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PubMed2001

Stereotypic leg searching movements in the stick insect: kinematic analysis, behavioural context and simulation.

Insects are capable of efficient locomotion in a spatially complex environment, such as walking on a forest floor or climbing in a bush. One behavioural mechanism underlying such adaptability is the searching movement that occurs after loss of ground contact. Here, the kinematic sequence of leg searching movements of the stick insect Carausius morosus is analysed. Searching movements are shown to be stereotypic rhythmic movement sequences consisting of several loops. The typical loop structure allows the mean tarsus trajectory to be calculated using a feature-based averaging procedure. Thus, it is possible to describe the common underlying structure of this movement pattern. Phase relationships between joint angles, analysed for searching front legs, indicate a central role for the thorax-coxa joint in searching movements. Accordingly, the stereotyped loop structure of searching differs between front-, middle- and hindlegs, with leg-specific patterns being caused by differing protraction/retraction movements in the thorax-coxa joint. A simple artificial neural network that had originally been devised to generate simple swing movements allows two essential features of empirical searching trajectories to be simulated: (i) cyclic movements and (ii) the smooth transition into a search trajectory as a non-terminated swing movement. It is possible to generate several loops of a middle-leg search, but the precise size and shape of the loops fall short of a real-life approximation. Incorporation of front-leg retraction or hind-leg protraction during searching will also require an extension to the current model. Finally, front-leg searching occurs simultaneously with antennal movements. Also, because leg searching movements are a local behaviour, the legs remaining on the ground continue their stance phase, causing a forward shift of the body, including the searching leg. As a result of this shift, the centre of the searched space is close to the anterior extreme position of the tarsus during walking, representing the location of most likely ground contact according to past experience. Therefore, the behavioural relevance of searching movements arises from the combined actions of several limbs.

Animals↗
PubMed2000

[Three-dimensional analysis of eye movements induced by roll and pitch tilt].

The torsional eye movements induced by the right and left ear-down position are known as "ocular counter-rolling" but the mechanism of the horizontal and vertical eye movements has not been clarified. The vertical eye movements induced by backward tilt are known as the "doll reflex", but clear eye movements are induced by forward tilt. The mechanism of horizontal and torsional eye movements are unclear. To detect 3D eye movements in the roll and pitch planes, we performed 3D analysis of eye movements by our video-oculographic method. During roll tilt, counter-torsional eye movements were clearly induced, but no definite, eye movements were observed in the horizontal and vertical components of eye movements. During pitch tilt, downward eye movements were observed following backward tilt, but no clear eye movements were observed following forward tilt. Moreover, no clear horizontal or torsional eye movements were observed during pitch tilt. These results suggest that the response to pitch tilt depends on the saccular input.

Adult↗
PubMed1975

Analysis of human mandibular movement.

The parametric electrical outputs of the six-transducer mandibulograph were used to analyze three-dimensional pathways, displacement profiles, and velocity profiles of selected mandibular areas during jaw movement. This was accomplished by means of digital computer implementation of derived mathematical equations of motion. Five jaw movements were studied: chewing, open-close, right lateral, left lateral and protrusive. The results demonstrate the analytical and diagnostic value of this method and provice new clarification and insight into the nature of mandibular movements. The following observations summarize the principal findings derived from the analysis of jaw movement patterns of a normal patient. The chewing jaw movement exhibited a smoothly coordinated sequence of events. Lateral jaw motion appeared to be prominent during the masticatory phase and throughout the movement cycle. Mastication was abruptly terminated by a vertical desscent of the mandible through the freeway space, until the condyles began their forward movement producing a rotation in the sagittal plane. T occlusal area continued its downward descent along a nearly vertical pathway producing a compressed figure eight pattern in the frontal plane. The open-close jaw movement exhibited minor periods of hesitancy. Jaw movement was initiated with a forward and downward movement of the condyle occurring at the same time as a downward and backward movement of the occlusal area. This motion produced a rotation in the sagittal plane about a moving axis which was not coincident with the intercondylar axis. The general form of the command open-close jaw movement was that of noncoincident curved pathways in the sagittal plane with little lateral displacement. Closing jaw movement occurred with the condyle in a protruded position...

Adult↗
PubMedDate not supplied

[Fetal movement and acceleration behavior in unimpaired and impaired newborn infants].

The following biophysical examination parameters were found by CTG-synchronous registration of fetal body and respiratory movements and compared in 7 fetuses impaired at birth (pHa less than 7.20, 1- and 5-minute Apgar scores less than or equal to 7 points) and 76 unimpaired born fetuses (pHa greater than or equal to 7.20, 1- and 5-minute Apgar scores greater than or equal to 8 points): number of fetal body movements per 10 minutes examination time; total and mean durations of these movements per 10 minutes; number of fetal respiratory movements per 10 minutes; number and total duration of fetal respiratory movement periods per 10 minutes; frequency of fetal respiratory movements; proportion of 10-minute periods with and without fetal body and/or respiratory movements and the amounts of the quotients from the amplitude of accelerations in fetal heart rate resulting from fetal body movements and the durations of these body movements. The mean interval between biophysical examination and childbirth was 11 days. Principally, the impaired born fetuses were less active in their movements than were unimpaired born fetuses. Apart from the frequency of fetal respiratory movements and the proportion of 10-minute periods without fetal body movements, the above mentioned parameters differ significantly with a probable error of alpha = 0.05. All biophysical parameters were registered on an uterus without labour and the cardiogram as well as the biophysical profile--with the exception of one fetus from the group of impaired borns--being unremarkable. The 10-minute periods without fetal body or respiratory movements were excluded from analysis.

Apgar Score↗
PubMed1990

[Spontaneous and induced fetal movement activity in the 2d trimester of pregnancy].

During routine screening in the first half of pregnancy the authors evaluated in 3446 foetuses the incidence of spontaneous movements and movements after their attempted induction by movement of the uterus, when no spontaneous movements were recorded during examination. The examinations were made by means of a rotation probe 3.5 MHz of a Sonoline 2 apparatus (Siemens) always between 7.30 and 11.30 a.m. It was revealed that: 1. Spontaneous motor activity of the foetus depends significantly ot the foetal age; during the period between the 12th and 16th week it was recorded in 94.4%, in the 17th to 21st week it declines to 87.4% and during the 22nd-25th week it rises again to 94.7%. 2. The number of foetuses where movements were recorded after the first movement of the uterus depends also significantly on foetal age: in the 12th-16th week it is 57.5% of the number of foetuses without spontaneous movement, in the 17th to 21st week 66.3% and in the 22nd to 25th week 66.7%. 3. On the basis of preliminary work it is not possible to decide whether the movements observed after movement of the uterus are spontaneous or induced, however, if attempts to induce movements would imply only prolonged examination and recording of spontaneous activity, it is justified. 4. In one foetus where we did not observe spontaneous activity nor movements after movement of the uterus we revealed during a check-up examination rapidly developing polycystic kidneys. 5. Observation of foetal movements during screening is not time consuming and should become a matter of routine.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1990

[Change in the zone of apposition of the human diaphragm associated with ventilatory movement].

The movement of the cephalic margin of the zone of apposition (ZOA) of the diaphragm associated with ventilatory movement was measured using ultrasonography in 24 healthy subjects and 45 patients with various pulmonary diseases. A transducer was placed on the lower chest wall, and movement of the cephalic margin of ZOA was measured during maximal inspiratory maneuver and expiratory maneuver from end expiratory position in supine and sitting positions in healthy subjects, and in the supine position in patients. In healthy subjects, there was a linear relationship between inspiratory or expiratory volumes and movement of the cephalic margin of ZOA. Movement in the supine position during vital capacity maneuver was 103.0 +/- 15.6 (mean +/- SD), 106.6 +/- 17.2, 108.5 +/- 18.2, and 114.8 +/- 16.3 mm on the left anterior, right anterior, left posterior, and right posterior axillary lines, respectively. In the supine position, movement on the right posterior axillary line was significantly larger than that measured on other axillary lines (p less than 0.05). Movement during maximal inspiratory maneuver in the supine position was significantly larger than that in the sitting position (p less than 0.01). Movement during maximal expiratory maneuver in the supine position was significantly smaller than that in the sitting position (p less than 0.01). Patients showed decreased movement and great differences in movement between the left and right anterior axillary lines. Seven patients out of 28 with normal spirograms showed decreased movement on either or both sides. These data suggest that: 1) the movement of the cephalic margin of ZOA reflects diaphragm displacement; and 2) difference in ventilatory function of right and left hemithorax can be detected by movement of the cephalic margin of ZOA.

Diaphragm↗
PubMed1988

Prostaglandins E1, E2, and D2 induce dark-adaptive retinomotor movements in teleost retinal cones and RPE.

In teleosts, retinomotor movements of photoreceptors and retinal pigment epithelium are regulated both by light and by an endogenous circadian rhythm. Light induces cones to contract, rods to elongate and RPE cells to disperse their pigment granules into their long apical projections; darkness induces opposite movements. When fish are maintained in prolonged constant darkness, appropriate movements nonetheless occur at subjective dusk and dawn. To explore the mechanisms of this light and circadian regulation, we have been investigating effects of several extracellular messengers known to be present in retina on retinomotor movements in the green sunfish (Lepomis cyanellus). Here we report that prostaglandin E1 (PGE1) can induce movements characteristic of dark onset (or night) in both cones and RPE in isolated light-adapted retinas in the light; ie, PGE1 induces cone elongation and RPE pigment granule aggregation. The extent of PGE1-induced cone and RPE movements were dose-dependent with maximal movement occurring at 250-500 nM; higher concentrations were not as effective. Incubations with PGE2 and PGD2 also induced dark-adaptive cone and RPE retinomotor movements, but PGF2 alpha did not. Further observations suggest that prostaglandins may play a role in mediating the induction of cone and RPE movements by dark onset: dark-induced movements were inhibited by pretreating light-adapted isolated retinas before dark culture with agents which inhibit endogenous prostaglandin synthesis. Both indomethicin (50 microM) and acetylsalicylic acid (50 microM), two inhibitors of the cyclooxygenase component of specific prostaglandin synthase, inhibited dark-induced cone elongation and pigment aggregation in cultured sunfish retinas. Another cyclooxygenase inhibitor, ibuprofen (50 microM) had no effect. Together the effectiveness of PGE1 inducing dark-adaptive movement and the inhibition of dark adaptive movement by cyclooxygenase inhibitors suggest that prostaglandins may play a role in vivo in mediating the induction of dark-adapted RPE and cone retinomotor movements by dark onset.

Alprostadil↗
PubMed1980

The postural support of movement in cat and dog.

The postural adjustment which accompanies single limb movement in the standing cat and dog was analyzed. Four trays equipped with strain gauges were used for measuring the vertical forces exerted by each limb before and during movement performance. Three types of movements were analyzed: flexion movements elicited by motor cortex stimulation, placing movements, conditioned movements of either forelimb or hindlimb (lift-off in cat, flexion with maintained final position in dog). In both cats and dogs the postural adjustment during movement consists of a bipedal stance on two diagonally opposite limbs. Large quantitative differences were observed depending on the type of movement. Cortical stimulation elicited an adjustment where changes of forces exerted by the forelimb a hindlimb were nearly equal. During conditioned fore- and hindlimb lift-off in the cat there was a tendency to use only forelimbs for the postural adjustment associated with forelimb movement and hindlimbs for the adjustments associated with hindlimb movement. For placing in the cat and conditioned movement in the dog, the adjustment was intermediate, that is a predominant contribution of forelimb support with forelimb movements but nevertheless an associated contribution from hindlimbs. The general significance of the results with respect to the mechanism of postural adjustment associated with movement is analyzed.

Animals↗
PubMed1997

Effect of respiratory acidosis on body movements in the chronically instrumented fetal lamb.

BACKGROUND: In respiratory acidosis, it is reported that the fetal breathing movements as well as the fetal heart rate variability increase. As the increase of these two kinds of fetal activities is occasionally observed in normal conditions, it is difficult to distinguish respiratory acidosis and normal conditions by mere observation of these activities. As the third diagnostic variable, if a different fetal body movement response to respiratory acidosis is observed, it would be helpful for better diagnosis in combination with other activities. We investigated the effect of respiratory acidosis on body movements in the chronically instrumented fetal lamb. METHODS: A total of four experiments were performed on four ewes. Respiratory acidosis was induced in the fetus by maternal administration of a high carbon dioxide gas mixture for 1 hour. Fetal body movements were observed by real-time ultrasonography. The frequency of body movements was expressed as the number of each movement in a 30-minute period. RESULTS: The mean pCO2 increased from 42.9 +/- 4.9 mmHg to 62.9 +/- 14.8 mmHg, and the mean pH decreased from 7.368 +/- 0.04 to 7.209 +/- 0.04 during the experiments. The frequency of fetal body movements significantly decreased. The percentage reduction of these movements of the same fetus during the experiments as compared to the control periods were as follows; the high-frequency movements, 89.2 +/- 9.7%; the rolling movements, 55.6 +/- 13.5%; the simple movements, 78.3 +/- 18.4%. CONCLUSIONS: Normoxemic respiratory acidosis, which is reported to increase fetal breathing movements, caused a marked reduction in fetal body movements. These findings suggest that the ultrasonographic dissociation of fetal behaviors in respiratory acidosis would be potentially helpful in the diagnosis of impending fetal jeopardy.

Acidosis, Respiratory↗
PubMed1986

Two-dimensional and three-dimensional movement of human polymorphonuclear leukocytes: two fundamentally different mechanisms of locomotion [corrected].

Patients with an inherited deficiency of the adherence glycoproteins LFA-1, Mac-1, and p150,95 are unable to mobilize polymorphonuclear leukocytes (PMNLs) to peripheral sites of inflammation. LFA-1/Mac-1/p150,95-deficient PMNL exhibited profoundly impaired movement stimulated by chemotactic factors when the cells were required to move over two-dimensional surfaces. Less impairment of movement was demonstrated in three-dimensional movement through cellulose filters. A possible explanation for this difference in cell translational mobility is that movement in cellulose filters is less adherence dependent than movement over a two-dimensional plastic surface. Movement of PMNL in collagen gels is known to be relatively independent of adherence. No deficiency of translational mobility of PMNL from LFA-1/Mac-1/p150,95-deficient patients was observed in collagen gels. Antibodies against the common beta subunit effectively blocked two-dimensional movement but had little effect on three-dimensional movement through cellulose filters or collagen gel matrices. HL-60 cells were employed as a model to investigate the effects of adherence on cell movement. Treatment of HL-60 cells with phorbol myristate acetate resulted in the appearance of Mac-1 and p150,95 on the cell surface. Concurrently, the cells exhibited increased adherence to glass and plastic. In spite of increased adherence, HL-60 cells showed no translational movement, indicating factors other than the ability to adhere were important in cell motility. These experiments implied that PMNLs undergo two fundamentally different kinds of motion, one adherence dependent (two-dimensional movement) and the other largely adherence independent (three-dimensional movement). These findings are consistent with the view that egress of PMNLs from the vascular space is adherence dependent. Movement through extravascular tissues may be adherence independent.

Antigens, Surface↗
PubMed1996

Training wh-question production in agrammatic aphasia: analysis of argument and adjunct movement.

The present research utilized aspects of the Principles and Parameters Approach (P&PA; Chomsky, 1991, 1993) in linguistic theory as well as findings from the psycholinguistic literature as a basis for examining sentence production in aphasic individuals. We examined the production of particular wh-movement constructions--wh-questions requiring movement of an argument noun phrase (i.e., who and what questions) and those which require adjunct movement (i.e., when and where questions). Using a single-subject experimental treatment paradigm, subjects were sequentially trained to produce these wh-questions and, throughout training, generalization to untrained wh-questions relying on similar wh-movement processes was tested. As well, the influence of training on aspects of narrative and conversational discourse was examined. Seven agrammatic aphasic subjects who evinced difficulty producing (and comprehending) "complex" sentences (e.g., passives, object relative clauses, wh-questions)--sentences that involve movement of noun phrases (NPs) out of their canonical positions, leaving behind a "trace" of that movement or "gap"--participated in the study. Subjects were trained to produce wh-questions by taking them through a series of steps emphasizing the lexical and syntactic properties (e.g., thematic role assignment, movement processes, and proper selection of wh-morpheme) of declarative sentence counterparts of target sentences. Results revealed improved sentence production abilities in all subjects under study in both constrained sentence production and, importantly, in discourse tasks. The argument/adjunct distinction was observed in the sentence production recovery patterns noted in six of the seven subjects. Three of the subjects evinced correct argument movement across trained and untrained question structures when wh-questions relying on argument movement were trained; similarly, for these subjects, training structures relying of adjunct movement resulted in improved adjunct movement. Three of the remaining four subjects who required additional treatment to alleviate their wh-morpheme selection deficits, too showed covariance between argument and adjunct movement structures with each type of movement emerging across structures in temporal sequence. We discuss these data in terms of the operations necessary to produce wh-questions, the importance of considering linguistic and psycholinguistic data when designing treatment programs for language disordered patients, and the contribution that detailed recovery data can make both to understanding the nature of sentence production deficits and to issues regarding normal sentence production.

Adult↗
PubMed1980

Body movements and retinal pattern displacements while approaching a stationary object in the walking fly, Calliphora erythrocephala.

When a walking fly approaches a stationary object two types of body movements are distinguishable. Type I body movements are characterized by low frequencies (0.4-1.3 Hz) and large amplitudes (28-65 degrees). Superimposed on these movements are type II body movements which are characterized by high frequencies (7.3-10.6 Hz) and small amplitudes (5.9-8.2 degrees) (Figs. 3-6; Table 1). Type II movements occur no matter whether the fly is fixating a pattern or orientating itself in homogeneous surroundings without any pattern. In contrast, only 72% of the flies with immobilized heads and 62% of the flies with movable heads make type I body movements. The amplitude of type I and type II body movements increases slightly after immobilization of the head. Binocular as well as monocular pattern projection occurs for the whole walking trajectory (Fig. 7-9). Monocular pattern projection seems to be more frequent in flies with immobilized heads than in those with movable heads. The degree of pattern fluctuations in the visual field of the flies increases slightly along the walking trajectory. Near the starting point in the centre of the arena it amounts to 5-7 degrees, while at the end of the walking trajectory it amounts to 8-10 degrees (Table 2). The following conclusions and hypothesis can be drawn from these experiments. 1. The graph BT for the direction of the fly's longitudinal axis can be approximated by the first derivative of the walking trajectory WT, that means, dWT(x)dx approximately BT(x) (Fig. 11) 2. The amplitudes of type II body movements are caused by the alternating movements of the legs during forward motion, while type I body movements are classified as exploring movements. During evolution of visually guided behaviour it is possible that blowflies have adapted their elementary movement detector system to type II body movements. 3. The types of pattern projection into the visual field of the fly while approaching an object can be explained by a simple neuronal network characterized by either inhibitory and/or excitatory influences of the visually activated neurones on the motor neurones generating the propulsive forces, that means the forward motion. In addition it is postulated that the large frontal and antero-lateral receptive fields of these neurones are not coupled with the motor centres on the same side of the body (Fig 12).

Animals↗
PubMed2004

Live cell imaging of mitochondrial movement along actin cables in budding yeast.

BACKGROUND: Mitochondrial inheritance is essential for cell division. In budding yeast, mitochondrial movement from mother to daughter requires (1) actin cables, F-actin bundles that undergo retrograde movement during elongation from buds into mother cells; (2) the mitochore, a mitochondrial protein complex implicated in linking mitochondria to actin cables; and (3) Arp2/3 complex-mediated force generation on mitochondria. RESULTS: We observed three new classes of mitochondrial motility: anterograde movement at velocities of 0.2-0.33 microm/s, retrograde movement at velocities of 0.26-0.51 microm/s, and no net anterograde or retrograde movement. In all cases, motile mitochondria were associated with actin cables undergoing retrograde flow at velocities of 0.18-0.62 microm/s. Destabilization of actin cables or mutations of the mitochore blocked all mitochondrial movements. In contrast, mutations in the Arp2/3 complex affected anterograde but not retrograde mitochondrial movements. CONCLUSIONS: Actin cables are required for movement of mitochondria, secretory vesicles, mRNA, and spindle alignment elements in yeast. We provide the first direct evidence that one of the proposed cargos use actin cables as tracks. In the case of mitochondrial inheritance, anterograde movement drives transfer of the organelle from mothers to buds, while retrograde movement contributes to retention of the organelle in mother cells. Interaction of mitochondria with actin cables is required for anterograde and retrograde movement. In contrast, force generation on mitochondria is required only for anterograde movement. Finally, we propose a novel mechanism in which actin cables serve as "conveyor belts" that drive retrograde organelle movement.

Actins↗
PubMed2004

Brain lateralization of motor imagery: motor planning asymmetry as a cause of movement lateralization.

Movement asymmetry in humans and animals is often considered as being induced by the brain lateralization of the motor system. In the present work, the hemispheric asymmetry for motor planning as a cause of behavioral lateralization was examined. This study was carried out on normal volunteers and patients suffering unilateral brain damage caused by a stroke. Motor planning was evaluated by using the motor imagery of hand movement, a mental representation of a motor pattern that includes its internal simulation but not its real execution. The present study shows marked similarities between virtual movement executed during motor imagery and real movements. Thus, performance time showed a high correlation between real and virtual movements in the following conditions: (1) during dominant and non-dominant hand movements; (2) in simple and complex motor tasks; (3) in young control subjects; (4) in stroke patients; and (5) control subjects aged-matched to stroke patients. Brain strokes increased the performance time in both real and virtual movements. Left-brain strokes decreased the velocity of the real movements in both hands, whereas right-brain strokes mainly disturbed movements in the left hand. A similar effect was observed for virtual movements, suggesting a left-brain dominance for motor planning in humans. However, two-handed movement tasks suggest a complex interaction during motor planning, an interaction that facilitates motor performance during mirror movements and delays motor execution during non-mirror movements.

Adult↗
PubMed2000

Developmental features of rapid aiming arm movements across the lifespan.

Using a lifespan approach, the authors investigated developmental features of the control of ballistic aiming arm movements by manipulating movement complexity, response uncertainty, and the use of precues. Four different age groups of participants (6- and 9-year-old boys and girls and 24- and 73-year-old men and women, 20 participants in each age group) performed 7 types of rapid aiming arm movements on the surface of a digitizer. Their movement characteristics such as movement velocity, normalized jerk, relative timing, movement linearity, and intersegment intervals were profiled. Analyses of variance with repeated measures were conducted on age and task effects in varying movement complexity (Study 1), response uncertainty (Study 2), and precue use (Study 3) conditions. Young children and senior adults had slower, more variant, less smooth, and less linear arm movements than older children and young adults. Increasing the number of movement segments resulted in slower and more variant responses. Movement accuracy demands or response uncertainty interacted with age so that the 6- and 74-year-old participants had poorer performances but responded similarly to the varying treatments. Even though older children and young adults had better performances than young children and senior adults, their arm movement performance declined when response uncertainty increased. The analyses suggested that young children's and senior adults' performances are poorer because less of their movement is under central control, and they therefore use on-line adjustments. In addition, older children and young adults use a valid precue more effectively to prepare for subsequent movements than do young children and senior adults, suggesting that older children and young adults are more capable of organizing motor responses than are young children and senior adults.

Adolescent↗
PubMed1985

Speed-accuracy characteristics of saccadic eye movements.

Speed-accuracy trade-off characteristic of horizontal saccadic eye movements were examined in this study. Unlike limb movements, saccadic eye movements are preprogrammed, unidimensional, and do not involve target impact. Hence, they provide an optimal test of the impulse variability account of the speed-accuracy trade-off in rapid movements. Subjects were required to alternately look at two target lights as fast and as accurately as possible for a period of 10 s. Target lights subtended angles of 5, 10, 15, and 20 degrees. By restricting target distances to less than 20 degrees of arc, the speed-accuracy relation was examined for single horizontal saccadic movements of the eye. movement of the dominant eye was tracked with an infra-red eye monitoring device. Fifty saccadic movements of the eye were recorded for each target distance and used to compute the average amplitude, duration, and velocity of eye movements, as well as, movement endpoint variability. An increase in both average velocity and movement endpoint variability with increasing movement amplitude was found. This, together with the unique features of the eye movement system, support the impulse variability account of the speed-accuracy trade-off in rapid movements.

Journal Article↗
PubMed1993

The potential extent of transmission of foot-and-mouth disease: a study of the movement of animals and materials in Southland, New Zealand.

A survey of Southland farms was conducted to assess the potential for foot-and-mouth disease dissemination through normal movement patterns of farm animals and materials over a period similar to what would be expected from the time the virus arrived on a property to the time of diagnosis. Each farmer participating in the survey was required to complete a diary, recording all movements of people, animals and materials on to or off a farm during a 14-day period. The mean number of movements recorded per farm was 50. The distribution of movement distances showed the majority of movements occurred within the immediate neighbourhood of the origin, with 31.5% and 59.5% of all movements occurring within 5 km and 10 km respectively. In order to contain 95% of all movements, an area where movement was controlled would have to have a radius of 100 km. The data was then used to construct a spatial simulation model to study the movements off a hypothetical index farm. When secondary movements off primary destinations were included in the model, the mean number of movements to be traced to contain the disease was 100 (range 77-160) for a 14-day simulation period. The area required to contain 95% of all movements tended to increase slightly, depending on the length of simulation run. The mean number of high risk movements that occurred over the 100 km radius was 3.4.

Journal Article↗
PubMed1997

Endoscopic observations on laryngeal symmetry and movements in young racing horses.

An endoscopic survey of young race horses was performed to examine the prevalence and character of laryngeal movements during quiet respiration. The main aim was to determine whether those arytenoid movements which could possibly reflect the efficiency of left dorsal cricoarytenoid muscle function changed over a period of time. Of the 452 horses examined, 439 were Thoroughbreds and 23 were Standardbreds, 250 were less than 2 years of age (6-21 months), and 202 were 2 years old. One hundred and nine of these horses were examined again 16 months later. Arytenoid movements were given one of four grades. Grades 1 and 2 were considered normal and unlikely to be the result of abnormal left dorsal cricoarytenoid muscle function, whilst grades 3 and 4 were considered likely, or almost certainly, the result of abnormal left dorsal cricoarytenoid muscle function. The percutaneous prominence of the muscular process of left and right arytenoid cartilages, endoscopic arytenoid movement on left and right sides, age, sex and breed was recorded. Chi squared analysis was used to determine the association between age, breed, sex and the other recorded variables, and the presence or absence of abnormal laryngeal movements. At the first examination, 48% of the horses had grade 1, 37% grade 2, 15% grade 3 and 0.2% grade 4 left laryngeal movements. Of the horses examined I6 months later, 52% had grade 1, 33% grade 2, 14% grade 3 and 1% grade 4 left laryngeal movements. Fifteen percent of horses with grade 1 and 9% with grade 2 initially were found to be grade 3 at the subsequent examination. Conversely, 53% of horses with grade 3 initially were found to be grade 1 and 21% grade 2 at the subsequent examination. One horse that was grade 3 at the initial examination was grade 4 at the subsequent examination. Overall, 43% of horses were graded the same, 29% were given a better grade and 28% were given a worse grade. Age and sex were not associated with abnormal left laryngeal movements. The presence of abnormal arytenoid movements was significantly less in Standardbreds, but significantly higher in those horses that had a more prominent muscular process of the left arytenoid cartilage. The number of grade 2 and 3 laryngeal movements recorded on the left side was significantly higher than the right. It was concluded that asymmetrical laryngeal movements are common in young race horses; at this age laryngeal movements may interchange between what is considered normal and abnormal; the proportion of young horses with normal or minor variations in their left arytenoid movements that develop more obvious degrees of asynchrony is low (12%); and the proportion of horses considered to have endoscopic evidence of deficient left abductor muscle function that eventually develop laryngeal hemiplegia is also low (5%).

Journal Article↗