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At least 433 records · Page 24Linked to original sources
PubMed2002

Implications of distracter effects for the organization of eye movements, hand movements, and perception.

The end positions of eye and hand movements were both drawn towards a distracter that was presented nearby the target. They thus showed a so-called global effect. In contrast, perception was not influenced by the presence of a distracter. These results are discussed with regard to the question whether eye, hand, and perception are based on shared or separate target representations and readout triggers. We conclude that separate representations and readout triggers for eye and hand are the most likely case.

Eye Movements↗
PubMed2005

Interaction between the movement protein of barley yellow dwarf virus and the cell nuclear envelope: role of a putative amphiphilic alpha-helix at the N-terminus of the movement protein.

The open reading frame 4 (ORF 4) gene product of barley yellow dwarf virus (BYDV) may act as a movement protein (MP) by assisting the transport of viral genomic RNA across the nuclear envelope (NE) of host plant cells. To investigate interactions between BYDV MP and the NE, wild-type and mutant open reading frame (ORF 4)-green fluorescent protein (GFP) fusion cistrons were expressed in insect cells. A fusion protein expressed by the wild-type ORF 4-GFP cistron associated with the NE and caused protrusions from its surface. The fusion protein expressed by the mutant ORF 4-GFP cistron lacked a putative amphiphilic alpha-helix at its N-terminus and although associating with the NE, showed decreased levels of protrusions. A peptide homologue of this putative alpha-helix induced an increase of 7 degrees C in the phase transition temperature of dimyrystoyl phosphatidylserine (DMPS) membranes, accompanied by a decrease in membrane fluidity, but exhibited no significant interaction with either dimyristoyl phosphatidylcholine (DMPC) or dimyristoyl phosphatidylethanolamine (DMPE) membranes. These results strongly support the view that BYDV MP may interact with the NE to help transport viral genomic RNA into the nuclear compartment. This function of BYDV MP appears to involve protrusions on the surface of the NE and may require the presence of an N-terminal amphiphilic alpha-helix, which is speculated to destabilize membranes, thereby assisting the entry of BYDV-GAV into the nuclear compartment.

Amino Acid Sequence↗
PubMed2000

Movement and mind: a functional imaging study of perception and interpretation of complex intentional movement patterns.

We report a functional neuroimaging study with positron emission tomography (PET) in which six healthy adult volunteers were scanned while watching silent computer-presented animations. The characters in the animations were simple geometrical shapes whose movement patterns selectively evoked mental state attribution or simple action description. Results showed increased activation in association with mental state attribution in four main regions: medial prefrontal cortex, temporoparietal junction (superior temporal sulcus), basal temporal regions (fusiform gyrus and temporal poles adjacent to the amygdala), and extrastriate cortex (occipital gyrus). Previous imaging studies have implicated these regions in self-monitoring, in the perception of biological motion, and in the attribution of mental states using verbal stimuli or visual depictions of the human form. We suggest that these regions form a network for processing information about intentions, and speculate that the ability to make inferences about other people's mental states evolved from the ability to make inferences about other creatures' actions.

Adult↗
PubMed1994

Control of fast elbow movement: a study of electromyographic patterns during movements against unexpectedly decreased inertial load.

Predictions of three models of single-joint motor control were compared with experimental observations of the changes in electromyographic (EMG) patterns during fast voluntary movements against an unexpectedly reduced inertial load. The subjects performed elbow flexions over 40 degrees "as fast as possible" in two series. During the first series, an approximately 40% decrease in inertia, simulated by a torque-motor, might occur unpredictably on half of the trials (unloaded trials). During the second series, all the trials were unloaded. The major findings are: (1) no differences in the antagonist burst latency in unexpectedly unloaded and unperturbed trials; (2) a decrease in the antagonist latency during expected unloadings; (3) a small, statistically non significant decrease in the first agonist burst EMG integral; and (4) a larger, statistically significant increase in the antagonist burst EMG integral in unexpectedly unloaded trials as compared to unperturbed trials. The data are in good correspondence with a version of the equilibrium-point hypothesis that assumes central programming of the beginning of the antagonist burst and incorporates the possibility of reflex-induced changes in EMG amplitudes.

Acceleration↗
PubMed1980

Fetal movements registered by the pregnant woman correlated to retrospective estimations of fetal movements from cardiotocographic tracings.

After reviewing 30 cardiotocographic tracings from 15 pregnant women who directly registered fetal movements (FM) on the cardiotocographic (CT) tracings, we have found no correlation between the actual number of FM and the FM found by retrospective estimation from CT tracings. Ours is the first study to show this lack of correlation. On the contrary, we have found that by using the "retrospective" or "indirect" methods, almost 90% of the FM are overlooked. This is a very important loss of information since registration of FM seems to be a good method for surveillance of the fetus at risk. We also discuss our own methods for overcoming these problems.

Female↗
PubMed1983

Conditioned turning in rats: dopaminergic involvement in the initiation of movement rather than the movement itself.

Adult rats received unilateral 6-hydroxydopamine lesions of the mesotelencephalic dopamine pathway following training to turn selectively in one direction for sugar-water reinforcement. The lesion abolished the rats' ability to turn selectively away from the lesioned side, whereas reinforced turning towards the lesioned side remained intact. The pattern of results suggested that the deficit was not attributable to primary motor, sensory or motivational impairments, but to an inability following lesion to initiate movement towards the opposite side.

Animals↗
PubMed2004

Functional neuroanatomical correlates of eye movements during rapid eye movement sleep in depressed patients.

In depressed patients, REM density, or the number of rapid eye movements (REMs) per minute of REM sleep, is a correlate of depression severity and clinical outcomes. We investigated the functional neuroanatomical correlates of average REM counts (RC), an automated analog of REM density, in depression. Thirteen medication-free depressed patients underwent all night polysomnography and positron emission tomography (PET) scans using [(18)F]fluoro-2-deoxy-d-glucose ([(18)F] FDG) during REM sleep. Regression analyses were conducted with Statistical Parametric Mapping (SPM-99). Average RC significantly and positively correlated with relative regional cerebral metabolic rate of glucose (rCMRglc) bilaterally in the striate cortex, the posterior parietal cortices, and in the medial and ventrolateral prefrontal cortices. Average RC were negatively correlated with rCMRglc in areas corresponding bilaterally to the lateral occipital cortex, cuneus, temporal cortices, and parahippocampal gyri. The areas where average RC was positively correlated with rCMRglc appear to constitute a diffuse cortical system involved in the regulation of emotion-induced arousal. The observed pattern of correlations suggests that average RC may be a marker of hypofrontality during REM sleep in depressed patients.

Adult↗
PubMed2000

Cell-to-cell movement of TMV RNA is temperature-dependent and corresponds to the association of movement protein with microtubules.

The movement protein (MP) of tobacco mosaic virus (TMV) is essential for spread of the viral RNA genome from cell to cell. During infection, the MP associates with microtubules, and it has been proposed that the cytoskeleton transports the viral ribonucleoprotein complex from ER sites of synthesis to plasmodesmata through which infection spreads into adjacent cells. However, microtubule association of MP was observed in cells undergoing late infection rather than in cells undergoing early infection at the leading edge of expanding infection sites where virus RNA cell-to-cell spread occurs. Therefore, alternative roles for microtubules in virus infection have been proposed, including a role in MP degradation. To further investigate the role of microtubules in virus pathogenesis, we tested the efficiency of cell-to-cell spread of infection and microtubule association of the MP in response to changes in temperature. We show that the subcellular distribution of MP is temperature-dependent and that a higher efficiency of intercellular transport of virus RNA at elevated temperatures corresponds to an increased association of MP with microtubules early in infection.

Green Fluorescent Proteins↗
PubMed1986

Relation between fetal heart rate accelerations, fetal movements, and fetal breathing movements.

The presence of fetal heart rate (FHR) accelerations is considered a sign of fetal well-being. Fetal body and breathing movements, as visualized by real-time ultrasound, were correlated to FHR accelerations in 16 high-risk pregnancies. The association between FHR accelerations (greater than 15 beats/min lasting 15 sec or more) and the different fetal behavioral states is described.

Female↗
PubMed2003

Context-dependent adaptation of visually-guided arm movements and vestibular eye movements: role of the cerebellum.

Accurate motor control requires adaptive processes that correct for gradual and rapid perturbations in the properties of the controlled object. The ability to quickly switch between different movement synergies using sensory cues, referred to as context-dependent adaptation, is a subject of considerable interest at present. The potential function of the cerebellum in context-dependent adaptation remains uncertain, but the data reviewed below suggest that it may play a fundamental role in this process.

Animals↗
PubMed1974

Potassium flux and leaf movement in Samanea saman. II. Phytochrome controlled movement.

Phytochrome, a membrane-localized biliprotein whose conformation is shifted reversibly by brief red or far-red light treatments, interacts with the rhythmic oscillator to regulate leaflet movement and potassium flux in pulvinal motor cells of Samanea. Darkened pinnae exposed briefly to red light (high P(fr) level) have less potassium in motor cells in the extensor region, more potassium in motor cells in the flexor region, and smaller angles than those exposed to far-red light (low P(fr) level). Increase in temperature from 24 degrees to 37 degrees increases the differential effect of the light treatments during opening (the energetic phase) but not during closure, implying that phytochrome controls an energetic process. It seems likely that phytochrome interacts with rhythmically controlled potassium pumps in flexor and extensor cells. During nyctinastic closure of white-illuminated pinnae, exposure to far-red light before darkening results in larger angles than does exposure to red. As in rhythmic opening, the angles of all pinnae and the differential effect of the light treatments increases with increasing temperature.

Bile Pigments↗
PubMed2005

The effect on IMRT conformality of elastic tissue movement and a practical suggestion for movement compensation via the modified dynamic multileaf collimator (dMLC) technique.

A major remaining problem in delivering radiotherapy, specifically intensity-modulated radiation therapy (IMRT), is the need to accommodate and correct for intrafraction movement. The developing availability of 4D computed tomographic images can potentially form the basis of the new field of image-guided IMRT. It is important to understand the effects on delivered dose of the patient breathing during IMRT and this paper models the effect which applies whether there is or is not a time component to the IMRT delivery method. It then goes on to suggest a practical correction strategy. The 'stretch-and-shift-the-planned-modulations' strategy is proposed and a practical method to deliver this is explained. This practical strategy is based on a modification of the dynamic multileaf collimator IMRT method whereby the leaves are arranged to 'breath' in tandem with the breathing of the patient. Some examples are also given from a study of mismatching the patient and leaf-correction motions.

Algorithms↗
PubMed1992

[Movement analysis with microgravitation: theory and practical aspects for the calculation of target movements with the MONIMIR helmet lamp].

A new optoelectronic system for movement analysis is introduced. This equipment was employed with success during an Austrian-Soviet space flight. The method for the determination of position and orientation is described with the aid of an example, namely the determination of the location of the intersection of a beam of light generated by a helmet-mounted lamp with a screen.

Electrooculography↗
PubMed1999

Relearning movements: modification of an incorrectly timed reversal movement.

The main purpose of this study was to examine if an inaccurately acquired motor response can be relearned through the provision of a limited number of correct KR trials. 26 subjects were assigned to one of three experimental groups: a no-KR group, an erroneous KR group, and a relearning group who were given correct KR after 125 trials of erroneous KR. Analysis showed a significant temporal correction of the reversal movement when the erroneous KR was replaced by valid verbal information during acquisition. This adaptation, however, was attenuated during retention, indicating that the limited number of correct KR trials did not wash out the effect of the invalid information provided during the first phase of acquisition.

Adolescent↗
PubMed1996

[Condylar movement in patient with skeletal mandibular prognathism during maximum opening and closing movement before and after surgery].

Condylar movement of patients with mandibular prognathism who received sagittal splitting ramus osteotomy (SSRO) was investigated using computer aided diagnostic axiography (CADIAX). Linear and angular parameters were used to evaluate the maximum opening and closing paths of the condyle projected on the sagittal plane. The motion paths of six subjects with mandibular prognathism (MP group) were examined immediately before surgery and during the retention period. The results were compared with the recording from six normal subjects (control group). The results were as follows: (1) The average change in the maximum translating distance of the condyle in the retention period was 99.4 +/- 14.5% of the presurgical value on right side and 97.8 +/- 20.8% on the left side. The difference was not significant. (2) The shape of the opening translating curve of the MP group was flatter than that of the control group, however, no significant differences were found between the pre- and postsurgical curves of the MP group. (3) The coordination between the maximum opening and closing paths of the control group was fairly stable and smooth. However, although some improvement was observed, the paths of the MP group were unstable even after surgical treatment and large individual variations were observed.

Adult↗
PubMedDate not supplied

Coactivation patterns of the medial and lateral hamstrings based on joint position and movement velocity during isokinetic movements.

The purpose of this investigation was to determine the effect of movement velocity (100 degrees x s(-1), 200 degrees x s(-1), 300 degees x s(-1), and 400 degrees x s(-1)) and joint position (0 degrees - 20 degrees [L0] 30 degrees - 50 degrees [L30], and 70 degrees - 90 degrees [L70] knee flexion) on reciprocal coactivation patterns of the medial and lateral hamstrings as determined by the amplitude and frequency spectrum of surface electromyography (SEMG). Thirteen female subjects (age = 22.7 +/- 2.1 years, mean height = 161.1 +/- 6.6 cm, mean weight = 63.5 +/- 5.8 kg) participated in the study. Bipolar surface electrodes were placed over the biceps femoris (BF) and medial hamstrings (MH) for determination of the root mean square (SEMGrms) and median frequency (SEMGmf) of the SEMG. Normalized SEMGrms values for the MH and BF were determined as a percentage of agonist SEMGrms activity for the same muscle during its agonist phase. Data were analyzed using separate 2 x 3 x 4 (muscle x position x angular velocity) repeated measures analysis of variance (ANOVA). For SEMGrms, there were significant muscle (p < 0.01) and position (p < or = 0.0001) main effects. Post-hoc analyses indicated the BF displayed greater muscle amplitude than the MH and that there was greater muscle amplitude at the L0 position (as the knee approached terminal extension). No velocity effect was noted (p > 0.05). For SEMGmf there were muscle x position (p < or = 0.05) and muscle x position x velocity (p < or = 0.01) interaction effects. Post-hoc analyses indicated the BF displayed a higher frequency spectrum than the MH at the L0 position. Secondly, velocity affected the BF and MH frequency spectrum such that values for both the MH and BF were lowest at 200 degrees x s(-1) and highest at 300 degrees x s(-1) (BF) and 400 degrees x s(-1) (MH). Velocity had little impact on the frequency spectrum in the midrange of the ROM (L30 position). Higher SEMGrms and SEMGmf values for the BF could be explained by the locking or screw home mechanism of the knee, and a way in which the human motor control system provides the limb with a dynamic braking system to control both extension and lateral rotational forces during the final stage of knee extension. It would appear that the way in which the body performs this function is not only to increase the amplitude of BF muscle firing but also to shift toward the recruitment of more fast-twitch motor units.

Adult↗
PubMed1993

A dynamical neural network model for motor cortical activity during movement: population coding of movement trajectories.

As a dynamical model for motor cortical activity during hand movement we consider an artificial neural network that consists of extensively interconnected neuron-like units and performs the neuronal population vector operations. Local geometrical parameters of a desired curve are introduced into the network as an external input. The output of the model is a time-dependent direction and length of the neuronal population vector which is calculated as a sum of the activity of directionally tuned neurons in the ensemble. The main feature of the model is that dynamical behavior of the neuronal population vector is the result of connections between directionally tuned neurons rather than being imposed externally. The dynamics is governed by a system of coupled nonlinear differential equations. Connections between neurons are assigned in the simplest and most common way so as to fulfill basic requirements stemming from experimental findings concerning the directional tuning of individual neurons and the stabilization of the neuronal population vector, as well as from previous theoretical studies. The dynamical behavior of the model reveals a close similarity with the experimentally observed dynamics of the neuronal population vector. Specifically, in the framework of the model it is possible to describe a geometrical curve in terms of the time series of the population vector. A correlation between the dynamical behavior of the direction and the length of the population vector entails a dependence of the "neural velocity" on the curvature of the tracing trajectory that corresponds well to the experimentally measured covariation between tangential velocity and curvature in drawing tasks.

Animals↗