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PubMed2004

Nutrition and lifestyle in relation to bowel movement frequency: a cross-sectional study of 20630 men and women in EPIC-Oxford.

OBJECTIVE: To investigate the relationships between nutritional and lifestyle factors and bowel movement frequency. DESIGN: Cross-sectional analysis using data from a prospective study. Mean numbers of bowel movements were calculated in relation to a range of factors. In addition, individuals were categorised according to frequency of bowel movements: fewer than 7 per week ('less than daily') versus 7 or more per week ('daily'), and odds ratios were calculated from logistic regression models. Results for each factor were adjusted for the other factors under consideration. SETTING: The European Prospective Investigation into Cancer and Nutrition, Oxford cohort (EPIC-Oxford), UK. PARTICIPANTS: In total, 20630 men and women aged 22-97 years at recruitment. Thirty per cent of the subjects were vegetarians or vegans. RESULTS: Women had fewer bowel movements on average than men, and were less likely to have daily bowel movements. Mean bowel movement frequency was higher in vegetarians (10.5 in men, 9.1 in women) and especially in vegans (11.6 in men, 10.5 in women) compared with participants who ate meat (9.5 in men, 8.2 in women). There were also significant positive associations between bowel movement frequency and body mass index (BMI), intakes of dietary fibre and non-alcoholic fluids, for both men and women. Vigorous exercise was positively associated with bowel movement frequency in women although results for men were less clear. Alcohol intake was positively associated with bowel movement frequency in men but not in women. CONCLUSION: Being vegetarian and especially vegan is strongly associated with a higher frequency of bowel movements. Moreover, having a high intake of dietary fibre and fluids and a high BMI are associated with an increase in frequency of bowel movements.

Adult↗
PubMed1985

Intermanual interactions during simultaneous execution and programming of finger movements.

In bimanual movements, some differences between the movements performed by the two hands cause interference, while others do not. Similarly, in choice between responses with the left and right hand some differences between the two movements increase RT, while others do not. It is suggested that both kinds of effects are, at least in part, due to the incompatibility between processes that determine characteristics of movements jointly for both hands and that are present during preparation as well as during execution. This hypothesis implies that during execution of one movement, programming of a different movement to be performed with the other hand should be impaired, as compared to a condition in which the successive movements of both hands are the same. this expectation was confirmed for finger movements of different forms where an effect on choice RT had been shown previously. On the other hand, interference between execution and programming is not to be expected when successive movements differ in characteristics that are likely to be specified separately for each hand, as indicated by a lacking effect in choice experiments. This expectation was confirmed for successive movements performed with different fingers of either hand as compared to movements performed with the same fingers.

Journal Article↗
PubMed1994

The effects of temporal-precision and time-minimization constraints on the spatial and temporal accuracy of aimed hand movements.

Discrete aimed hand movements, made by subjects given temporal-accuracy and time-minimization task instructions, were compared. Movements in the temporal-accuracy task were made to a point target with a goal movement time of 400 ms. A circular target then was manufactured that incorporated the measured spatial errors from the temporal-accuracy task, and subjects attempted to contact the target with a minimum movement time and without missing the circular target (time-minimization task instructions). This procedure resulted in equal movement amplitude and approximately equal spatial accuracy for the two task instructions. Movements under the time-minimization instructions were completed rapidly (M = 307 ms) without target misses, and tended to be made up of two submovements. In contrast, movements under temporal-accuracy instructions were made more slowly (M = 397 ms), matching the goal movement time, and were typically characterized by a single submovement. These data support the hypothesis that movement times, at a fixed movement amplitude versus target width ratio, decrease as the number of submovements increases, and that movements produced under temporal-accuracy and time-minimization have different control characteristics. These control differences are related to the linear and logarithmic speed-accuracy relations observed for temporal-accuracy and time-minimization tasks, respectively.

Journal Article↗
PubMed1991

Motor function of the monkey globus pallidus. 1. Neuronal discharge and parameters of movement.

In order to examine the role of the basal ganglia (BG) in the regulation of basic movement parameters, we recorded extracellularly from pallidal neurons in conscious monkeys during the performance of a sequential wrist movement task which was composed of a series of holds and ballistic jumps. The movement sequence was predictable and had to be performed within specified time restraints. We recorded the activity of 297 neurons whose discharges were related to the movement task. We included only neurons whose discharges were related to movements at or about the wrist joint by prior examination outside the behavioural paradigm. Each neuron discharged preferentially to one direction of movement at or about the wrist joint. No consistent correlation was found between neuronal discharge and initial joint position, static load application, amplitude of movement or velocity of movement. The mean onset of neuronal discharge was 2 ms after the onset of EMG activity. The findings implied little contribution from the pallidal neurons in the execution of the current movement or to the movement's parameters. The implications are that the basal ganglia are likely to be concerned with other aspects of movement control.

Animals↗
PubMed1999

The evoked heart rate response to periodic leg movements of sleep.

STUDY OBJECTIVES: Periodic leg movements of sleep are currently subdivided based upon whether or not they are associated with EEG arousal. "Autonomic" arousals, characterized by elevations in heart rate and blood pressure without AASM-defined EEG changes, have been associated with daytime somnolence in experimental protocols. In this study, we will describe the heart rate response to periodic leg movements of sleep, both with and without associated arousals. DESIGN: Heart rate was averaged for each of the ten cardiac cycles before, and after, the onset of individual periodic leg movements occurring in non-REM sleep for eight patients with Periodic Limb Movement Disorder (PLMD). Records were blindly scored (without EKG data) to determine if AASM-defined EEG arousals occurred within two seconds of leg movement onset. Leg movements during wakefulness were performed by four non-patient controls as a control condition. SETTING: Sleep Disorders Center INTERVENTIONS: None MEASUREMENTS AND RESULTS: A significant rise in heart rate was observed following the onset of individual leg movements of sleep (N = 796), which was also significantly larger than that seen after waking leg movements (N = 275). Although heart rate elevation was 10%-40% higher when leg movements were associated with AASM-defined arousal, these differences did not reach statistical significance. CONCLUSIONS: Periodic leg movements of sleep are associated with cardiac acceleration, even in the absence of AASM-defined arousal. It appears premature to conclude that periodic leg movements of sleep not associated with visible EEG arousal are clinically insignificant.

Adult↗
PubMed2003

Rapid eye movement density is reduced in the normal elderly.

STUDY OBJECTIVES: While there is general agreement on the age changes in non-rapid eye movement sleep, there is conflicting evidence on whether eye movement density (EMD) in rapid eye movement sleep is affected by aging. We therefore performed computer measurement of EMD in young and elderly normal subjects. DESIGN: Sleep electroencephalogram and electrooculogram were recorded in each subject on 4 nonconsecutive baseline nights. Eye movement density in the elderly subjects was compared to that in young adults. SETTING: A sleep research laboratory with 4 separate bedrooms. INTERVENTIONS: Not applicable. PARTICIPANTS: Subjects were 19 young normal adults and 19 elderly normal adults. MEASUREMENTS AND RESULTS: Digitized electrooculograms were analyzed with the extensively validated zero-cross period-amplitude module of PASS PLUS software. The EMD was measured as 0.3 to 2 Hz integrated amplitude per 20-second stage of rapid eye movement sleep. Eye-movement incidence was the number of half waves. Eye-movement amplitude was the sum of peak-trough excursions (curve length) in the average half wave. We also counted visually the number of 2-second epochs with eye movements for 1 baseline night in both groups. The EMD in the elderly subjects was substantially and significantly lower than in the young subjects. Visual scoring of EMD on 1 baseline night confirmed the statistically significant difference between age groups. Period-amplitude analysis revealed that a lower eye-movement incidence rather than reduced amplitude caused the lower EMD in the elderly. The EMD was significantly correlated within subjects across the nonconsecutive baseline nights in both groups; in both, subjects' EMD average across 2 nights provided a correlation greater than .90 with the 4-night mean. CONCLUSIONS: The incidence of eye movements during rapid eye movement sleep is substantially reduced in the elderly. We hypothesize that this reduction is due to degenerative (aging) rather than developmental brain changes. The correlation analysis indicates that EMD is a reasonably stable individual trait in both young and elderly adults. These results encourage normative studies of EMD over a wider age span and continued exploration of the relation of EMD to cognitive function in the elderly.

Adult↗
PubMed1985

Relationship of periodic movements in sleep (nocturnal myoclonus) and the Babinski sign.

To obtain a comprehensive clinical description of periodic movements in sleep, the first 11 videotaped movements of nine patients were studied. These leg movements were characterized by active dorsiflexion of the ankle (91%), dorsiflexion and fanning of the small toes (82%), and dorsiflexion of the great toe (72%). Partial flexion of the knee and hip occurred in 28%. Simultaneous dorsiflexion of the ankle and small toe was almost always the initial change, either preceding or occurring simultaneously with extension of the great toe. Knee and hip flexion almost always followed foot movements. Tonic and/or clonic movements, usually about the ankle, occurred in 75%; plantar flexion of the ankle occurred in 21% at the end of a leg movement. Periodic movements in sleep were thus characterized on detailed videographic analysis by movements similar to the Babinski response. Since both the normally occurring nocturnal Babinski response and periodic movements in sleep are also almost entirely NREM related, the author proposes that periodic movements in sleep are due to the NREM loss of supraspinal inhibitory influences on the pyramidal tract and that the characteristic foot and leg movements are Babinski-type responses secondary to this.

Adult↗
PubMedDate not supplied

A study of normal baby movements.

Twenty-five normal newborns aged between 3 and 6 days had their movements recorded by clinical observation in a controlled environment, chart recording from an automatic movement mattress over 4 hours, and cine photography triggered by the movement mattress. Over 80 different individual types of movement were grouped into six categories: progression movements (obligatory reciprocal movements), symmetrical movements (slower flexion or extension movements), startle movements, asymmetrical tonic neck reflex and 'Moro', facial movements and athetoid movements. The normal newborn's motor activity is significantly related to the level of arousal, gestational age, and environmental variables such as position, temperature, light and noise.

Arousal↗
PubMed1981

Interference effects in recalling movements.

In two experiments, the interaction of location and distance cues in the recall of pre-selected movements was investigated. In Expt 1, separate groups of subjects were required to remember either ther terminal location of, or the distance moved during, a criterion movement pre-selected within a 30 cm response region. Following either a 5 s or 30 s unfilled retention interval, subjects were required to recall the criterion movement using the particular movement cue (i.e. location or distance) in question. In Expt 2, a similar procedure was used, except that recall of the criterion movement followed either a 5 s or a 20 s unfilled, or a 20 s filled (backward counting) retention interval. Systematic manipulation of both the direction and magnitude of the starting position for recall movements revealed the subjects were unable to make the movement uninfluenced by the "unattended' movement cue. The interfering effect of this irrelevant cue was independent of the ongoing activity during the retention interval. The results suggest that memory for preselected movements is based on a combination of the two movement cues generated during production of the criterion movement.

Cues↗
PubMed2005

Brain activation during ideomotor praxis: imitation and movements executed by verbal command.

BACKGROUND: Ideomotor apraxia is a disorder of both imitation movements and movements executed by verbal command. Lesion studies have identified the left parietal lobe as the neural correlate for ideomotor praxis (IP), although there are opposing views. OBJECTIVES: To localise the neural substrates for IP using functional magnetic resonance imaging. Brain regions activated by both imitation and verbal command movements were tested against a simple self paced movement. METHODS: Twenty two young, right handed, healthy subjects were examined. Functional and anatomical data were acquired. The experiment comprised three motor conditions (imitation, movements executed by verbal command, and finger bending/unbending) and a rest condition. All motor tasks were performed using the left hand. Eighteen drawings of left hand postures were presented for the imitation condition. Identical postures were instructed verbally for the verbal command condition. The finger bending/unbending movement was self paced. Blood oxygenation level dependent (BOLD) signal increases were compared during two kinds of IP (imitation and verbal command movements) and during finger bending/unbending movements. RESULTS: The depth of the posterior part of the left intraparietal sulcus and bilateral precunei were activated during both imitation and verbal command movements. The difference in BOLD signal between imitation and verbal command movements was localised in the dorsal and ventral occipital areas. BOLD signal differences for movements executed by verbal command against imitation were observed in the superior temporal areas. CONCLUSIONS: The depth of the posterior part of the left intraparietal sulcus and bilateral precunei are the neural substrates for IP.

Adult↗
PubMed1993

Movement-related inputs to intermediate cerebellum of the monkey.

1. The primary goal of this study was to characterize the information about single-joint forelimb movements supplied to intermediate cerebellar cortex by mossy fibers. Discharge of mossy fibers and Golgi cells was studied while monkeys operated six devices that required movements about specific joints. Additional control experiments in anesthetized cats and monkeys established criteria for identification of mossy fibers and Golgi cells. 2. The control experiments demonstrate that mossy fibers can be distinguished from Purkinje and Golgi cells by the waveshapes of their action potentials. Asynaptic activation from the inferior cerebellar peduncle, in combination with histological localization of recording sites in granular layer or subcortical white matter, verified that mossy fibers produce a variety of waveshapes that are characterized by brief initial phases and relatively small amplitudes. The same waveshapes were observed for the mossy fiber recordings from awake monkeys, and many identified mossy fibers had sensory properties similar to those found in the awake animals. From these combined criteria, we conclude that the recordings in the awake animals were from mossy fibers. Golgi cells, recorded exclusively in the granular layer of cerebellar cortex, were characterized by action potentials of longer duration and larger amplitude as compared with mossy fibers, and none were asynaptically activated from the inferior cerebellar peduncle. 3. Units were isolated while the monkeys made free-form and tracking movements. We studied movement-related discharge of 80 mossy fibers and 12 Golgi cells. Mossy fibers showed high modulations during use of at least one of the six manipulanda and had clear preferences for movement about a specific joint, although they often showed consistent but weaker firing during movement about a neighboring joint. Separation of movements by more than one joint produced a large reduction in discharge: shoulder units never fired well to movements of the finger, and finger units never fired well to movement of the shoulder. 4. The tracking task required maintenance of fixed limb positions (a static phase) as well as movements between these positions (a dynamic phase). Of 80 mossy fibers, 18% had purely tonic discharge patterns, 63% were phasic-tonic, and 20% were purely phasic. Discharge patterns were reciprocal (45%), bidirectional (42%), or unidirectional (13%). 5. Eighty percent of the mossy fibers exhibited tonic discharge that was significantly (P < 0.01) correlated with joint angle (r = 0.65 +/- 0.19, mean +/- SD), and about one third had phasic components that were significantly correlated with movement velocity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1996

Neurons in the supplementary eye field of rhesus monkeys code visual targets and saccadic eye movements in an oculocentric coordinate system.

1. We investigated whether neurons in the supplementary eye field (SEF) of macaque monkeys code saccadic eye movements in oculocentric coordinates (relative to the current direction of fixation) or in craniocentric coordinates (relative to the head). Craniocentric coding in SEF had been previously suggested by the convergent appearance of electrically elicited saccades originating at different orbital positions. 2. We primarily studied SEF neurons that started responding before the beginning of saccades because such presaccadic activity is likely related to saccade generation and metrics. Using a memory-saccade task, we classified the presaccadic activity of each neuron as either purely visual related, purely movement related, or both visual and movement related. 3. We then mapped the response fields (receptive fields and movement fields) of SEF neurons from different orbital positions. When mapped relative to a central fixation point, the strongest responses for a given SEF neuron invariably occurred for a particular polar direction with fairly symmetrical declines for departures from that direction. When tested using other fixation point locations, their strongest responses almost always continued to occur for stimuli having the same polar direction relative to each fixation point tested, and thus they appeared to code both stimulus direction and saccade direction in an oculocentric coordinate system. 4. The effect of eye position on SEF presaccadic activity was quantified in two ways by computing, for each neuron, 1) an "intersection distance," the eccentricity of the point where extensions of the neuron's optimal polar directions measured at two eccentric orbital positions converged, and 2) an "orbital perturbation index" such that an index of 0 corresponded to no change in the neuron's optimal polar direction across different orbital positions (i.e., perfectly oculocentric response fields) and an index of 1 corresponded to optimal polar directions that converged to the same craniocentric goal regardless of initial eye position (i.e., perfectly craniocentric response fields). For neurons with both visual and movement responses, these measures were calculated separately for each type of activity using tasks that temporally separated the visual cue presentation and the saccade to it. 5. Almost all of the intersection distances were well beyond the oculomotor range (+/- 50 degrees) of the monkey (38/39 for movement activity and 62/66 for visual activity). The median intersection distance for visual activity was very large (274 degrees), and the median for movement activity was slightly divergent (beyond infinity). Thus SEF neurons rarely showed a conspicuous convergence of response field direction. 6. Likewise, the mean orbital perturbation indexes were very small (-0.04 +/- 0.21, mean +/- SD, for movement activity and 0.09 +/- 0.15 for visual activity), also indicating that SEF neurons code stimuli and saccades in an oculocentric manner. 7. For neurons with both visual and movement activities, the orbital perturbation indexes of the two activities were not significantly correlated (r = 0.16), even though their characteristic directions (optimal polar direction estimated from the center of the screen) were almost the same (circular correlation, r+ = 0.97). The lack of a significant correlation between the visual and movement activity orbital perturbation indexes is consistent with the hypothesis that most of the variation in this index represents statistically independent errors of measurement. Conversely, the strong covariation of visual and movement activity characteristic directions indicates that directional preference is a fundamental functional property of SEF presaccadic activity.(ABSTRACT TRUNCATED)

Animals↗
PubMed1996

Functionally defined smooth and saccadic eye movement subregions in the frontal eye field of Cebus monkeys.

1. Intracortical microstimulation was used to localize and define the smooth and saccadic eye movement subregions of the frontal eye field (FEF) and the supplementary eye field (SEF) in nine hemispheres of six Cebus apella monkeys and to map the hand/arm areas in the dorsal premotor area and other adjacent areas in five hemispheres of three C. apella monkeys. Monkeys were anesthetized during experiments with Telazol, a dissociative agent that has no significant effect on microstimulation-induced eye movement parameters (current threshold, velocity, and duration). The functional subregions were defined with the use of low threshold current (< or = 50 microA). Electrically elicited eye movements were videotaped and quantified. The two types of eye movements were clearly distinguished by their significantly different duration and velocity (P < 0.0001) and their different responses to long stimulus trains. 2. The saccadic subregion of the FEF in Cebus monkeys is in the same location as in macaque monkeys (Walker's areas 8a and 45). Most of the functional and anatomic characteristics of the saccadic subregion of Cebus are the same as those reported in the saccadic FEF subregion of macaque monkeys. 3. A subregion in which only smooth eye movements were evoked was found in the posterior shoulder of the superior arcuate sulcus near its medial tip. A band of inexcitable cortex separated the SEF and this smooth eye movement subregion of the FEF. This supports the proposal that the smooth eye movement subregion is independent of the SEF but is analogous to the saccadic subregion of the FEF. The existence of two subregions of the FEF was further confirmed by single-unit recording results. It is proposed that the smooth eye movement subregion in Cebus monkeys may be comparable with the one described in macaque monkeys. 4. Both saccadic and smooth eye movements were also reliably evoked in the SEF in each hemisphere studied. This result strongly indicates that the SEF is concerned with not only saccadic eye movements, as previously reported, but also with smooth (pursuit) eye movements.

Animals↗
PubMed1993

Spatial and temporal characteristics of rapid cursor-positioning movements with electromechanical mice in human-computer interaction.

This research examines how people make movements with pointing devices during human-computer interaction. It specifically concerns the perceptual-motor processes that mediate the speed and accuracy of cursor positioning with electromechanical mice. In three experiments we investigated the spatial and temporal characteristics of positioning movements made with a mouse, analyzing subjects' speed and accuracy as a function of the types of targets that the movements had to reach. Experiment 1 required rapid and accurate horizontal movements to targets that were vertical ribbons located at various distances from the mouse's starting location. The targets for Experiments 2 and 3, respectively, were vertical lines having various heights and rectangular boxes having various heights and widths. Constraints on movement distance along the primary (that is, horizontal) line of motion had the greatest effects on total positioning times. However, constraints on movement distance along a secondary (vertical) line of motion also affected total positioning times significantly. These effects may be localized in different phases of movements (e.g., movement execution and verification). The duration of movement execution (i.e., physical motion) depends primarily on the target distance, whereas the duration of movement verification (i.e., check for endpoint accuracy) depends primarily on target height and width. A useful account of movement execution is provided by stochastic optimized-submovement models, which have significant implications for designing mice and menu-driven displays.

Adult↗
PubMed2005

Instruction in reliability and magnitude of evaluation parameters at each phase of a sit-to-stand movement.

The sit-to-stand movement strategy of each subject is different depending on whether the subjects perform voluntary movements or have concrete instructions (i.e., stand quickly), which is strongly reflected in the performance of each sit-to-stand movement phase. Thirty young-adult male subjects participated in this study (M age=20.7 yr; SD=2.6). Subjects performed the two movements from a chair height adjusted to the subject's lower thigh length. In the self-administered (SA) condition, subjects voluntarily stood up from the chair without instruction, and in the assigned-ordered (AO) condition subjects stood up from the chair as fast as possible. Vertical floor reaction force and electromyograms of the rectus femoris and tibialis anterior muscles were measured, and 15 parameters were selected. The parameters in the phase between the peak value of the floor reaction force and completion of the movement was highly reliable regardless of instruction. However, other parameters had different reliabilities between the instruction conditions. In particular, the parameters in the phase between starting the movement and the peak value of the floor reaction force under the assigned-order were higher than those of the self-administered condition. Moreover, the sit-to-stand movement was conducted faster in the assigned-order condition during the phase between starting the movement and buttocks-syneresis, and the peak value of the floor reaction force and completion of the movement. From the above, in the assigned-order condition "as fast as possible," the anteflexion bending movement and extension of knee and trunk joints were faster, and anteflexion movement was repeated more similarly under a concrete instruction such as moving as fast as possible.

Adolescent↗
PubMed1983

Rate and distribution of body movements during sleep in humans.

Body movements were measured during sleep with a mechanoelectrical transducer in 11 healthy adults. Also measured were the electroencephalogram (EEG), electrooculogram (EOG), and electromyogram (EMG). Each subject slept alone in a quiet room for 21 to 44 consecutive nights. Body movements were classified as minor movements (actogram signal or head leads artifact), major movements (actogram signal plus head leads artifact), or movement time (MT). There was a strong relationship between rate of body movements and sleep stages, with the rate decreasing along the following sequence of stages: W greater than S1 greater than REM greater than S2 greater than S (3 + 4). If the body movements for all nights are pooled per subject, the distribution of body movement rates shows hardly any overlap for the Stages 1, REM, 2, and (3 + 4). The relative frequency of body movements seems to be regulated by a stage-dependent mechanism. The reliability of the body movement rate was determined by computing correlations between pairs of adjacent nights, which resulted in a rtt = .69. When 2 to 9 nights were pooled stepwise according to a split-half procedure, the mean rtt increased and reached values between .80 and .90, which means that body movements are a reliable sleep measure especially if the time base is large enough.

Adult↗
PubMed1999

Ideomotor apraxia in Alzheimer disease and left hemisphere stroke: limb transitive and intransitive movements.

OBJECTIVE: Ideomotor apraxia was studied in patients with Alzheimer disease (AD) and unilateral left hemispheric damaged (LHD) stroke to determine whether these groups differed. BACKGROUND: Given that the neuropathology of AD is bilateral and more diffuse than the localized involvement in patients after an LHD stroke, and given that the cognitive deficits in AD are more widespread than in LHD stroke, the authors predicted that patients with these disorders would differ in response to an auditory command task administered to evaluate ideomotor apraxia, and that the two patient groups would be significantly more impaired than healthy matched control subjects. METHODS: Twenty-one persons were studied, including equal numbers of patients with AD, patients with unilateral LHD stroke, and control subjects. An auditory command test of limb apraxia was administered and videotaped to score performance and to code spatial-temporal or content errors. RESULTS: The patients with AD and LHD stroke were significantly more impaired than healthy control subjects. Whereas the patients with AD and LHD stroke were equally apraxic and did not differ in their performance of transitive limb movements, the patients with AD were significantly more impaired than the patients with stroke when performing intransitive limb movements. A positive correlation was found between severity of dementia and severity of apraxia in the patients with AD. The patients with LHD stroke were as likely to make spatial-temporal as content errors when performing intransitive limb movements, whereas the patients with AD made content errors only. Error types produced with transitive limb movements did not differ between groups; spatial-temporal errors were the most common errors made both by patients with AD and patients with LHD stroke. CONCLUSIONS: As predicted, patients with AD and with LHD stroke were impaired when producing limb movements after auditory command, and both patient groups were significantly more impaired than the healthy adults. Patients with AD were significantly more impaired than patients with stroke when performing intransitive limb movements, and error types differed by group. Patients with AD and patients with stroke were equally impaired when performing transitive movements, and error types did not differ by group. Patients with ideomotor apraxia are often degraded in their production of transitive and intransitive movements, and the observation that performance may differ depending on the type of limb movement suggests that movement representations for transitive and intransitive movements may be at least partially independent.

Aged↗
PubMed1975

Cinemicrographic studies on beta granule movement in monolayer culture of islet cells.

Monolayer cultures of adult rat islets were used for cinemicrographic studies on the movement of beta granules in the cytoplasm of beta cells. Stimulation of insulin release by glucose produced a significant increase in the amount of beta granule movement in the cultured cells. Disruption of the microtubular system with vinblastine or stabilization of microtubules with deuterium oxide inhibited the induction of granule movement by glucose. Incubation of the cultures in the absence of calcium inhibited glucose-induced movement of beta granules, whereas the subsequent addition of calcium permitted movement to occur. The addition of epinephrine also inhibited glucose-induced beta granule movement. In the presence of nonstimulating levels of glucose, movement of beta granules was present. The amount of movement varied from cell to cell suggesting a difference in base line activity of individual beta cells. The movement of individual beta granules was saltatory in type, and the average rate of movement was 1.5 mum. per second. The study demonstrated that directed movement of beta granules occurs following stimulation with glucose and adds further support to the hypothesis that the microtubular-microfilamentous system is involved in the intracellular translocation of beta granules to the cell surface where they are released by emiocytosis.

Animals↗