Investigation on the cooperative grasping capabilities of human thumb and index finger

The maximum cooperative grasping mass and diameter of the human thumb and index finger were investigated by 7560 grasp-release trials on various masses of solid cylinders and various sizes of rings. The maximum grasping mass of the participants’ thumbindex finger depended on gender, age and the sum of thumb-index finger lengths (P 0.05). The maximum grasping diameter of the participants’ thumb-index finger depended on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length (P 0.05). There was a non-linear regression model for the dependence of the maximum grasping mass on gender, age and the sum of thumb-index finger lengths and another non-linear regression model for the dependence of the maximum grasping diameter on the age, sum of thumb-index finger lengths and ratio of index finger to thumb length. Two regression models were useful in the optimal size design of robotic hands intending to replicate thumb-index finger grasping ability. This research can help to define not only a reasonable grasp mass and size for a bionic robotic hand, but also the requirements for hand rehabilitation

Developing Fine Motor Skills in Preschool Age Children

Based on the findings of the literature review, fine motor skills are an important skill to develop during the preschool years. Marr, Cermak, Cohan and Henderson (2003) described the importance of fine motor skills to engage in valued occupations in addition to educational activities. A child\u27s occupations that demand fine motor skills may be dressing, tying shoes, play, among other daily tasks. If a child has difficulty with fine motor skills it could have a negative outcome on their daily lives and how they perform in school. Children who have difficulty coordinating the small muscle groups in their hands have difficulty dressing, feeding themselves, and manipulating pencils, crayons and scissors. This difficulty may prevent them from meeting the demands of school (Losse et al., 1991). The acquisition of fine motor skills is an important aspect of children\u27s developmental growth as fine motor skills enable children to participate in valued occupations in the areas of activities of daily living, education, play and social participation. National education goals describe fine motor skills as one of the dimensions needed by kindergarten children for learning readiness (National Education Goals Panel, 1993). With opportunities imbedded in their day, preschool children increase the refinement of fine motor skills. Fine motor skills are an important component of handwriting and manipulating classroom objects. Handwriting is both a means of communication and necessary life skill. Handwriting is still the most immediate form of graphic communication (Sasson, 1990). Research has shown that it is\u27 important to develop good writing habits early. Early childhood educators and pediatric occupational therapists should focus on developing fine motor skills in preschool children to enhance readiness for learning (Case-Smith, 2000; Kagan, Moore, & Bredekamp, 1995). Difficulty in fine motor skills can interfere with academic achievement. No other school task requires as much synchronization as handwriting (Levine, Oberklaid, & Meltzer, 1981). Feder and Majnemer (2007) found the percentage of children with handwriting difficulties ranged from 10-30%. The purpose of this scholarly project is to educate parents, teacher and occupational therapist of the importance of developing good fine motor skills in preschool age children. This will ensure that a child will have the opportunity to reach their maximal potential in the area of handwriting and completing classroom work. A resource was developed that could be used by parents, educators and daycare providers to promote fine motor skill development in preschool age children. This project is a resource manual that contains fine motor activities that can be incorporated throughout the day to provide children the opportunities to work on fine motor skills. The methods used in this project included an extensive review of literature including scholarly articles, books, and educational resources available for teachers and parents. The benefit of this project includes increased awareness about the importance of fine motor skills development in preschool age children and the developmental milestones associated with the age, and activities to incorporate into the daily life to benefit fine motor skill developmen

The Precision of the Human Hand: Variability in Pinch Strength and Manual Dexterity

Changes in hand morphology throughout human evolution have facilitated the use of forceful pad-to-pad precision grips, contributing to the development of fine motor movement and dexterous manipulation typical of modern humans. Today, variation in human hand function may be affected by demographic and/or lifestyle factors, but these remain largely unexplored. We measured pinch grip strength and dexterity in a heterogeneous cross-sectional sample of human participants (n = 556) to test for the potential effects of sex, age, hand asymmetries, hand morphology, and frequently practiced manual activities across the lifespan. We found a significant effect of sex on pinch strength, dexterity, and different directional asymmetries, with the practice of manual musical instruments, significantly increasing female dexterity for both hands. Males and females with wider hands were also stronger, but not more precise, than those with longer hands, while the thumb-index ratio had no effect. Hand dominance asymmetry further had a significant effect on dexterity but not on pinch strength. These results indicate that different patterns of hand asymmetries and hand function are influenced in part by life experiences, improving our understanding of the link between hand form and function and offering a referential context for interpreting the evolution of human dexterity

Neuroplasticity induced by peripheral nerve stimulation

PhD ThesisNon-invasive methods have been developed to induce plastic changes in the sensorimotor cortex. These rely on stimulating pairs of afferent nerves. By associative stimulation (AS) of two afferent nerves, excitability changes in the motor cortex occur as indicated by studies reporting changes in motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). Repetitive stimulation of those nerves has a potential in rehabilitation and treatment of neurological disorders like stroke or spinal cord injury. Despite promising results and applications in human subjects using these methods, little is understood about the underlying basis for the changes which are seen. In the present study, behavioural, electrophysiological and immunohistochemical assessments were performed before and after paired associative and non-associative (NAS) median and ulnar nerve stimulation. Two macaque monkeys were trained to perform a skilled finger abduction task using refined behavioural methods. Monkeys were not able to move their thumb and index finger as selectively after one hour of paired AS as indicated by an increased number of errors and decreased performance measures. NAS however decreased error numbers and led to increased performances. Additionally, I recorded from identified pyramidal tract neurons and unidentified cells in primary motor cortex (M1), in two macaque monkeys before and after one hour of AS (and NAS) of the median and ulnar nerve. Cell discharge was recorded in response to electrical stimulation of each nerve independently. Some cells in M1 showed changed firing rates in response to nerve stimulation after AS (and NAS). Subsequently, structural changes in response to one week of paired AS were investigated. The laminar-specific density of parvalbumin-positive interneurons, perineuronal nets and the colocalisation of these two entities changed on the stimulated (in comparison to the non-stimulated) sensorimotor cortex. These findings suggest that the sensorimotor cortex undergoes plastic changes in response to AS (and NAS).Wellcome Trus

Ergonomic aspects of harvesting apples by hand

Following Parliamentary debates in 1980 on the quality of fresh market produce, in particular apples, a grant was awarded for research into the ergonomics of harvesting and marketing apples. The objectives were to study ways to improve the quality of English apples in the market place by examining the ergonomics and the cost effectiveness of methods of hand-picking apples. This involved: participation observation studies, observation of professional pickers, surveys and questionnaires, in an effort to define problem areas and to prepare a criticism of present methods. Additional studies of potential fatigue and stress both in fieldwork and in simulation were intended as a preliminary investigation to devise a preferred picking method and to redesign picking and handling aids where appropriate. [Continues.

Attention and time constraints in performing and learning a table tennis forehand shot

This is a section on p. S95 of article 'Verbal and Poster: Motor Development, Motor Learning and Control, and Sport and Exercise Psychology' in Journal of Sport and Exercise Psychology, 2010, v.32, p.S36-S237published_or_final_versio

EEG coherence between the verbal-analytical region (T3) and the motor-planning region (Fz) increases under stress in explicit motor learners but not implicit motor learners

This journal supplement contains abstracts of NASPSPA 2010Free Communications - Verbal and Poster: Motor Learning and Controlpublished_or_final_versionThe Annual Conference of the North American Society for the Psychology of Sport and Physical Activity (NASPSPA 2010), Tucson, AZ., 10-12 June 2010. In Journal of Sport and Exercise Psychology, 2010, v. 32 suppl., p. S13

On action intent : behavioural correlates of reach-to-grasp actions

Evidence from electrophysiology suggests that non-human primates produce reach-to-grasp movements based on their functional end-goal rather than on the biomechanical requirements of the movement. However, the invasiveness of direct-electrical stimulation and single-neuron recording studies have precluded analogous investigations in humans. In this thesis, I present behavioural evidence in the form of kinematic analyses suggesting that the cortical circuits responsible for reach-to-grasp actions in humans are organized in a similar fashion. Grasp-to-eat movements are produced with significantly smaller and more precise maximum grip apertures (MGAs) than are grasp-to-place movements directed toward the same objects, despite near identical mechanical requirements of the two subsequent (i.e., -eat and –place) movements. Furthermore, the fact that this distinction is limited to right-handed movements suggests that the system governing reach-to-grasp movements is asymmetric. I posit that this asymmetry may be responsible, at least in part, for the preponderance of right-hand dominance among the global population