Interstitial Nucleus of Cajal Encodes Three-Dimensional Head Orientations in Fick-Like Coordinates

2007 ◽  
Vol 97 (1) ◽  
pp. 604-617 ◽  
Author(s):  
Eliana M. Klier ◽  
Hongying Wang ◽  
J. Douglas Crawford

Two central, related questions in motor control are 1) how the brain represents movement directions of various effectors like the eyes and head and 2) how it constrains their redundant degrees of freedom. The interstitial nucleus of Cajal (INC) integrates velocity commands from the gaze control system into position signals for three-dimensional eye and head posture. It has been shown that the right INC encodes clockwise (CW)-up and CW-down eye and head components, whereas the left INC encodes counterclockwise (CCW)-up and CCW-down components, similar to the sensitivity directions of the vertical semicircular canals. For the eyes, these canal-like coordinates align with Listing’s plane (a behavioral strategy limiting torsion about the gaze axis). By analogy, we predicted that the INC also encodes head orientation in canal-like coordinates, but instead, aligned with the coordinate axes for the Fick strategy (which constrains head torsion). Unilateral stimulation (50 μA, 300 Hz, 200 ms) evoked CW head rotations from the right INC and CCW rotations from the left INC, with variable vertical components. The observed axes of head rotation were consistent with a canal-like coordinate system. Moreover, as predicted, these axes remained fixed in the head, rotating with initial head orientation like the horizontal and torsional axes of a Fick coordinate system. This suggests that the head is ordinarily constrained to zero torsion in Fick coordinates by equally activating CW/CCW populations of neurons in the right/left INC. These data support a simple mechanism for controlling head orientation through the alignment of brain stem neural coordinates with natural behavioral constraints.

2020 ◽  
Author(s):  
Gui Chen ◽  
Mona Al Awadi ◽  
David William Chambers ◽  
Manuel O Lagravère-Vich ◽  
Tianmin Xu ◽  
...  

Abstract Background: With the aid of implants, Björk identified the two-dimensional mandibular stable structures in cephalogram during facial growth. However, we don't know the three-dimensional stable structures exactly. The purpose of this study was to identify the most stable mandibular landmarks in growing patients using three-dimensional images.Methods: The sample was comprised of two cone-beam computed tomography (CBCT) scans taken about 4.6 years apart in 20 growing patients between the ages of 12.5 (T1) to 17.1 years (T2). After head orientation, landmarks were located on the chin (Pog), internal symphysis (Points C, D and E), and mandibular canals, which included the mental foramina (MF and MFA) and mandibular foramina (MdF). The linear distance change between Point C and these landmarks was measured on each CBCT to test stability through time. The reliability of the suggested stable landmarks was also evaluated. Results: The total distance changes between Point C and points D, E, Pog, MF, and MFA were all less than 1.0 mm from T1 to T2. The reliability measures of these landmarks, which were measured by the Cronbach alpha, were above 0.94 in all three dimensions for each landmark. From T1 to T2, distance changes from Point C to the right and left mandibular foramina were respectively 3.39±3.29 mm and 3.03±2.83 mm. Conclusions: During a growth period that averaged 4.6-years, ranging from 11.2 to 19.8 years, the structures that appeared relatively stable and could be used in mandibular regional superimposition included Pog, landmarks on the inferior part of the internal symphysis, and the mental foramen. The centers of the mandibular foramina, the starting points of the mandibular canal, underwent significant changes in the transverse and sagittal dimensions.


Author(s):  
Rex T. Shea ◽  
Jiri Kral

Oblique and offset impacts occur more frequently than full frontal impacts and the resulting occupant and vehicle kinematics are more complicated. Simulations of these test modes are more involved with added vehicle degrees of freedom. Additional occupant interactions with the vehicle interior need to be considered so that the occupant kinematics can be correlated more accurately. In order to capture the vehicle motion in an offset or oblique impact, a prescribed motion approach is preferred where the vehicle is given a three-dimensional motion with six degrees of freedom. With a planar motion assumption, the dominant angular motion about the vertical direction can be derived from linear accelerations measured at two locations where the vehicle deformation is a minimum. In a previous study the angular kinematics was given to a coordinate origin located on the vehicle centerline and longitudinally near the rear rocker. The instantaneous center of rotation was assumed to be fixed at this point during the event. This is referred to as Method I in this paper. A new approach, referred to as Method II, applied translational displacement to three bodies, which carried the passenger compartment through stiff spring elements. The displacements were integrated from measured accelerations, eliminating the uncertainty of a shifting center of rotation. Both methods assumed the vehicle frame between the front and rear rockers as a rigid body. The IP and steering column intrusions and floor deformations were neglected. The results from both methods were correlated to a pair of 40 kph 30 degree angle impact tests and an IIHS ODB test. Method II showed a slightly better timing correlation for the angle tests and the IIHS ODB test. However, both methods didn’t predict the lateral head contact for the driver in the left angle test and the passenger in the right angle test. More interior details have to be included in the model to capture the lateral motion of the occupants. The prescribed motion method is a more general approach than the commonly used inverse kinematics method, and can be applied to full frontal impact as well. The versatility of the method provides a basis for a modular approach in occupant simulations.


1995 ◽  
Vol 73 (2) ◽  
pp. 766-779 ◽  
Author(s):  
D. Tweed ◽  
B. Glenn ◽  
T. Vilis

1. Three-dimensional (3D) eye and head rotations were measured with the use of the magnetic search coil technique in six healthy human subjects as they made large gaze shifts. The aims of this study were 1) to see whether the kinematic rules that constrain eye and head orientations to two degrees of freedom between saccades also hold during movements; 2) to chart the curvature and looping in eye and head trajectories; and 3) to assess whether the timing and paths of eye and head movements are more compatible with a single gaze error command driving both movements, or with two different feedback loops. 2. Static orientations of the eye and head relative to space are known to resemble the distribution that would be generated by a Fick gimbal (a horizontal axis moving on a fixed vertical axis). We show that gaze point trajectories during eye-head gaze shifts fit the Fick gimbal pattern, with horizontal movements following straight "line of latitude" paths and vertical movements curving like lines of longitude. However, horizontal (and to a lesser extent vertical) movements showed direction-dependent looping, with rightward and leftward (and up and down) saccades tracing slightly different paths. Plots of facing direction (the analogue of gaze direction for the head) also showed the latitude/longitude pattern, without looping. In radial saccades, the gaze point initially moved more vertically than the target direction and then curved; head trajectories were straight. 3. The eye and head components of randomly sequenced gaze shifts were not time locked to one another. The head could start moving at any time from slightly before the eye until 200 ms after, and the standard deviation of this interval could be as large as 80 ms. The head continued moving for a long (up to 400 ms) and highly variable time after the gaze error had fallen to zero. For repeated saccades between the same targets, peak eye and head velocities were directly, but very weakly, correlated; fast eye movements could accompany slow head movements and vice versa. Peak head acceleration and deceleration were also very weakly correlated with eye velocity. Further, the head rotated about an essentially fixed axis, with a smooth bell-shaped velocity profile, whereas the axis of eye rotation relative to the head varied throughout the movement and the velocity profiles were more ragged. 4. Plots of 3D eye orientation revealed strong and consistent looping in eye trajectories relative to space.(ABSTRACT TRUNCATED AT 400 WORDS)


2007 ◽  
Vol 98 (2) ◽  
pp. 696-709 ◽  
Author(s):  
A. G. Constantin ◽  
H. Wang ◽  
J. C. Martinez-Trujillo ◽  
J. D. Crawford

Previous studies suggest that stimulation of lateral intraparietal cortex (LIP) evokes saccadic eye movements toward eye- or head-fixed goals, whereas most single-unit studies suggest that LIP uses an eye-fixed frame with eye-position modulations. The goal of our study was to determine the reference frame for gaze shifts evoked during LIP stimulation in head-unrestrained monkeys. Two macaques ( M1 and M2) were implanted with recording chambers over the right intraparietal sulcus and with search coils for recording three-dimensional eye and head movements. The LIP region was microstimulated using pulse trains of 300 Hz, 100–150 μA, and 200 ms. Eighty-five putative LIP sites in M1 and 194 putative sites in M2 were used in our quantitative analysis throughout this study. Average amplitude of the stimulation-evoked gaze shifts was 8.67° for M1 and 7.97° for M2 with very small head movements. When these gaze-shift trajectories were rotated into three coordinate frames (eye, head, and body), gaze endpoint distribution for all sites was most convergent to a common point when plotted in eye coordinates. Across all sites, the eye-centered model provided a significantly better fit compared with the head, body, or fixed-vector models (where the latter model signifies no modulation of the gaze trajectory as a function of initial gaze position). Moreover, the probability of evoking a gaze shift from any one particular position was modulated by the current gaze direction (independent of saccade direction). These results provide causal evidence that the motor commands from LIP encode gaze command in eye-fixed coordinates but are also subtly modulated by initial gaze position.


Free-flying houseflies have been filmed simultaneously from two sides. The orientation of the flies’ body axes in three-dimensional space can be seen on the films. A method is presented for the reconstruction of the flies’ movements in a fly-centred coordinate system, relative to an external coordinate system and relative to the airstream. The flies are regarded as three-dimensionally rigid bodies. They move with respect to the six degrees of freedom they thus possess. The analysis of the organization of the flight motor from the kinematic data leads to the following conclusions: the sideways movements can, at least qualitatively, be explained by taking into account the sideways forces resulting from rolling the body about the long axis and the influence of inertia. Thus, the force vector generated by the flight motor is most probably located in the fly’s midsagittal plane. The direction of this vector can be varied by the fly in a restricted range only. In contrast, the direction of the torque vector can be freely adjusted by the fly. No coupling between the motor force and the torques is indicated. Changes of flight direction may be explained by changes in the orientation of the body axes: straight flight at an angle of sideslip differing from zero is due to rolling. Sideways motion during the banked turns as well as the decrease of translation velocity observed in curves are a consequence of the inertial forces and rolling. The results are discussed with reference to studies about the aerodynamic performance of insects and the constraints for aerial pursuit.


2008 ◽  
Vol 100 (3) ◽  
pp. 1677-1685 ◽  
Author(s):  
Farshad Farshadmanesh ◽  
Pengfei Chang ◽  
Hongying Wang ◽  
Xiaogang Yan ◽  
Brian D. Corneil ◽  
...  

The interstitial nucleus of Cajal (INC) is thought to control torsional and vertical head posture. Unilateral microstimulation of the INC evokes torsional head rotation to positions that are maintained until stimulation offset. Unilateral INC inactivation evokes head position-holding deficits with the head tilted in the opposite direction. However, the underlying muscle synergies for these opposite behavioral effects are unknown. Here, we examined neck muscle activity in head-unrestrained monkeys before and during stimulation (50 μA, 200 ms, 300 Hz) and inactivation (injection of 0.3 μl of 0.05% muscimol) of the same INC sites. Three-dimensional eye and head movements were recorded simultaneously with electromyographic (EMG) activity in six bilateral neck muscles: sternocleidomastoid (SCM), splenius capitis (SP), rectus capitis posterior major (RCPmaj.), occipital capitis inferior (OCI), complexus (COM), and biventer cervicis (BC). INC stimulation evoked a phasic, short-latency (∼5–10 ms) facilitation and later (∼100–200 ms) a more tonic facilitation in the activity of ipsi-SCM, ipsi-SP, ipsi-COM, ipsi-BC, contra-RCPmaj., and contra-OCI. Unilateral INC inactivation led to an increase in the activity of contra-SCM, ipsi-SP, ipsi-RCPmaj., and ipsi-OCI and a decrease in the activity of contra-RCPmaj. and contra-OCI. Thus the influence of INC stimulation and inactivation were opposite on some muscles (i.e., contra-OCI and contra-RCPmaj.), but the comparative influences on other neck muscles were more variable. These results show that the relationship between the neck muscle responses during INC stimulation and inactivation is much more complex than the relationship between the overt behaviors.


1997 ◽  
Vol 86 (6) ◽  
pp. 1031-1035 ◽  
Author(s):  
Tetsuro Kawaguchi ◽  
Shigekiyo Fujita ◽  
Kohkichi Hosoda ◽  
Yuji Shibata ◽  
Masaki Iwakura ◽  
...  

✓ The authors describe transverse process hyperrotation and unilateral apophyseal joint subluxation as a novel mechanism of rotational vertebral artery (VA) occlusion. The patient, a 56-year-old man, complained of episodic bilateral blindness when rotating his head more than 90° to the right. Plain cervical x-ray films showed spondylotic osteophytes of the right C4–5 uncovertebral portion. Dynamic angiography revealed right VA occlusion at C4–5 and left VA occlusion at C1–2 with head rotation to the right. It was demonstrated on three-dimensional images constructed from computerized tomography scans that C-4 transverse process hyperrotation compressed the right VA against the apex of the C-5 subluxating superior articular process via the inner surface of the transverse process anterior root (processus costarius) rather than the osteophytes. It is also proposed that the true site of occlusion is different from that observed in angiographic studies.


Author(s):  
Tuomas Huumo

Abstrakti. Projektiiviset grammit (kieliopilliset sanat, esimerkiksi edessä, oikealla, yläpuolella) asemoivat muuttujan (Figure) kolmiulotteiseen koordinaatistoon, jonka suhteutuskohtana on kiintopiste (Ground). Grammeilla on lisäksi skalaarisia merkityksiä, joita voidaan korostaa astemääritteiden avulla. Artikkelissa tarkastellaan suomen projektiivisten grammien esiintymismahdollisuuksia astemääritteiden kanssa, jotka ilmaisevat joko avointa (melko, hyvin) tai sulkeista skaalaa (melkein, aivan). Tarkastelussa erottuu kolme astemääritteen ja grammin yhteisesiintymän päätyyppiä. Tyypissä (1) muuttuja sijaitsee säiliömäisen kiintopisteen (kuten rakennuksen) sisäpuolella. Skalaarinen merkitys perustuu tällöin muuttujan vähenevään etäisyyteen kiintopisteen yhdestä sisärajasta (esimerkiksi seinästä): mitä lähempänä muuttuja sijaitsee rajaa, sitä korkeampi skalaarisuus (Istuin teatterissa melko edessä ~ ihan vasemmalla). Tyypissä (1) esiintyy niin avoimen kuin sulkeisen skaalan astemääritteitä. Kahdessa muussa päätyypissä muuttuja sijaitsee kiintopisteen ulkopuolella, ja skalaarisuus perustuu joko (2) muuttujan ja kiintopisteen välisen etäisyyden vähenemiseen (Auto seisoi ihan ’välittömästi’ oven edessä) tai (3) muuttujan skalaarisesti vähenevään poikkeamaan koordinaatiston jostain akselista (Lamppu riippui melkein ~ täsmälleen ’suoraan’ pöydän yläpuolella). Tyypeissä (2) ja (3) esiintyy vain sulkeisen skaalan astemääritteitä. Abstract. Tuomas Huumo: What degree modifiers reveal about the meaning of Finnish spatial grams? Projective spatial grams (‘in front of’, ‘to the right of’, ‘above’) localize Figure (F) in a three-dimensional coordinate system with Ground (G) as its origin. This paper addresses the compatibility of Finnish projective grams with degree modifiers (DM). DMs comprise two types: a) open-scale DMs (‘somewhat’, ‘rather’, ‘very’) and b) closed-scale DMs (‘almost’, ‘quite’, ‘completely’). Three types of scalar meaning are observed. The first one (1) applies when F is inside G, and the scalar conceptualization is based on a decreasing distance between F and one extremity of the inside of G. In type (1), both open- and closed-scale DMs are felicitous. The two other types concern situations in which F is outside G and the scalar meaning is based on either (2) a decreasing distance between F and G or (3) an increasing preciseness of F’s alignment on an axis. In (2) and (3), only closed-scale DMs are felicitous. Kokkuvõte. Tuomas Huumo: Mida kõnelevad astmemäärused soome keele projektiivsete grammide tähenduse kohta? Projektiivsed grammid (‘ees’, ‘paremal’, ‘kohal’) lokaliseerivad kujundi (Figure) kolmemõõtmelises koordinaatsüsteemis, mille alguspunktiks on taust (Ground). Artiklis analüüsitakse soome keele projektiivsete grammide koosesinemise võimalusi kaht tüüpi astmemäärustega: a) avatud skaala astmemäärused (intensiivsusmäärused, nt ‘natuke’, ‘üsna’, ‘väga’) ja b) suletud skaala astmemäärused (täielikkusastme määrused, nt ‘peaaegu’, ‘täiesti’). Autor eristab kolme astmemääruse ja grammi koosesinemise põhitüüpi. Tüübis (1) asub kujund kolmemõõtmelise tausta seespool. Skalaarne tähendus põhineb kujundi ning tausta siseruumi ühe serva vahelise kauguse vähenemisel: mida lähemal paikneb kujund servale, seda kõrgem on skalaarsus (nt ‘Istusin teatris üsna ees ~ päris vasakul’). Tüübis (1) esinevad nii avatud kui suletud skaala astmemäärused. Ülejäänud kahes tüübis paikneb kujund väljaspool tausta, ning skalaarsus põhineb kas (2) kujundi ja tausta vahelise kauguse vähenemisel (nt ‘Auto seisis peaaegu ~ täitsa ukse ees’) või (3) kujundi asendi väheneval kõrvalekaldel koordinaatsüsteemi teatud teljest (nt ‘Lamp rippus peaaegu ~ täpselt laua kohal’). Tüüpides (2) ja (3) esinevad ainult suletud skaala astmemäärused.


2015 ◽  
Vol 129 (5) ◽  
pp. 430-434 ◽  
Author(s):  
D-K Kim ◽  
D-R Kim ◽  
S H Jeong ◽  
G J Kim ◽  
K-H Chang ◽  
...  

AbstractObjectives:This study was conducted to investigate the angles and orientation of semicircular canals, and the coplanarity of functional canal pairs.Methods:Fluid signals in semicircular canals were reconstructed with three-dimensional reconstruction software using 20 temporal bone magnetic resonance images of normal subjects. The angles between each pair of semicircular canals were measured.Results:The mean angles between the anterior and horizontal semicircular canal plane, the horizontal and posterior semicircular canal plane, and the anterior and posterior semicircular canal plane were 83.7°, 82.5° and 88.4°, respectively. Pairs of contralateral synergistic canal planes were formed 15.1° between the right and left horizontal semicircular canal planes, 21.2° between the right anterior and left posterior semicircular canal, and 21.7° between the left anterior and right posterior semicircular canal.Conclusion:Each semicircular canal makes an almost right angle with other canals, but synergistically acting functional canal pairs of both ears do not lie in exactly the same plane.


2012 ◽  
Vol 108 (11) ◽  
pp. 2867-2883 ◽  
Author(s):  
Farshad Farshadmanesh ◽  
Patrick Byrne ◽  
Hongying Wang ◽  
Brian D. Corneil ◽  
J. Douglas Crawford

The relationship between neck muscle electromyography (EMG) and torsional head rotation (about the nasooccipital axis) is difficult to assess during normal gaze behaviors with the head upright. Here, we induced acute head tilts similar to cervical dystonia (torticollis) in two monkeys by electrically stimulating 20 interstitial nucleus of Cajal (INC) sites or inactivating 19 INC sites by injection of muscimol. Animals engaged in a simple gaze fixation task while we recorded three-dimensional head kinematics and intramuscular EMG from six bilateral neck muscle pairs. We used a cross-validation-based stepwise regression to quantitatively examine the relationships between neck EMG and torsional head kinematics under three conditions: 1) unilateral INC stimulation (where the head rotated torsionally toward the side of stimulation); 2) corrective poststimulation movements (where the head returned toward upright); and 3) unilateral INC inactivation (where the head tilted toward the opposite side of inactivation). Our cross-validated results of corrective movements were slightly better than those obtained during unperturbed gaze movements and showed many more torsional terms, mostly related to velocity, although some orientation and acceleration terms were retained. In addition, several simplifying principles were identified. First, bilateral muscle pairs showed similar, but opposite EMG-torsional coupling terms, i.e., a change in torsional kinematics was associated with increased muscle activity on one side and decreased activity on the other side. s, whenever torsional terms were retained in a given muscle, they were independent of the inputs we tested, i.e., INC stimulation vs. corrective motion vs. INC inactivation, and left vs. right INC data. These findings suggest that, despite the complexity of the head-neck system, the brain can use a single, bilaterally coupled inverse model for torsional head control that is valid across different behaviors and movement directions. Combined with our previous data, these new data provide the terms for a more complete three-dimensional model of EMG: head rotation coupling for the muscles and gaze behaviors that we recorded.


Sign in / Sign up

Export Citation Format

Share Document