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At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Electrically induced recovery of gait components for older patients with chronic stroke.

OBJECTIVE: To compare the gains for chronic stroke patients in volitional gait pattern attained from treatment with functional neuromuscular stimulation (FNS) and intramuscular electrodes (IM) with gains attained using conventional therapy, including treatment with FNS using surface electrodes (surface-stim). DESIGN: This single-subject research design consisted of a series of two subjects. Three months of conventional therapy and surface-stim were followed by treatment using the FNS-IM system. Two stroke patients had cerebrovascular accident 1 or 4 yr before the study and ambulated with a cane. Interventions consisted of 3 months of conventional exercise and gait training including surface-stim, followed by 7-14 months of treatment with the FNS-IM system. Treatments occurred up to 3 times/wk for 1-hr sessions and a home program. Outcome measures consisted of six kinematic gait components, as measured by a six-camera video-based data-acquisition system. Coordination of isolated joint movement was measured according to the Fugl-Meyer scale. RESULTS: Both subjects improved during conventional therapy to some degree. During FNS-IM treatment, gains were made beyond those attained during conventional therapy. Statistically significant differences were found between conventional and FNS-IM therapy. CONCLUSIONS: For these two subjects, gains in volitional control of gait were made during conventional treatment (including surface-stim); for these two subjects during FNS-IM treatment, additional gains were made in volitional gait pattern, beyond those attained during conventional therapy.

Aged↗
PubMed1976

Daydream styles and sleep disturbance.

This study investigates the relationship between individuals' styles of day-dreaming and the occurrence of two types of sleep disturbance: insomnia and nightmares. Ninety-nine college undergraduates responded to a questionnaire consisting of subscales from the Singer-Antrobus Imaginal Processes Inventory and scales measuring extent of sleep disturbance; measures of response bias and samples of volitional waking fantasy were also obtained. Correlational and factor analytic treatment of the data indicated significant direct relationships between reports of sleep disturbance and the Guilty-Dysphoric and Anxious-Distractible daydream styles; sleep disturbance was unrelated to the Positive-Vivid daydream style. A response bias interpretation appeared insufficient to explain the findings. Aspects of the daydream styles also were found in the samples of volitional waking fantasy. Broader fantasy styles emerged which extend the daydream styles into the areas of volitional fantasy, sleep disturbance, dream recall, and mood.

Adult↗
PubMedDate not supplied

Impact of gestational age on preterm motor development at 4 months chronological and adjusted ages.

A cohort of 62 low-risk preterm infants was identified and followed prospectively through the first 4 months of life to assess whether motor development is determined by biological maturity or the duration of the extrauterine experience. After identification, the cohort was subdivided into two groups according to gestational age at birth: less than 32 weeks gestation (n = 23) and greater than or equal to 32 weeks gestation (n = 39). Neuromotor assessments were performed on every infant at both 4 months chronological and 4 months adjusted ages. Analyses revealed that (1) the two groups of infants differed significantly at 4 months chronological age in terms of tone, primitive reflexes and volitional movement, but not in automatic reactions, and (2) the two groups of infants differed significantly at 4 months adjusted age in terms of primitive reflexes, but not in tone, automatic reactions or volitional movement. These findings suggest that the development of volitional movement and tone appear to evolve according to biological maturity alone. In contrast, primitive reflexes and automatic reactions in the preterm infant may be influenced by both biological maturation and environmental experience.

Child Development↗
PubMed1983

Sequential and non-speech praxic abilities in developmental verbal apraxia.

Verbal and non-verbal sequential abilities were compared in a group of 10 children with developmental verbal apraxia. Manual gestures, constructional praxic abilities and non-speech volitional oral movements were also studied. Results indicated that these children were deficient in verbal sequential abilities, both with reference to their non-verbal sequential abilities and to normative data. As a group, the children did not present manual-gestural or constructional apraxias, nor oral apraxias for single non-speech volitional movements. However, most had difficulty with sequences of non-speech volitional oral movements.

Adolescent↗
PubMed1990

Putative cerebral cortical involvement in the ventilatory response to inhaled CO2 in conscious man.

1. The response of the diaphragm to both transcranial magnetic stimulation and electrical phrenic nerve stimulation was studied in thirteen normal subjects under conditions of either a 'reflex' drive to ventilation with inhaled CO2 or during volitional ventilation of similar magnitude. 2. The induced compound action potential in the diaphragm was recorded using an oesophageal electrode, and in some cases transdiaphragmatic pressure was recorded using oesophageal and gastric balloon catheters. 3. The response of the diaphragm to transcranial magnetic stimulation was invariably facilitated with volitional inspiration; there was either minimal or no response at functional residual capacity. 4. Facilitation with inspiration was also seen during a 'reflex' drive to ventilation with inhaled CO2 in the presumed absence of any volitional contribution to ventilation. A similar degree of facilitation was seen with voluntary ventilation of similar magnitude and pattern. 5. If the facilitation is predominantly a cortical phenomenon, then these results imply that there is a behavioural component in the previously supposed purely 'reflex' drive to ventilation with inhaled CO2. We also discuss the interpretation of these results if some of the facilitation occurs at the phrenic motoneurone.

Action Potentials↗
PubMed1996

Palatal and pharyngeal reflexes in health and in motor neuron disease.

Palatal and pharyngeal sensation and motor responses, and volitional palatal movement, were tested in 171 healthy adults and 43 patients with motor neuron disease. In healthy adults palatal and pharyngeal sensation and volitional palatal elevation were present in all; the palatal and pharyngeal motor responses could not be elicited on first testing in two (1.1%) and seven (4.1%) subjects respectively. Pharyngeal motor responses were more easily elicited in older subjects and palatal responses were more easily elicited in women. Eye watering and retching were the most common accompanying features. In 57 normal subjects tested on five occasions there was considerable variation in the stimulus required to elicit the motor responses within subjects: in none of four subjects (7%) who initially had absent responses were they always absent. Pharyngeal motor responses were more easily elicited in patients with motor neuron disease than in matched normal subjects; within the motor neuron disease group pharyngeal motor responses elicited by tongue depression were associated with the symptom of food or drink "going down the wrong way" > 1/month and a reduction in average volume per swallow (ml) and swallowing capacity (ml/s). Volitional palatal elevation was absent in five patients (11.6%). In six of eight patients with motor neuron disease studied repeatedly (on between two and seven occasions) the palatal and pharyngeal responses were elicited with the same stimulus on each occasion. In healthy adults palatal and pharyngeal sensation and motor responses should be present although considerable variation occurs in the stimulus required. In patients with motor neuron disease features of impaired swallowing are associated with a brisk rather than a depressed pharyngeal response.

Adolescent↗
PubMed1998

Assessment of respiratory muscle function and strength.

Measurement of respiratory muscle strength is useful in order to detect respiratory muscle weakness and to quantify its severity. In patients with severe respiratory muscle weakness, vital capacity is reduced but is a non-specific and relatively insensitive measure. Conventionally, inspiratory and expiratory muscle strength has been assessed by maximal inspiratory and expiratory mouth pressures sustained for 1 s (PImax and PEmax) during maximal static manoeuvre against a closed shutter. However, PImax and PEmax are volitional tests, and are poorly reproducible with an average coefficient of variation of 25%. The sniff manoeuvre is natural and probably easier to perform. Sniff pressure, and sniff transdiaphragmatic pressure are more reproducible and useful measure of diaphragmatic strength. Nevertheless, the sniff manoeuvre is also volition-dependent, and submaximal efforts are most likely to occur in patients who are ill or breathless. Non-volitional tests include measurements of twitch oesophageal, gastric and transdiaphragmatic pressure during bilateral electrical and magnetic phrenic nerve stimulation. Electrical phrenic nerve stimulation is technically difficult and is also uncomfortable and painful. Magnetic phrenic nerve stimulation is less painful and transdiaphragmatic pressure is reproducible in normal subjects. It is a relatively easy test that has the potential to become a widely adopted method for the assessment of diaphragm strength. The development of a technique to measure diaphragmatic sound (phonomyogram) during magnetic phrenic nerve stimulation opens the way for noninvasive assessment of diaphragmatic function.

Electric Stimulation↗
PubMed2006

Active head movements facilitate compensation for effects of prism displacement on dynamic gait.

STUDY DESIGN: Four groups, between-subjects study. OBJECTIVES: To investigate the effects of exercise on adaptation of normal subjects who had been artificially spatially disoriented. BACKGROUND: Many patients referred for rehabilitation experience sensory changes, due to age or disease processes, and these changes affect motor skill. The best way to train patients to adapt to these changes and to improve their sensorimotor skills is unclear. Using normal subjects, we tested the hypothesis that active, planned head movement is needed to adapt to modified visual input. METHODS AND MEASURES: Eighty male and female subjects who had normal balance on computerized dynamic posturography (CDP) and the dynamic gait index (DGI), were randomly assigned to four groups. All groups donned diagonally shift lenses and were again assessed with CDP and DGI. The four groups were then treated for 20 min. Group 1 (control group) viewed a video, Group 2 performed exercise that involved translating the entire body through space, but without separate, volitional head movement, Group 3 performed exercises which all incorporated volitional, planned head rotations, and Group 4 performed exercises that involved translating the body (as in Group 2) and incorporated volitional, planned head motion (as in Group 3). All subjects were post-tested with CDP and DGI, lenses were removed, and subjects were retested again with CDP and DGI. RESULTS: The groups did not differ significantly on CDP scores but Groups 3 and 4 had significantly better DGI scores than Groups 1 and 2. CONCLUSIONS: Active head movement that is specifically planned as part of the exercise is more effective than passive attention or head movements that are not consciously planned, for adapting to sensorimotor change when it incorporates active use of the changed sensory modality, in this case head motion.

Adaptation, Physiological↗
PubMed1990

Reflex responses to ankle perturbations during electrical stimulation of muscle: 1. Measurement techniques and preliminary examples.

Electrical stimulation of muscle has been proposed as a technique to restore function to paralyzed muscles. But, from a control stand-point, little is known about how such artificial activation interacts with the still intact spinal reflex loops. We have developed instrumentation to measure and compare ankle compliance and muscle EMG activity when the ankle is subjected to perturbations in torque or angular position from bias positions that are achieved volitionally or via electrical muscle stimulation. We deliver precise torque or position perturbations (step, ramp, sinusoidal, random) to the ankle via a pivoting footplate driven by a computer-controlled torque motor. Angular displacement, torque, acceleration, and 2 to 4 channels of electromyographic (EMG) data are collected on analog (VHS) tape and simultaneously digitized and stored. Torque or position biases to normal ankle equilibrium position are applied volitionally (for the neurologically intact) or via electrical stimulation of the Gastroc/Soleus or the Tibialis Anterior muscle (for either the neurologically intact or spinal cord injured). A special stimulator/recording amplifier permits the recording of EMG signals from the muscle being stimulated. An overview of the features and response characteristics of the perturbation system and a comparison from preliminary studies of responses at different biases achieved volitionally versus those achieved by stimulation are presented.

Ankle Joint↗
PubMed1995

Felonious sex crime: the possibility of unilateral cerebral irradiation for the offenders.

Some felonious sex crimes might result from compulsions that the perpetrator finds impossible to control. Under judicial systems derived from British law, the court should be extraordinarily careful in mandating any medical procedure. However, if a rapist or child molester voluntarily asks a physician for help, then medical ethics might allow destruction of part of the patient's brain for the purpose of controlling compulsive behaviour. The part of the human brain primarily associated with volition might be near the anterior cingulate sulcus. Could unilateral irradiation of an area near the anterior cingulate sulcus partially destroy the patient's volition? By leaving intact the patient's will based on language and by partially destroying the patient's will based on intuition, could the physician diminish the patient's will to commit felonious sex crimes? Would some patients reject chemical castration but accept unilateral irradiation of an area near the anterior cingulate sulcus?

Adult↗
PubMed2005

Poor antisaccade performance in schizophrenia: an inhibition deficit?

The antisaccade task appears to be particularly suitable for analyzing processes involved in executive control of action. Schizophrenic patients show enhanced rates of erroneous reflexive saccades in this task. This is commonly interpreted as a failure of inhibitory mechanisms. The role of volitional saccade generation is largely neglected in these accounts. In this study, experimental variations of the antisaccade task were applied to manipulate the contribution of volitional processes on antisaccade performance. Fifteen patients with a diagnosis of schizophrenia and 15 healthy control participants performed antisaccade tasks requiring them to look to the mirror location of a peripheral visual stimulus at the onset of this stimulus (standard antisaccade task) or after a brief delay (delayed antisaccade task). As expected, schizophrenic patients showed more reflexive saccade errors than controls. In the delay conditions, reflexive errors decreased, and this effect was significantly stronger in schizophrenic patients. Latencies of correct antisaccades tended to be longer in patients than in control participants. The results suggest that the generation of voluntary saccades is at least in part responsible for the antisaccade deficit in schizophrenic patients. More comprehensive models to account for executive deficits in the antisaccade task must be considered.

Adult↗
PubMed2004

Quadriceps femoris muscle weakness and activation failure in patients with symptomatic knee osteoarthritis.

PURPOSE: Quadriceps weakness is common in patients with knee osteoarthritis (OA), and has been attributed to failure of voluntary activation. Methodological differences may have contributed to previous reports of extensive failure of voluntary activation in patients with osteoarthritis. The purpose of this study was to determine the extent of quadriceps muscle weakness and activation failure in middle aged patients with symptomatic medial knee osteoarthritis using maximum voluntary isometric contractions (MVIC) and a burst superimposition technique. METHODS: Measurements of quadriceps MVIC and extent of voluntary activation were made in 12 subjects with knee OA and 12 similarly aged uninjured subjects. Voluntary activation was tested by superimposing a train of electrical stimulation on a maximal effort volitional contraction of the quadriceps muscle. RESULTS: The group of subjects with knee OA had significantly less quadriceps strength relative to body mass index (BMI) than the group of control subjects (p=0.010). No difference in voluntary activation was observed (p=0.233), however, 50% of the OA group, and only 25% of the control group failed to fully activate the quadriceps. DISCUSSION: The finding of quadriceps weakness is consistent with past literature. Providing adequate instruction, feedback, and several attempts to maximally contract the muscle likely yielded greater volitional activation (thus less activation failure) than had been reported previously. This finding has implications for the rehabilitation of weakened quadriceps in patients with knee osteoarthritis.

Adult↗
PubMed1998

Ego depletion: is the active self a limited resource?

Choice, active response, self-regulation, and other volition may all draw on a common inner resource. In Experiment 1, people who forced themselves to eat radishes instead of tempting chocolates subsequently quit faster on unsolvable puzzles than people who had not had to exert self-control over eating. In Experiment 2, making a meaningful personal choice to perform attitude-relevant behavior caused a similar decrement in persistence. In Experiment 3, suppressing emotion led to a subsequent drop in performance of solvable anagrams. In Experiment 4, an initial task requiring high self-regulation made people more passive (i.e., more prone to favor the passive-response option). These results suggest that the self's capacity for active volition is limited and that a range of seemingly different, unrelated acts share a common resource.

Adult↗
PubMed1987

Exoneration of the mentally ill.

Mental illness may be manifested in the impairment of understanding or of volitional control. Impairment of understanding may be manifested in delusions. Impairment of volitional control is shown when a person is unable to act in accordance with good reasons that he himself accepts. In order for an impairment of understanding or of self-control to exculpate, the offence must be causally connected with the impairment in question. The rationale of exculpation in general, which applies also to the case of mental illness, is that the offence does not indicate a morally bad attitude in the offender. A consequence of this rationale is that Kenny is wrong to hold that no injustice would result from the elimination of the legal defence of diminished responsibility.

Delusions↗
PubMed1999

"Task-oriented" exercise improves hamstring strength and spastic reflexes in chronic stroke patients.

BACKGROUND AND PURPOSE: Despite the belief that after cerebral infarction only limited functional gains are possible beyond the subacute period, we tested the hypothesis that a 12-week program of "task-oriented" treadmill exercise would increase muscle strength and decrease spastic reflexes in chronic hemiparetic patients. METHODS: Fourteen subjects, aged 66+/-3 (mean+/-SEM) years, with residual gait deviations due to remote stroke (>6 months), underwent repeated measures of reflexive and volitional (concentric and eccentric) torque with use of isokinetic dynamometry on the hamstring musculature bilaterally. Torque output was measured at 4 angular velocities (30(o), 60(o), 90(o), and 120(o)/s). RESULTS: After 3 months of 3 times/wk low-intensity aerobic exercise, there were significant main effects (2 legs [P<0.01]x2 times [P<0. 01]x4 angular velocities [P<0.05]) for concentric torque production. Torque/time production in the concentric mode also improved significantly in the paretic (50%, P<0.01) and nonparetic hamstrings (31%, P<0.01). Eccentric torque/time production increased by 21% (P<0.01) and 22% (P<0.01) in the paretic and nonparetic hamstrings, respectively. Passive (reflexive) torque/time generation in the paretic hamstrings decreased by 11% (P<0.027). Reflexive torque/time was unchanged in the nonparetic hamstrings (P=0.45). CONCLUSIONS: These findings provide evidence that progressive treadmill aerobic exercise training improves volitional torque and torque/time generation and reduces reflexive torque/time production in the hemiparetic limb. Strength changes associated with improved functional mobility in chronic hemiparetic stroke survivors after treadmill training will be reported in future articles.

Aged↗
PubMed2004

Consistent chronostasis effects across saccade categories imply a subcortical efferent trigger.

Saccadic chronostasis refers to the subjective temporal lengthening of the first visual stimulus perceived after an eye movement, and is most commonly experienced as the "stopped clock" illusion. Other temporal illusions arising in the context of movement (e.g., "intentional binding") appear to depend upon the volitional nature of the preceding motor act. Here we assess chronostasis across different saccade types, ranging from highly volitional (self-timed saccades, antisaccades) to highly reflexive (peripherally cued saccades, express saccades). Chronostasis was similar in magnitude across all these conditions, despite wide variations in their neural bases. The illusion must therefore be triggered by a "lowest common denominator" signal common to all the conditions tested and their respective neural circuits. Specifically, it is suggested that chronostasis is triggered by a low-level signal arising in response to efferent signals generated in the superior colliculus.

Adult↗
PubMedDate not supplied

Emergence and the cognitive neuroscience approach to psychiatry.

In this paper, I introduce the philosophical notion of strong emergence and argue that it is almost exclusively applied to properties related to (conscious) subjective experience. Contrary to the still common attitude of refraining anxiously from these topics, I argue that we have a promising scientific approach to them: the cognitive neurosciences. I list a spectrum of interesting, potentially strongly emergent properties already investigated, and discuss the example of volition in more detail. Psychiatric disorders, like antisocial personality disorder, schizophrenia, and obsessive compulsive disorder, open new ways for understanding aspects of volition such as willed action, decision making, and agency. I conclude that the notion of strong emergence is only a preliminary label which, however, might be understood as a challenge for empirical scientists to explain and understand phenomena related to subjectivity and consciousness.

Antisocial Personality Disorder↗
PubMedDate not supplied

Reliability of surface electromyographic measurements from subjects with spinal cord injury during voluntary motor tasks.

In this study, the reliability of surface electromyographic data (root-mean-square) for volitional motor tasks drawn from a standardized protocol was assessed. For each motor task, 5 s epochs of data were analyzed with a new method to generate a measure called the voluntary response index (VRI). The VRI consists of two components, magnitude and similarity index (SI), that were separately analyzed for repeatability. We examined three repetitions of each of 10 volitional motor tasks in 69 subjects with spinal cord injury (American Spinal Injury Association [ASIA] Impairment Scale [AIS], classifications C and D: 34 AIS-C and 35 AIS-D) for short-term (within-day) reliability. In 6 of the 69 subjects (3 each, AIS-C and AIS-D), the entire study was repeated after 1 week and results were assessed for intermediate-term (1 week apart) reliability. The reliability of the method for voluntary motor tasks was assessed by intraclass correlation coefficient (ICC), analysis of variance, coefficient of variance, and Pearson's correlation. Good reliability was found for magnitude (ICC = 0.71-0.99, Pearson's r = 0.77-0.99) and for SI (ICC = 0.65-0.96, Pearson's r = 0.72-0.93) for three repeated tests (within-day). Significant difference was found for studies completed 1 week apart for magnitude (p = 0.02) but not for SI (p = 0.57). In addition, SI showed less variation than magnitude (p < 0.001). No significant difference of magnitude and SI between tasks was observed.

Algorithms↗