Specific Grip Research Articles

Relationship between Physical Fitness and Cyberbullying Patterns (Cybervictimization and Cyberperpetration) in Spanish Adolescents.

(1) Background: Cyberbullying is a growing problem among adolescents, and deeper knowledge of this phenomenon could facilitate the implementation of adequate prevention and intervention strategies. Therefore, the aim of this study was to analyze the relationships between victimization and aggression patterns in cyberbullying and physical fitness levels in Spanish adolescents. (2) Methods: A total of 741 adolescents aged 12 to 19 years from two high schools in Andalusia, Spain (mean = 14.52 ± 1.96 years; 50.9% girls, 49.1% boys) participated in the study. The participants underwent the EUROFIT battery test and completed the Spanish version of the European Cyberbullying Intervention Project Questionnaire (ECIPQ) scale. T-test, bivariate correlations and a linear regression analysis were used for statistical analysis. (3) Results: The study results indicated positive relationships between cyberbullying patterns, especially cybervictimization, and age, as well as several physical fitness measures, including BMI, sit-ups, sit-and-reach, and handgrip tests. On the other hand, cyberperpetration was positively related only to age and the specific grip strength test. Further statistical analysis revealed that cybervictimization was primarily influenced by age, while cyberperpetration was mainly influenced by age and performance in a functional test (sit-and-reach). (4) Conclusions: Cyberbullying roles, both as victims and aggressors, may not be strongly influenced by isolated physical fitness factors. Thus, in order to reach a more comprehensive understanding and better explanations of individual involvement in cyberbullying behavior, future studies should analyze psychological and social factors along with the variables considered in this study.

Analysis of grip specificity on force production in grapplers and its effect on bilateral deficit grip specificity and bilateral deficit in force production among grapplers.

The use of strength training is important for athletes in combat sports such as judo and jiu-jitsu. Specificity is key when prescribing strength training programs for athletes, considering maximal strength, muscular power and strength-endurance. Grappling combat sports require grip control, which is necessary to execute throwing techniques and groundwork. The aim of this study was to verify the bilateral strength deficit in general and in grappling combat sport-specific action in the control group and grapplers. A sample of 73 subjects, divided into 2 groups, was used: the Student Group (15 females and 16 males) and the Grappler Group (29 males and 13 females). The male and female participants attended four laboratory sessions over a 48-hour interval, the first two to familiarize themselves with the Electromechanical Functional Dynamometer (EMFD), and the last two to collect maximal isometric strength data, using a standard grip and a judo/jiujitsu specific grip. Significant differences in mean and peak forces (p < 0.001) were found, with high performance combat sport athletes having greater maximal isometric strength compared to students both bilaterally and unilaterally (p < 0.001). All comparisons also indicated higher values for males compared to females (p < 0.001). The results suggest that specific training in combat sports as well as sex differences play a significant role in maximal isometric strength performance. The type of grip used affects the application of force in the upper limb isometric strength tests, finding a main effect of grip type (p < 0.001), with the standard grip obtaining higher levels. However, the dominance between hands remains constant. More research is needed on specific judogi/jiu-jitsu-gi grips and their impact on maximal isometric strength with the EMFD.

The effect of grip location on Kirschner wire bend characteristics: An in vitro study.

To determine the effect of Kirschner wire (K-wire) grip location on bend angle, bend radius, and torque when performing a Z-bend technique. Experimental study. Ten samples at each of five grip locations for each of three K-wire diameters. K-wires of three diameters (0.9, 1.1, 1.6 mm) were drilled into PVC pipe, and a Jacob's chuck was used to bend the wires at five periodic grip locations (distance from the bone model). Torque, bend angle, and bend radius were determined for each sample. Outcome variables were statistically analyzed by grip location to determine significant relationships. A grip location of 2.0cm in the 0.9 mm K-wire group minimized bend angle (mean ± SD: 75.92° ± 0.81) and bend radius (2.89 mm ± 0.08). A grip location of 3.0cm in the 1.1 mm K-wire group minimized bend angle (72.88° ± 0.98) and bend radius (2.47 mm ± 0.20). A grip location of 3.0cm minimized bend angle (74.38° ± 1.93) and bend radius (2.71 mm ± 0.27) in the 1.6 mm K-wire group. Torque at these grip locations for the 0.9, 1.1, and 1.6 mm K-wires was 6.50 N-m ± 0.0, 11.00 N-m ± 0.0, and 19.05 N-m ± 0.16, respectively. Bend angle and bend radius can be minimized by bending K-wires at specific grip locations, though torque is not minimized at these locations. Clinical significance These findings provide an evidence-based recommendation of where surgeons should grip K-wires when bending them.

Interface assembly of specific recognition gripper wrapping on activated collagen fiber for synergistic capture effect of iodine

Efficient capture of radioactive iodine (129I, 131I) is of great significance in spent fuel treatment. In this paper, a new adsorbent named Catechin@ACF was successfully prepared through interface assembly of specific recognition gripper with plant polyphenols (catechin) on activated collagen fiber (ACF), and the catechin membrane with specific grip on iodine was successfully constructed on the surface of ACF. The results showed that the adsorbent assembled catechin membrane was rich in aromatic rings, hydroxyl groups and imine adsorption sites, and possessed specific recognition and capture characteristics of iodine. Moreover, the as-prepared Catechin@ACF showed excellent capture capacity for iodine vapor and iodine in organic solution with the maximum capture capacity of 2122.68 mg/g and 258.29 mg/g, respectively. In iodine-cyclohexane solution, the adsorption process was in according with the Pseudo first order kinetic and Langmuir isothermal model. In addition, the specific recognition and capture mechanism analysis indicated that the aromatic rings, phenolic hydroxyl groups and imine groups in the catechin membrane were the specific and effective grippers for iodine, and finally iodine formed a stable conjugated system with the adsorbent in the form of I- and I3-. Therefore, the as-prepared specific iodine capturer Catechin@ACF was expected to play a vital role in the capture of radioactive iodine in spent fuel off-gas because of its specific recognition, high capture capacity, large-scale preparation, and environment-friendly.

The influence of tool use experience on efficient grasping in children

ABSTRACT The present study deals with the influence of specific motor experiences on efficient grasp planning. Forty 5- to 6-year-old children learned to use an unfamiliar tool with either a thumb-up or a thumb-down grip to accomplish a task. Before and after training, the extent to which children would rotate the tool using an awkward initial grip (thumb-down) to ensure a comfortable end-grip (end-state comfort), a pattern that has been interpreted as representing efficient grasping, was measured. The number of thumb-down grips increased only in the group that had trained to use the tool with this specific grip, but did not change after a training with an incongruent thumb-up grip. This demonstrates how the experience with specific tool-use-related grips influences efficient grasping.

Making Sense of Complex Sensor Data Streams

This concept paper draws from our previous research on individual grip force data collected from biosensors placed on specific anatomical locations in the dominant and non-dominant hand of operators performing a robot-assisted precision grip task for minimally invasive endoscopic surgery. The specificity of the robotic system on the one hand, and that of the 2D image-guided task performed in a real-world 3D space on the other, constrain the individual hand and finger movements during task performance in a unique way. Our previous work showed task-specific characteristics of operator expertise in terms of specific grip force profiles, which we were able to detect in thousands of highly variable individual data. This concept paper is focused on two complementary data analysis strategies that allow achieving such a goal. In contrast with other sensor data analysis strategies aimed at minimizing variance in the data, it is necessary to decipher the meaning of intra- and inter-individual variance in the sensor data on the basis of appropriate statistical analyses, as shown in the first part of this paper. Then, it is explained how the computation of individual spatio-temporal grip force profiles allows detecting expertise-specific differences between individual users. It is concluded that both analytic strategies are complementary and enable drawing meaning from thousands of biosensor data reflecting human performance measures while fully taking into account their considerable inter- and intra-individual variability.

Does the Grip Width Affect the Bench Press Performance of Paralympic Powerlifters?

To verify the effects of using different grip widths in bench press performance in Paralympic powerlifting athletes. Twelve experienced Paralympic powerlifting male athletes (25.40 [3.30]y, 70.30 [12.15]kg) participated in the study. Maximal dynamic strength and maximal isometric strength (MIS) were determined. Then, mean propulsive velocity (MPV) using 25%, 50%, and 100% of maximal dynamic strength load and time to achieve 30%, 50%, and 100% of MIS were assessed with 4 different grip widths, specifically the biacromial distance (BAD: 42.83 [12.84]cm), 1.3 BAD (55.68 [16.70]cm), 1.5 BAD (63.20 [18.96]cm), and 81cm. Electromyographic analysis was performed during MIS assessment in the pectoralis major sternal portion, anterior deltoid, triceps brachii long head, and pectoralis major clavicular portion. Large differences were found between MPV performed with different grip widths using 25% of maximal dynamic strength load (P = .02, ηp2=.26). The 1.5 BAD grip tended to show greater force generation and MPV. Moreover, the time needed to achieve 30%, 50%, and 100% of MIS differed between grip widths (P = .03, ηp2=.24), with the lowest values obtained in the 1.5 BAD. Despite the nonstatistical differences that were found, grip widths caused moderate effects on muscle myoelectric activation, showing greater values for pectoralis major clavicular portion and pectoralis major sternal portion, for the 1.3 BAD and 1.5 BAD, respectively. The 1.5 BAD the grip width tended to show greater MPV values and faster contractile responses. These results highlighted the importance of choosing the specific grip width for improvement of performance in Paralympic powerlifting athletes, by increasing velocity of movement and force production in a shorter time, with greater activation of primary muscles.

Einfluss eines aktiven Hand-Exoskeletts auf die Muskelaktivität im Unterarm bei industriellen Montage-Greifarten

Influence of an active hand exoskeleton on muscle activity of the forearm in industrial assembly grip types Objective: The study aims to identify the effects of the soft exoskeleton Bioservo IronHand® on muscle activity of the forearm flexor muscles in the following gripping tasks relevant to automotive assembly: 2-finger grip (2Finger), 5-finger grip (5Finger), full-hand grip (HandUmf). Methods: Twelve subjects were included in the study. The following exoskeleton conditions were applied to each subject for each grip task: Exoskeleton off (Off), Exoskeleton on, Locking Tendency 0 % (On_LT0) and Exoskeleton on, Locking Tendency 85 % (On_LT85) in order to examine their effects on the myoelectrical muscle activity of the forearm flexors at 50 % of the individual maximum hand strength (measured at M. flexor digitorum superficialis). Results: In the 2Finger condition, mean muscle activity, normalised to maximal muscle activation (MVE), increased significantly in On_LT0 (22.84 %MVE) compared to Off (18.51 %MVE, +4.33 %MVE, 95% CI [+1.88 %MVE; +6.78 %MVE]). No significant differences in muscle activity were observed for the 5Finger condition (Off: 19.38 %MVE, On_LT0: 20.37 %MVE, and On_LT85: 18.80 %MVE). For 2Finger and 5Finger conditions, clear intraindividual increases of muscle activity (&gt; Root Mean Square Error) were observed for one-third and one-quarter of all subjects respectively. In the HandUmf condition, mean muscle activity decreased significantly in both On_LT0 (28.87 %MVE, –4.35 %MVE, 95% CI [–1.36 %MVE; –7.35 %MVE]) and On_LT85 (26.98 %MVE, –6.24 %MVE, 95% CI [–3.25 %MVE ; –9.24 %MVE]) compared to Off (33.23 %MVE). Conclusion: The soft exoskeleton Bioservo IronHand® may reduce myoelectrical muscle activity of the forearm flexor muscles at 50 % of the maximum hand strength during HandUmf by 13 % (95% CI [4 %; 22 %]) for On_LT0 and 19 % (95% CI [10 %; 28 %]) for On_LT85 conditions. However, in 2Finger and 5Finger grip tasks, up to one third of the subjects showed increases in muscle activity of up to 120 % (reference level without support). Based on these results, the suitability of the exoskeleton remains questionable at least for these specific grip tasks at 50 % of the maximum hand strength. Keywords: exoskeleton – hand – work – grip – electromyography (EMG)

The effects of acute blood flow restriction on climbing-specific tests

The aim of the study was to compare climbing specific performance tests with and without blood flow restriction (BFR). Thirty one climbers (age 26.9 ± 5.5 years, height 177.2 ± 7.5 cm, weight 70.5 ± 8.3 kg, fat percentage 11.9 ± 4.1 %, climbing skill 18.9 ± 4.0 IRCRA scale) performed climbing specific grip tests measuring isometric strength (peak force, rate of force development and maximal voluntary contraction (and dynamic strength (power and peak velocity in pull-up) on a 23-mm campus rung. Further, an intermittent finger endurance (7 seconds work, 3 seconds rest at 60% of maximal voluntary contraction) test to failure was conducted. All tests were performed on two separate occasions (separated by 2–5 days) with and without blood flow restriction (200 mmHg) in a randomized order. The results demonstrated no differences in the isometric strength tests (p = 0.496–0.850, ES = 0.060–0.170), dynamic strength test (p = 0.226–0.442, ES = 0.200–0.330) or the intermittent finger endurance test (p = 0.563, ES = 0.160). In conclusion, no differences were observed in the maximal isometric pull-up test, dynamic pull-up test or finger endurance tests including measurements as peak force, MVC, RFD, power output, peak velocity or time to fatigue at 60% of MVC with and without BFR.

Comparative analysis of the influence of a high-fat/high-carbohydrate diet on the level of anxiety and neuromotor and cognitive functions in Wistar and DAT-KO rats.

We compared anxiety, neuromotor, and cognitive functions in mutant rats with different allelic variants of dopamine transporter DAT knockout receiving balanced or excess in fat and fructose diet. The experiments were performed in DAT−/− homozygotes, DAT+/− heterozygotes, and DAT+/+ wild type rats. The genotype of DAT‐KO rats was confirmed by restriction analysis of DAT gene compared to behavioral responses in the open field test (OF). Animals in the first groups of each strain were fed a balanced AIN93M diet; and those in the second groups with a high‐fat/high‐fructose diet. Neuromotor function was studied as grip strength, and behavioral responses were assessed in the elevated plus maze and conditioned passive avoidance response tests. The mass of the internal organs and white and brown fat, as well as selected lipid and nitrogen metabolism parameters in blood plasma were determined at the end of the experiment. DAT−/− had the highest specific grip strength, and showed an increase in initial exploratory activity in comparison with DAT+/− and DAT +/+. The exploratory activity was significantly reduced in the second test compared to the first one in DAT−/− and DAT+/− of first but not second group. Anxiety decreased with age in the second groups of DAT+/− and DAT+/+ (but not in DAT−/−) and was higher in DAT+/+ than in DAT+/− and DAT−/−. Excess fat and fructose resulted in the deterioration of short‐term memory in DAT+/+. Lipidomic indices of blood plasma were less responsive to diet in DAT−/− and DAT−/+ in comparison to DAT+/+. The increased AsAT/AlAT activity ratio in DAT−/− compared with those in DAT+/+ suggests the activation of catabolism activity in the mutants. The consumption of excess fat and fructose significantly modified the effects produced by DAT gene allelic variants presumably due to the influence on the processes of dopamine metabolism.

Влияние L-карнитина на иммунологические, интегральные и биохимические показатели мышей, получающих рацион с избытком жира и фруктозы

Effect of l-carnitine (Car) 300 mg/kg body weight consumption on physiological, integral biochemical, morphological and immunological parameters was studied in mice of inbred line DBA/2J and tetrahybrids of DBCB receiving during 65 days the high-fat diet with replacement of drinking water with a 30% fructose solution (HFCR). The level of search activity and anxiety of animals was studied in the test “Elevated plus maze” (EPM), muscle tone was determined by the specific grip force of the front paws. After completing the experiment, such indices were determined as the mass of internal organs, white and brown adipose tissue, liver morphology using light optical microscopy, concentrations of glucose, total and HDL cholesterol, triglycerides, enzyme activity of AlAT, AsAT, creatine phosphokinase (CPK), lipase on biochemical analyzer, insulin, leptin, ghrelin, IL-3, 5, 10, 12p (70), RANTES levels by multiplex immunoanalysis. It was shown that, in contrast to DBA/2J, DBCB mice responded to Car additive with an increase in the specific energy consumption of the diet. In these animals, Car consumption contributed to a decrease in the signs of fatty liver, a more pronounced (compared with DBA/2J) normalization of liver transaminases and CPK levels, decrease in the level of leptin and the leptin / ghrelin ratio. The EPM test showed that Car consumption potentiated the effect of increased mobility in DBA/2J mice and increased anxiety in DBCB mice. The influence of Car on insulin, IL-3, IL-12p(70) levels was similar in both populations of mice. The findings suggest a positive effect of Car on a number of lipid metabolism indicators and hepatoprotective effects in mice DBCB sensitive to HFCR and indicate the promise of using Car and its combinations with other biologically active food substances as a means of dietary correction of obesity and related alimentary-dependent diseases.

Handgrip strength in old and oldest old Swiss adults \u2013 a cross-sectional study

BackgroundHandgrip strength is indicative of overall physical health and mobility in the elderly. A reduction in strength below a certain threshold severely increases the risk of mobility limitations and is predictive for adverse outcomes such as dependence in daily activities and mortality. An overview of age- and geography- specific handgrip strength values in older adults provide a reference for further investigations and measures in clinical practice to identify people at risk for clinically meaningful weakness. The aim of this study was to evaluate handgrip strength in the Swiss-German population aged 75 and over.MethodsIn a cross-sectional study, maximal isometric handgrip strength of the dominant hand was evaluated in 244 Swiss people aged 75 years and over (62.7% women), with mean age (SD) of 84.5 (5.6) years in men and 83.1 (5.9) years in women. Demographic data and information about comorbidities, medication, fall history, global cognitive function, self-reported physical activity and dependence in activities of daily living were collected, and correlated with grip strength measures. Age- and gender specific grip strength values are reported as means, standard deviations and standard error of mean.ResultsSex-stratified handgrip strength was significantly lower with advancing age in men (p < .01), from 37.7 (6.5) kg to 25.6 (7.6) kg and in women (p < .01) from 22.2 (4.0) kg to 16.5 (4.7) kg. Handgrip strength in our sample was significantly higher than in Southern European countries. Handgrip strength was independently associated with age, height and ADL dependence in men and women. Overall, 44% of men and 53% of women had handgrip strength measures that were below the clinically relevant threshold for mobility limitations.ConclusionThis study reports the age- and sex-stratified reference values for handgrip strength in a representative sample of the Swiss population, aged 75–99 years. Although grip strength decreased with advancing age in both sexes; the relative decline was greater in men than women. Nonetheless men had significantly higher grip strength in all age groups. While the Swiss population sampled had greater grip strength than that reported in other European countries, about 50% were still classified as at risk of mobility limitations.

Passing Glasses

Passing an object is an everyday action with which most people are familiar. It involves detailed organizations of the body within a spatial and material setting. One place where objects are continuously passed is at the optician. Based on more than 700 hours of video recordings at 11 Danish opticians, this article shows how passing glasses is accomplished in an institutional context where the optician is interactionally constructed as responsible for securing the safe passing and avoiding the (problematic) drop. The paper contributes to EMCA studies on passings by showing how these actions may display deontic responsibilities, and how the passings are accomplished mainly by the optician using a specific grip, relying on tactile experiences, constantly monitoring the customer behaviour, and embodily anticipating next actions.

Cortical Substrate of Supraspinal Fatigue following Exhaustive Aerobic Exercise Localizes to a Large Cluster in the Anterior Premotor Cortex.

Strenuous exercise leads to a progressive reduction in the performance of voluntary physical exercise. This is due to a process described as fatigue and is defined as the failure to maintain the required or expected power output. While some of this is muscular in origin, there are data suggestive of how fatigue is modulated by cortical signals, leading to a concept of central fatigue. The previously reported fatigue-induced changes in cortical activity may have been due to blood oxygen-dependent (BOLD) signal drift and/or neural habituation alone. We implemented a functional magnetic resonance imaging paradigm to effectively isolate brain areas responsible for central (supraspinal) fatigue following exercise. Our data identify a large cluster that includes dominant the anterior ventral premotor cortex (aPMv), the insula and postcentral gyrus as critical nodes in the brain network where supraspinal fatigue might have their functional neural imprints. Findings here show that activity in the ipsilateral aPMv and the adjacent areas in the premotor cortex correlates with both localized fatigue (fatigue specific hand grip contraction), and generalized full body exhaustive fatigue. In addition, from a methodological standpoint, we have also shown that the effects of BOLD signal drift can be modeled and removed to arrive at specific brain activity patterns in our experiments. Once the loci of central fatigue are isolated in this way, treatments aimed at modulating activity in these premotor areas may reduce exercise-induced fatigue and perhaps also benefit various clinical conditions in which fatigue is a major symptom.

The extended object-grasping network.

Grasping is the most important skilled motor act of primates. It is based on a series of sensorimotor transformations through which the affordances of the objects to be grasped are transformed into appropriate hand movements. It is generally accepted that a circuit formed by inferior parietal areas AIP and PFG and ventral premotor area F5 represents the core circuit for sensorimotor transformations for grasping. However, selection and control of appropriate grip should also depend on higher-order information, such as the meaning of the object to be grasped, and the overarching goal of the action in which grasping is embedded. In this review, we describe recent findings showing that specific sectors of the ventrolateral prefrontal cortex are instrumental in controlling higher-order aspects of grasping. We show that these prefrontal sectors control the premotor cortex through two main gateways: the anterior subdivision of ventral area F5-sub-area F5a-, and the pre-supplementary area (area F6). We then review functional studies showing that both F5a and F6, besides being relay stations of prefrontal information, also play specific roles in grasping. Namely, sub-area F5a is involved in stereoscopic analysis of 3D objects, and in planning cue-dependent grasping activity. As for area F6, this area appears to play a crucial role in determining when to execute the motor program encoded in the parieto-premotor circuit. The recent discovery that area F6 contains a set of neurons encoding specific grip types suggests that this area, besides controlling "when to go", also may control the grip type, i.e., "how to go". We conclude by discussing clinical syndromes affecting grasping actions and their possible mechanisms.

Muscle Weakness and Physical Disability in Older Americans: Longitudinal Findings from the U.S. Health and Retirement Study.

Muscle weakness is an important indicator of disability, chronic disease and mortality. While we recently proposed sex/race specific grip strength cutpoints for clinical muscle weakness in a diverse, nationally representative sample of older Americans, the extent to which these cutpoints predict physical disability remains unknown. To examine whether sex/race specific muscle weakness cutpoints predict physical disability status in a nationally representative sample of Americans age 65+. We used data from the 2006-2010 Health and Retirement Study. Fully-adjusted, weighted multinomial logistic regression models were used to quantify the odds of experiencing the onset, progression or persistence of disability in activities of daily living (ADL) among weak versus non-weak individuals over a 2-year period. General community, nationally representative sample of older Americans. Population-based, community dwelling sample of older American adults aged 65-years+; 57 percent were women, 91% were White and the mean age was 75 years. Main Outcome(s) and Measure(s): The primary outcome of interest was disability dynamics, defined by changes in ADL status across at 2- year period. The primary exposure was clinical muscle weakness as defined by previously identified cutpoints. Hypotheses were formulated before analyses were conducted. In this nationally representative sample (n= 8,725), 44% of individuals were classified as weak at baseline. At follow-up, 55% remained independent with no change in their ADL status, 11% had an onset of disability and 4% progressed in their disability status. The odds of experiencing an onset of ADL disability was 54% higher among weak individuals compared those who were not weak at baseline (OR= 1.54, 95% CI= 1.54, 1.5, p<.0001); the odds of experiencing a progression in physical disability status was 2.16 times higher among those who were weak at baseline compared to non-weak individuals (OR= 2.16, 95% CI= 2.15, 2.16, p<.0001). This is the first study to use grip strength weakness cut-points to identify those who may be at greatest risk for experiencing physical disability in later life. Results underscore the importance of using population-specific cutpoints for clinical weakness in order to identify individuals at greatest risk for adverse health outcomes.

Task specific grip force control in writer’s cramp

ObjectiveWriter’s cramp is defined as a task specific focal dystonia generating hypertonic muscle co-contractions during handwriting resulting in impaired writing performance and exaggerated finger force. However, little is known about the generalisation of grip force across tasks others than writing. The aim of the study was to directly compare regulation of grip forces during handwriting with force regulation in other fine-motor tasks in patients and control subjects. MethodsHandwriting, lifting and cyclic movements of a grasped object were investigated in 21 patients and 14 controls. The applied forces were registered in all three tasks and compared between groups and tasks. In addition, task-specific measures of fine-motor skill were assessed. ResultsAs expected, patients generated exaggerated forces during handwriting compared to control subjects. However there were no statistically significant group differences during lifting and cyclic movements. The control group revealed a generalisation of grip forces across manual tasks whereas in patients there was no such correlation. ConclusionWe conclude that increased finger forces during handwriting are a task-specific phenomenon that does not necessarily generalise to other fine-motor tasks. SignificanceForce control of patients with writer’s cramp in handwriting and other fine-motor tasks is characterised by individualised control strategies.

Selectivity for grip type and action goal in macaque inferior parietal and ventral premotor grasping neurons

Grasping objects requires the selection of specific grip postures in relation to the objects' physical properties. Furthermore, grasping acts can be embedded in actions aimed at different goals, depending on the context in which the action is performed. Here we assessed whether information on grip and action type integrate at the single-neuron level within the parieto-frontal motor system. For this purpose, we trained three monkeys to perform simple grasp-to-eat and grasp-to-place actions, depending on contextual cues, in which different grip types were required in relation to target features. We recorded 173 grasping neurons: 86 from the inferior parietal area PFG and 87 from the ventral premotor area F5. Results showed that most neurons in both areas are selective for grip type, but the discharge of many of them, particularly in PFG, appears to differ in relation to action context. Kinematics data and control experiments indicated that neuronal selectivity appears more likely to depend on the action goal triggered by the context than on specific contextual elements. The temporal dynamics of grip and goal selectivity showed that grasping neurons reflect first "how" the object has to be grasped (grip), to guide and monitor the hand shaping phase, and then "why" the action is performed (goal), very likely to facilitate subsequent motor acts following grasping. These findings suggest that, in the parieto-frontal system, grip types and action goals are processed by both parallel and converging pathways, and area PFG appears to be particularly relevant for integrating this information for action organization.

Methods for increasing the efficiency of a hinged joint of a dredge scoop chain

The experimental data on the serviceability of the components of a hinged joint of the dredge scoop chain subjected to high specific pressures, low-temperature grip, and abrasion during their operation are presented. The comparative analysis of different methods for increasing the reliability of the joint components (surfacing, thermal treatment, alloying of pins from G13 steel, etc.) is given.

Decoding the activity of grasping neurons recorded from the ventral premotor area F5 of the macaque monkey

Many neurons in the monkey ventral premotor area F5 discharge selectively when the monkey grasps an object with a specific grip. Of these, the motor neurons are active only during grasping execution, whereas the visuomotor neurons also respond to object presentation. Here we assessed whether the activity of 90 task-related F5 neurons recorded from two macaque monkeys during the performance of a visually-guided grasping task can be used as input to pattern recognition algorithms aiming to decode different grips. The features exploited for the decoding were the mean firing rate and the mean interspike interval calculated over different time spans of the movement period (all neurons) or of the object presentation period (visuomotor neurons). A support vector machine (SVM) algorithm was applied to the neural activity recorded while the monkey grasped two sets of objects. The original set contained three objects that were grasped with different hand shapes, plus three others that were grasped with the same grip, whereas the six objects of the special set were grasped with six distinctive hand configurations. The algorithm predicted with accuracy greater than 95% all the distinct grips used to grasp the objects. The classification rate obtained using the first 25% of the movement period was 90%, whereas it was nearly perfect using the entire period. At least 16 neurons were needed for accurate performance, with a progressive increase in accuracy as more neurons were included. Classification errors revealed by confusion matrices were found to reflect similarities of hand grips used to grasp the objects. The use of visuomotor neurons' responses to object presentation yielded grip classification accuracy similar to that obtained from actual grasping execution. We suggest that F5 grasping-related activity might be used by neural prostheses to tailor hand shape to the specific object to be grasped even before movement onset.