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Elderly show decreased adjustments of motor synergies in preparation to action.

BACKGROUND: Aging is associated with decreased manual dexterity. Recent findings have identified changes in multi-finger synergies in elderly individuals. The purpose of current work was to study age-related changes in adjustments of multi-finger synergies in preparation to a quick targeted force pulse production task. METHODS: Right-handed elderly and young subjects produced quick force pulses by pressing on individual force sensors with the four fingers of the right hand. Prior to the force pulse, the subjects produced a constant low level of the total force. An index of multi-finger synergies was computed across trials for each time sample for each subject and each condition. FINDINGS: During steady-state force production, subjects showed co-variation of commands to fingers that stabilized the total force. An index of this co-variation started to decrease prior to the initiation of the force pulse (anticipatory synergy adjustment). Anticipatory synergy adjustments in young subjects started earlier and were larger than in elderly subjects. In particular, young and elderly subjects showed significant anticipatory synergy adjustments starting about 150ms and about 50ms prior to the force pulse initiation, respectively. There were no significant differences between the two groups in other indices of performance such as reaction time, time to peak force, and magnitude of the peak force. INTERPRETATION: We conclude that healthy aging is associated with decreased feed-forward adjustments of multi-finger synergies in preparation to action. This may contribute to the age-related decline in the hand function. Based on similarities in age-related changes in anticipatory postural adjustments and anticipatory synergy adjustments we suggest a hypothesis that the two phenomena may share common mechanisms.

Adult↗

Modulation of motor cortex excitability after upper limb immobilization.

OBJECTIVE: To examine the mechanisms of disuse-induced plasticity following long-term limb immobilization. METHODS: We studied 9 subjects, who underwent left upper limb immobilization for unilateral wrist fractures. All subjects were examined immediately after splint removal. Cortical motor maps, resting motor threshold (RMT), motor evoked potential (MEP) latency and MEP recruitment curves were studied from abductor pollicis brevis (APB) and flexor carpi radialis (FCR) muscles with single pulse transcranial magnetic stimulation (TMS). Paired pulse TMS was used to study intracortical inhibition and facilitation. Compound muscle action potentials (CMAPs) and F waves were obtained after median nerve stimulation. In 4/9 subjects the recording was repeated after 35-41 days. RESULTS: CMAP amplitude and RMT were reduced in APB muscle on the immobilized sides in comparison to the non-immobilized sides and controls after splint removal. CMAP amplitude and RMT were unchanged in FCR muscle. MEP latency and F waves were unchanged. MEP recruitment was significantly greater on the immobilized side at rest, but the asymmetry disappeared during voluntary muscle contraction. Paired pulse TMS showed an imbalance between inhibitory and excitatory networks, with a prevalence of excitation on the immobilized sides. A slight, non-significant change in the strength of corticospinal projections to the non-immobilized sides was found. TMS parameters were not correlated with hand dexterity. These abnormalities were largely normalized at the time of retesting in the four patients who were followed-up. CONCLUSIONS: Hyperexcitability occurs within the representation of single muscles, associated with changes in RMT and with an imbalance between intracortical inhibition and facilitation. These findings may be related to changes in the sensory input from the immobilized upper limb and/or in the discharge properties of the motor units. SIGNIFICANCE: Different mechanisms may contribute to the reversible neuroplastic changes, which occur in response to long-term immobilization of the upper-limbs.

Action Potentials↗

The ipsilateral silent period in boys with attention-deficit/hyperactivity disorder.

OBJECTIVE: Characterize maturation of transcallosal inhibition (ipsilateral silent period [iSP]) in attention deficit/hyperactivity disorder (ADHD) using transcranial magnetic stimulation (TMS). BACKGROUND: Maturation of the iSP is related to acquisition of fine motor skills in typically developing children suggesting that dexterous fine motor skills depend upon mature interhemispheric interactions. Since neuromotor maturation is abnormal in boys with ADHD we hypothesized that iSP maturation in these children would be abnormal. We studied iSP maturation in 12 boys with ADHD and 12 age-matched, typically developing boys, 7-13 years of age. METHODS: Surface electromyographic activity was recorded from right first dorsal interosseus (FDI). During background activation, focal TMS was delivered at maximal stimulator output over the ipsilateral motor cortex. RESULTS: Maturation of finger speed in boys with ADHD was significantly slower than that in the control group. The iSP latency decreased with age in the control group but not in the ADHD group. CONCLUSIONS: These findings suggest the presence of a complex relationship between abnormalities of certain interhemispheric interactions (as represented by iSP latency) and delayed maturation of neuromotor skills in boys with ADHD. SIGNIFICANCE: These data provide preliminary physiologic evidence supporting delayed or abnormal development of interhemispheric interactions in boys with ADHD.

Adolescent↗

Differential modulations of intracortical neural circuits between two intrinsic hand muscles.

OBJECTIVE: To investigate whether the intracortical inhibitory (ICI) and facilitatory (ICF) circuits in the primary motor cortex between the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles are modulated differently. METHODS: We conducted paired-pulse transcranial magnetic stimulation in combination with different current directions (anterior-medially: AM, and posterior-laterally: PL) under relaxed and active muscle conditions with interstimulus intervals (ISIs) between 2 and 16 ms. RESULTS: In both muscle conditions, the conditioned motor-evoked potential (MEP) responses obtained with the AM current direction (preferentially eliciting early I-waves) were similar between the two muscles at all ISIs, but the MEP responses obtained with the PL current direction (preferentially eliciting late I-waves) were different between FDI and ADM muscles, in that the conditioned MEP responses in FDI muscle were inhibited at all ISIs under both muscle conditions, whereas those in ADM muscle were suppressed at only short ISIs (2-4 ms). CONCLUSIONS: These results indicate that the inhibitory connections operating for the corticospinal tract neurons in FDI muscle are more potent, and, conversely, that those in ADM muscle are weaker. SIGNIFICANCE: The different modulations of ICI circuits between FDI and ADM muscles is an important neural mechanism which may contribute to different functional demands (finger dexterity).

Adult↗

Impairments in precision grip correlate with functional measures in adult hemiplegia.

OBJECTIVE: Analysis of a precision grip-lift task provides measures to assess functional disability of the hand, but the correlation between these measures and accepted tests of motor function in stroke patients has not been established. METHODS: Seventeen subacute stroke patients were studied to compare parameters of a precision grip-lift task between the affected and unaffected side, and to correlate them with function. Functional impairment was assessed with the Action Research Arm Test and the Fugl-Meyer assessment, as well as grip strength and maximal finger-tapping speed. The grip force (GF) and load force (LF) were recorded as patients lifted a custom-built manipulandum. All measures were recorded on two separate occasions, at least 1 week apart. RESULTS: There was good reproducibility between testing sessions for the grip-lift and functional measures. The affected hand gripped the manipulandum for longer prior to lift-off than the unaffected hand, and the normal close temporal coupling between the rate of change of GF and LF during the lift was disrupted. These two measures correlated more highly with the ARAT than the FMA and, when combined with measures of grip strength and tapping speed, explained 71% of the variance of the ARAT. CONCLUSIONS: The grip-lift task is a sensitive measure of impaired dexterity following stroke and provides measures which correlate well with a commonly applied functional assessment scale. SIGNIFICANCE: This task may be used clinically to detect changes in the hemiplegic upper limb during rehabilitation and recovery.

Aged↗

Use of a cognitive ergonomics approach to compare usability of a multidose dry powder inhaler and a capsule dry powder inhaler: an open-label, randomized, controlled study.

BACKGROUND: Usability (ease of use) is an important feature of inhalers to ensure optimal dose delivery OBJECTIVE: The aim of this study was to compare the usability of a multidose dry powder inhaler (mDPI) and a capsule dry powder inhaler (cDPI) in older individuals, using a range of qualitative and quantitative techniques from the field of cognitive ergonomics. METHODS: Participants aged >50 years were enrolled in this 2-visit, open-label, randomized, controlled, parallel-group study conducted at Northumbria University, Newcastle upon Tyne, United Kingdom. Participants who had used an inhaler or were inhaler naive were randomized to use the mDPI or cDPI. At visit 1, the inhaler procedure was demonstrated twice by the investigator. Participants then repeated the procedure (although they were not expected to inhale because no drug was to be administered) until they made 3 consecutive correct attempts. They also undertook a range of tests to assess their confidence in using the device, manual dexterity, and self-efficacy At visit 2 (2 days later), participants made a single inhaler attempt before receiving any demonstrations from the investigator; this was intended to simulate clinical practice, in which the patient may not use an inhaler for a few days after it is prescribed. Participants then completed the inhaler procedure 10 times while undertaking a concurrent distracter task. The number of critical errors (ie, those having a high impact on dose delivery) was recorded for all attempts. To facilitate subsequent correlation analyses, an overall performance measure was derived from a combination of the results of the single inhaler trial and the 10 trials with a distracter. RESULTS: Eighty individuals (51 women, 29 men; mean [SD] age, 74.1 [7.5] years) participated in the study(40 participants per device). Forty of the participants (50%) had used an inhaler previously; 40 (50%) were inhaler naive. Based on the overall performance measure, participants testing the mDPI made significantly fewer critical errors than participants testing the cDPI (P < 0.001). Participants rated both inhalers as easy to use but were overconfident concerning their ability to use the 2 devices. CONCLUSIONS: In this study of usability of an mDPI and a cDPI in older participants, participants found both inhalers easy to use, but fewer critical errors were made with the mDPI compared with the cDPI. However, the results suggest a degree of overconfidence and the need for continual monitoring of patients' inhalation technique, especially with the cDPI.

Administration, Inhalation↗

Robotic surgery setup simulation with the integration of inverse-kinematics computation and medical imaging.

At present, there are representative robot operation systems such as da Vinci and ZEUS which have realized minimally invasive surgery by the use of dexterous manipulators. In the operating room, medical staff must prepare and set up an environment in which the robot has optimal freedom of motion and its functions can be fully demonstrated for every case. The range of motion in which the robot can reach and be maneuvered is restricted by the fixed point of the trocar site. We have developed a preoperative planning system with the function of volume rendering of medical images and automatic positioning by applying an inverse-kinematics computation of surgical robot. The motion of a surgical robot can be simulated in advance with the intuitive interface and kinematics computation program running in the background of the system. If robotic surgery planning with volume rendering of DICOM images is possible, the discussion of a surgical plan can be directly made just after the diagnosis considering the patient-specific structure. This kind of setup platform would be essential for the future introduction of surgical robotics into an operating room.

Algorithms↗

Cortical topography of human anterior intraparietal cortex active during visually guided grasping.

Dexterous manual prehension requires successfully transforming sensory representations of an object's intrinsic spatial properties (e.g., shape) into motor plans for configuring the opposition space of the hand. In macaques, these sensorimotor transformations are accomplished in a circuit connecting the anterior intraparietal sulcus (area AIP) with inferior frontal cortex (area F5ab). Activation in the human anterior intraparietal sulcus (aIPS) during visually guided grasping suggests a homologue of macaque area AIP. If true, then despite individual variation in cortical topography, visually guided grasping should be consistently associated with focal activation at the junction of the IPS and postcentral sulcus. FMRI was used to test this hypothesis in 14 right-handed adults. Despite substantial variability in IPS topography, a contrast between pincer grasping vs. reaching to complex asymmetrical shapes revealed activation foci at the junction of the IPS and postcentral gyrus in all 14 individuals. This site is likely within the most superior, rostral aspect of Brodmann's area 40, corresponding to area PF or PDE as defined by von Economo and Koskinas, and area 86 as defined by Vogt and colleagues. In both humans and macaques this region appears to play a key role in visually guided grasping.

Adult↗

Perspectives in endoscopic cardiac surgery.

Surgical telemanipulators are obviously used in cardiac surgery to provide the surgeon in a confined space the same stereoscopic vision, full dexterity, unimpaired hand-eye alignment and tactile feedback as in open surgery. This is the basic concept that enables the controlled fine soft tissue manipulation that is needed in bypass grafting and valve surgery. In 2005, a total of 2984 cardiac procedures were performed worldwide using the da Vinci system. This includes totally endoscopic coronary artery bypass grafting (TECAB), mitral valve repair (MVR) procedures, ASD closure and cardiac tissue ablation for atrial fibrillation.

Cardiac Surgical Procedures↗

Demographic, clinical, and neurocognitive predictors of quality of life in schizophrenia patients receiving conventional neuroleptics.

We sought to evaluate demographic, clinical, and neurocognitive predictors of self-rated life quality and hospitalization in schizophrenia patients without the potentially cognition-enhancing influence of newer generation neuroleptic medication. A sample of 55 atypical neuroleptic-naive schizophrenia patients was assessed at index and 3 years later. Index neurocognitive measures included general intellectual ability (IQ), executive ability (Wisconsin Card Sorting Test [WCST]), verbal memory (California Verbal Learning Test [CVLT]), and manual dexterity (Purdue Pegboard). These measures, along with demographic (age, sex, education) and clinical (symptoms, prior hospitalizations) variables, were entered into regression equations to predict life quality (Sickness Impact Profile [SIP]) at follow-up, as well as rehospitalization during the 3-year period. Stability data were also analyzed. Demographic and cognitive data predicted subjective quality of life, but not rehospitalization. Changes in memory over time rather than performance levels related to life quality at follow-up. Rehospitalization was related only to demographic data and previous hospital admissions. The findings support the predictive value of selected aspects of neurocognition in relation to a subjective outcome domain in schizophrenia.

Adolescent↗

The telecommunication revolution in the medical field: present applications and future perspective.

In the present review, we analyze the achievements of telecommunication innovations in the medical field focusing on patient care and medical-education aspects. In this regard, the telecommunication revolution has offered medical professionals the possibility to transmit information of any sort zeroing transmission time latency and annihilating spatial distances. Although telemedicine is still in its infancy, multiple applications of this science have already been successfully tested. As an example, robotically mediated telesurgery has it made possible for surgeons to operate standing at a considerable distance from the operating table without even touching or directly seeing the surgical field. Moreover, medical education and medical consulting have acquired new and wider ranges of applicability thanks to the introduction of teleproctoring, telementoring, and teleconsulting. Finally, in the very near future, telepresence surgery will permit "virtual" operations on patients where surgeons can project their manual dexterity, psychomotor skills, and problem-solving ability to remote locations. In this context, telemedicine will support a more equal distribution of medical knowledge and promote excellence in patients' care even in the most disadvantaged environments.

Humans↗

Reliability and validity of a qualitative and quantitative motor test for 5- to 6-year-old children.

Clumsiness in preschool children may be a precursor to impaired academic performance and psychological and developmental problems. It is assumed that in this age group especially the qualitative aspects (=pattern) of a movement reflect variations in motor development. Currently available motor tests for this age group, however, mostly objectify quantitative aspects of a movement alone and do not objectify qualitative aspects. The aim of this study was to develop a new, valid, and reliable tool (Maastricht's Motor Test (MMT)) to objectify qualitative and quantitative aspects of movement in 5- to 6-year-old children. The test covers Static Balance (14 items), Dynamic Balance (20 items), Ball Skills (eight items), and Diadochokinesis and Manual Dexterity (28 items). About 50% of the items measure qualitative aspects and 50% quantitative aspects of movements. In total 487 subjects were recruited from the first year of primary school. To validate the test, one school doctor's global judgment was used as a form of expert validity. Sensitivity and specificity were calculated for different cut-off points. Intra-class correlation coefficients (ICC) of inter-rater (N = 42), intra-rater (N = 24), and test-retest (N = 43) agreement were determined. ICCs of the qualitative total score ranged from 0.61 to 0.95 and were comparable with those of the total quantitative score. The MMT can be used to objectify both qualitative and quantitative aspects of movements. The additional value of the qualitative observations has to be determined in children with various developmental problems.

Age Factors↗

Robot-assisted versus standard videoscopic aortic replacement. A comparative study in pigs.

BACKGROUND: Reconstruction of the infrarenal aorta for aneurysms is routinely performed through laparotomy. A less invasive videoscopic approach has not gained wide acceptance due to technical difficulties. Robotic systems could potentially improve imaging of the operative field and surgeon's dexterity during videoscopic surgery and therefore might facilitate the performance of this procedure. The aim of this animal study was to compare the safety and efficacy of a robot-assisted videoscopic aortic replacement to the standard videoscopic approach. MATERIALS AND METHODS: In 10 female pigs, the infrarenal aorta was partially replaced by a 10 mm polytetrafluoroethylene (PTFE) interposition graft through a videoscopic retroperitoneal approach, using the da Vinci robot system (robot group). Ten other pigs were operated on in a similar fashion, using standard videoscopic instruments (control group). Relevant procedure times, blood loss and complications were registered. Efficacy of the anastomoses was evaluated by measuring patency and blood loss after removing the clamps. Furthermore, circumference and number of stitches were evaluated at autopsy. RESULTS: The procedure, suturing and clamping times were significantly shorter in the robot group and blood loss was less. In the control group, the inferior vena cava was injured in one pig. In two cases in the control group, haemostasis could not be established after clamp removal. At autopsy, all anastomoses in the robot group were adequate. In the control group, a stitch crossing the aortic lumen was found in two distal anastomoses and a large distance (>3 mm) between two stitches was encountered at least once in 12/20 suture lines. All 20 grafts were patent. No anastomotic narrowing was encountered. The number of stitches used for proximal and distal anastomosis was higher in the robot group. CONCLUSION: This study demonstrates the superiority of robot-assisted videoscopic aortic replacement over standard videoscopic techniques in an animal model.

Anastomosis, Surgical↗

Benign childhood epilepsy with occipital paroxysms: neuropsychological findings.

Benign childhood epilepsy with occipital paroxysms is classified among childhood benign partial epilepsies. The absence of neurological and neuropsychological deficits has long been considered as a prerequisite for a diagnosis of benign childhood partial epilepsy. Much evidence has been reported in literature in the latest years suggesting a neuropsychological impairment in this type of epilepsy, particularly in the type with Rolandic paroxysms. The present work examines the neuropsychological profiles of a sample of subjects affected by the early-onset benign childhood occipital seizures (EBOS) described by Panayotopulos. The patient group included 22 children (14 males and 8 females; mean age 10.1+/-3.3 years) diagnosed as having EBOS. The patients were examined with a set of tests investigating neuropsychological functions: memory, attention, perceptive, motor, linguistic and academic (reading, writing, arithmetic) abilities. The same instruments have been given to a homogeneous control group as regards sex, age, level of education and socio-economic background. None of the subjects affected by EBOS showed intellectual deficit (mean IQ in Wechsler Full Scale 91.7; S.D. 8.9). Results show a widespread cognitive dysfunction in the context of a focal epileptogenic process in EBOS. In particular, children with EBOS show a significant occurrence of specific learning disabilities (SLD) and other subtle neuropsychological deficits. We found selective dysfunctions relating to perceptive-visual attentional ability (p<0.05), verbal and visual-spatial memory abilities (p<0.01), visual perception and visual-motor integration global abilities (p<0.01), manual dexterity tasks (p<0.05), some language tasks (p<0.05), reading and writing abilities (p<0.01) and arithmetic ability (p<0.01). The presence of cognitive dysfunctions in subjects with EBOS supports the hypothesis that epilepsy itself plays a role in the development of neuropsychological impairment. Supported by other studies that have documented subtle neuropsychological deficits in benign partial epilepsy, we stress the importance of reconsidering its supposed "cognitive benignity", particularly in occipital types.

Adolescent↗

Deterministic dynamics control oscillations of bone marrow cell proliferation.

OBJECTIVE: The production of blood cells in vivo, both normal and tumoral, displays oscillatory dynamics. Many cells in long-term cultures also show large amplitude oscillations of proliferative rate. Therefore we examined the proliferation dynamics of mouse bone marrow cells (MBM) and their clonogenic progenitor production (BMP), in order to characterize these dynamics. METHODS: Five Dexter-type cultures of MBM cells and their clonogenic BMP production were examined for up to seven-months periods of time. The recorded time series exhibited a complex pattern of oscillations with variable amplitudes. We previously reported a method that allowed analysis of such nonlinear dynamics of hepatoma cell proliferation. We applied this method, based on the two-dimensional recurrent representation of data, to analyze the fluctuations of bone marrow cells proliferation. RESULTS: The proliferation rate of mouse bone marrow cells shows large amplitude oscillations every 2 to 3 weeks. Mathematical analysis revealed a deterministic mechanism that controls all proliferation local maxima of MBM cells. Dynamics for progenitor production resembled that of parental cells. This reflects a predominant negative feedback on bone marrow cell proliferation. CONCLUSION: These dynamics were opposite of that previously described for hepatoma cells where the dominant control is applied to the local minima (troughs of proliferation). Therefore, the complex system of cell proliferation is controlled by a bipolar mechanism, with a predominant dampening command depending on the cell type. We propose that the dominant dampening control of local maxima in bone marrow cells protects the stock of stem cells.

Animals↗

Dietary supplementation of omega-3 polyunsaturated fatty acids worsens forelimb motor function after intracerebral hemorrhage in rats.

Dietary intake of omega-3 polyunsaturated fatty acids has been associated with decreased clotting ability and increased risk of hemorrhagic stroke. The aim of the current study was to assess the effect of dietary supplementation of omega-3 polyunsaturated fatty acid on functional outcome after hemorrhagic stroke. Rats were maintained on a diet containing approximately 30% of energy as either fish oil (rich in omega-3 fatty acids) or safflower oil (rich in omega-6 fatty acids) and subjected to either intracerebral hemorrhage or sham surgery. Behavioral tests, infarct measurement, and MR imaging techniques were used to assess outcome. While there was no significant difference in infarct volume between rats on different diets, animals maintained on a diet enriched with fish oil exhibited increased cerebral blood flow after surgery. These animals were significantly more impaired than rats fed the safflower-oil-enriched diet in tests of forelimb dexterity and fine motor control. These results suggest that high intake of omega-3 polyunsaturated fatty acids may not only increase the risk of hemorrhagic stroke as shown in previous studies, but most importantly may lead to a more severe motor impairment and a poorer functional outcome after such an event.

Animals↗

Parkinsonian action tremor: interference with object manipulation and lacking levodopa response.

It has been postulated that Parkinsonian action tremor is distinct from classical resting tremor and that it may contribute to a loss of manual dexterity in Parkinson's disease. We analyzed pinch grip coordination in 20 patients with Parkinson's disease. An object with and without an additional 500 g weight was grasped, lifted and held for a short time with opposed thumb and index finger. Force sensors recorded the force exerted by both fingers. Spectral analysis of the force traces was performed. Transition times between grasping and lifting the object were measured. 18 age matched normal volunteers served as a control group. While holding the object, there were force oscillations in the 3.5-6.5 Hz band indicating (reemerging) classical Parkinsonian tremor in 65% of the patients. This was reduced to 15-20% under levodopa. Oscillations in the 6-15 Hz band were found in 30% (50% with weight) of the patients, remaining unchanged under levodopa, and in 10% (20% with weight) of the normal controls. During lift initiation, 6-15 Hz oscillations were found in all patients and the majority of controls. The band power was positively correlated with the movement transition times in the severely akinetic patients and was significantly higher than in controls. It remained unchanged under levodopa. Our data confirm that Parkinsonian action tremor activated during complex voluntary movements is distinct from classical resting tremor. It does not show a clear levodopa response but affects dextrous movement coordination when associated with clinically severe overall akinesia.

Adult↗

The translocation mechanism of P-glycoprotein.

Multidrug transporters are involved in mediating the failure of chemotherapy in treating several serious diseases. The archetypal multidrug transporter P-glycoprotein (P-gp) confers resistance to a large number of chemically and functionally unrelated anti-cancer drugs by mediating efflux from cancer cells. The ability to efflux such a large number of drugs remains a biological enigma and the lack of mechanistic understanding of the translocation pathway used by P-gp prevents rational design of compounds to inhibit its function. The translocation pathway is critically dependent on ATP hydrolysis and drug interaction with P-gp is possible at one of a multitude of allosterically linked binding sites. However, aspects such as coupling stoichiometry, molecular properties of binding sites and the nature of conformational changes remain unresolved or the centre of considerable controversy. The present review attempts to utilise the available data to generate a detailed sequence of events in the translocation pathway for this dexterous protein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗