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PubMed1999

Effect of field size, head motion, and rotational velocity on roll vection and illusory self-tilt in a tumbling room.

The effect of field size, velocity, and visual fixation upon the perception of self-body rotation and tilt was examined in a rotating furnished room. Subjects sat in a stationary chair in the furnished room which could be rotated about the body roll axis. For full-field conditions, complete 360 degrees body rotation (tumbling) was the most common sensation (felt by 80% of subjects). Constant tilt or partial tumbling (less than 360 degrees rotation) occurred more frequently with a small field of view (20 deg). The number of subjects who experienced complete tumbling increased with increases in field of view and room velocity (for velocities between 15 and 30 degrees s-1). The speed of perceived self-rotation relative to room rotation also increased with increasing field of view.

Adolescent↗
PubMed2002

Buildup and decay of a three-dimensional rotational aftereffect obtained with a three-dimensional figure.

Gaps in past literature have raised questions regarding the kinds of stimuli that can lead to three-dimensional (3-D) rotation aftereffects. Further, the characteristics of the buildup and decay of such aftereffects are not clear. In the present experiments, rotation aftereffects were generated by projections of cube-like stimuli whose dynamic perspective motions gave rise to the perception of rotation in unambiguous directions; test stimuli consisted of similar cubes whose rotation directions were ambiguous. In experiment 1, the duration of the adaptation stimulus was varied and it was found that the 3-D rotation aftereffect develops with a time constant of approximately 26 s. In experiment 2, the duration between adaptation and testing was varied. It was found that the 3-D rotation aftereffect has a decay constant of about 9 s, similar to that observed with 2-D motion aftereffects. Experiment 3 showed that the rotation aftereffects were not simple depth aftereffects. To account for these aftereffects and related data, a modification of an existing neural-network model is suggested.

Adult↗
PubMed2006

Central visual persistences: II. Effects of hand and head rotations.

In an earlier paper, kinesthetic effects on central visual persistences (CPs) were reported, including the ability to move these images by hand following eye closure. While all CPs could be translated anywhere within the frontal field, the present report documents a more selective influence of manual rotations on CPs in the same subjects. When common objects or figures drawn on cards were rotated (while holding one end of the object or one corner of a card between thumb and forefinger), it was found that CPs of larger objects rotated with the hand. By contrast, CPs of smaller objects, parts of objects, and textures remained stable in space as the hand rotated. It is proposed that CPs of smaller stimuli and textures are represented mainly by the ventral stream (temporal cortex) while larger CPs, which rotate, are represented mainly by the dorsal stream (parietal cortex). A second discovery was that CPs of small objects (but not of line segments or textures) could be rotated when the thumb and fingers surrounded the edges of the object. It is proposed that neuronal convergence of visual and tactile information about shape increases parietal responses to small objects, so that their CPs will rotate. Experiments with CPs offer new tools to infer visual coding differences between ventral and dorsal streams in man.

Adult↗
PubMed2003

Rotation of the proteolipid ring in the V-ATPase.

V0V1-ATPase is a proton-translocating ATPase responsible for acidification of eukaryotic intracellular compartments and for ATP synthesis in archaea and some eubacteria. We demonstrated recently the rotation of the central stalk subunits in V1, a catalytic sector of V0V1-ATPase (Imamura, H., Nakano, M., Noji, H., Muneyuki, E., Ohkuma, S., Yoshida, M., and Yokoyama, K. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 2312-2315), but the rotation of the proteolipid ring, a predicted counterpart rotor in the membrane V0 sector, has remained to be proven. V0V1-ATPase that retained sensitivity to N',N'-dicyclohexylcarbodiimide was isolated from Thermus thermophilus, immobilized onto a glass surface through the N termini of the A subunits of V1, and decorated with a bead attached to a proteolipid subunit of V0. Rotation of beads was observed in the presence of ATP, and direction of rotation was always counterclockwise viewed from the membrane side. The rotation proceeded at approximately 3.0 rev/s in average at 4 mm ATP and was abolished by N',N'-dicyclohexylcarbodiimide treatment. Thus, the rotation of the central stalk in V1 accompanies rotation of a proteolipid ring of V0 in the functioning V0V1-ATPase.

Models, Molecular↗
PubMed2004

Position of the humeral head and rotator cuff tear: an anatomical observation in cadavers.

BACKGROUND: The relationship between the humeral head position and rotator cuff tears is not well described. MATERIAL AND METHODS: We performed an anatomical study of 22 cadaveric shoulders to find out the relationship between the normal anatomical position of the humeral head and tears of the rotator cuff. After dissection, the rotator cuff pathology was documented. The position of the humeral head was noted in relation to the acromion. The humeral head with intact acromion and articulated shoulder joint was photographed from the superior aspect of the joint and the area of the humeral head outside the acromion was measured, i.e. the part of the humeral head lateral to the lateral border of the acromion process. The relationship between rotator cuff pathology and uncovering of the humeral head was determined. RESULTS: 9 specimens had a partial cuff tear, while 4 had a complete tear. Those specimens with a rotator cuff tear had a mean area of 83% of the humeral head under the acromion. The specimens that did not show a rotator cuff tear had a mean area of 61% of the humeral head under the acromion. INTERPRETATION: We suggest that there is individual variation in anatomical position of the humeral head in relation to the acromion and that this position correlates with the occurrence of rotator cuff pathology.

Cadaver↗
PubMed1996

Changes in cortical activity during mental rotation. A mapping study using functional MRI.

Mental imagery is an important cognitive method for problem solving, and the mental rotation of complex objects, as originally described by Shepard and Metzler (1971), is among the best studied mental imagery tasks. Functional MRI was used to observe focal changes in blood flow in the brains of 10 healthy volunteers performing a mental rotation task. On each trial, subjects viewed a pair of perspective drawings of three-dimensional shapes, mentally rotated one into congruence with the other, and then determined whether the two forms were identical or mirror-images. The control task, which we have called the 'comparison' condition, was identical except that both members of each pair appeared at the same orientation, and hence the same encoding, comparison and decision processes were used but mental rotation was not required. These tasks were interleaved with a baseline 'fixation' condition, in which the subjects viewed a crosshair. Technically adequate studies were obtained in eight of the 10 subjects. Areas of increased signal were identified according to sulcal landmarks and are described in terms of the Brodmann's area (BA) definitions that correspond according to the atlas of Talaraich and Tournoux. When the rotation task was contrasted with the comparison condition, all subjects showed consistent foci of activation in BAs 7a and 7b (sometimes spreading to BA 40): 88% had increased signal in middle frontal gyrus (BA 8) and 75% showed extrastriate activation, including particularly BAs 39 and 19, in a position consistent with area V5/human MT as localized by functional and histological assays. In more than half of the subjects, hand somatosensory cortex (3-1-2) was engaged, and in 50% of subjects there was elevated signal in BA 18. In frontal cortex, activation was above threshold in half the subjects in BAs 9 and/or 46 (dorsolateral prefrontal cortex). Some (four out of eight) subjects also showed signal increases in BAs 44 and/or 46. Premotor cortex (BA 6) was active in half of the subjects during the rotation task. There was little evidence for lateralization of the cortical activity or of engagement of motor cortex. These data are consistent with the hypothesis that mental rotation engages cortical areas involved in tracking moving objects and encoding spatial relations, as well as the more general understanding that mental imagery engages the same, or similar, neural imagery as direct perception.

Adult↗
PubMed2005

Selective impairment of hand mental rotation in patients with focal hand dystonia.

Mental rotation of body parts determines activation of cortical and subcortical systems involved in motor planning and execution, such as motor and premotor areas and basal ganglia. These structures are severely impaired in several movement disorders, including dystonia. Writer's cramp is the most common form of focal hand dystonia. This study investigates whether patients affected by writer's cramp present with difficulties in tasks involving mental rotation of body parts and whether any impairments are specific to the affected hand or generalized to other body parts. For this purpose we tested 15 patients with right writer's cramp (aged 21-68 years, 8 women) and 15 healthy control subjects (10 women, age and education matched). Stimuli consisted of realistic photographs of hands and feet presented on a computer monitor in different orientations with respect to the upright canonical orientation. In each trial, subjects gave a laterality judgement by reporting verbally whether the presented body part was left or right. Two main results of the study are, firstly, writer's cramp patients are slower than controls in mentally rotating hands [F (1,28) = 5.4; P = 0.028] but not feet, and secondly, the pattern of response times to stimuli at various orientations suggests that the mental motor imagery of controls and patients reflects the type of processes and mechanisms called into play during actual execution of the same movements. In particular, increased difficulty in rotating right-sided stimuli at 120 degrees and left-sided stimuli at 240 degrees would suggest that mental rotation of body parts reflects the anatomical constraints of real hand movements. In conclusion, patients with writer's cramp presented mental rotation deficits specific to the hand. Importantly, deficits were present during mental rotation of both the right (affected) and the left (unaffected) hand, thus suggesting that the observed alterations may be independent and even exist prior to overt manifestations of dystonia.

Adult↗
PubMed1984

Analysis of rotation accompanying shoulder flexion.

For effective rehabilitation of the shoulder, physical therapists must have correct knowledge of shoulder motion. Reports conflict on whether medial or lateral rotation of the humerus accompanies shoulder flexion. The purpose of this study was to determine the relationship between flexion and rotation at the glenohumeral joint. We determined rotation that accompanied active shoulder flexion by using a universal full-circle goniometer and an adjustable wooden bracket that served as a base for a gravity-activated angle finder. Therapists performed passive shoulder flexion with the humerus held allowing no rotation and then held in medial or lateral rotation. We used single-tailed t tests to determine analysis. We found significant differences (p less than .01) between the amount of shoulder rotation accompanying active shoulder flexion between men and women. Medial rotation of the shoulder accompanied active flexion in all subjects. Physical therapists should consider these results when the goal of treatment is to increase shoulder flexion.

Adolescent↗
PubMed1996

Coracoacromial ligament: in situ load and viscoelastic properties in rotator cuff disease.

The coracoacromial ligament plays a role in rotator cuff disease. The changes in the in situ load and viscoelastic properties of the coracoacromial ligament in shoulders with rotator cuff tears were evaluated. Coracoacromial ligaments from 16 cadaveric shoulders (8 with rotator cuff tears, 8 without tears) were evaluated via biomechanical testing of bone ligament bone specimens. An in situ load existed in the coracoacromial ligaments of 19.6 +/- 15.4 N (rotator cuff tear) and 18.3 +/- 9.8 N (no rotator cuff tear). This difference was not statistically significant. Cyclic loading of the ligaments demonstrated a greater drop in peak stress in rotator cuff tear shoulders than in normal shoulders, whereas the stress relaxation response was not different. These changes in the coracoacromial ligament in shoulders with cuff tears may be attributable to ultrastructural changes within the ligament as a result of an altered loading environment. It remains unknown whether they occur as a result of a rotator cuff tear or if they contribute to the pathogenesis of cuff disease.

Aged↗
PubMedDate not supplied

Changes in pelvic rotation after soft tissue and bony surgery in ambulatory children with cerebral palsy.

The authors performed a retrospective review of pelvic rotation in 59 children with cerebral palsy who underwent lower extremity surgery and pre- and postoperative gait analysis. Two groups were studied: a femoral derotation osteotomy (FDRO) group and a soft tissue surgery only (no FDRO) group. Both groups exhibited abnormal pelvic rotation preoperatively and normalization of this abnormal pelvic rotation postoperatively. Though the mean change in pelvic rotation was small (3.3 degrees +/- 6.0 degrees), some patients demonstrated postoperative changes as large as 21 degrees. Variability in pelvic rotation was greater in the no FDRO group than in the FDRO group. Improvement in pelvic rotation occurred both in children with unilateral (hemiplegic) involvement and in those with bilateral (diplegic or quadriplegic) involvement. Surgeons planning lower extremity surgery in children with cerebral palsy should expect improvement in abnormal pelvic rotation in both hemiplegic and diplegic patients, whether or not bony surgery is planned in addition to soft tissue surgery.

Cerebral Palsy↗
PubMed2000

Rotational alignment of humerus after closed locked nailing.

OBJECTIVE: Rotational malalignment that may happen during closed nailing of humeral fractures is, to date, an unexplored area of investigation. The purpose of this study was to examine the effect of arm position during surgery on humeral rotational alignment and the effect of this alignment on shoulder motion and function. METHODS: Thirty patients with eventual fracture healing after closed humeral locked nailing were retrospectively studied: 15 had retrograde nailing; 15, antegrade. Retrograde nailing was performed with the patient in a decubitus position and with the upper arm anteriorly flexed and the forearm perpendicular to the operating table. Antegrade nailing was performed with the patient in a semisitting position and with the upper arm in the so-called resting position. The humeral retroversion angle as measured by computed tomographic scan, range of shoulder rotation, and Neer score of the shoulder for the fractured and the intact humeri were determined, and the discrepancy (i.e., value for the intact subtracted from that for the fractured) between the two was noted. To test the effect on alignment of positioning during retrograde nailing, we similarly determined retroversion angles for another 15 patients treated in a supine resting position. RESULTS: Between antegrade nailing and retrograde nailing in decubitus position, there was a significant difference in the mean discrepancies for the retroversion angles and the range of external rotation of the shoulder in the neutral and abduction positions, but no significant difference for internal rotation of the shoulder and Neer score. Between antegrade nailing and retrograde nailing in supine resting position, there was no significant difference in the mean discrepancy for the retroversion angle. CONCLUSION: Positioning of the arm may significantly affect humeral rotational alignment and range of motion during closed nailing. Until a reliable method for intraoperative measurement of humeral rotation is devised, we recommend that closed nailing of humeral shaft fractures be performed with the patient's upper arm in the resting position shown in this study.

Adolescent↗
PubMed1997

Rotational vertebral artery occlusion: a mechanism of vertebrobasilar insufficiency.

OBJECTIVE: Symptomatic dynamic changes in blood flow secondary to vertebral artery compression with rotational head motion are evaluated in a series of patients as a cause for posterior circulation transient ischemic attacks. These cases are classic examples of rotational vertebral artery occlusion and allow for the discussion of the anatomic basis, angiographic features, and treatment options. ILLUSTRATIVE CASES: In our series, symptoms of vertebrobasilar insufficiency were reproducible with rotational head movement. Compression of the vertebral artery was demonstrated angiographically. The correct site of occlusion of the vertebral artery was apparent only by dynamic angiography with progressive head rotation. All of the patients presented in the illustrative cases had occlusion at the C2 level; however, one patient had been previously misdiagnosed and another had an additional site of occlusion. The anatomic course of the vertebral artery is described in addition to the sites of rotational occlusion. CONCLUSION: Rotational vertebral occlusion is an important cause of vertebrobasilar symptoms, which may lead to permanent neurological deficit if left undiagnosed. Dynamic angiography is the established method of diagnosis. Great care must be taken to avoid misdiagnosing the site of occlusion or missing a second occlusive site. For this reason, it is crucial to have a thorough understanding of the anatomic course of the vertebral artery and the muscular and tendinous insertions, which may cause rotational occlusion. The decision for treatment must be based on the site of occlusion as well as the assessment of the patient as a surgical candidate. A review of the literature reveals that surgical treatment is effective and must be considered to avoid further morbidity.

Adult↗
PubMed1998

Effect of 360 degrees and 180 degrees rotation SPET acquisitions on myocardial polar map: comparison of 201Tl-, 99Tcm- and 123I-labelled radiopharmaceuticals.

Both 360 degrees and 180 degrees rotation acquisition methods have been used in myocardial single photon emission tomography (SPET) studies. We compared both methods using 201Tl, 99Tcm and 123I radiopharmaceuticals with phantoms and clinical models. Myocardial phantom studies with anterior and inferior defects were performed using 201Tl, 99Tcm and 123I. Clinical models of 14 typical situations, including normal subjects, patients with anterior or inferior defects and a high right hemi-diaphragm, were studied. The radiopharmaceuticals were 201Tl, 99Tcm-sestamibi, 123I-BMIPP and 123I-MIBG. Four sets of 180 degrees anterior rotation data with starting angles of (A) posterior, (B) LPO 30 degrees, (C) LPO 60 degrees and (D) left lateral direction were generated and compared with 360 degrees rotation SPET. A polar map display was used for quantification. In phantom studies, the defect contrast on the map was higher in the anterior defect with 180 degrees rotation than with 360 degrees rotation. However, it was decreased in the inferior defect, particularly with 201Tl, because of decreased wall activity around the defect. In the patient model with anterior or inferior defects, the defect contrast was improved with 180 degrees SPET by up to 10%. A slight decrease in the normal region was also noted in the 180 degrees reconstruction. The effect of diffuse liver activity on the inferior region depended on the rotation range. A patient with a high right hemi-diaphragm showed a lower inferior count with 360 degrees SPET. In conclusion, the 360 degrees acquisition was superior to the 180 degrees acquisition in the phantom with defects. Clinically, the quantitative differences in radionuclide types (99Tcm, 123I or 201Tl) were not significant for quantifying a moderate degree (50-60% of peak count) of defect. However, we note quantitative variation depending on the rotation range in the 180 degrees method.

3-Iodobenzylguanidine↗
PubMed1976

Rotation of lathe-cut hydrogel lenses on the eye.

The rotation lathe-cut HydroCurveTM gel contact lens was measured on six eyes to evaluate the parameters that influence lens rotation and to determine if this lens could be used to correct astigmatism. Of the 72 observations made, 73.6% showed some lens rotation, and 33.4% of the sample rotated more than 5 degrees per 10 blinks. Of the observations in which rotation was noted, 88.7% were encyclorotation. These results are similar to those found for spin-cast hydrogel lenses. None of the lens parameters evaluated seemed to be related to lens rotation, whereas the eye parameters studied were. Lenses were more likely to rotate on eyes with smaller corneal diameters, smaller palpebral apertures, and corneal curvatures steeper than 4 3.00 DK (X2, N =72, p less than 0.05). Our findings indicate that some method of lens stabilization will be needed before lathe-cut hydrogel lenses can be used to effectively correct astigmatism.

Adult↗
PubMed1984

Axial rotation and lateral bending in the normal lumbar spine measured by three-dimensional radiography.

A three-dimensional radiographic technique was used to investigate the ranges of active axial rotation and lateral bending plus the accompanying rotations in the planes other than that of the primary voluntary movements in two groups of normal male volunteers. There was approximately 2 degrees of axial rotation at each intervertebral joint with L3-4 and L4-5 being slightly more mobile. Lateral bending of approximately 10 degrees occurred at the upper three levels, while there was significantly less movement of 6 degrees and 3 degrees at L4-5 and L5-S1, respectively. In the upper lumbar spine, axial rotation to the right was accompanied by lateral bending to the left and vice versa. At L5-S1, axial rotation and lateral bending generally accompanied each other in the same direction, while L4-5 was a transitional level. These measurements in vivo demonstrated that there was no simple mechanical coupling of the rotations, and that the lordotic shape of the lumbar spine together with muscular control are probably the two principal factors determining the relation between the primary and accompanying rotations.

Adult↗
PubMed1987

Rotation of the cervical spine. A CT study in normal subjects.

A computed tomography (CT) study of rotation of the cervical spine was undertaken in normal subjects aged 20 to 26 years. Section scans through the neck were made with the head in maximal rotation to the right or the left. Occiput, cervical spine, and first thoracic vertebra, thus, were depicted in different degrees of rotation with respect to the sagittal plane. These differences indicated the maximal degree of rotation in each of the eight segments between occiput and thoracic spine. Mean values for these segments were 1.0 degree, 40.5 degrees, 3.0 degrees, 6.5 degrees, 6.8 degrees, 6.9 degrees, 5.4 degrees and 2.1 degrees, respectively. Measurement error proved to be relatively small. By means of CT sections in the plane of the intervertebral joints (in three subjects in midposition, in one subject in maximal rotation of the head to one side) an axis of rotation could be constructed from the anatomic shape of the uncovertebral joints. The theory of Hall that the unciform processes are essential for rotation is confirmed and further elaborated.

Adult↗
PubMed1989

Three-dimensional motion analysis of the cervical spine with special reference to the axial rotation.

The purpose of this study is to obtain basic data on the rotational motion of the cervical spine. Twenty normal men aged 25 to 31 years were investigated. Biplanar roentgenograms of the neck with the head held in neutral and maximally rotated positions were taken in a reference frame. Three sets of x-ray films were measured using a three-dimensional analysis system composed of a digitizer and a personal computer. Total axial rotation was 105 degrees on an average between the occiput and the C7 vertebra. Seventy percent of the total axial rotation occurred between the occiput and the C2 vertebra. Each motion segment between the C2 and C7 vertebrae showed from 4 degrees to 8 degrees rotation on an average. When the head was rotated, lateral bending occurred by coupling in the same direction as rotation at each segment below the C3-C4 level, and in the opposite direction above the C2-C3 level. At the same time, flexion took place by coupling at each segment below the C5-C6 level, and extension above the C4-C5 level.

Adult↗
PubMed1994

Torque of trunk flexion and trunk flexion with axial rotation in healthy men and women.

The purpose of this study was to determine normal values for torque of trunk flexion and trunk flexion with axial rotation. Eighty-two healthy subjects (39 men, 43 women) were tested for isometric torque of trunk flexion at four angles, and eccentric and concentric torque at 30 degrees/sec. All tests were performed in three positions of axial rotation: neutral rotation, trunk rotated 30 degrees to the right, and trunk rotated 30 degrees to the left. The results of two separate three-way analyses of variance (gender vs. position vs. angle/contraction) indicated that the torque of men was greater than that of women, eccentric torque was greater than concentric, and the torque in neutral rotation was greater than in right or left rotation. Isometric torque decreased with increased trunk flexion. Regression and correlation analyses demonstrated that gender was generally the best predictor of torque, and that all the torque measures were significantly correlated.

Abdominal Muscles↗