Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Volition”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed1980

Volition following hemiplegia.

Following a minimum period of 11 weeks after cerebrovascular accident and resulting hemiplegia, 100 adult patients were assessed, over a period of 3 years, for sensory-motor deficits affecting the function of the paralyzed upper extremity. This paper presents only the assessment of voluntary control, the disturbances of voluntary motion, and the interrelationship between the components of voluntary motion and other clinical manifestations. Kendall rank order correlations were computed for this purpose. In the voluntary control of gross arm motions, forearm supination and spontaneity of arm usage appeared to be most significant in predicting the presence of other synergistic components. The isolated muscle function revealed during execution of functional tasks showed the ability to grasp an object as the least affected task and dropping a coin in a slot as the most difficult. Inability to perform voluntary motion was primarily related to the limitation of active and passive motion of the shoulders, elbow, wrist, and hand.

Aged↗
PubMed1993

The volitional nature of the simplest reflex.

Recent studies suggest that none of the behaviors of the vertebrate CNS are fixed responses incapable of change. Even the simplest reflex of all, the two-neuron, monosynaptic spinal stretch reflex (SSR), undergoes adaptive change under appropriate circumstances. Operantly conditioned SSR change occurs gradually over days and weeks and is associated with a complex pattern of CNS plasticity at both spinal and supraspinal sites.

Animals↗
PubMed2005

Is inhibition of return a reflexive effect?

The inhibition of return (IOR) phenomenon is routinely considered an effect of reflexive attention because the paradigm used to generate IOR employs peripheral cues that are uninformative as to where a target will appear. Because the cues are spatially unreliable it is thought that there is no reason for attention to be committed volitionally to them, and hence, the IOR effect is considered reflexive. What has been generally overlooked, however, is that the cues provide reliable temporal information as to when a target will occur. This predictive information is used by participants to prepare volitionally for when a target is likely to appear. We investigated whether the IOR effect is a product of the volitional application of attention to peripheral cues for the use of their temporal information. To test this idea we rendered the temporal information provided by peripheral cues unreliable. While this eliminated participants using the cues volitionally, it did not abolish the IOR phenomenon. These data demonstrate two new findings. First, the IOR effect is fundamentally a reflexive phenomenon. Second, when peripheral cues are not used volitionally, the IOR effect is attenuated. Together, the present findings indicate that the IOR effect can be modulated by volitional (top-down) processes but it is not the product of them. We argue that an intimate link between fronto-parietal regions and the superior colliculus provide a functional neural mechanism for this volitional effect to impact IOR.

Adult↗
PubMed2003

Voluntary activation and decreased force production of the quadriceps femoris muscle after total knee arthroplasty.

BACKGROUND AND PURPOSE: Quadriceps femoris muscle weakness as manifested by a decrease in force-generating capability is a persistent problem after total knee arthroplasty (TKA). The authors hypothesized that (1) patients with a TKA would have decreased quadriceps femoris muscle performance (weakness) and impaired volitional activation when compared with a group of older adults without knee pathology, (2) pain and age would account for a large portion of the variability in volitional activation after surgery, and (3) volitional activation in the TKA group would account for a large portion of the variability in force production. SUBJECTS: Comparison subjects were 52 volunteers (mean age=72.2 years, SD=5.34, range=64-85). The TKA group comprised 52 patients (mean age=64.9 years, SD=7.72, range=49-78) with a diagnosis of osteoarthritis who had undergone a tricompartmental, cemented TKA. METHODS: Knee extension force was measured using a burst superimposition technique, where a supramaximal burst of electrical stimulation was superimposed on a maximal voluntary isometric contraction (MVIC). The amount of failure of volitional activation is determined by the amount of electrical augmentation of force beyond a person's MVIC at the instant of the application of the electrical burst. RESULTS: The average normalized knee extension force of the TKA group was 64% lower than that of the comparison group. The average volitional activation deficit in the TKA group (26%) was 4 times as great as the comparison group's deficit (6%). Age did not correlate with quadriceps femoris muscle activation, and knee pain explained only a small portion of the variance in knee extension force (r2=.17). Volitional activation was highly correlated with knee extension force production (r2=.65). DISCUSSION AND CONCLUSION: Considerable quadriceps femoris muscle inhibition after surgery has several implications for recovery. Rehabilitation programs that focus on volitional exercise alone are unlikely to overcome this pronounced failure of activation. Early interventions focused at improving quadriceps femoris muscle voluntary activation may improve efforts to restore muscle force.

Age Factors↗