Motor strength as a feature of concepts and visual representations

In this article, we define motor strength as the extent to which a concept is associated with body movements and the motor system that guides body movements. We extend this notion to one of the features of visual representations of some concepts and discuss the role of the motor system in understanding concepts and visual representations that have a significant degree of motor strength. It is suggested that when a concept is understood in its literal sense, the employment of the motor system and gestures in processing that concept depends on its degree of motor strength. If a concept is understood in its metaphorical sense, the employment of the motor system and gestures is dependent on the degree of motor strength of the base of the metaphor through which that concept is understood. The degree of motor strength of a concept relies on its motor affordances and its associations with people's past experiences. Because the motor system plays an essential role in the grounding of many abstract concepts in the physical environment, the notion of motor strength can help psychologists acquire a clearer understanding of how concepts with varying degrees of motor strength are grounded in the physical environment.

How can transforming representation of mathematical entities help us employ more cognitive resources?

This article discusses the cognitive process of transforming one representation of mathematical entities into another representation. This process, which has been called mathematical metaphor, allows us to understand and embody a difficult-to-understand mathematical entity in terms of an easy-to-understand entity. When one representation of a mathematical entity is transformed into another representation, more cognitive resources such as the visual and motor systems can come into play to understand the target entity. Because of their nature, some curves, which are one group of visual representations, may have a great motor strength. It is suggested that directedness, straightness, length, and thinness are some possible features that determine degree of motor strength of a curve. Another possible factor that can determine motor strength of a curve is the strength of association between shape of the curve and past experiences of the observer (and her/his prior knowledge). If an individual has had the repetitive experience of observing objects moving along a certain curve, the shape of the curve may have a great motor strength for her/him. In fact, it can be said that some kind of metonymic relationship may be formed between the shapes of some curves and movement experiences.

Optimal timing of referral for nerve transfer surgery for postoperative C5 palsy

OBJECTIVE

Cervical nerve 5 palsy can occur following surgery for cervical spine pathology. The prognosis of C5 palsy is generally favorable, and most patients recover useful function. However, some patients do not recover useful strength. Nerve transfers are a potential effective treatment of postoperative severe C5 palsy. This study aimed to further delineate the natural history of recovery from postoperative C5 palsy, determine whether lack of recovery at specific time points predicts poor recovery prognosis, and thereby determine a reasonable time point for referral to a complex peripheral nerve specialist.

METHODS

The authors conducted a retrospective review of 72 patients who underwent surgery for cervical spondylosis and stenosis complicated by C5 palsy. Medical Research Council (MRC) motor strength grades were recorded preoperatively; immediately postoperatively; at discharge; and at 2 weeks, 3 months, 6 months, and 12 months postoperatively. Univariate and multivariate logistic regression models were used to identify demographic and clinical risk factors associated with recovery of useful strength after severe C5 palsy.

RESULTS

The mean patient age was 62.5 years, and 36.1% of patients were female. Thirty patients (41.7%) experienced severe C5 palsy with less than antigravity strength (MRC grade 2 or less) at discharge. Twenty-one (70%) of these patients recovered useful strength (MRC grade 3 or greater) at 12 months postoperatively, and 9 patients (30%) did not recover useful strength at 12 months. Of those patients with persistent severe C5 palsy at 3 months postoperatively, 50% recovered useful strength at 12 months. Of those patients with persistent severe C5 palsy at 6 months postoperatively, 25% recovered useful strength at 12 months. No patient with MRC grade 0 or 1 strength at 6 months postoperatively recovered useful strength. A history of diabetes was associated with the occurrence of severe C5 palsy. On multivariate analysis, female sex was associated with recovery of useful strength.

CONCLUSIONS

Most patients with severe C5 palsy recover useful strength in their C5 myotome within 12 months of onset. However, at 3 months postoperatively, patients with persistent severe C5 palsy had only a 50% chance of recovering useful strength by 12 months. Lack of recovery of useful strength at 3 months postoperatively is a reasonable time point for referral to a complex peripheral nerve center to establish care and to determine candidacy for nerve transfer surgery if severe C5 palsy persists.

Motor examinations in psychiatry

The capacity for voluntary motor activity underpins all behavior. Although psychiatrists are acutely aware of behavior, we tend to think of its abstract motives more than its concrete mechanisms. This article reviews the basic brain mechanisms of voluntary motor activity, the most useful pyramidal tract or upper motor neuron signs, and their relevance to specific patient groups of interest to psychiatrists.