Effect of Sensory Deprivation on Maximal Force Abilities from Local to Non-local Digits

Abstract

The present study investigates the effect of sensory deprivation of the index and middle finger on motor function of all digits during maximal voluntary force production tasks. A total of 27 subjects performed maximal isometric pressing tasks by using different instructed finger combinations. Subjects completed the same tasks in two visits: a control visit when they had normal sensory feedback in all fingers, and an anesthesia visit when digital nerve blocks were performed on their right index and middle fingers. We evaluated three aspects of motor adaptation on both local (anesthetized) and non-local (non-anesthetized) digits during maximal force production: (1) task-relevant and overall force magnitude, (2) force directional application, and (3) digital individuation and force sharing. Our results indicate that selective digital anesthesia resulted in decreased maximal force magnitude, changed direction of force production, and significant changes extended to non-local digits. The motor weakness and inefficiency revealed in the non-local digits implies that sensory information from each digit can be shared across the digits to assist motor execution within the same hand.     

Sequential dependencies in driving

The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find significant sequential effects in pedal-press response times that depend on the history of recent stimuli and responses. Response times are slowed up to 100 ms in particular cases, a delay that has dangerous practical consequences. Further, we observe a significant number of history-related pedal misapplications, which have recently been noted as a cause for concern in the automotive safety community. By anticipating these consequences of sequential context, driver assistance systems could mitigate the effects of performance degradations and thus critically improve driver safety.     

IMAGINATIVE CONTAGION

Abstract: The aim of this article is to expand the diet of examples considered in philosophical discussions of imagination and pretense, and to offer some preliminary observations about what we might learn about the nature of imagination as a result. The article presents a number of cases involving imaginative contagion: cases where merely imagining or pretending that P has effects that we would expect only perceiving or believing that P to have. Examples are offered that involve visual imagery, motor imagery, fictional emotions, and social priming. It is suggested that imaginative contagion is a more prevalent phenomenon than has typically been recognized.     

Primes, contingent attention, and training: effects on a child's motor behavior

The use of primes, contingent attention, and training sessions to assess a child's engagement and skill in six large motor activities was examined using a combination reversal and multiple-baseline design. Assessment was based on four levels: proximity to equipment, touching equipment, unskilled participation, and skilled participation. Before training, priming (suggestion to the child) was more effective than contingent attention for increasing the subject's engagement (but not skill) in five activities and for increasing skilled participation in one activity. Training of four activities in the natural environment effectively increased the subject's skill level in five activities. Thus, training appeared to generalize to one of these five activities in this setting and also to skillfully executed stair climbing in an adjoining setting. After training, primes and contingent attention were sufficient to maintain both the subject's skill level and engagement in all activities. Postchecks in the same setting the following semester with different teachers revealed only slight increases in participation, as compared to previous baselines, but all participation was at the skilled level. Social interaction, which was not experimentally manipulated, did not systematically vary in relation to changes in experimental conditions.     

Developmental dyspraxia and developmental coordination disorder

This article discusses the role developmental dyspraxia plays in developmental coordination disorder (DCD), based upon a review of literature on apraxia, developmental dyspraxia, and DCD. Apraxia and dyspraxia have often been equated with DCD. However, it is argued that apraxia and dyspraxia primarily refer to the problems of motor sequencing and selection, which not all children with DCD exhibit. The author proposes to distinguish developmental dyspraxia from DCD. Other issues discussed include the assessment, etiology, and treatment of developmental dyspraxia and DCD, and the relationship between DCD and learning disabilities. A research agenda is offered regarding future directions to overcome current limitation.     

Norms for 439 action events: Familiarity,emotionality, motor activity,and memorability

A total of 128 male and female university students having Swedish as their mother tongue rated 439 actions on a 7-point scale in the dimensions of Familiarity, Emotionality, Motor Activity, and Memorability under instructions to imagine themselves performing each action (e.g., “to roll a ball”, “to break a match”). Overall mean ratings were higher for women than for men in all four dimensions. High reliabilities were obtained in each scale. Intercorrelations between the dimensions were low to moderate, indicating that different characteristics of the actions were assessed. It is demonstrated that the ratings of the four dimensions are in agreement with previous categorisations of actions along the same or similar dimensions and with findings related to memory performance. Furthermore, control studies performed on the Familiarity dimension show that norm values are highly correlated with ratings given by participants in standard enacting and nonenacting conditions and with ratings in a condition where objects were present. These norms offer possibilities to control for and vary item characteristics of importance in the study of actions and the memory of actions.     

The influence of geographic region on the seasonality of early motor development

This investigation was conducted to determine whether the strong seasonality effect on infant motor development that has been noted in moderate climates would be replicated with infants born in a geographic region with more extreme conditions. One hundred and forty-five full-term infants (72 males, 73 females) born in Edmonton, alberta were assessed using the Alberta Infant Motor Scale (AIMS) at 7 months of age. No seasonality effects on the AIMS total scores or the prone, supine, sitting, or standing subsection scores were detected. A weak and statistically non-significant correlation was obtained between the average monthly AIMS scores and the average monthly temperatures 7 months after birth. These results suggest that extreme climatic conditions in urban geographic regions may dampen effects of season of birth on infant motor development.     

Predicting preschool motor and cognitive performance in appropriate-for-gestational-age children born at ≤ 32 weeks gestation

Although many follow-up studies have been performed on preterm infants, little attention has been devoted to prediction of motor skills in the preschool or school years. We studied the relationship of performance on the Bayley Scales of Infant Development at a mean corrected age of 21 months to performance on the McCarthy Scales of Children's Abilities at a mean corrected age of 44.7 months for 43 appropriate-for-gestational-age (AGA) children born at ≤ 32 weeks gestation. Motor scores were stable over time with a significant correlation between the Bayley Psychomotor Developmental Index (PDI) and the McCarthy Motor subscale (r = 0.60; p = 0.0001). Scores of cognitive abilities also showed a significant correlation between the Bayley Mental Developmental Index (MDI) and the McCarthy General Cognitive Index (r = 0.42; p = 0.009). Small-for-gestational-age (SGA), very low-birthweight (≤ 1500 grams) children scored lower on the McCarthy General Cognitive Index (p = 0.01) and on the Motor subscale (p = 0.047) than the AGA children. We concluded that motor performance of AGA children born at ≤ 32 weeks gestation is stable from toddlerhood to preschool age. We suggest that SGA children be excluded from studies of motor performance of prematurely born children.