Excitability changes in human forearm corticospinal projections and spinal reflex pathways during rhythmic voluntary movement of the opposite limb.

Rhythmic movements brought about by the contraction of muscles on one side of the body give rise to phase-locked changes in the excitability of the homologous motor pathways of the opposite limb. Such crossed facilitation should favour patterns of bimanual coordination in which homologous muscles are engaged simultaneously, and disrupt those in which the muscles are activated in an alternating fashion. In order to examine these issues, we obtained responses to transcranial magnetic stimulation (TMS), to stimulation of the cervicomedullary junction (cervicomedullary-evoked potentials, CMEPs), to peripheral nerve stimulation (H-reflexes and f-waves), and elicited stretch reflexes in the relaxed right flexor carpi radialis (FCR) muscle during rhythmic (2 Hz) flexion and extension movements of the opposite (left) wrist. The potentials evoked by TMS in right FCR were potentiated during the phases of movement in which the left FCR was most strongly engaged. In contrast, CMEPs were unaffected by the movements of the opposite limb. These results suggest that there was systematic variation of the excitability of the motor cortex ipsilateral to the moving limb. H-reflexes and stretch reflexes recorded in right FCR were modulated in phase with the activation of left FCR. As the f-waves did not vary in corresponding fashion, it appears that the phasic modulation of the H-reflex was mediated by presynaptic inhibition of Ia afferents. The observation that both H-reflexes and f-waves were depressed markedly during movements of the opposite indicates that there may also have been postsynaptic inhibition or disfacilitation of the largest motor units. Our findings indicate that the patterned modulation of excitability in motor pathways that occurs during rhythmic movements of the opposite limb is mediated primarily by interhemispheric interactions between cortical motor areas.

Role of peripheral afference during acquisition of a complex coordination task.

It has long been supposed that the interference observed in certain patterns of coordination is mediated, at least in part, by peripheral afference from the moving limbs. We manipulated the level of afferent input, arising from movement of the opposite limb, during the acquisition of a complex coordination task. Participants learned to generate flexion and extension movements of the right wrist, of 75 degrees amplitude, that were a quarter cycle out of phase with a 1-Hz sinusoidal visual reference signal. On separate trials, the left wrist either was at rest, or was moved passively by a torque motor through 50 degrees, 75 degrees or 100 degrees, in synchrony with the reference signal. Five acquisition sessions were conducted on successive days. A retention session was conducted 1 week later. Performance was initially superior when the opposite limb was moved passively than when it was static. The amplitude and frequency of active movement were lower in the static condition than in the driven conditions and the variation in the relative phase relation across trials was greater than in the driven conditions. In addition, the variability of amplitude, frequency and the relative phase relation during each trial was greater when the opposite limb was static than when driven. Similar effects were expressed in electromyograms. The most marked and consistent differences in the accuracy and consistency of performance (defined in terms of relative phase) were between the static condition and the condition in which the left wrist was moved through 50 degrees. These outcomes were exhibited most prominently during initial exposure to the task. Increases in task performance during the acquisition period, as assessed by a number of kinematic variables, were generally well described by power functions. In addition, the recruitment of extensor carpi radialis (ECR), and the degree of co-contraction of flexor carpi radialis and ECR, decreased during acquisition. Our results indicate that, in an appropriate task context, afferent feedback from the opposite limb, even when out of phase with the focal movement, may have a positive influence upon the stability of coordination.

Neural compensation for compliant loads during rhythmic movement.

An experiment was performed to characterise the movement kinematics and the electromyogram (EMG) during rhythmic voluntary flexion and extension of the wrist against different compliant (elastic-viscous-inertial) loads. Three levels of each type of load, and an unloaded condition, were employed. The movements were paced at a frequency of 1 Hz by an auditory metronome, and visual feedback of wrist displacement in relation to a target amplitude of 100 degree was provided. Electromyographic recordings were obtained from flexor carpi radialis (FCR) and extensor carpi radialis brevis (ECR). The movement profiles generated in the ten experimental conditions were indistinguishable, indicating that the CNS was able to compensate completely for the imposed changes in the task dynamics. When the level of viscous load was elevated, this compensation took the form of an increase in the rate of initial rise of the flexor and the extensor EMG burst. In response to increases in inertial load, the flexor and extensor EMG bursts commenced and terminated earlier in the movement cycle, and tended to be of greater duration. When the movements were performed in opposition to an elastic load, both the onset and offset of EMG activity occurred later than in the unloaded condition. There was also a net reduction in extensor burst duration with increases in elastic load, and an increase in the rate of initial rise of the extensor burst. Less pronounced alterations in the rate of initial rise of the flexor EMG burst were also observed. In all instances, increases in the magnitude of the external load led to elevations in the overall level of muscle activation. These data reveal that the elements of the central command that are modified in response to the imposition of a compliant load are contingent, not only upon the magnitude, but also upon the character of the load.

Concussions in hockey: there is cause for concern.

PURPOSE: The purpose of the study was to document various aspects of concussion in Canadian Amateur hockey including demographics, causes, treatment, and prevention in order to guide future recommendations on how to reduce injury. METHODS: A detailed prospective and retrospective concussion history was obtained from British Columbia Junior Hockey League players over the course of two seasons (1998-2000). RESULTS: Higher rates of concussions occur in games versus practice, and there was an overrepresentation of forwards injured versus defensemen or goaltenders. There was between 4.63 and 5.95 concussions per 1000 player/game hours with the average age of the first hockey-related concussion in the 15th year. The greatest cause of concussion was contact with the ice and/or the boards. Fighting was not a major cause of concussion, although other illegal actions such as elbowing were. CONCLUSIONS: The primary recommendation to reduce the number and severity of concussions is to eliminate plays where there is a demonstrable intent to injure another player. Concussions in hockey are of considerable concern; however, there is now encouraging information with respect to the treatment of these injuries.

Once-a-day Concerta methylphenidate versus three-times-daily methylphenidate in laboratory and natural settings.

OBJECTIVE: Methylphenidate (MPH), the most commonly prescribed drug for attention-deficit/hyperactivity disorder (ADHD), has a short half-life, which necessitates multiple daily doses. The need for multiple doses produces problems with medication administration during school and after-school hours, and therefore with compliance. Previous long-acting stimulants and preparations have shown effects equivalent to twice-daily dosing of MPH. This study tests the efficacy and duration of action, in natural and laboratory settings, of an extended-release MPH preparation designed to last 12 hours and therefore be equivalent to 3-times-daily dosing. METHODS: Sixty-eight children with ADHD, 6 to 12 years old, participated in a within-subject, double-blind comparison of placebo, immediate-release (IR) MPH 3 times a day (tid), and Concerta, a once-daily MPH formulation. Three dosing levels of medication were used: 5 mg IR MPH tid/18 mg Concerta once a day (qd); 10 mg IR MPH tid/36 mg Concerta qd; and 15 mg IR MPH tid/54 mg Concerta qd. All children were currently medicated with MPH at enrollment, and each child's dose level was based on that child's MPH dosing before the study. The doses of Concerta were selected to be comparable to the daily doses of MPH that each child received. To achieve the ascending rate of MPH delivery determined by initial investigations to provide the necessary continuous coverage, Concerta doses were 20% higher on a daily basis than a comparable tid regimen of IR MPH. Children received each medication condition for 7 days. The investigation was conducted in the context of a background clinical behavioral intervention in both the natural environment and the laboratory setting. Parents received behavioral parent training and teachers were taught to establish a school-home daily report card (DRC). A DRC is a list of individual target behaviors that represent a child's most salient areas of impairment. Teachers set daily goals for each child's impairment targets, and parents provided rewards at home for goal attainment. Each weekday, teachers completed the DRC, and it was used as a dependent measure of individualized medication response. Teachers and parents also completed weekly standardized ratings of behavior and treatment effectiveness. To evaluate the time course of medication effects, children spent 12 hours in a laboratory setting on Saturdays and medication effects were measured using procedures and methods adapted from our summer treatment program. Measures of classroom behavior and academic productivity/accuracy were taken in a laboratory classroom setting during which children completed independent math and reading worksheets. Measures of social behavior were taken in structured, small-group board game settings and unstructured recess settings. Measures included behavior frequency counts, academic problems completed and accuracy, independent observations, teacher and counselor ratings, and individualized behavioral target goals. Reports of adverse events, sleep quality, and appetite were collected. RESULTS: On virtually all measures in all settings, both drug conditions were significantly different from placebo, and the 2 drugs were not different from each other. In children's regular school settings, both medications improved behavior as measured by teacher ratings and individualized target behaviors (the DRC); these effects were seen into the evening as measured by parent ratings. In the laboratory setting, effects of Concerta were equivalent to tid MPH and lasted at least through 12 hours after dosing. Concerta was significantly superior to tid MPH on 2 parent rating scores, and when asked, more parents preferred Concerta than preferred tid IR MPH or placebo. Side effects on children's sleep and appetite were similar for the 2 preparations. In the lab setting, both medications improved productivity and accuracy on arithmetic seatwork assignments, disruptive and on-task behavior, and classroom rule following. Both medications improved children's rule following and negative behavior in small group board games, as well as in unstructured recess settings. Individual target behaviors also showed significant improvement with medication across domains in the laboratory setting. Children's behavior across settings deteriorated across the laboratory day, and the primary effect of medication was to prevent this deterioration as the day wore on. Results support the use of background behavioral treatment in clinical trials of stimulant medication, and illustrate the utility of a measure of individualized daily target goals (ie, the DRC) as an objective measure of medication response in both the laboratory and natural school settings. CONCLUSION: This investigation clearly supports the efficacy of the Concerta long-acting formulation of MPH for parents who desire to have medication benefits for their child throughout the day and early evening. (ABSTRACT TRUNCATED)

A comparison of morning-only and morning/late afternoon Adderall to morning-only, twice-daily, and three times-daily methylphenidate in children with attention-deficit/hyperactivity disorder.

OBJECTIVE: 1) To compare standard twice-daily methylphenidate (MPH) dosing with a single morning dose of MPH and of Adderall during a typical school-day time period, and 2) to conduct a dose-response study of the effects of a late-afternoon (3:30 PM) dose of MPH and Adderall on evening behavior and side effects. DESIGN: Within-subject, placebo-controlled, crossover design. SETTING: Intensive summer treatment program with a comprehensive behavioral approach. STUDY PARTICIPANTS: Twenty-one children with attention-deficit/hyperactivity disorder (19 boys and 2 girls), between the ages of 6 and 12 years. INTERVENTIONS: Children received, in random order with daily crossovers, each of the following conditions: 1) placebo, 2) 0.3 mg/kg of MPH received 3 times, 3) 0.3 mg/kg of MPH received twice (7:30 AM and 11:30 AM) with 0.15 mg/kg received at 3:30 PM, 4) 0.3 mg/kg of MPH received once in the morning only, 5) 0.3 mg/kg of Adderall received at 7:30 AM and at 3:30 PM, 6) 0.3 mg/kg of Adderall once in the morning with 0.15 mg/kg received at 3:30 PM, 7) 0.3 mg/kg of Adderall received in the morning only. OUTCOME MEASURES: Daily rates of behaviors in social and academic settings, and standardized ratings from counselors and teachers, were assessed for the hours between 8:00 AM and 3:30 PM (a typical school-day). Relative sizes of the medication effects were compared hourly between first daily ingestion (7:30 AM) and 4:45 PM to assess the time course of the 2 drugs. Effects of the 3:30 PM doses on functioning in the evenings at home were evaluated using parent ratings of behavioral and side effects. RESULTS: A single morning dose of Adderall produced equivalent behavioral effects to those of MPH received twice-daily and behavioral effects of that single morning dose lasted throughout the school-day period. One morning dose of MPH was less effective than either 2 daily doses of MPH or 1 dose of Adderall, and seemed to wear off in the early to mid-afternoon. For some children a single morning dose of MPH maintained their behavior for an entire school day in the context of the summer treatment program. On parent ratings of evening behavior, 0.3 mg/kg of MPH at 3:30 PM was superior to 0.15 mg/kg at 3:30 PM, but there was no difference between the 2 doses of Adderall. Compared with placebo at 3:30 PM, only the 0.3 mg/kg dose of MPH caused significant improvement in parent ratings. In placebo versus Adderall comparisons, all doses, even the condition that consisted of Adderall in the morning and placebo at 3:30 PM, produced a significant change in evening behavior. CONCLUSIONS: The results show that, at least in the context of an intensive behavioral intervention, a single morning dose of Adderall had behavioral effects throughout an entire school day period that were equivalent to standard twice-daily MPH dosing. These results indicate that Adderall may be used as a long-acting stimulant for children for whom midday dosing is a problem. Further study including dose-response comparisons, effects in regular school settings, and direct comparisons with comparable doses of MPH and d-amphetamine will help to clarify the time course and relative advantages of Adderall.

The consequences of negative scaffolding for students who learn slowly--a commentary on C. Addison Stone's "The metaphor of scaffolding: its utility for the field of learning disabilities".

In this commentary, we discuss the outcomes of effective scaffolding, the processes by which successful scaffolding works, and consider implications for children with learning disabilities or below-average academic progress. Scaffolding aims at transferring responsibility for task accomplishment from a competent person to a learner. In the context of children with educational problems, we explicate our view that current practices in many schools may result in a kind of reverse-scaffolding, preventing rather than encouraging transfer of responsibility for tasks.

The effectiveness and efficiency of health promotion in specialty clinic care.

Chronic illnesses make up the majority of health problems in North America. Many chronically ill persons adjust over time to their illnesses; however, there remains a small but important group of those less adjusted, who are concentrated in specialty clinics and are high users of health care resources. This randomized clinical trial investigated the impact of health promotion interventions in the form of problem-solving counseling or phone support that augmented conventional clinic medical care. Chronically ill, poorly adjusted outpatients (n = 293) attending clinics were randomly assigned to receive additional problem-solving counseling, phone call support, or neither. Psychosocial adjustment to illness, utilization, and expenditures of health services were the main outcomes measured. There were no overall significant differences between groups in their change in psychosocial adjustment and expenditures for health and social care. However, interaction analyses (P < 0.05) gave an indication of who might benefit from these interventions. Those who lived alone and infrequently used problem-solving behaviors to cope with their illness significantly improved their adjustment to illness and had fewer health service expenditures if they received problem-solving counseling. Supportive telephone calls were most effective for those who lived with someone and frequently used problem-solving coping behaviors. These findings suggest that health promotion services should be targeted to outpatients described by specific social support and coping characteristics.

Problem-solving counselling or phone-call support for outpatients with chronic illness: effective for whom?

The purpose of this randomized controlled trial (RCT) was to determine the effectiveness of problem-solving counselling or phone-call support provided by nurses to outpatients not well adjusted to chronic illness. Subjects (N = 293) completed measures at baseline and after the six-month period of intervention for psychosocial variables including coping behaviours, purpose in life, and psychosocial adjustment to illness. Subjects receiving phone-call support from nurses demonstrated less psychological distress. Results also suggest that problem-solving counselling improves psychosocial adjustment to chronic illness for outpatients who live alone, infrequently use problem-solving coping skills, or frequently use avoidance coping methods. As well, outpatients with a low purpose in life who show infrequent use of problem-solving coping skills appear to benefit most from problem-solving counselling provided by nurses. On the other hand, those not well adjusted who frequently use problem-solving coping seem to be served more effectively by phone-call support.

Changing conceptions of cognitive behavior modification: retrospect and prospect.

A retrospective analysis of cognitive behavior modification reveals that 3 major metaphors have been offered to explain the role that cognitions play in behavior change. These metaphors include cognition as a form of conditioning, information processing, and, currently, narrative construction. The implications of using each of these metaphors are discussed.

War-related stress. Addressing the stress of war and other traumatic events.

A task force on war-related stress was convened to develop strategies for prevention and treatment of psychological, psychosocial, and psychosomatic disorders associated with the Persian Gulf War and other extreme stressors facing communities in general. The task force focused on the return home, reunion, and reintegration of service personnel with their families and work. Although the Persian Gulf War was won with relative ease, negative psychological sequelae may develop in some individuals because of the stress of war, family disruption, financial difficulty, and changes in family routines. Typical stress reactions and modes of coping that are usually unsuccessful or destructive were outlined, and suggestions were made for monitoring these. In addition, guidelines for successful coping were developed. Special attention was given to children's reactions and needs. Recommendations were made for outreach and intervention on the policy, systems (e.g., schools, businesses, governmental agencies), family, and individual levels.

Cognition and behaviour change.

For the past decade we have been attempting to understand the role of cognition in psychopathology and behaviour modification. The purpose of the present paper is to highlight and discuss what we consider to be some of the most important findings and issues that have emerged. While many other investigators are conducting related research, we have limited our review and discussion to work conducted by Meichenbaum and his colleagues. The research program and the field in general have been reviewed in more detail by Meichenbaum (1977). See an annual newsletter on cognitive-behaviour modificaiton for further detailed reviews (Meichenbaum, 1975-1979). Initially, we were interested in developing and evaluating treatment procedures that blended cognitive and behavioural components. While this work continued, we have become interested in attempting to formulate an integrative model of behaviour change (Meichenbaum, 1977). The following review and discussion will describe the research program that led us to highlight the role of cognition in behaviour change.

The work of worrying in children undergoing surgery.

This study examined the relationship involving children's level of anxiety, defensiveness, and play patterns 1 week prior to, during, and 1 week after hospitalization for minor surgery. A 7-month follow-up was also conducted in order to assess the children's recall for hospital events and coping style. The results suggested that two classes of children could be identified. The children in one group distinguished themselves in terms of their disposition to engage in the "work of worrying" (i.e., were low defensive prior to hospitalization, actively played with stress-related toys prior to hospitalization, and reported minimal distress and anxiety following surgery). Those in the second group were highly defensive, avoided playing with stress-related toys, and reported most anxiety following surgery. The parallel between children and adults patterns of dealing with surgery was considered in terms of Janis's (1978) model of coping with psychological stress.

Cognitive factors in biofeedback therapy.

The role that the client's cognitions (viz., his self-statements and images) play in each of the various phases of biofeedback training is examined. Biofeedback training is conceptualized as including three phases: initial conceptualization, skills-acquisition and -rehearsal, and transfer of treatment. Cognitive-behavior modification procedures to alter or employ the clients' cognitions at each of these phases of treatment are described. A cognitive theory of self-control is offered, postulating a three-stage mediational change process whereby: (1) the client must become an observer of his behavior and physiological responses; (2) this recognition becomes the cue to emit incompatible cognitions and behaviors; and, finally, (3) the content of the client's cognitions following change influences the generalization and persistence of treatment effects. The implications of this theory for biofeedback training are discussed.