group differences in omission errors; however, the DCD group made significantly more commission errors to happy no-go faces. The particular pattern of performance in DCD confirms earlier reports of (hot) EF deficits. Specifically, a problem of inhibitory control appears to underlie the atypical pattern of performance seen in DCD on both cold and hot EF tasks. Disrupted coupling between cognitive control and emotion processing networks, such as fronto-parietal and fronto-striatal networks, may contribute to reduced inhibitory control in DCD. The implications for a broader theoretical account of DCD are discussed, as are implications for intervention.

The influence of task paradigm on motor imagery ability in children with Developmental Coordination Disorder.

Children with Developmental Coordination Disorder (DCD) have difficulty imagining movements such that they conform to the customary temporal constraints of real performance. We examined whether this ability is influenced by the choice of task used to elicit motor imagery (MI). Performance of typically developing (TD) (n=30) and children with DCD (n=30) was compared on two tasks: the Visually Guided Pointing Task (VGPT) and the Computerized Virtual Radial Fitts Task (C-VRFT). Since the VGPT places higher demands on executive functions like working memory but requires less spatial planning, we reasoned that the C-VRFT would provide a purer measure of motor imagery (or simulation). Based on our earlier work, we predicted that imagery deficits in DCD would more likely manifest on the C-VRFT. Results showed high correlations between tasks in terms of executed and imagined movement time suggest that both tasks measure MI ability. However, group differences were more pronounced in the imagined condition of the radial Fitts' task. Taken together, the more spatially complex C-VRFT appears to be a more sensitive measure of motor imagery, better discriminating between DCD and TD. Implications for theory and practice are discussed.

Deficits of hot executive function in developmental coordination disorder: sensitivity to positive social cues.

Recent research shows that children with motor coordination problems (or developmental coordination disorder - DCD) show deficits in not only cool executive function (EF), but also hot EF. We aimed to determine whether this deficit of hot EF is due to heightened sensitivity to rewarding stimuli, specifically, or to a general deficit of cognitive control, like inhibition. Using two versions of a go/no-go task, one with neutral facial expressions and the other with happy and fearful faces, we compared 12 children with DCD with 28 typically-developing children, aged 7-12 years. Like earlier studies, children responded faster to happy faces. Both groups showed comparable accuracy in response to go targets, and also had similar commission errors, except when the no-go stimulus was a happy face. Importantly, the DCD group made significantly more commission errors to happy faces failing to suppress their response on more than half of the no-go trials. These results suggest a heightened sensitivity to emotionally significant distractors in DCD; this type of impulsivity may undermine self-regulation in DCD, with possible implications for adaptive function and emotional well-being. We argue that the interaction of cognitive control and emotion processing networks may be disrupted in DCD or delayed in development.

Motor, visual and egocentric transformations in children with Developmental Coordination Disorder.

AIM: This study aimed to test the internal modelling deficit (IMD) hypothesis using the mental rotation paradigm. BACKGROUND: According to the IMD hypothesis, children with Developmental Coordination Disorder (DCD) have an impaired ability to internally represent action. Thirty-six children (18 DCD) completed four tasks: two versions of a single-hand rotation task (with and without explicit imagery instructions), a whole-body imagery task and an alphanumeric rotation task. RESULTS: There was partial support for the hypothesis that children with DCD would display an atypical pattern of performance on the hand rotation task, requiring implicit use of motor imagery. Overall, there were no significant differences between the DCD and control groups when the hand task was completed without explicit instructions, on either response time or accuracy. However, when imagery instructions were introduced, the controls were significantly more accurate than the DCD group, indicating that children with DCD were unable to benefit from explicit cuing. As predicted, the controls were also significantly more accurate than the DCD group on the whole-body task, with the accuracy of the DCD group barely rising above chance. Finally, and as expected, there was no difference between the groups on the alphanumeric task, a measure of visual (or object-related) imagery. CONCLUSIONS: The inability of the DCD group to utilize specific motor imagery instructions and to perform egocentric transformations lends some support to the IMD hypothesis. Future work needs to address the question of whether the IMD itself is subgroup-specific.

Conscious sedation training received by specialist registrars in restorative dentistry in the UK: a survey.

OBJECTIVE: To investigate conscious sedation training received by Specialist Registrars in Restorative Dentistry (SpRs) during their training programme. DESIGN: Postal questionnaire survey in the UK. Setting SpRs and recently certificated Consultants in Restorative Dentistry (CRDs). METHOD: A questionnaire was sent to 81 current SpRs in Restorative Dentistry and CRDs who had been awarded a Certificate of Completion of Specialist Training within the previous three years. One follow-up letter was sent to non-responders. RESULTS: The completed questionnaire was returned by 67 (83%) SpRs and CRDs. Analysis revealed that 44 (69%) respondents had received conscious sedation training during their specialist training programme and that 50 (78%) respondents carried out restorative dental treatment under sedation during their programme. Thirteen (20%) respondents had not received conscious sedation training in their programmes but eight (13%) SpRs indicated that sedation training was planned. Training experiences differed throughout the UK: 29 (66%) respondents gained experience in inhalational and single agent intravenous sedation techniques under the supervision of an experienced colleague. Fourteen (32%) respondents who performed sedation had not been on a resuscitation course in the previous year. These included nine (21%) current SpRs. Sixteen (53%) current SpRs intended to offer restorative dental treatment under sedation after specialist training. Fifty-nine (92%) respondents thought that all SpRs in Restorative Dentistry should receive sedation training and 42 (71%) thought that a structured core course would be the most appropriate format. CONCLUSIONS: Although the majority of SpRs and recently certificated CRDs considered that all SpRs should receive training in conscious sedation via a core course during the restorative dentistry training programme, a small number had not received or planned to undertake such training. Conscious sedation training experiences differed throughout the UK and SpRs treated a wide range of deserving patient categories under sedation. It is encouraging that many SpRs hope to continue employing sedation techniques after their restorative dentistry training has finished. The results of this survey should inform all those involved with restorative dentistry training programmes.

Multiple idiopathic external apical root resorption: report of four cases.

Multiple idiopathic external root resorption is an unusual condition that may present in a cervical or an apical form. In this article, we review the published literature relating to multiple idiopathic external apical root resorption and present four clinical cases. We consider the aetiology of this condition and discuss the various treatment options.

Internal representation of movement in children with developmental coordination disorder: a mental rotation task.

Recent studies show that children with developmental coordination disorder (DCD) have difficulties in generating an accurate visuospatial representation of an intended action, which are shown by deficits in motor imagery. This study sought to test this hypothesis further using a mental rotation paradigm. It was predicted that children with DCD would not conform to the typical pattern of responding when required to imagine movement of their limbs. Participants included 16 children with DCD and 18 control children; mean age for the DCD group was 10 years 4 months, and for controls 10 years. The task required children to judge the handedness of single-hand images that were presented at angles between 0 degrees and 180 degrees at 45 degrees intervals in either direction. Results were broadly consistent with the hypothesis above. Responses of the control children conformed to the typical pattern of mental rotation: a moderate trade-off between response time and angle of rotation. The response pattern for the DCD group was less typical, with a small trade-off function. Response accuracy did not differ between groups. It was suggested that children with DCD, unlike controls, do not automatically enlist motor imagery when performing mental rotation, but rely on an alternative object-based strategy that preserves speed and accuracy. This occurs because these children manifest a reduced ability to make imagined transformations from an egocentric or first-person perspective.

Recording the retruded contact position: a review of clinical techniques.

The retruded contact position (RCP) is an important maxillomandibular relation in restorative dentistry. This review will describe RCP and consider its importance and use in the restorative dental treatment of the dentate and edentulous subject. A comparative account of the various mandibular guidance methods used to obtain a RCP record will be presented, followed by recommendations for fixed and removable clinical prosthodontic practice.

Genotypic and phenotypic studies of murine intestinal lactobacilli: species differences in mice with and without colitis.

Lactobacilli represent components of the commensal mammalian gastrointestinal microbiota and are useful as probiotics, functional foods, and dairy products. This study includes systematic polyphasic analyses of murine intestinal Lactobacillus isolates and correlation of taxonomic findings with data from cytokine production assays. Lactobacilli were recovered from mice with microbiota-dependent colitis (interleukin-10 [IL-10]-deficient C57BL/6 mice) and from mice without colitis (Swiss Webster and inducible nitric oxide synthetase-deficient C57BL/6 mice). Polyphasic analyses were performed to elucidate taxonomic relationships among 88 reference and murine gastrointestinal lactobacilli. Genotypic tests included single-locus analyses (16S ribosomal DNA sequencing and 16S-23S rRNA intergenic spacer region PCR) and genomic DNA profiling (repetitive DNA element-based PCR), and phenotypic analyses encompassed more than 50 tests for carbohydrate utilization, enzyme production, and antimicrobial resistance. From 20 mice without colitis, six Lactobacillus species were recovered; the majority of the mice were colonized with L. reuteri or L. murinus (72% of isolates). In contrast, only, L. johnsonii was isolated from 14 IL-10-deficient mice. Using an in vitro assay, we screened murine isolates for their ability to inhibit tumor necrosis factor alpha (TNF-alpha) secretion by lipopolysaccharide-activated macrophages. Interestingly, a subpopulation of lactobacilli recovered from mice without colitis displayed TNF-alpha inhibitory properties, whereas none of the L. johnsonii isolates from IL-10-deficient mice exhibited this effect. We propose that differences among intestinal Lactobacillus populations in mammals, combined with host genetic susceptibilities, may account partly for variations in host mucosal responses.

Fine motor deficiencies in children with developmental coordination disorder and learning disabilities: an underlying open-loop control deficit.

Thirty-two children with Developmental Coordination Disorder (DCD) and learning disabilities (LD) and their age-matched controls attending normal primary schools were investigated using kinematic movement analysis of fine-motor performance. Three hypotheses about the nature of the motor deficits observed in children with LD were tested: general slowness hypothesis, limited information capacity hypothesis, and the motor control mode hypothesis. Measures of drawing movements were analyzed under different task conditions using a Fitts' paradigm. In a reciprocal aiming task, the children drew straight-line segments between two targets 2.5 cm apart. Three Target Sizes were used (0.22, 0.44, and 0.88 cm). Children used an electronic pen that left no trace on the writing tablet. To manipulate the degree of open-loop movement control, the aiming task was performed under two different control regimes: discrete aiming and cyclic aiming. The kinematic analysis of the writing movements of the 32 children with DCD/LD that took part in the experimental study confirmed that besides learning disabilities they have a motor learning problem as well. Overall, the two groups did not differ in response time, nor did they respond differently according to Fitts' Law. Both groups displayed a conventional trade-off between Target Size and average Movement Time. However, while movement errors for children with DCD/LD were minimal on the discrete task, they made significantly more errors on the cyclic task. This, together with faster endpoint velocities, suggests a reduced ability to use a control strategy that emphasizes the terminal control of accuracy. Taken together, the results suggest that children with DCD/LD rely more on feedback during movement execution and have difficulty switching to a feedforward or open-loop strategy.

The trouble with teething--misdiagnosis and misuse of a topical medicament.

For many clinicians and parents "teething" remains a convenient diagnosis to explain all manner of local and systemic upset in the young child. Many therapies are on the market to help alleviate the symptoms of primary tooth eruption. In this article we highlight the problems of "teething" as a diagnosis by presenting a case where an initial misdiagnosis of teething compromised a patient's life. The same patient then suffered from topical analgesic misuse during the recovery period.

Abnormalities of motor and praxis imagery in children with DCD.

In an earlier study using the visually guided pointing task (VGPT) the authors showed that the timing of imagined movement sequences in children with developmental coordination disorder (DCD) does not conform to the conventional speed-for-accuracy trade-off (or Fitts' law [P.M. Fitts, Journal of Experimental Psychology 47 (1954) 381-391]) that occurs when the distance and accuracy requirements of movements are varied [P. Maruff, P.H. Wilson, M. Trebilcock, J. Currie, Neuropsychologia 37 (1999b) 1317-1324]. The present study sought to replicate this earlier finding and to examine (using a weight manipulation) whether this deficit was also attributable to inaccurate programming of relative force. The chronometry of real and imagined movements was investigated in a group of 20 children with DCD aged between 8 and 12 years and a group of controls matched on age and verbal IQ (VIQ). Movement duration was tested for real and imagined movements using the preferred hand, with the VGPT performed under two load conditions: with and without the addition of a weight attached to a pen. Group means of each subjects' mean movement duration were calculated and plotted against target width for each of the four conditions [Movement type (2) x Load (2)] and a logarithmic curve was fitted to the data points. In the control group, the speed-for-accuracy trade-off for both real and imagined performance conformed to Fitts' law under each load condition. In the DCD group only real movements conformed to Fitts' law. Moreover, the effect of load differed between groups--for real movements, movement duration did not differ between load and no-load conditions for either group, while for imagined movements, movement duration increased under the load condition for the control group only. These results replicate and extend the results of our earlier study. This pattern of performance suggests that children with DCD have an impairment in the ability to generate internal representations of volitional movements which may reflect an impaired ability to process efference copy signals. The ability to programme both relative force and timing appears to underly this difficulty. Results have implications for the use of (guided) motor imagery training in order to facilitate the development of motor skill in children with DCD.

The ability to execute saccades on the basis of efference copy: impairments in double-step saccade performance in children with developmental co-ordination disorder.

The double-step saccade task (DSST) was used to test the hypothesis that children with developmental co-ordination disorder (DCD) who experience deficits in motor imagery have difficulty processing the visual spatial consequences of intended movements using efference copy signals. In order to ensure that the second saccade in the DSST was executed in the absence of visual cues and had to be programmed on the basis of extra-retinal information (efference copy), we analysed only those double-step ensembles where latency plus duration of first saccades was greater than 240 ms (total presentation time of the targets). No significant differences between DCD and control children were evident on measures of latency of first saccades, intersaccadic interval and first saccade error. As predicted, children with DCD who have impaired motor imagery demonstrated specific deficits on the DSST where efference copy had been used to program the saccade sequence. More specifically, these children were less accurate in terms of final eye position on second saccades. Our results raise the possibility that abnormalities in the processing of efference copy signals could underlie motor clumsiness in the majority of children with DCD. Furthermore, the origin of this deficit in efference copy probably exists at the level of the parietal lobe.

Development of the psychological impact of tinnitus interview: a clinician-administered measure of tinnitus-related distress.

The development of valid and reliable methods for assessing psychological aspects of tinnitus continues to be an important goal of research. Such assessment methods are potentially useful in clinical and research contexts. Existing self-report measures have a number of disadvantages, and so a need exists to develop a form of assessment that is less open to response bias and the effects of experimental demand. A new approach, the Psychological Impact of Tinnitus Interview (PITI), is described, and some preliminary data on its psychometric properties are reported. The results suggest that the PITI is capable of providing a measure of separate, relatively independent dimensions of tinnitus-related distress--namely, sleep difficulties, general distress, mood, suicidal aspects, and avoidance of or interference with normal activities. This method may lead to more refined measures of these dimensions of tinnitus-related psychological difficulties. The PITI should be regarded as a promising assessment tool for use in experimental settings, pending further work on its content, coding method, and administration.

Bannayan-Riley-Ruvalcaba syndrome: report of a family.

Bannayan-Riley-Ruvalcaba (BRR) syndrome is a rare inherited condition. We describe the protean orofacial manifestations of this syndrome in one family and consider their management. The dental surgeon should be aware of this entity, its orofacial connotations and the possible association with Cowden's syndrome.

Asymmetries between dominant and non-dominant hands in real and imagined motor task performance.

Motor imagery is a dynamic state in which an individual mentally simulates the performance of a specific motor action or motor task. Recent behavioural and neuroimaging evidence suggests that the same neurocognitive networks control real and imagined movements. This hypothesis was tested by investigating whether motor asymmetries related to cerebral dominance also occurred for imagined movements. Fifty subjects performed the visually guided pointing task of Sirigu et al. [Sirigu, A., Duhamel, J., Cohen, L., Pillon, B., Dubois, B. and Agid, Y., The mental representation of hand movements after parietal cortex damage. Science, 1996, 273, 1564-1567.] using their dominant and non-dominant hands. Analysis of group data indicated that both real and imagined movement conformed to Fitts' law. Analysis of individual data indicated that asymmetries arising from motor dominance in real movements also occurred for imagined movements. However, the relative slowing and error associated with the non-dominant hand was greater for imagined movements than for real movements. These asymmetries support the hypothesis that real and imagined movements are represented within the same neurocognitive networks but suggest that asymmetries in performance related to handedness are greater for imagined movements. In addition, while the visually guided pointing task provides a useful test of the ability to make imagined movements, asymmetries in the speed and reliability of imagined performance are significantly greater than those for real performance.

A critical analysis of directive counselling as a component of tinnitus retraining therapy.

Tinnitus retraining therapy (TRT) has been presented as a new approach to tinnitus management. In this paper a number of theoretical and practical problems with TRT are identified. These problems relate to the distinction between directive counselling and cognitive therapy, the adequacy of the cognitive therapy components, the nature of the outcome data which have been presented to date, the theoretical basis for the treatment, and the conceptual clarity of terms such as perception, attention and coping. The stated goal of removal of the perception of tinnitus may lead to confusion about the likely outcome of TRT for most patients. Methodological limitations in the research which has been published to date preclude any claims about the efficacy of TRT at the present time. It is suggested that randomized, controlled studies which include no-treatment and placebo conditions need to be undertaken. Studies are required in which the efficacy of the counselling and white noise components can be clearly isolated. Suggestions are made about the role of psychologists and non-psychologists in the provision of counselling and cognitive therapy services to tinnitus patients.