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At least 19 recordsLinked to original sources

PubMed1993

Regional cerebral blood flow during volitional expiration in man: a comparison with volitional inspiration.

1. Positron emission tomographic (PET) imaging of regional cerebral blood flow (rCBF), using a new 3-dimensional technique of data collection, was used to identify areas of neuronal activation associated with volitional inspiration and separately with volitional expiration in five normal male subjects. A comparison of the activated areas was also undertaken to isolate regions specific for one or other active task. 2. Scans were performed during intravenous infusion of H2(15)O under conditions of (a) volitional inspiration with passive expiration, (b) passive inspiration with volitional expiration and (c) passive inspiration with passive expiration. Four measurements in these three conditions were performed in each subject. Breathing pattern was well matched between conditions. 3. Regional increases in brain blood flow, due to increased neural activity associated with either active inspiration or active expiration, were derived using a pixel by pixel comparison of images obtained during the volitional and passive ventilation phases. Data were pooled from all runs in all subjects and were then processed to detect statistically significant (P < 0.05) increases in rCBF comparing active inspiration with passive inspiration and active expiration with passive expiration. 4. During active inspiration significant increases in rCBF were found bilaterally in the primary motor cortex dorsally just lateral to the vertex, in the supplementary motor area, in the right lateral pre-motor cortex and in the left ventrolateral thalamus. 5. In active expiration significant increases in rCBF were found in the right and left primary motor cortices dorsally just lateral to the vertex, the right and left primary motor cortices more ventrolaterally, the supplementary motor area, the right lateral pre-motor cortex, the ventrolateral thalamus bilaterally, and the cerebellum. 6. Using this modified and more sensitive PET technique, these findings essentially replicate those for volitional inspiration obtained in a previous study. For volitional expiration the areas activated are more extensive, but overlap with those involved in volitional inspiration. 7. The technique used has been successful in demonstrating the regions of the brain involved in the generation of volitional breathing, and probably in the volitional modulation of automatic breathing patterns such as would be required for the production of speech.

Abdominal Muscles↗

PubMed1993

Independent control of reflex and volitional EMG modulation during sinusoidal pursuit tracking in humans.

It is well known that during volitional sinusoidal tracking the long-latency reflex modulates in parallel with the volitional EMG activity. In this study, a series of experiments are reported demonstrating several conditions in which an uncoupling of reflex from volitional activity occurs. The paradigm consists of a visually guided task in which the subject tracked a sinusoid with the wrist. The movement was perturbed by constant torque or controlled velocity perturbations at 45 degrees intervals of the tracking phase. Volitional and reflex-evoked EMG and wrist displacement as functions of the tracking phase were recorded. The relationship of both short-latency (30-60 ms) and longer-latency (60-100 ms) reflex components to the volitional EMG was evaluated. In reflex tracking, the peak reflex amplitude occurs at phases of tracking which correspond to a maximum of wrist joint angular velocity in the direction of homonymous muscle shortening and a minimum of wrist compliance. Uncoupling of the reflex and volitional EMG was observed in three situations. First, during passive movement of the wrist through the sinusoidal tracking cycle perturbation-evoked long-latency stretch reflex peak is modulated as for normal, volitional tracking. However, with passive joint movement the volitional EMG modulation is undetectable. Second, a subset of subjects demonstrate a normally modulated and positioned long-latency reflex with a single peak. However, these subjects have distinct bimodal peaks of volitional EMG. Third, the imposition of an anti-elastic load (positive position feedback) shifts the volitional EMG envelope by as much as 180 degrees along the tracking phase when compared with conventional elastic loading. Yet the long-latency reflex peak remains at its usual phase in the tracking cycle, corresponding to the maximal velocity in the direction of muscle shortening. Furthermore, comparison of the results from elastic and anti-elastic loads reveals a dissociation of short- and long-latency reflex activity, with the short-latency reflex shifting with the volitional EMG envelope. Comparable results were also obtained for controlled velocity perturbations used to control for changes in joint compliance. The uncoupling of the reflex and volitional EMG activity in the present series of experiments points to a flexible relationship between reflex and volitional control systems, altered by peripheral input and external load.

Adult↗

PubMed2004

Locating volition.

In this paper, it is examined how neuroscience can help to understand the nature of volition by addressing the question whether volitions can be localized in the brain. Volitions, as acts of the will, are special mental events or activities by which an agent consciously and actively exercises her agency to voluntarily direct her thoughts and actions. If we can pinpoint when and where volitional events or activities occur in the brain and find out their neural underpinnings, this can substantively aid to demystify the concept of volition. After first discussing some methodological issues regarding whether it is possible to locate volition in the brain, various approaches by which neuroscientists and psychologists explore the neural correlates and substrates of volition are examined. Although different psychological conceptualizations of volition shape different perspectives toward understanding the functions of volition, the explorations of the neural basis of volition converge on certain common brain areas and structures. A unifying conception of volition that helps to make better sense of recent empirical findings is then suggested.

Brain↗

PubMed2002

MRI quantification of muscle activity after volitional exercise and neuromuscular electrical stimulation.

OBJECTIVE: The efficacy, and even the depth, of muscle stimulation during surface electrode neuromuscular electrical stimulation (NMES) is a matter of debate. This study addresses these issues by assessing the utility of a magnetic resonance imaging (MRI) technique in localizing and quantitating changes in the nature of MRI signals in the quadriceps muscle after volitional exercise and NMES. DESIGN: Volitional isometric and NMES-evoked quadriceps muscle activity was evaluated in two controlled trials. In the first, isometric quadriceps strength was determined during NMES and maximal volitional isometric exercise in six healthy men. In the second, changes in the ratio of MRI T2 signal intensities before and after volitional isometric exercise and NMES were used to quantitate MRI signal changes associated with muscle activation in 12 additional healthy men. RESULTS: MRI clearly detected quadriceps muscle tissue activation after both volitional and stimulated contractions, even though the NMES knee extension torque was only 23.5% that of maximal volitional isometric exercise. In particular, the T2 intensity ratios increased 26.5% +/- 17.3% (mean +/- standard deviation) after volitional exercise and 12.9% +/- 12.8% after NMES. This pattern of volitional isometric exercise, producing larger T2 intensity ratio values than NMES, was present in both deep and superficial layers and throughout the quadriceps muscle. CONCLUSIONS: Although volitional muscle contractions were several times stronger than those induced by NMES in this study, our findings support the idea that MRI can provide a noninvasive way to quantitate and localize volitional and electrically stimulated muscle activation.

Adult↗

PubMed1999

Effects of volitional lifestyle on rest-activity cycle in the aged.

The present study investigated the relationship among volitional lifestyle, activity and sleep in the aged. We selected 28 subjects over 65 years of age to survey volition to lifestyle. High-volitional group (14 Ss, mean age: 74.1 years, seven males and seven females) and low-volitional group (14 Ss, mean age: 73.0 years, seven males and seven females) were identified by the scale of self-confidence and the Philadelphia Geriatric Center morale scale. Wrist activities were monitored by Actigraph for 10 or 14 consecutive days. The subjects recorded sleep logs by themselves for those days. It was found that high volitional aged individuals had a relatively well structured sleep in comparison with low volitional aged individuals, and that most of them took a clock dependent habitual nap around 14.00 h. On the other hand, low volitional aged individuals had a relatively poor structured sleep, and took a nap time-dependently after 8 h from the morning rising time. These results suggest that high volitional aged individuals build a short nap into their well organized sleep-life habits.

Aged↗

PubMed2000

How hallucinations may arise from brain mechanisms of learning, attention, and volition.

This article suggests how brain mechanisms of learning, attention, and volition may give rise to hallucinations during schizophrenia and other mental disorders. The article suggests that normal learning and memory are stabilized through the use of learned top-down expectations. These expectations learn prototypes that are capable of focusing attention upon the combinations of features that comprise conscious perceptual experiences. When top-down expectations are active in a priming situation, they can modulate or sensitize their target cells to respond more effectively to matched bottom-up information. They cannot, however, fully activate these target cells. These matching properties are shown to be essential towards stabilizing the memory of learned representations. The modulatory property of top-down expectations is achieved through a balance between top-down excitation and inhibition. The learned prototype is the excitatory on-center in this top-down network. Phasic volitional signals can shift the balance between excitation and inhibition to favor net excitatory activation. Such a volitionally mediated shift enables top-down expectations, in the absence of supportive bottom-up inputs, to cause conscious experiences of imagery and inner speech and thereby to enable fantasy and planning activities to occur. If these volitional signals become tonically hyperactive during a mental disorder, the top-down expectations can give rise to conscious experiences in the absence of bottom-up inputs and volition. These events are compared with data about hallucinations. The article predicts where these top-down expectations and volitional signals may act in the laminar circuits of visual cortex and, by extension, in other sensory and cognitive neocortical areas, and how the level of abstractness of learned prototypes may covary with the abstractness of hallucinatory content. A similar breakdown of volition may lead to delusions of control in the motor system.

Attention↗

PubMed2001

Cerebral cortical representation of reflexive and volitional swallowing in humans.

The purpose of this study was to compare cerebral cortical representation of experimentally induced reflexive swallow with that of volitional swallow. Eight asymptomatic adults (24-27 yr) were studied by a single-trial functional magnetic resonance imaging technique. Reflexive swallowing showed bilateral activity concentrated to the primary sensory/motor regions. Volitional swallowing was represented bilaterally in the insula, prefrontal, cingulate, and parietooccipital regions in addition to the primary sensory/motor cortex. Intrasubject comparison showed that the total volume of activity during volitional swallowing was significantly larger than that activated during reflexive swallows in either hemisphere (P < 0.001). For volitional swallowing, the primary sensory/motor region contained the largest and the insular region the smallest volumes of activation in both hemispheres, and the total activated volume in the right hemisphere was significantly larger compared with the left (P < 0.05). Intersubject comparison showed significant variability in the volume of activity in each of the four volitional swallowing cortical regions. We conclude that reflexive swallow is represented in the primary sensory/motor cortex and that volitional swallow is represented in multiple regions, including the primary sensory/motor cortex, insular, prefrontal/cingulate gyrus, and cuneus and precuneus region. Non-sensory/motor regions activated during volitional swallow may represent swallow-related intent and planning and possibly urge.

Adult↗

PubMed2004

Implicit/explicit motive discrepancies and volitional depletion among managers.

The compensatory model of motivation and volition is based on the assumption that discrepancies between implicit and explicit motives lead to psychological conflict, and that resolution of this conflict requires volitional regulation and consumes volitional strength. This suggests that implicit/explicit motive discrepancies (IED) are responsible for decreases in volitional strength. A longitudinal field study with 82 managers was conducted to test this proposition. Results show that IED longitudinally predicted decreases in volitional strength. Furthermore, structural equation modeling revealed that volitional strength mediated the relation between IED and impaired subjective well-being. The theoretical and practical implications of these results are discussed, particularly with respect to volitional depletion.

Adult↗

PubMed2002

Volitional lifestyle in healthy elderly: its relevance to rest-activity cycle, nocturnal sleep, and daytime napping.

Sleep-related problems are prevalent among the aged. The present study examined the influence of a mentally active or "volitional" lifestyle on the rest-activity cycle, nocturnal sleep, and daytime napping in the healthy elderly. 14 aged individuals with a high Volitional lifestyle (M = 74.1 yr. old) and 14 with a Low Volitional lifestyle (M = 73.0 yr. old) were screened by questionnaires including the Philadelphia Geriatric Center Morale scale and the Self-confidence scale. Their activity levels were monitored by a wrist actigraph system for 14 consecutive days. They were also asked to record daily sleep logs. The total times of nocturnal sleep and daytime napping did not differ between the groups. However, the acrophases of circadian (tau = 24 hr.) and circasemidian (tau = 12 hr.) activity cycles were more advanced in the Low Volitional group. In addition, the High Volitional group took a daytime nap with a better timing than did the Low Volitional group: the former started a nap during the phase in which their activity level was going down, whereas the latter when their activity level was going up. These results suggest that high volitional lifestyle may be related to better rest-activity cycle in the healthy elderly.

Aged↗

PubMed1999

Analysis of volition latency on antisaccadic eye movements.

The antisaccadic paradigm can be applied to test the suppression of reflexive saccades and the activation of volitional saccades simultaneously. The impaired frontal cortex has been shown to have difficulty in suppressing reflexive saccade (prosaccade) to make a successful antisaccade. Degraded antisaccade performance can also be observed in patients with Parkinson's disease (PD). The studies of PD based on the prosaccadic and antisaccadic paradigms have shown controversial findings; the latency between patients and age-matched controls could be either with or without significant difference. Even with this inconsistency, our previous study and recent analysis have supported that the latency of both prosaccade and antisaccade increases significantly for patients with PD. The objective of this study is to investigate whether prolonged antisaccade latency is caused by the affected volitional decision process (volition latency) or simply by the delayed initiation of saccade with direction opposite to the cue, by measuring prosaccade and antisaccade latency from the intermingled paradigms. Eleven mildly affected patients with idiopathic PD and eight age-matched normal subjects were tested in this study. As compared to the age-matched control, the results showed that prosaccade, antisaccadic, and volition latency of the patients was significantly elevated (P<0.01). We conclude that antisaccade performance for the PD patients was degraded for both the volition decision process and the initiation of saccade with direction opposite to the cue. Also, volition latency analysis is a more objective method than prosaccade and antisaccade latency analysis, which can be compared among results obtained from different analysis methodologies.

Aged↗

PubMed2005

An examination of the measurement properties of the pediatric volitional questionnaire.

The Pediatric Volitional Questionnaire (PVQ) is a 15- item play-based assessment of a child's motivational strengths and weaknesses in various settings based on the Model of Human Occupation. A previous study examined the PVQ's ability to provide a valid measure of volition in ten non-disabled children. This study combined data from the previous study with data on eight children with disabilities to further test the instrument's psychometric properties. Data on 36 observations of the 18 participants were observed by a total of 20 raters. Each rater was randomly assigned to rate videotapes. Data were analyzed using the Rasch Measurement Model. Results indicate that the 15 items of the scale work well together to measure volition and were well matched to the volitional levels of the sample group. Nineteen of the twenty raters used the scale in a valid manner, though scores were affected by the extent of severity/leniency of the rater. All eighteen participants were validly rated and the scale items effectively differentiated levels of volition among the eighteen children. These findings supported the conclusion that the PVQ provides a valid and sensitive measure of volition. The study also found that the 4-point rating scale operated as a 3-point scale in this study and that raters differentiated in their severity/ leniency. These latter findings indicate the need to further clarify the rating scale.

Child↗

PubMed2000

The role of volitional effort in the Bielschowsky head tilt test: a clinical and oculographic assessment.

PURPOSE: To determine whether volitional effort on the part of the subject can influence the results of the Bielschowsky Head Tilt Test. PATIENTS AND METHODS: Bielschowsky Head Tilt testing was performed in five normal subjects. Vertical amplitudes were measured with prism alternate cover testing when the head tilt was voluntary (volitionally maintained in a tilted position by the subject), forced (restrained in the tilted position by the examiner while the patient actively resisted) and active (restrained in a tilted position by the examiner with the subject actively trying to increase the tilt). Three-dimensional scleral search coil recordings were performed in three additional normal subjects using the same paradigm to determine the effect of volition on the torsional positions of the eyes. RESULTS: No vertical deviation of the eyes was detectable with prism alternate cover testing in any position of tilt, regardless of whether the tilt was voluntary, forced, or active. Volitional attempts to tilt the head were preceded by a transient ipsiversive torsional movement of the measured eye, which was quickly followed by a normal ocular counterroll. Following completion of the counterroll, the position of the eyes was constant for any position of head tilt, regardless of whether the tilt was forced, active, or voluntary. CONCLUSION: Anticipatory torsional movements of the eyes are evoked by an attempted volitional head movement in the roll plane and its associated innervation to the cervical musculature. However, these volitional movements do not alter the final torsional position of the eyes, which is a function of the degree of head tilt and the normal ocular counterroll. These anticipatory torsional movements do not influence the results of the Bielschowsky Head Tilt Test clinically by prism alternate cover testing.

Adult↗

PubMed1999

The importance of volitional narrative in treatment: An ethnographic case study in a work progran.

The revised theory of the model of human occupation expands the concept of volition to include volitional narrative. This paper focuses on the application of this theory of volition to a client's experience in a work program. This ethnographic case study describes the volitional narrative and life world of one client who attended the occupational therapy work based program. For fifteen months the client was the subject of narrative interviews, participant observation, videotapes and telephone contacts. The findings will illustrate how knowledge of a client's volitional narrative and life world can shed critical light on understanding treatment conflicts. Finally, the discussion will underscore how important it is for work based programs to be designed to encourage therapists to adapt their treatment approaches to maximize the opportunities to seek out the client's volitional narratives and to create meaningful experiences that are consistent with the client's life world.

Journal Article↗

PubMed2003

Cortical control mechanisms in volitional swallowing: the Bereitschaftspotential.

OBJECTIVE: This research sought to identify a well-defined pre-motor potential, the Bereitschaftspotential (BP), as a manifestation of cortical contribution to the pre-motor planning of volitional swallowing. METHODS: EEG data were collected from 20 research participants during volitional execution of swallowing and finger movement tasks. A5 second pre-movement epoch for each task was triggered on EMG identification of movement onset. A grand average for each task representing approximately 2400 trials across all research participants was derived to compare and contrast morphological features of the derived waveform. RESULTS: Volitional pharyngeal swallowing and finger movement generated similar waveform characteristics of duration and slope; however, statistically significant differences were identified in polarity and in amplitude at four points both early and late in the epoch. Additionally, swallowing produced a pre-motor waveform with a rapid declination of EEG activity in the final 500 msec prior to movement onset. CONCLUSIONS: This study demonstrates activation of the supplementary motor cortex preceding the onset of volitional swallowing. However, unlike purely voluntary movements, the volitional pharyngeal swallowing task, as assessed with this methodology, does not appear to recruit the primary motor cortex. Thus engagement of the swallowing response appears to rely on indirect parallel pathways between extrapyramidal cortical motor planning regions and lower motor neurons.

Adolescent↗

PubMed1998

Moral volition: the fifth and final domain leading to an integrated theory of conscience understanding.

OBJECTIVES: To define discrete developmental levels of understanding of the ways in which normal children and adolescents link autonomy and will to moral obligation and to study the correlation between this progression and previously identified stages of conscience conceptualization. METHOD: One hundred thirty-two normal volunteers between the ages of 5 and 17 years were individually interviewed using the moral volition section of the semistructured Stilwell Conscience Interview. Analysis of the interviews resulted in five levels of understanding of moral self-evaluation and volitionally chosen behavior. RESULTS: Analyses of variance and covariance showed that the five levels of moral volition had significant correlation with five conceptualization stages, with stage criteria showing a stronger correlation than age. Self-identified tasks of oughtness were hierarchically defined beginning with those defining a morality of restraint followed by moralities of mastery/sufficiency, virtuous striving, idealization, and individual responsibility. Perception of increased independence of self in interaction with conscience was noteworthy at stages 4 and 5. CONCLUSIONS: Moral volition is the domain of conscience functioning that defines understanding of moral self-evaluation and volitionally chosen actions; five levels of understanding can be demonstrated in normal children between the ages of 5 and 17 years.

Adolescent↗

PubMed1998

Modeling the Mediating Role of Volition in the Learning Process.

According to action-control theory, volition plays a mediating role between the intention to learn (motivation) and goal-directed behavior (the use of learning strategies). Although extensive theoretical work has been done to document this flow of events, more empirical studies have been needed to identify the specific means by which volitional control protects the intention to learn and maintains the attempts to learn; our intention here was to address this gap in the literature. Using data from a sample of 487 college students in two different domains, we found that the positive effects of intrinsic goal orientation and self-efficacy on cognitive engagement were augmented by volitional control. We also found that the effects of volition differed by domain as well as by the type of learning strategy being considered. These results suggest that volitional control merits greater attention from those doing research in self-regulated learning. Copyright 1998 Academic Press.

Journal Article↗

PubMed2003

Personality systems interactions theory and the theory of planned behaviour: evidence that self-regulatory volitional components enhance enactment of studying behaviour.

The role of volitional components specified by personality systems interactions theory in enhancing behavioural prediction was examined in a longitudinal investigation of students' studying. Participants completed measures specified by the theory of planned behaviour and questionnaire measures of 'conscious attention control', 'implicit attention control' and 'self-determination' from the volitional components inventory. Behaviour was assessed 2 weeks later. Regression analyses showed that volitional components increased variance explained in behaviour by 10-18%, after taking into account strength of motivation to study assessed by attitude, subjective norm, perceived behavioural control and intention from the theory of planned behaviour. Moreover, consistent with elements of personality systems interactions theory, moderator effects were obtained. Participants who reported self-determination, conscious attention control and implicit attention control were more likely to enact their intentions. Volitional components were also associated with increased studying among participants who perceived a low subjective norm for studying. Volitional components improved prediction of studying after accounting for past behaviour in the regression models.

Adolescent↗

PubMed2003

Volitional impairment and the sexually violent predator.

This article discusses psychiatry's limited conceptualization of volitional capacity and its application to sexually violent predator laws by exploring two legal opinions critical to predator case law (Kansas v. Hendricks and Kansas v. Crane). The author reviewed pertinent psychiatric literature on impaired volition to identify potential contributions and limitations that psychiatry may offer the legal field. Assessment of the ego dystonic nature of impaired self-regulation, utilization of recent advances in self-assessment and laboratory evaluation of impulsive behavior, and dimensional categorization of a volitional capacity construct are recommended as an approach to the assessment and understanding of an inability to control concept. This paper concludes that elements of volition may be psychiatrically evaluated in a way that contributes to the Court's understanding of that capacity. However, further study is needed to operationally define volitional capacity and address issues of assessment validity and reliability.

Criminal Law↗