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At least 19 recordsLinked to original sources

PubMed1978

Nocturnal rotation in normal rats: correlation with amphetamine-induced rotation and effects of nigrostriatal lesions.

Normal unoperated rats were observed to rotate (turn in circles) at night. For most (91.7%) rats, the preferred direction of rotation was consistent across hours and days and was the same as the direction of rotation elicited by D-amphetamine (1.0 mg/kg) during the day. The magnitudes of nocturnal and D-amphetamine-induced rotation were also highly correlated. After rats showed stable diurnal patterns of rotation, unilateral lesions were made in either the substantia nigra, the nigrostriatal bundle or the caudate nucleus. All lesions produced transient contralateral rotation within the first 24-48 h after surgery. The time-course of this contralateral rotation was more prolonged after nigral lesions than after nigrostriatal bundle lesions and least after caudate lesions, suggesting that the duration of a degeneration release of dopamine is proportional to the length of the degenerating axon. Lesion size was correlated with the intensity of contralateral rotation but not with the time-course. At each rostralcaudal level, the magnitude of contralateral rotation was greater if the lesion was in the side of the brain opposite to the preoperative direction of rotation than if in the same side. By three days after surgery, all rats returned to a mostly normal diurnal cycle with the direction of rotation now being ipsilateral to the lesion. D-Amphetamine potentiated the ipsilateral rotation, though rats with lesions in the same side of the brain as the preoperative direction of rotation had larger drug responses than rats with similar lesions in the opposite side of the brain. By one month after surgery, the direction of spontaneous rotation of most rats had returned to the preoperative direction. As at all other times, the magnitude of rotation was, in part, dependent on the side of the lesion with respect to the preoperative bias. It is suggested that, following a unilateral lesion, compensatory processes occur to a greater extent if the lesion is in the normally more active side of the brain.

Animals↗

PubMed1992

Translational head movements of pigeons in response to a rotating pattern: characteristics and tool to analyse mechanisms underlying detection of rotational and translational optical flow.

Pigeons freely standing in the centre of a two-dimensionally textured cylinder not only rotate but also laterally translate their head in response to the pattern sinusoidally oscillating or unidirectionally rotating around their vertical axis. The translational head movement dominates the response at high oscillation frequencies, whereas in a unidirectionally rotating drum head translation declines at about the same rate as the rotational response increases. It is suggested that this is a consequence of charging the 'velocity storage' in the vestibulo-ocular system. Similar to the rotational head movement (opto-collic reflex), the translational head movement is elicited via a wide-field motion sensitive system. The underlying mechanism can be described as vector integration of movement vectors tangential to the pattern rotation. Stimulation of the frontal visual field elicits largest translational responses while rotational responses can be elicited equally well from any azimuthal position of a moving pattern. Experiments where most of the pattern is occluded by a screen and the pigeon is allowed to view the stimulus through one or two windows demonstrate a short-range inhibition and long-range excitation between movement detectors that feed into the rotational system. Furthermore, the results obtained from such types of experiments suggest that the rotational system inhibits the translational system. These mechanisms may help the pigeon to decompose image flow into its translational and rotational components. Because of their translational response to a rotational stimulus, it is concluded, however, that pigeons either generally cannot perfectly perform the task or they need further visual information, like differential image motion, that was not available to them in the paradigms.

Animals↗

PubMed1991

Axes of eye rotation and Listing's law during rotations of the head.

1. The vestibuloocular reflex (VOR) was examined in four alert monkeys during rotations of the head about torsional, vertical, horizontal, and intermediate axes. Eye positions and axes were recorded in three dimensions (3-D). Visual targets were used to optimize gaze stabilization. 2. Axes of eye rotation during slow phases showed small but systematic deviations from collinearity with the axes of head rotation. These noncollinearities apparently resulted from vector summation of torsional, vertical, and horizontal VOR components with different gains. 3. VOR gain was lowest about a head-fixed torsional axis that was correlated with the primary gaze direction, as determined by Listing's law for saccades. As a result, rotation of the head about a partially torsional axis produced noncollinear slow phases, with axes that tilted toward Listing's plane. 4. During slow phases, eye position changed not only in the direction of rotation, but also systematically in other directions. Even axes of eye rotation within Listing's plane caused eye position to move out of the plane to a torsional position that was then held. Thus Listing's law for saccades cannot be a product of plant mechanics. 5. VOR slow phases were simulated with the use of a model that incorporated 3-D rotational kinematics into the indirect path and the oculomotor plant. This demonstrated that the observed pattern of position changes is the expected consequence of rotating the eye about a fixed axis and that to hold these positions the indirect path must employ a 3-D velocity-to-position transformation. 6. Quick phases not only corrected the violations of Listing's law produced by slow phases but anticipated them by directing the eye toward a plane rotated in the direction of head rotation. This was modeled by inputting the vestibular signal to a Listing's law operator that is shared by the quick phase and saccadic systems.

Animals↗

PubMed1992

[The temporal course of nystagmus reactions after rotational stimulation (modified Veits long rotational method). Part II. Recommendations for the simplification of nystagmus evaluation in the rotational test].

In this study, on the basis of the graphics showing the time course of the nystagmus reactions following rotatory stimuli (Part I), some practical proposals are made on how the nystagmus responses following the rotatory test can be routinely analysed more quickly. The recommendations are oriented to the requirement that the selection of defined 30-second-intervals during the per- and postrotatory phase for the nystagmus analysis should reflect the total reaction in healthy subjects as well as in patients with acute vestibular lesions in a representative manner. It is also shown that reducing the analysis intervals to only 15 seconds or selecting unfavourable segments, can lead to an unacceptable falsification of the results.

Electronystagmography↗

PubMed1991

Rotating the plane of imposed vibration can rotate the plane of flagellar beating in sea-urchin sperm without twisting the axoneme.

When the head of a sea-urchin sperm is held in the tip of a micropipette and vibrated laterally, the flagellum beats in phase with the imposed vibration. Rotation of the plane of pipette vibration around the head axis induces a corresponding rotation of the plane of beating, in both live and reactivated sperm. Detailed analysis of the waveforms occurring at different stages of this rotation shows that the characteristic asymmetry of the flagellar bending waves rotates along with the plane of beat. The positions of small polystyrene beads attached as markers on the axonemes of demembranated sperm flagella appear unaffected by the rotation of the beat plane and asymmetry. The imposed rotation of the waveform is thus the result of a rotation of the coordinated pattern of sliding among the doublet tubules of the axoneme, and is not accompanied by a twisting of the whole axonemal structure. These data indicate that neither the plane of flagellar beat nor the direction of beat asymmetry is tightly dependent upon a structural or chemical specialization of particular members of the nine outer doublet microtubules, but that both are the result of some regulatory structure that can be forced to rotate relative to the outer structure of the axoneme.

Animals↗

PubMed1992

Mental rotation, physical rotation, and surface media.

Subjects made mirror-normal discriminations on alphanumeric characters shown in different orientations in the picture plane. Either the characters or the background rotated during stimulus presentation in Experiments 1-3. Character rotation in the direction of mental rotation facilitated mental rotation, whereas rotation in the opposite direction inhibited it. In Experiment 4, characters were presented in different surface media so as to stimulate only one representation at a time. Mental rotation performance was similar whether the stimuli were defined by luminance, color, texture, relative motion, or binocular disparity, suggesting that mental rotation occurs at a level beyond that of the independent analyses of these different media. These results support those of Experiments 1-3 in excluding the participation of low-level motion analysis centers in the mental rotation processes.

Adult↗

PubMed1990

Rotational relaxation rate of 1,6-diphenyl-1,3,5-hexatriene in cytoplasmic membranes of Bacillus subtilis. A new model of heterogeneous rotations.

The temperature dependence of fluorescence anisotropy, lifetime and differential tangent of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its polar trimethylammonium derivative (TMA-DPH) were investigated in cytoplasmic membranes of Bacillus subtilis. The fluorescence parameters were compared in the two types of membranes prepared from bacteria cultivated at 20 and 40 degrees C. Steady-state anisotropy measurements showed that within a broad range of temperatures, membranes cultivated at 20 degrees C exhibit significantly lower values than those prepared from cells cultivated at 40 degrees C. The temperature dependence of lifetime and differential tangent measurements (differential polarized phase fluorimetry) were fully consistent with steady-state anisotropy data of both DPH and TMA-DPH. The low anisotropy values in the case of TMA-DPH could be explained by a shorter lifetime and higher temperature-induced decrease as compared with DPH. Surprisingly, the temperature dependence of rotational rate R calculated according to the model of hindered rotations (Lakowicz 1983) gave misleading results. When increasing the temperature from 5 to 25 degrees C, a marked drop of rotational relaxation rate was observed. The minimum R values were measured between 25 and 30 degrees C and further increase of temperature (up to 60 degrees C) was reflected as increase of the R values. Therefore, a new model of "heterogeneous rotations" was developed. This model assumes that even at low temperatures (approaching 0 degrees C) where the differential tangent reaches zero, a fraction of fast rotating molecules exists. The ratio between fast and slowly rotating molecules may be expressed by this model, the newly calculated rotational rates are fully consistent with anisotropy, lifetime and differential tangent measurements and represent the monotonically increasing function of temperature.

Bacillus subtilis↗

PubMed1976

Mental rotation by the blind: does mental rotation depend on visual imagery?

Congentially blind adventitiously blind, and blindfolded sighted adults made same-different judgments of pairs of tactile forms. Two forms were presented in the same orientation, or one form differed from the other by a clockwise rotation of 30 degrees, 60 degrees, 120 degrees, or 150 degrees. Like the reaction times for the sighted and the adventitiously blind, reaction times for the congenitally blind increased as a linear function of angular discrepancy between stimuli, suggesting that the congentially blind, like the sighted and adventitiously blind, mentally rotated one form into congruence with the other to make judging easier. Corroboration of the mental rotation inference came from subjects' introspective reports. Inasmuch as the congenitally blind presumably do not have the ability to visually represent form, the present results suggest that mental rotation does not depend upon visual imagery. Thus, with respect to current speculation as to whether visual imagery is a necessary component of mental rotation, the present findings suggest that it is not.

Adolescent↗

PubMed1992

Role of the capsulo-ligamentous structures in rotation and combined flexion-rotation of the lumbar spine.

We carried out experiments on whole cadaveric lumbar spines in order to determine the role that each of the capsulo-ligamentous structures play in axial rotation in the neutral position and in the flexed position. Eight specimens were first tested intact, then after division of all the apophyseal joint capsules between L1 and the sacrum. Another five specimens were also first tested intact, then after division of the supra- and interspinous ligaments and yellow ligament, and finally after cutting the posterior longitudinal ligament and posterior annulus at each level as well. The results show that there is considerable variation in the axial rotation of the lumbar vertebrae within the same spine and across different spines. The apophyseal joint capsules limit rotation both in neutral and flexed positions. In flexion, the amplitude of rotation in the lumbar spine is reduced. Of the capsulo-ligamentous structures, it is the posterior annulus and the posterior longitudinal ligament that seem to play the more important role in limiting axial rotation while the spine is flexed.

Adult↗

PubMed1991

Effect of arm rotation on MR imaging of the rotator cuff.

The effect of humeral rotation on the appearance of the rotator cuff tendon in oblique coronal magnetic resonance images was evaluated in 70 such images. Internal rotation produced overlap of the supraspinatus and infraspinatus tendons with soft-tissue interposition or apparent discontinuity of the tendon in 22 cases, including 14 of 15 shoulders positioned in the first 30 degrees between extreme internal and external rotation. Imaging in internal rotation makes assessment of the tendon difficult and should be avoided.

Humans↗

PubMed1977

Maxillary rotation during human growth: annual variation and correlations with mandibular rotation. A metal implant study.

For a longitudinal study of the maxillary rotation, based on lateral headplates, a material of 22 patients with metallic implants in both jaws has been used. It has been established that the degree of maxillary rotation shows variations in direction and in intensity each year. It is smaller, in absolute value, than the degree of mandibular rotation. Due to the fact the direction of the maxillary and mandibular rotations are not always the same, it appears that the interaction between the maxillary and mandibular rotations plays an important role in the vertical and sagittal relationships of both jaws.

Adolescent↗

PubMed1977

Induction of illusory self-rotation and nystagmus by a rotating sound-field.

Subjects seated in darkness often experience illusory self-rotation when exposed to a rotating sound field. Compelling illusions of self-rotation are generally accompanied by nystagmoid movements of the eyes with the slow phase in the direction opposite that of the experienced self-rotation. These phenomena are related to the functioning of a spatial constancy mechanism by which a stable distinction is normally maintained between movements of self and movements of the environment. The appearance of nystagmus during illusory self-rotation indicates that apparent body orientation can influence oculomotor control.

Acoustic Stimulation↗

PubMed1987

A two-population model of rat rotational behavior: effects of unilateral nigrostriatal 6-hydroxydopamine on striatal neurochemistry and amphetamine-induced rotation.

Rats received intrastriatal or intranigral injections of 6-hydroxydopamine (6-OHDA) on the same side towards which they made most of their turns during a previous test of amphetamine-induced rotational behavior. One week later they were retested for amphetamine-induced rotational behavior and it was found that only approximately half of them increased their rotational behavior towards the lesioned side more than non-lesioned controls. In fact, compared to their pre-operative behavior numerous rats decreased or actually reversed their net turning towards the lesioned side. While the post-lesion rotational behavior of the two groups of rats was clearly different, pre-operative turning was not. Furthermore, the neurochemical effects of the intracerebral 6-OHDA injections were not different in the two groups of rats, either with respect to the magnitude of the resulting dopamine (DA) depletion, or with respect to the compensatory increase in the turnover of DA by surviving DA neurons on the lesioned side. The data are discussed in terms of their lack of support for current notions about the role of nigrostriatal DA in turning, and in terms of their support for a two-population model we have previously proposed. An additional, unrelated, finding from the present work was that bilateral striatal serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels decreased bilaterally one week following unilateral intrastriatal administration of 6-OHDA.

Animals↗

PubMed1990

Off-resonance rotating frame spin-lattice NMR relaxation studies of phosphorus metabolite rotational diffusion in bovine lens homogenates.

The rotational diffusion behavior of phosphorus metabolites present in calf lens cortical and nuclear homogenates was investigated by the NMR technique of 31P off-resonance rotating frame spin-lattice relaxation as a means of assessing the occurrence and extent of phosphorus metabolite-lens protein interactions. 31P NMR spectra of calf lens homogenates were obtained at 10 and 18 degrees C (below and above the cold cataract phase transition temperature, respectively) at 7.05 T. Effective rotational correlation times (tau 0,eff) for the major phosphorus metabolites present in cortical and nuclear bovine calf lens homogenates were derived from nonlinear least-squares analysis of R vs omega e (spectral intensity ratio vs precessional frequency about the effective field) data with the assumption of isotropic reorientational motion. Intramolecular dipole-dipole (1H-31P, 31P-31P), chemical shift anisotropy (CSA), and solvent (water) translational intermolecular dipole-dipole (1H-31P) relaxation contributions were assumed in the analyses. In those cases where the limiting value of the spectral intensity ratio failed to reach unity at large offset frequency, a modified formalism incorporating chemical exchange mediated saturation transfer between two sites was used. Values of tau 0,eff for phosphorus metabolites present in the cortex varied from a low of ca. 2 ns [L-alpha-glycero-phosphocholine (GPC)] to a high of 12 ns (alpha-ATP) at 10 degrees C, whereas at 18 degrees C the range was from ca. 1 to 9 ns. For the nucleus the tau 0,eff values ranged from ca. 3 ns (GPC) to 41 ns (Pi) at 10 degrees C; at 18 degrees C the corresponding values ranged from 4 to 39 ns. For PME (phosphomonoester; in lens the predominant metabolite is L-alpha-glycerol phosphate) at 18 degrees C evidence was obtained for binding and subsequent exchange with solid like protein domains. The diversity in tau 0,eff values for lenticular phosphorus metabolites is suggestive of differential binding to more slowly tumbling macromolecular species, most likely lens crystallin proteins. Corresponding measurement of tau 0,eff values for the mobile protein fraction present in calf lens cortical and nuclear homogenates at 10 and 18 degrees C, by 13C off-resonance rotating frame spin-lattice relaxation, provided average macromolecular correlation times that were assumed to represent the bound metabolite state. A fast-exchange model (on the T1 time scale), between free and bound forms, was employed in the analysis of the metabolite R vs omega e curves to yield the

Animals↗

PubMed1992

Triazolam blocks the initial rotational effects of quinpirole but permits the later developing reduction of dopamine D2-mediated rotational behavior and dopamine D2 receptors.

Continuous infusion of the dopamine D2 receptor agonist quinpirole into mice with unilateral striatal 6-hydroxydopamine lesions initially produces a supersensitive rotational behavior. This is followed by reductions of dopamine D2-mediated behavior and dopamine D2 receptors. In this study we attempted to determine if it is possible to inhibit the acute increase in D2-mediated behavior while still allowing the reduction of D2-mediated behavioral responses and dopamine D2 receptors to occur. Mice were implanted with Alzet minipumps containing either quinpirole alone or quinpirole combined with the GABA receptor modulator triazolam or the dopamine D2 receptor antagonist sulpiride, and rotational behavior was monitored for the 6 days of infusion. The pumps were then removed, and D2 receptors in striatal membranes were determined. Triazolam completely blocked the initial rotational behavior normally induced by implanting quinpirole. However, the quinpirole-induced reduction of D2-mediated behavioral responses and D2 receptors still occurred. Continuous infusion of sulpiride also inhibited the rotational behavior produced by quinpirole, but it prevented the reduction of dopamine D2 receptors. We conclude that up-regulated dopamine receptors and dopaminergic behaviors can be reversed by the continuous administration of a dopamine receptor agonist and that this reversal can occur without producing an initial exacerbation of dopaminergic responses. These results suggest that this type of treatment regimen might be useful for treating clinical conditions associated with dopaminergic supersensitivity.

Analysis of Variance↗

PubMed1991

[The arrangement of trans-septal fibers in rotated and non-rotated emerged teeth in beagle dogs].

Transseptal fibers of the periodontal ligament are thought to play a role in relapse after orthodontic correction of rotated teeth. The aim of this study was to compare the location of the attachment site and the arrangement of the transseptal fibers in rotated emerged and non-rotated emerged teeth. In five dogs, unilaterally, the first upper premolars were reimplanted into a rotated position, before emergence. Histological evaluation showed that in the experimental as well as in the control specimens transseptal fibers developed. In all cases transseptal fibers bridged the shortest distance between two adjacent teeth. It was concluded that the attachment site of the transseptal fibers is not determined by tooth anatomy itself, but by the tooth position and its orientation in the dental arch during transseptal fiber development.

Animals↗

PubMed1976

A spectroscopic technique for measuring slow rotational diffusion of macromolecules. 2: Determination of rotational correlation times of proteins in solution.

Experiments have been performed to test the validity of measurements of slow rotational diffusion using eosin isothiocyanate as a probe. When eosin-protein conjugates are covalently bound to Sepharose 4B, the dichroism of the flash-induced absorption transient does not decay with time. The magnitude of the dichroism is smaller than for eosin in solid solution. These results, together with measurements with highly viscous solutions, demonstrate the existence of a rapid but restricted independent motion of the eosin probe. This causes a partial loss of pf dochroism leaving a residual dichroism whose time dependence is determined by the rotational motion of the protein. Rotational correlation times in the microsecond-millisecond time range have been determined for eosinprotein conjugates dissolved in glycerol-water mixtures of varying viscosity. The measured values are in good agreement with theoretical predictions and show the correct dependence on the viscosity of the medium and the size and state of association of the protein.

Animals↗

PubMed1991

An experimental study in dogs of transseptal fiber arrangement between teeth which have emerged in rotated or non-rotated positions.

Transseptal fibers of the periodontal ligament are thought to play a role in relapse after orthodontic derotation. The aim of this study was to compare the location of the attachment site and the arrangement of the transseptal fibers in rotated emerged and non-rotated emerged teeth. In five dogs, unilaterally, the first upper premolars were replaced into a rotated position, before emergence. Histological evaluation showed that transseptal fibers developed in the experimental as well as in the control specimens. In all cases, transseptal fibers bridged the shortest distance between two adjacent teeth. It was concluded that the attachment site of the transseptal fibers was not determined by the tooth anatomy itself, but by the tooth position and its orientation in the dental arch during transseptal fiber development.

Animals↗