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PubMed1988

Standardized biomechanical measurement for varus-valgus stiffness and rotation in normal knees.

Seventeen female and 24 male subjects had varus and valgus and apparent rotations measured using a standardized mechanical testing device that cyclically applied a 20-Nm moment in each direction. Five parameters--apparent varus rotation, apparent valgus rotation, apparent overall rotation, varus stiffness, and valgus stiffness showed intersubject variations approaching 40%. Right-left variations in the same subject averaged 12%, with no significant right-left differences overall. Female knees rotated 66% more than male knees and were 35% less stiff. The ratio of apparent valgus rotation to apparent varus rotation averaged 0.775, and the ratio of valgus stiffness to varus stiffness averaged 1.23 for all knees. Stiffness and rotation parameters were highly correlated for both genders in the valgus phase of testing. Results suggest that although magnitudes of measured parameters vary considerably from subject to subject, common relationships between parameters from the same normal knee exist.

Adult↗
PubMed1997

Intranigral transplants of fetal ventral mesencephalic tissue attenuate D1-agonist-induced rotational behavior.

Rats were given unilateral 6-hydroxydopamine lesions and tested 4 weeks later for rotational behavior elicited by either systemic or intranigral injections of dopamine agonists. Subsequently, transplants of fetal (E14) ventral mesencephalic (VM) or cortical tissue were implanted into the lesioned substantia nigra and allowed to develop and integrate within the parenchyma of the host midbrain for a 4-week period before rotational behavior was retested. In animals receiving transplants of fetal VM tissue, systemic injections of amphetamine (5.0 mg/kg,i.p.) or the D2-agonist, quinpirole (0.2 mg/kg, s.c.), elicited rotational behavior that was quantitatively similar to rotational behavior observed (1) before animals received transplants of fetal VM tissue or (2) in animals with midbrain transplants of fetal cortical tissue. Intranigral administration of quinpirole (10.0 microg) immobilized most animals and did not elicit rotational behavior in any animals regardless of treatment. Rotational behavior elicited by systemic administration of the D1-agonist, SKF 82958 (0.01 mg/kg, s.c.), was slightly attenuated by VM transplants placed into the midbrain. Rotational behavior elicited by intranigral injections of SKF 82958 (7.5 microg) was markedly reduced in animals with VM transplants. These data support the hypothesis that midbrain D1-receptors modulate the expression of dopamine agonist-induced rotational behavior.

Animals↗
PubMed2001

Regional brain activity during different paradigms of mental rotation in healthy volunteers: a positron emission tomography study.

Positron emission tomography (PET) was used to observe changes in regional cerebral blood flow (rCBF) in 10 right-handed healthy volunteers performing two paradigms of mental rotation. In one paradigm, subjects mentally rotated a single alphanumeric stimulus to determine whether it was shown in a normal or mirror-image position. In a second paradigm, subjects mentally rotated and compared pairs of figurative stimuli to determine whether the stimuli were identical or mirror-images. In both paradigms, rCBF was compared with a control task that used identical stimuli, but required no mental rotation. Mental rotation of single alphanumeric stimuli engendered activation in the primary somatomotor area in the left precentral gyrus. Mental rotation of paired figures engendered activation in the left superior parietal lobule and the right frontal medial gyrus. A deactivated area was located in the medial part of the left superior frontal gyrus. Comparison of both paradigms revealed that the left gyrus precentralis was activated significantly during the alphanumeric condition and that the left gyrus lingualis was significantly activated during the paired figures condition. Motor processes may be an inherent part of every mental rotation but the type of motor involvement appears strongly dependent on the specific task or the specific stimuli. Similar paradigms, designed to isolate the same cognitive function, in the same subjects, using the same imaging technology and methodology, but differing only in stimulus material, lead to different areas of neural activation. Task specificity determines the most significant changes in cerebral blood flow in different mental rotation paradigms.

Adult↗
PubMed1986

Postural responses in the cat to unexpected rotations of the supporting surface: evidence for a centrally generated synergic organization.

Postural reactions to disruptions of stance are rapid and automatic in both quadrupeds and bipeds. Current evidence suggests that these postural responses are generated by the central nervous system as patterns involving muscle synergies. This study attempted to test this hypothesis of a centrally generated postural mechanism by determining whether the same postural response could be evoked in the freely-standing cat under two different biomechanical conditions. The present work is an extension of previous experiments in which the stance of cats was perturbed by a horizontal translation of the supporting surface in the anterior and posterior directions (Rushmer et al. 1983). We now tested whether simple rotation of the metacarpo- and metatarsophalangeal (M-P) joints that mimics the digit rotation occurring during platform translation, was sufficient to evoke the translation postural response. The rotational perturbations were biomechanically different from translations in that the rotation did not cause displacement of the centre of mass of the animal, nor did it result in any significant movement about any but the M-P joints. Even so, rotational perturbations did evoke the appropriate translational muscle synergies in all four animals. Both plantar flexion rotation and headward translation activated the posterior hindlimb synergy (which included gluteus medius, semitendinosus and lateral gastrocnemius). Similarly, dorsiflexion rotation and tailward translation both activated the same anterior hindlimb synergy (iliopsoas, vastus lateralis and tibialis anterior) together with the forelimb synergy The postural responses elicited by rotational perturbations were biomechanically inappropriate, and caused the animal to displace its own centre of mass away from the stable, control position.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Motion perceptions induced by off-vertical axis rotation (OVAR) at small angles of tilt.

Off-vertical axis rotation in darkness induces a perception of body motion which lasts as long as rotation continues. Perceived body motion is the combination of two simultaneous displacements. The most easily perceived is a translation without rotation along a conical path, at the frequency of the actual rotation. Meanwhile, the subjects feel as if they were always facing towards the same direction. The summit of the cone is generally below the head, from the waist to below the feet, and subjects have a sense of progression in the direction opposite to actual spinning. Some subjects feel, on the contrary, the summit of the cone above their heads, and the progression in the direction of spinning. Subjects also perceived another body motion, although it was faint for some of them. It consists of a rotation at low velocity in the same direction as progression along the cone. The axis of the cone is perceived as slowly rotating along a larger cone. These motion perceptions increase with tilt angle and rotation velocity. They probably result from the analysis by the Central Nervous System of the acceleration acting on the otoliths. The perceived trajectory would be reconstructed from estimates of gravity, and kinematic variables such as head translational acceleration and velocity, and head rotational velocity. The same variables would account for OVAR-induced nystagmus. Motion sickness would result from the impossibility of reconstructing a consistent body movement from most sets of values of these variables.

Adult↗
PubMed1975

Apomorphine-induced rotation in normal rats and interaction with unilateral caudate lesions.

Apomorphine (i.p.) induced rotational behavior (i.e. circling) in normal unoperated rats. This rotation increased with increasing dose up to 10.0 mg/kg, after which the dose-response curve appeared to plateau. Although there was large variability among rats, rotation for each rat was consistent in both direction and magnitude from week to week. Rotation was not antagonized by alpha-methyl-para-tyrosine. When rats with unilateral lesions of the caudate nucleus were tested with apomorphine, postoperative rotation was significantly influenced by the direction of preoperative rotation; rats rotated more postoperatively if the lesion was made ipsilateral rather than contralateral to their preoperative direction of rotation. These results suggest that there is a bilateral asymmetry of dopaminergic receptors in the nigro-striatal pathways of normal rats.

Animals↗
PubMed2006

Dynamics of the horizontal vestibuloocular reflex after unilateral labyrinthectomy: response to high frequency, high acceleration, and high velocity rotations.

Loss of vestibular information from one labyrinth results in a marked asymmetry in the horizontal vestibuloocular reflex (VOR). The results of prior studies suggest that long-term deficits in VOR are more severe in response to rapid impulses than to sinusoidal head movements. The goal of the present study was to investigate the VOR following unilateral labyrinthectomy in response to different stimuli covering the full range of physiologically relevant head movements in macaque monkeys. The VOR was studied 1-39 days post-lesion using transient head perturbations (up to 12,000 degrees/s(2)), rapid rotations (up to 500 degrees/s), and sinusoidal rotations (up to 15 Hz). In response to rotations with high acceleration or velocity, both contra- and ipsilesional gains remained subnormal. VOR gains decreased as a function of increasing stimulus acceleration or velocity, reaching minimal values of 0.7-0.8 and 0.3-0.4 for contra and ipsilesional rotations, respectively. For sinusoidal rotations with low frequencies and velocities, responses to contralesional stimulation recovered within approximately 4 days. With increasing velocities and frequencies of rotation, however, the gains of contra- and ipsilesional responses remained subnormal. For each of the most challenging stimuli tested (i.e., 12,000 degrees/s(2 )transient head perturbations, 500 degrees/s fast whole-body rotations and 15 Hz stimulation) no significant compensation was observed in contra- or ipsilesional responses over time. Moreover, we found that gain of the cervico-ocular reflex (COR) remained negligible following unilateral loss indicating that neck reflexes did not contribute to the observed compensation. VOR responses elicited by both sinusoidal and transient rotations following unilateral labyrinthectomy could be described by the same mathematical model. We conclude that the compensated VOR has comparable response dynamics for impulses and sinusoidal head movements.

Acceleration↗
PubMed1999

Listing's plane rotation with convergence: role of disparity, accommodation, and depth perception.

Earlier studies have reported temporal rotation of Listing's plane with convergence of the eyes causing torsion, which is dependent on eye elevation. The amount by which the planes rotate differs from study to study. To gain insight into the functional significance of the temporal tilt of Listing's plane for vision, we examined whether the rotation of the plane depends on the visual conditions, namely on the stimuli driving vergence. In different conditions, accommodative vergence, disparity-vergence, combinations of disparity with accommodation or depth perception were used and the resulting rotation of Listing's plane was measured. Our findings show, for the first time, that the relationship between convergence and Listing's-plane temporal rotation depends on the stimuli driving vergence. When the stimulus contains only disparity cues, vergence and Listing's plane rotate immediately and consistently among subjects. Accommodative vergence, the mutual couplings between vergence and accommodation, can influence the orientation of Listing's plane, but they do so in a idiosyncratic way. The largest rotation was elicited by stereograms combining disparity-vergence with depth perception. These findings support the idea of a functional role of Listing's plane rotation for binocular vision, perhaps for depth perception.

Accommodation, Ocular↗
PubMed2004

Differential activity of regions of transversus abdominis during trunk rotation.

The role of the abdominal muscles in trunk rotation is not comprehensively understood. This study investigated the electromyographic (EMG) activity of anatomically distinct regions of the abdominal muscles during trunk rotation in six subjects with no history of spinal pain. Fine-wire electrodes were inserted into the right abdominal wall; upper region of transversus abdominis (TrA), middle region of TrA, obliquus internus abdominis (OI) and obliquus externus abdominis (OE), and lower region of TrA and OI. Surface electrodes were placed over right rectus abdominis (RA). Subjects performed trunk rotation to the left and right in sitting by rotating their pelvis relative to a fixed thorax. EMG activity was recorded in relaxed supine and sitting, and during an isometric hold at end range. TrA was consistently active during trunk rotation, with the recruitment patterns of the upper fascicles opposite to that of the middle and lower fascicles. During left rotation, there was greater activity of the lower and middle regions of contralateral TrA and the lower region of contralateral OI. The upper region of ipsilateral TrA and OE were predominately active during right rotation. In contrast, there was no difference in activity of RA and middle OI between directions (although middle OI was different between directions for all but one subject). This study indicates that TrA is active during trunk rotation, but this activity varies between muscle regions. These normative data will assist in understanding the role of TrA in lumbopelvic control and movement, and the effect of spinal pain on abdominal muscle recruitment.

Abdominal Muscles↗
PubMed2000

Assessment of relative rotational alignment in total knee arthroplasty: usefulness of the modified Eckhoff method.

In 1995, Eckhoff and colleagues demonstrated a new method for assessing relative rotational alignment of the femoral and tibial components in total knee arthroplasty (TKA). We studied the usefulness of a modified Eckhoff method. Five knee prostheses (Natural Knee, Deltafit, and three different sizes of Press-Fit Condylar) were used in an in-vitro study. A series of lateral radiographs were taken with the femoral component rotated in 1 degrees increments from 15 degrees internal rotation to 15 degrees external rotation. The rotation of the implant was calculated based on the geometric relationship of pegs that were present symmetrically on the medial and lateral sides of the femoral components in all prostheses. In a study of the clinical applications, two independent observers measured the relative rotation of 18 knees in 16 patients after TKA, using this method. In the in-vitro study, the measurement error of rotation averaged 0.27 degrees, and the maximum error was 0.96 degrees. Clinically, the mean difference between the measurements of the two observers in each knee was 0.64 degrees; there was a high correlation between the values measured by the two observers (r = 0.89; P<0.0001). This is a useful method for determining the relative rotation in TKA accurately and reproducibly.

Arthroplasty, Replacement, Knee↗
PubMed2001

Radiographic assessment of scapular rotational tilt in chronic shoulder impingement syndrome.

This study presents an objective evaluation of both scapular upward and axial rotational tilts in shoulder impingement syndrome, using a scapular spine line defined on antero-posterior (AP) radiographs of the shoulder as the referential line. Twenty-seven patients with unilateral shoulder motion pain, who were diagnosed as having chronic shoulder impingement syndrome, were enrolled in the study. Scapular upward and axial rotational tilts were compared between the affected and contralateral shoulders. AP radiographs were obtained at shoulder abduction angles of 0 degrees, 45 degrees, and 90 degrees, and the X-ray films were digitized by computer. The upward and axial rotational tilts of the scapula were then evaluated on the digital images. In shoulder impingement syndrome, both upward and axial external rotations of the scapula were impaired at the painful arc angle of abduction. This tended to be more apparent for the axial rotation of the scapula than for the upward rotation. These reductions in scapular rotations reduce available clearance for the rotator cuff and humeral greater tuberosity as the shoulder is abducted.

Adult↗
PubMed1982

Molar occlusion and mandibular rotation: a longitudinal study.

The human dentition undergoes a process of complex development. Growth of the skeleton, morphology and function of the soft tissues (muscles in particular and airway), space considerations, and other factors influence the development of the dentition. The present study considered two of the factors involved: molar relationship in the sagittal plane and mandibular rotation. Forty-two persons from the Burlington sample were studied to determine whether changes in molar relation between the mean of ages 7 to 12 years were correlated with the rotational growth pattern of the mandible. The sample was divided into forward rotators (FR) and backward rotators (BR), based on the changes in the SN-corpus axis angle over time. The statistically significant difference of 4.04 degrees in change of the SN-CA angle over time, between the FRs and BRs, indicates that this method of characterizing the two different types of growers is useful. It is interesting to note, however, that the FRs and BRs, on an average, initially had the same SN-corpus axis angles. The molar relationship was determined on the basis of the cusp-fossa relationship in the sagittal plane. In the twenty-eight forward rotators and fourteen backward rotators the molar relationship did not change in a predictable fashion. Statistically significant correlations were not found between molar occlusion and growth direction patterns. Also, the SN-corpus-axis angle, at a single point in time, is not a good predictor of whether an individual is going to exhibit a forward or backward mandibular rotational growth pattern. The change in molar occlusion during the process of growth and development is a multifactorial phenomenon and cannot be predicted on the basis of the direction of mandibular growth rotation between the ages of 7 and 12 years.

Cephalometry↗
PubMed1982

Chlorpromazine methiodide-induced barrel rotation: an antimuscarinic effect.

Barrel rotation is a motor response observed in rats in which the animal twists about its long axis and rolls laterally. This response was first described following intracerebroventricular injection of somatostatin. The pharmacologic specificity of the response has been questioned, and its physiologic basis is unknown. Recently, barrel rotation following intraventricular injection of quaternary chlorpromazine, chlorpromazine methiodide (CPZMI), has been reported. We have studied the specificity and pharmacologic basis of CPZMI-induced barrel rotation. The response was not induced by 26 compounds injected as controls, and was induced by 6 anti-muscarinic compounds. Dose-response relationships for onset, duration and magnitude of CPZMI-induced barrel rotation response were studied; number of rotations increased linearly with CPZMI dose up to 20 micrograms, after which number of rotations decreased and toxic effects (sedation, seizures) occurred. CPZMI barrel rotation was inhibited by intraventricular injection of the muscarinic agonist carbachol and enhanced by intraventricular or systemic atropine. Muscarinic and dopamine receptor studies indicated that CPZMI has high affinity for the muscarinic cholinergic receptor and low affinity for the spiperone binding site. Modified Scatchard analysis of CPZMI displacement of [3H]QNB at the muscarinic receptor is consistent with muscarinic antagonist properties. We conclude that CPZMI-induced barrel rotation has a specific pharmacologic basis, that of muscarinic cholinergic antagonism.

Animals↗
PubMed1991

Differential modulation of (+)-amphetamine-induced rotation in unilateral substantia nigra-lesioned rats by alpha 1 as compared to alpha 2 agonists and antagonists.

In rats sustaining unilateral 6-hydroxy-dopamine lesions of the substantia nigra (SN), the indirect dopaminergic agonist, (+)-amphetamine (AMPH), dose-dependently induced robust, ipsilateral rotation: this could be dose-dependently abolished by the dopamine (D2/D1) antagonist, haloperidol. The selective alpha 1 antagonist, prazosin, dose-dependently attenuated the action of AMPH though rotation was not completely abolished. In the presence of a constant dose of prazosin, the dose-response curve for induction of rotation by AMPH was shifted to the right. The action of prazosin was mimicked by a further alpha 1 antagonist, corynanthine. In contrast, the selective alpha 1 agonist, ST 587, potentiated the rotation evoked by AMPH. The selective alpha 2 antagonist, idazoxan, dose-dependently potentiated the action of AMPH and, in the presence of a constant dose of idazoxan, the dose-response curve for AMPH was shifted to the left. This effect of idazoxan was mimicked by a further alpha 2 antagonist, yohimbine. In distinction, the selective alpha 2 agonist, UK 14,304, dose-dependently attenuated the action of AMPH, an action mimicked by the alpha 2 partial agonist, clonidine. Upon administration alone, the above mentioned drugs did not induce rotation. The data indicate that activation and antagonism of alpha 1 receptors enhance and inhibit rotation, respectively, whereas activation and antagonism of alpha 2 receptors inhibit and enhance rotation, respectively. These findings demonstrate an opposite alpha 1 and alpha 2 receptor-mediated control of rotation in this model. They suggest that an increase and decrease in noradrenergic tone, respectively, facilitate and inhibit locomotor activity controlled via the nigro-striatal dopaminergic pathway. The possible relevance of these findings to Parkinson's disease is discussed.

Adrenergic alpha-Agonists↗
PubMed1991

A model of the alar ligaments of the upper cervical spine in axial rotation.

Although there are seven vertebrae in the human cervical spine, over 50% of the total axial rotation occurs between the first and second vertebrae, at the atlanto-axial joint. Such motion is possible because of the lack of an intervertebral disc and the shape of the articular facets. The limitation of axial rotation, essential because the spinal cord and vertebral arteries cross this joint, is achieved with ligamentous structures, of which the left and right alar ligaments are primary. When one of the alar ligaments was cut in previous tests of human cadaveric spine (n = 10), the axial rotation to both sides significantly increased. This result does not agree with the long-held hypothesis that axial rotation is limited only by the alar on the side opposite rotation. The purpose of this work was to develop a model of the alar ligaments in axial rotation that is consistent with recent experimental observations. This model predicts that both alars must be intact to limit axial rotation; if one alar is injured, the normal mechanism becomes nonfunctional. The model also predicts the observation that a significant percentage of rotation at the atlanto-axial joint occurs freely, without ligamentous resistance. A physical and a mathematical description of the model is presented. Cadaveric experimental data are demonstrated to support the model.

Biomechanical Phenomena↗
PubMed1994

Reductions in body temperature and spontaneous activity in rats exposed to horizontal rotation: abolition following chemical labyrinthectomy.

The effect of horizontal rotation of male rats (70 rpm) on core temperature and spontaneous motor activity levels was examined. In Experiment 1, subjects were chemically labyrinthectomized (VNX) by intratympanic (IT) injections of sodium arsanilate and control rats (VNS) received IT injections of saline. Half of the rats in each group were subsequently rotated and the other half sham rotated. Measurement of body temperature prior to, immediately after, and 20 min following rotation revealed significant (all p < 0.01) reductions in temperature immediately after treatment, and 20 min later, in VNS rats. Sham-rotated VNS and all VNX rats failed to exhibit any significant changes in temperature following treatment. In Experiment 2, motor activity level was monitored in chemically labyrinthectomized (VNX) and control (VNS) rats prior to, and following, horizontal rotation. The VNS rats exhibited large (all p < 0.01) depressions in measures of horizontal and vertical spontaneous motor activity following rotation treatment, whereas VNX rats exhibited similar levels of activity in the pre- and postrotation period. These experiments show that, as in humans, exposing rats to horizontal rotation results in reduction of body temperature and motor activity, and that these physiological and behavioral changes require a functional vestibular system.

Animals↗
PubMed1990

Sensitization of rotation behavior in rats with unilateral 6-hydroxydopamine or kainic acid-induced striatal lesions.

Following unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra or unilateral kainic acid (KA) lesions of the striatum rats displayed rotation behavior in response to apomorphine (0.25 mg/kg SC or 1 mg/kg SC for the 6-OHDA- and KA-lesioned rats respectively). Three to five days following the initial apomorphine challenge rats were challenged under identical conditions with the same dose of apomorphine received previously. Both 6-OHDA- and KA-lesioned rats demonstrated a significant increase in the total number of rotations. Following a subsequent challenge with apomorphine, rats showed further increases in the total number of rotations. With the second and the subsequent apomorphine challenges there were significant increases in the maximal number of rotations, a significant decrease in the time of onset of rotation behavior and in some cases an increase in the duration of the rotation behavior. These increases in rotation behavior following repeated challenges with apomorphine indicate a supersensitivity to dopamine receptor agonists distinct from that elicited by lesions and chronic antagonist treatments. Furthermore, the utility of the rotation behavior model for testing the efficacy of dopaminergic agonists might be compromised if repeated challenges in individual animals are employed.

Animals↗
PubMed1992

Effects of tibial rotations on patellar tracking and patello-femoral contact areas.

The object of this study is to determine the effect of tibial rotations on the three-dimensional patello-femoral motions and contact areas during a physiological loading condition, the knee-extension exercise. A commercially available device, the 3-SPACE digitizer and tracker system, was used to collect the motion data, utilizing cadaveric human lower limbs as well as the geometric measurements describing the articular surfaces at the patello-femoral joint. It was found that tibial rotations caused statistically significant differences, at the 0.05 level, in patellar tilt, patellar rotation and patellar medial-lateral shift. It was also found that while the magnitude of the total contact area at a given knee flexion angle did not change significantly with tibial rotations, medial and lateral components of the total contact areas were affected by tibial rotations. Medical femoral contact areas increased with internal tibial rotations at all flexion angles; lateral femoral contact areas increased with external tibial rotations at all flexion angles. This correlates well with the kinematic data since it was found that the patella shifted medially with internal tibial rotations at all flexion angles, and titled more medially near full-extension causing an increase in the medial contact areas and a decrease in the lateral contact areas.

Biomechanical Phenomena↗