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PubMed1999

Parallel pathways mediating manual dexterity in the macaque.

Transmission of information along appropriately structured parallel pathways ensures that a great deal of information can be transferred from the source to the target very quickly, and with great security-essential features of any motor control system. Studies over the last two decades have established that the corticospinal and corticocerebellar pathways mediating manual dexterity in the primate are structurally organized to sustain the parallel transmission of sensorimotor information in multiple pathways. Serial, hierarchical control systems now seem insufficient to regulate voluntary hand movements. To achieve the required coordination, and precision and speed of execution, they must be combined with parallel control systems, which themselves incorporate elaborate feedforward and feedback controls. To illustrate these issues, two aspects of the structural organization of parallel sensorimotor pathways mediating manual dexterity in the macaque are reviewed. First, we examine the structure of the multiple corticospinal neuron subpopulations projecting from different areas of the frontoparietal cortex and how they are modified following hemisection of the cervical spinal cord. The remarkable recovery of hand function following spinal hemisection, despite the absence of any structural 'bridging' of the interrupted spinal pathways, and the fact that this is accountable in a parallel but not in a purely serial transmission system, are then reviewed. The second aspect of parallel distributed transmission examined is its occurrence within a single population of relay neurons. Our recent structural analysis of the somatic/dendritic organization of rubrospinal neurons in macaque red nucleus is used. The very large dendritic fields of individual neurons, extending over one-third or more of the nucleus, provide a framework for extracting precise somatotopic information from an input population whose axon terminal arbors overlap extensively, and, which, without effective filtering, would provide poor spatial resolution.

Animals↗

PubMed2002

Measurement of manipulative dexterity in patients with hand-arm vibration syndrome.

OBJECTIVES: The purpose of the study was to assess quantitative measurements of the manipulative dexterity of patients suffering from hand-transmitted vibration disorder, and to investigate a possible link with impaired tactile perception in their hands. SUBJECTS AND METHODS: The subjects were 30 patients with hand-arm vibration syndrome, 30 office workers and 20 manual laborers of similar ages. Manipulative dexterity was assessed by measuring the performance time of buttoning-unbuttoning a work jacket with five buttons and of picking up and transferring 30 red beans, one by one, with the fingers from one plate to another. Patients were also examined on vibrotactile thresholds at 125 Hz as well as pain thresholds. RESULTS: The buttoning-unbuttoning time and the bean transfer time were significantly prolonged in the patients compared with the worker groups. The patients showed a close correlation between the buttoning-unbuttoning time and the bean transfer time. Performance times did not differ between patients with vibration-induced white finger and those without it. Those times also correlated with the vibrotactile and pain thresholds in the patients. When a cut-off value was set at 2 SDs from the mean performance times of the manual laborers, exceeding the cut-off value was found in 70% of the patients for the button-unbutton test and in 80% of those for the bean transfer test. All patients with moderately or severely increased vibrotactile and pain thresholds exceeded that value in performing the two tasks. CONCLUSION: The present measurements quantitatively showed impaired manipulation in patients with hand-arm vibration syndrome. Such difficulty with manipulation seems to be associated with the impaired tactile sensation in their hands.

Arm↗

PubMed2005

Cor triatriatum dexter in two adult patients.

Cor triatriatum dexter, in which the right atrium (RA) is divided into two chambers by a membrane, is a very rare congenital abnormality. In this abnormality, there is a high incidence of associated congenital abnormalities, particularly of the right heart. We presented two men with cor triatriatum dexter. Echocardiography is discussed as a non-invasive diagnostic tool.

Adult↗

PubMed2004

Cor triatriatum dexter, atrial septal defect, and Ebstein's anomaly in an adult given a diagnosis by transthoracic and transesophageal echocardiography: a case report.

Cor triatriatum dexter is a very rare congenital abnormality in which the right atrium is divided into two chambers by a membrane. In this abnormality, there is a high incidence of associated congenital abnormalities, particularly of the right heart. In this case study, a 67-year-old man with Ebstein's anomaly, atrial septal defect, and cor triatriatum dexter is presented and echocardiography is discussed as a noninvasive diagnostic tool.

Aged↗

PubMed2005

Training on bench models improves dexterity in ureteroscopy.

INTRODUCTION: There is a need for alternative training in endourology. Computerised simulators have been introduced but have, so far, not been compared to real surgery. Bench models have proved to be comparable to real surgery when performing standard procedures in the upper urinary tract. OBJECTIVE: To validate training on bench models as a tool to improve dexterity in semi-rigid ureteroscopy. METHODS: Urology residents were tested when performing semi-rigid ureteroscopy on a bench model (Mediskills), before and after training. All standard equipment and instruments, including fluoroscopy, were available. For the test procedure we used a task-specific checklist and a global score (maximum score 10 + 9 = 19). After base line assessment, the participants practised under supervision. After training they were reassessed, using the same procedure as previously. RESULTS: The performance was significantly better after the training. Results before/after were: 5.1/9.2, 2.6/7.8 and 7.7/17.2 for task-specific checklist, global score and total score respectively. All residents felt more familiar with the instruments and the procedure after the training. CONCLUSION: Training on bench models for ureteroscopy enhanced the manual dexterity as well as familiarity with the method and is recommendable before operating on patients.

Education, Medical, Graduate↗

PubMed2004

Role of the spacer in the singlet-singlet energy transfer mechanism (Förster vs Dexter) in cofacial bisporphyrins.

The cofacial bisporphyrins H4DPS (DPS = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzothiophene), H4DPO (DPO = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzofuran), H4DPX (DPX = 4,5-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-9,9-dimethylxanthene), H4DPA (DPA = 1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]anthracene), and H4DPB (DPB = 1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]biphenylene) have been monometalated by Zn(OAc)2.2H2O and by GaCl3 to explore the singlet-singlet energy transfer from the photoexcited metal porphyrin center to the linked free base porphyrin. The spectroscopic (UV-vis and fluorescence) and photophysical properties (fluorescence lifetimes, tauF, and quantum yields, phiF) have been investigated at 298 and 77 K in degassed 2-MeTHF for the donor-acceptor systems, (Zn)H2DPS, (Zn)H2DPO, (Zn)H2DPA, (Zn)H2DPX, and (Zn)H2DPB, as well as for the bis-zinc complexes, (Zn)2DPS, (Zn)2DPO, (Zn)2DPX, and (Zn)2DPB, respectively, and the monoporphyrin derivatives, H2P, (Zn)P, and (Ga-OMe)P (P2- = 5-phenyl-2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin-dianion). The singlet-singlet energy transfer rate constants (KET) were obtained using KET = (1/tauF -1/tauFo), where tauFo is the fluorescence lifetime of the corresponding bis-zinc(II) systems (or (Zn)P and (Ga-OMe)P) where no energy transfer occurs. The tauF value for three bis-zinc(II) compounds varies from 1.69 to 2.01 ns and is 1.84 (at 298 K) and 3.20 ns (at 77 K) for (Ga-OMe)P. In the donor-acceptor bismacrocycles, depending on the spacer and the temperature, the fluorescence lifetimes decrease down to 50-240 ps. The KET values range from approximately 4 to approximately 21 (ns(-1)) and have been analyzed considering both the Förster and the Dexter mechanisms. Using the C(meso)-C(meso) distance parameters in the calculations, the Förster and Dexter mechanisms operate for DPS and DPO, and for DPA, DPX, and DPB spacer systems, respectively. The limit distance where one mechanism dominates over the other is estimated to be around 5-6 A.

Journal Article↗

PubMed1986

Effects of brief cold exposure on finger dexterity and sensibility in subjects with Raynaud's phenomenon.

Treatment of the person with Raynaud's phenomenon is directed toward improving hand function during cold exposure. To assess treatment objectively, hand function after cold stress needs to be assessed. The purpose of this study was to determine whether two-point discrimination and finger dexterity were affected differentially between a healthy sample and subjects with Raynaud's symptoms as a result of exposure to an ice bath. The results showed a decreased performance on the Purdue Pegboard test and in two-point discrimination for both groups. A statistically significant decrease for performance on the Purdue Pegboard test was noted when the Raynaud's group was compared with the control group. Perception of cold pain also was statistically greater in the Raynaud's group but did not correlate with the reduction in finger dexterity. We discuss the use of ice water immersion as a potential evaluation procedure for assessing improved hand function in patients undergoing temperature biofeedback and other treatment methods.

Adult↗

PubMed2003

Surgical correction of cor triatriatum dexter in a dog under extracorporeal circulation.

A shiba inu dog with marked abdominal distension was diagnosed with cor triatriatum dexter and surgical correction was performed under extracorporeal circulation. The total duration of cardiac arrest was 11 minutes and total perfusion time was 34 minutes. The dog had an uneventful postoperative recovery. Postoperative contrast radiography of the caudal vena cava revealed normal flow into the right heart. Abdominal distension was no longer observed. Although several methods have been used to treat cor triatriatum dexter in dogs, the authors consider surgical correction under extracorporeal circulation to be a reliable approach.

Animals↗

PubMed1990

Cor triatriatum dexter: antemortem diagnosis in an adult by cross sectional echocardiography.

Cor triatriatum dexter is a rare cardiac abnormality in which the right atrium is subdivided into two distinct chambers. This anomaly is generally attributed to the persistence of the right sinus venosus valve and it is frequently associated with severe malformations of other right heart structures. The antemortem diagnosis of the membrane may be difficult and its presence is often only established at necropsy. In a woman of 56 with Ebstein's anomaly the echocardiographic features of cor triatriatum dexter were examined before and during cardiac catheterisation. These investigations showed the position of the membrane, that there was no gradient between the two atrial chambers, and that there were perforations in the centre of the membrane.

Cor Triatriatum↗

PubMed2001

Toward a physiological understanding of human dexterity.

Dexterity, defined as the skillful manipulation of the hands, is now amenable to physiological investigation. Two topics are discussed here: grasping (i.e., hand-object coupling) and bimanual coordination. Dexterity depends on powerful, distributed neural networks and is particularly vulnerable to brain lesions. A knowledge of physiological mechanisms is needed to deal with these neurological problems.

Functional Laterality↗

PubMed1983

The role of the corticospinal tract in the evolution of human digital dexterity.

A morphometric analysis of the corticospinal tract's relation to digital dexterity was performed on 21 species theoretically related to man's ancestral lineage. The results indicate that the Primate line is not unique among mammals with respect to the cortical control of digital dexterity. A comparative analysis suggests that two changes took place early in Primate evolution: a reduction in functional distance (i.e. number of synapses) between neocortex and spinal motor neurons innervating the digits, and an extension of direct neocortical influence beyond the cervical segments of the spinal cord. A further change progressed throughout Primate evolution, from the mid-Eocene to the present, in which the overall size of the corticospinal tract increased steadily as though consolidating the cortical influence over body musculature, especially that of the digits.

Animals↗

PubMedDate not supplied

The effects of solvent exposure on memory and motor dexterity in working children.

OBJECTIVES: Children working in vehicle spray-painting, mechanical, and other trade workshops are at significant risk of exposure to organic solvents and, as a result, may be at significant risk of developing clinical and subclinical signs of neurotoxicity. This study reports on the association between exposure to solvents and neurobehavioral performance on a number of non-computerized tests for working children exposed to solvents in comparison with nonexposed working children and nonexposed children at school. METHODS: A convenience cross-sectional sample of 300 male children aged 10-17 years was recruited for study. The exposed working group and the two nonexposed groups (working and nonworking school) were matched, as far as possible, on geographic location of residence and age. Neurotoxic effects were assessed through a questionnaire and the child's performance on a selection of neurobehavioral tests. RESULTS: Exposed working children scored worse on the overall neurotoxicity symptoms score (mean=6.8; standard deviation [SD]=3.6) compared with the nonexposed working children (mean=1.3; SD=2.0) and school children (mean=1.2; SD=1.8). Analysis of the non-computerized neurobehavioral tests demonstrated that exposed working children performed significantly worse than the two nonexposed groups on the motor dexterity and memory tests. Results of the mood test showed that exposed working children were more angry and confused than the nonexposed groups. CONCLUSION: There is an association between exposure to solvents and lower neurobehavioral performance, with significant neurobehavioral deficits among children exposed to solvents in comparison with working children not exposed to solvents and nonworking school children. Memory and motor dexterity appear to be particularly affected in solvent-exposed working children.

Adolescent↗

PubMedDate not supplied

Measuring dexterity in children using the Nine-hole Peg Test.

The purpose of this study was to measure dexterity in children aged 4-19 years using the Nine-hole Peg Test. Four hundred and six children were tested with their dominant hand and then their nondominant hand. A commercial version of the Nine-hole Peg Test was used. An analysis of variance showed a main effect for age, gender, and hand dominance. Speed of dexterity improved with age. In all age groups, females performed faster than males. Participants performed faster with the dominant hand than the nondominant hand. The normative data collected provide information for comparing scores to children with different diagnostic categories to screen for fine motor difficulties.

Adolescent↗

PubMed1995

Dexterity and sexuality: is there a relationship?

In all the recent research on sexuality, one striking analogy that has been largely overlooked is that of sexuality and dexterity. This article is a parallel synthesis of the current knowledge of these two subjects. Although there does not seem to be a causal relationship between these two traits (a particular dextral tendency does not imply any associated sexual tendency, or vice versa), a short description of past attitudes and beliefs concerning left-handedness illustrates the historical similarity of social bias against homosexuality. Second, a discussion of the current scientific information on dexterity and sexuality reveals how these tendencies are in fact analogous. Finally, the article questions how society can maintain its discriminatory policies against homosexuality when it is no more a distinctive trait in human nature than left-handedness.

Adult↗

PubMed1998

Two measures of laterality in handedness: the Edinburgh Handedness Inventory and the Purdue Pegboard test of manual dexterity.

This study investigated the relationship between a paper-and-pencil measure of laterality in handedness, the Edinburgh Handedness Inventory, and a test of manual dexterity, the Purdue Pegboard test. Individuals of extreme handedness based on the Edinburgh Handedness Inventory (laterality Quotients of +90 to +100 and -100 and +54; 50 each) were recruited to complete the Purdue Pegboard test of manual dexterity. Subjects in the sinistral group had significantly smaller mean discrepancy scores in performance between their hands [t80 = 5.12, p = .0001] and much greater variance in performance than dextral subjects (F1,98 = 2.85, p = .0001). These findings suggest that paper-and-pencil measures of lateral preference for handedness may not identify proficiency of subgroups within a sinistral group.

Functional Laterality↗

PubMed2000

An investigation of finger and manual dexterity.

In ergonomics, handgrip has been perceived as one of the most important hand functions; however, other types of functions of the hand are also important to the ergonomist, such as finger and manual dexterity, on which few ergonomic studies have been done. This experiment involved 60 male and female college students whose performance (number of pegs placed into a board in 30 sec.) of finger dexterity were statistically significantly different between the right and left hands and between women and men. The interaction of hand and sex was significant.

Biomechanical Phenomena↗

PubMed2003

Normative data and developmental characteristics of hand function for elementary school children in Suwon area of Korea: grip, pinch and dexterity study.

This study was designed to establish norms of hand function, and to identify developmental characteristics of hand function among the Korean children. 712 elementary school children participated in measurement of grip strength, three kinds of pinch strength, and dexterity. The hand strength of the Korean children appeared to be weaker than that of western children. The grip strength of boys was significantly stronger than that of girls in all ages for both hands. The order of magnitude of three kinds of pinch strength was, in descending order, lateral pinch, palmar pinch and tip pinch for both boys and girls. There was no significant difference of hand function according to the type of hand dominance in boys. However, girls with left hand dominance showed weakness of bilateral grip, right tip pinch, and bilateral lateral pinch strength compared with girls with right hand dominance. In conclusion, this study provided normative data of hand functions including dexterity, and enabled us to identify some developmental characteristics of hand functions for the Korean elementary school children.

Age Factors↗

PubMed1995

The effectiveness of cut-proof glove liners: cut and puncture resistance, dexterity, and sensibility.

Five types of commercial glove liners (within double latex gloves) were compared to single and double latex gloves for cut and puncture resistance and for relative manual dexterity and degree of sensibility. An apparatus was constructed to test glove-pseudofinger constructs in either a cutting or puncture mode. Cutting forces, cutting speed, and type of blade (serrated or scalpel blade) were varied and the time to cut-through measured by an electrical conductivity circuit. Penetration forces were similarly determined with a scalpel blade and a suture needle using a spring scale loading apparatus. Dexterity was measured with an object placement task among a group of orthopedic surgeons. Sensibility was assessed with Semmes-Weinstein monofilaments, two-point discrimination, and vibrametry using standard techniques and rating scales. A subjective evaluation was performed at the end of testing. Time to cut-through for the liners ranged from 2 to 30 seconds for a rapid oscillating scalpel and 4 to 40 seconds for a rapid oscillating serrated knife under minimal loads. When a 1 kg load was added, times to cut-through ranged from 0.4 to 1.0 second. In most cases, the liners were superior to double latex. On average, 100% more force was required to penetrate the liners with a scalpel and 50% more force was required to penetrate the liners with a suture needle compared to double latex. Object placement task times were not significantly liners compared to double latex gloves. Semmes-Weinstein monofilaments, two-point discrimination, and vibrametry showed no difference in sensibility among the various liners and double latex gloves. Subjects felt that the liners were minimally to moderately impairing. An acclimation period may be required for their effective use.

Equipment Design↗