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PubMed1980

Trajectory of contralateral entorhinal axons which reinnervate the fascia dentata of the rat following ipsilateral entorhinal lesions.

Unilateral destruction of the entorhinal area in the rat results in the proliferation of a pathway from the surviving contralateral entorhinal area to the fascia dentata denervated by the lesions (the crossed temporodentate pathway). The present study analyzes the point of entry of these reinnervating fibers into the fascia dentata, and their trajectory within the reinnervated zones utilizing orthograde transport of tritiated proline or horseradish peroxidase (HRP). Following injections of tritiated proline or HRP into the surviving entorhinal area in animals with long standing unilateral entorhinal lesions labeled axons could be visualized entering the contralateral fascia dentata via two routes. Labeled fibers could be traced from the dorsal hippocampal commissure (the dorsal psalterium) into the rostral tip of the fascia dentata (the fasciola cinerea) and from the terminal field of the crossed temporo-ammonic tract in regio superior into adjacent portions of the stratum moleculare of the fascia dentata. Within the stratum moleculare, most of the labeled axons had predominantly a caudal and lateral orientation. Exceptions to this predominant trajectory were found in the case of some of the axons which entered the ventral blade of the rostral fascia dentata, and coursed laterally from their point of entry. Comparisons of the trajectory of the crossed temporodentate projections with that of the normal ipsilateral pathway indicated that while the predominant trajectory of the fibers was roughly comparable, the polarity of the projections was in part opposite. Specifically, the normal ipsilateral pathway travels in a caudorostral direction, while the majority of fibers of the crossed temporodentate pathway apparently project rostrocaudally. The significance of this difference in the pattern of innervation is discussed with respect to the normal functioning of the temporodentate circuitry.

Animals↗
PubMed1983

Three-channel Lissajous' trajectory of human auditory brain stem evoked potentials.

By simultaneously recording from 3 orthogonal electrode montages, and plotting the 3 voltage-time records on three-dimensional voltage-voltage-voltage coordinates, a spatial Lissajous' trajectory is obtained. This 3-Channel Lissajous' Trajectory (3CLT) represents the simultaneous voltage values from 3 independent montages and, assuming a uniform volume conductor, it includes all the information required for calculation of the dipole equivalent of surface-recorded activity. In 3CLT time is not explicitly graphed, but is implied as motion along the trajectory. Thanks to the small distribution of the generators of BAEPs, relative to their distance from the recording electrodes, 3CLT of BAEPs holds the promise of summarizing all activity from the surface. Comparing 3CLT of BAEPs to left vs. right ear stimulation has confirmed the lateralization of components I and III, but has also shown lateralization for the other components, which detailed surface mapping studies had overlooked. 3CLT may offer a more sensitive, yet less cumbersome, alternative to detailed surface mapping of BAEPs. The full promise of 3CLT can only be evaluated after quantitative indices of the trajectory are developed.

Adult↗
PubMed1984

Geometrical analysis of human three-channel Lissajous' trajectory of auditory brain-stem evoked potentials.

Three-channel Lissajous' trajectories (3CLTs) of auditory brain-stem evoked potentials (ABEPs) were obtained for a group of 15 normal humans. 3CLTs were studied using geometric spatial descriptors of rate of bending (curvature), local planarity (torsion), as well as the parameters of best fit planes along the trajectory. Point-by-point analysis enabled objective determination of apices (curvature maxima) which divided the trajectory to curvilinear segments. Consecutive apices defined planar segments (each consisting of two curvilinear segments) along the trajectory. Of the two possibilities of arranging apices in the middle of planar segments only one yielded consistently planar segments. The alternative set of apex triads represented transitions between truly planar segments. The variability of position and orientation measures of planar segments was greater than that of apex latencies and plane limits. The significance of planes, as well as their generation, in 3CLT of ABEP, remains to be studied.

Adult↗
PubMed1994

Multichannel evoked potentials as voltage space trajectories.

Multichannel brain evoked potentials can be represented as trajectories V(t) in n-dimensional voltage space, analogous to three-channel Lissajous trajectories (3-CLT). Equations of motion are developed based on an arbitrary number of dipole generators at arbitrary locations within the brain, and the properties of 3-CLT are generalized to the higher dimensional case. The trajectory is shown to be limited to k < n dimensions, and k channels are found to be sufficient for predicting the potential difference between any two points on the head, provided that an empirically determined set of linear functionals is known. A method for choosing the "best" m-channel montage (m < or = k) is described, by associating with each montage an alternating m-tensor on Rk. Planar analysis of the voltage trajectories is generalized to the k-dimensional case, in which m-planes are compared using a mapping between the Grassman manifold and real projective space.

Brain↗
PubMed1986

Human smooth pursuit: effects of stimulus extent and of spatial and temporal constraints of the pursuit trajectory.

We compared the quality of monocular smooth pursuit obtained with either a single point, a full-field stripe pattern or their combination as the target for unidirectional stimulus motion at velocities between 9 and 90 deg/sec. A point target moving in a fixed trajectory maximally constrains target selection as well as pursuit trajectory, whereas a full-field multicontoured pattern leaves the subject maximal freedom in these respects. To unconfound effects of pattern extent from those of spatial and temporal constraints, we presented point targets under conditions in which the subject was free to choose the location, extent and temporal structure of his pursuit trajectory ("free range"). Pursuit velocity gains were lowest for the point target moving in a fixed trajectory. Gain improved when the subject was free to pursue the same target moving at the same velocity in his own preferred range and rhythm. A further improvement was reached by showing the stripe pattern in addition to, and moving in conjunction with the spot. A final increase in gain occurred when the spot was removed, and the subject was allowed to pursue any feature of the uniformly moving, multicontoured pattern. No asymmetries were found between monocular pursuit with the right or the left eye, pursuit of rightward and leftward motion or between nasal- and temporalward motion. Effects of the type of target on the structure of the nystagmoid pursuit eye movements were slight or absent.

Eye Movements↗
PubMed2006

A new obstetric forceps for the training of junior doctors: a comparison of the spatial dispersion of forceps blade trajectories between junior and senior obstetricians.

OBJECTIVE: The purpose of this study was to create a new instrument for the training of doctors in the use of forceps and to compare the trajectories of forceps blades between junior and senior obstetricians. STUDY DESIGN: We equipped a simulator and forceps with spatial location sensors. The head of the fetus was in an occipitoanterior location, at a "+5" station. Forceps blade trajectories were analyzed subjectively with the 3-dimensional spatial graph and objectively based on 3 points of special interest. Each obstetrician performed 4 forceps blades placements. We compared the trajectories of junior and senior obstetricians. RESULTS: For senior operators, spatial dispersion was "excellent," "very good," or "good" in 92% of cases, whereas this was the case for only 38% of junior doctors (92% vs 38%; P < .001). CONCLUSION: A new instrument has been designed to demonstrate the trajectory of forceps blades during application in a simulator. The instrument captures the difference in experience between senior and junior clinicians.

Computer Simulation↗
PubMed2006

Self-prediction of hedonic trajectories for repeated use of body products and foods: poor performance, not improved by a full generation of experience.

This study extends earlier work by [Kahneman, D., and Snell, J. (1992). Predicting a changing taste: Do people know what they will like? Journal of Behavioral Decision Making, 5, 187-200.]. suggesting that people are poor at predicting changes in liking. This is an important issue because an absence of this ability would make it difficult for people to optimize their own choices. Twenty undergraduates and 20 of their parents sampled four relatively unfamiliar consumer products, two foods and two body products, for 8 days. On Day 1, participants rated their initial liking and predicted their liking after seven daily uses of the products. Predictions were compared to actual liking on Day 8. Consistent with prior work, participants were poor at predicting their actual hedonic trajectories because they underestimated the degree to which their preferences would change. Contrary to predictions, parents were no better than students at this task, even though they had some 20-39 years more experience in observing their own hedonic trajectories. There is no evidence for any parent-child resemblance in either liking for the products or ability to accurately predict hedonic trajectory, and no evidence for consistency in ability to predict trajectories across the four different products. In general, participants underestimate the degree to which their preferences will change.

Adolescent↗
PubMed2004

Trajectory of coronary motion and its significance in robotic motion cancellation.

OBJECTIVES: To characterize remaining coronary artery motion of beating pig hearts after stabilization with an 'Octopus' using an optical remote analysis technique. METHODS: Three pigs (40, 60 and 65 kg) underwent full sternotomy after receiving general anesthesia. An 8-bit high speed black and white video camera (50 frames/s) coupled with a laser sensor (60 microm resolution) were used to capture heart wall motion in all three dimensions. Dopamine infusion was used to deliberately modulate cardiac contractility. Synchronized ECG, blood pressure, airway pressure and video data of the region around the first branching point of the left anterior descending (LAD) coronary artery after Octopus stabilization were captured for stretches of 8 s each. Several sequences of the same region were captured over a period of several minutes. Computerized off-line analysis allowed us to perform minute characterization of the heart wall motion. RESULTS: The movement of the points of interest on the LAD ranged from 0.22 to 0.81 mm in the lateral plane (x/y-axis) and 0.5-2.6 mm out of the plane (z-axis). Fast excursions (>50 microm/s in the lateral plane) occurred corresponding to the QRS complex and the T wave; while slow excursion phases (<50 microm/s in the lateral plane) were observed during the P wave and the ST segment. The trajectories of the points of interest during consecutive cardiac cycles as well as during cardiac cycles minutes apart remained comparable (the differences were negligible), provided the hemodynamics remained stable. Inotrope-induced changes in cardiac contractility influenced not only the maximum excursion, but also the shape of the trajectory. Normal positive pressure ventilation displacing the heart in the thoracic cage was evident by the displacement of the reference point of the trajectory. CONCLUSIONS: The movement of the coronary artery after stabilization appears to be still significant. Minute characterization of the trajectory of motion could provide the substrate for achieving motion cancellation for existing robotic systems. Velocity plots could also help improve gated cardiac imaging.

Animals↗
PubMed2005

Synthesis of standing-up trajectories using dynamic optimization.

Dynamic optimization as a tool to compute standing-up trajectories was investigated. Sit-to-stand manoeuvres in five intact persons and five trans-femoral amputees were measured. Movements and ground reaction forces acting on the body were recorded. A five-segment 3D dynamic model of standing-up was developed. In each particular subject, the optimization criterion which yielded trajectories that best resemble the measured standing-up movement was determined. Since the intact persons used considerably different criteria in choosing the standing-up trajectories than the amputees, the optimal trajectories were computed by minimizing cost functionals (CF) with distinctive structures for each group of individuals. In intact persons, a unique cost functional was found which yielded realistic standing-up manoeuvres. In amputees, subject-specific sets of parameters indicating slightly different preferences in optimizing the effort of particular muscle groups were used.

Adult↗
PubMed2025

Intersectionality in a sociogenomic world: How do race, disability, socioeconomic status, and polygenic prediction interact to affect perceptions of educational trajectories?

PURPOSE: Education is important for lifelong skills and economic growth; however, student placement decisions may be shaped by social biases. As genomic information captured via polygenic scores becomes more available, it may also inform student placement decisions. We assessed the intersectional effects of polygenic scores, race, disability, and socioeconomic status on US adults' views of educational trajectories using an online experimental survey design. METHODS: A total of 1367 US adults were randomized to one of 16 conditions and prompted to read a short vignette about a boy named Michael, also depicted in an image. Each condition varied Michael's race (Black/White), disability (wheelchair user/no), socioeconomic status (high/low), and polygenic score (high/low) for educational attainment (EA-PGS). After reading the vignette, the respondents were asked to answer multichoice questions about Michael's immediate and long-term educational trajectories. RESULTS: Variation in Michael's EA-PGS strongly influenced participants' expectations regarding (1) the most appropriate immediate educational program for Michael (ie, general, special, or gifted education), (2) whether he would graduate high school, and, if so, (3) the highest educational degree he would complete in his lifetime (associate, bachelor, master, or PhD). Across these responses, high EA-PGS was associated with more socially desirable outcomes, whereas the opposite was true for low EA-PGS. Depicting Michael in a wheelchair significantly influenced respondents' expectations that his most appropriate immediate educational trajectory would be special. There were significant interactions between Michael's race, disability, socioeconomic status, and the EA-PGS. CONCLUSION: Information about children's EA-PGS may affect their views about their immediate and long-term educational trajectories. The negative effects of low EA-PGS were comparable to those of high EA-PGS. The EA-PGS may be interpreted in ways that compound the existing stereotypes related to a child's race, disability, and socioeconomic status.

Humans↗
PubMed2004

Tobacco smoking trajectory and associated ethnic differences among adolescent smokers seeking cessation treatment.

PURPOSE: To examine smoking trajectories in a clinical sample of adolescent smokers seeking cessation treatment, including: (a) smoking onset (initial, daily) and time intervals from initial to daily smoking and from daily smoking to treatment request, (b) associations between current level of tobacco dependence and smoking history, and (c) differences in smoking trajectory between African-American and non-African-American youth. METHODS: Four hundred and thirty-two adolescent smokers (aged 13-17 years, 61.8% female, 32% African-American) responding to various media advertisement completed a telephone interview as part of pre-eligibility screening for a smoking cessation trial. Smoking trajectory data included age at onset of initial and daily smoking, intervals between those time points, and cigarettes smoked per day (CPD). Tobacco dependence was assessed using the Fagerström Test for Nicotine Dependence (FTND). Data were analyzed using regression models and multiple analyses of covariance. RESULTS: Initial smoking occurred at a mean age of less than 12 years and daily smoking at age 13 years. Earlier onset of daily smoking was associated with higher FTND scores and longer duration from daily smoking to treatment request. For the entire sample, the time interval from initial to daily smoking was 1.14 years. When the sample was divided into early (before age 14 years) and later (at or after age 14 years) initiators, early initiators showed a slower progression from initial to daily smoking compared with late initiators (16 months vs. 6 months). Compared with non-African-American teen smokers, African-American youth reported a 1-year delay in onset of both initial and daily smoking. CONCLUSIONS: Early age of daily smoking and short time interval from initial to daily smoking highlight a brief window of opportunity to prevent the development of tobacco addiction and its consequences. Ethnic differences in smoking trajectory uncovered in this report call for ethnically tailored interventions to reduce youth smoking.

Adolescent↗
PubMed2005

Externalizing behaviors as predictors of substance initiation trajectories among rural adolescents.

PURPOSE: The purpose of the current study was to investigate the influence of externalizing behaviors on substance initiation trajectories among rural adolescents over a 42-month period. METHODS: Data were obtained from 198 rural adolescents (105 boys, 93 girls) who were participating in a longitudinal study. At the baseline assessment, subjects were on average 12.3 years of age. RESULTS: Controlling for gender, higher baseline levels of externalizing were associated with a greater number of substances initiated over time. The initiation trajectory was curvilinear. Girls, compared with boys, reported a lower number of substances initiated at baseline, a greater linear growth trajectory, and a deceleration of growth over time. CONCLUSIONS: The influence of adolescent externalizing behaviors on baseline levels and growth trajectories of substance initiation and the utility of latent growth curve modeling in the study of longitudinal change are discussed.

Adolescent↗
PubMed2005

The design and characteristic features of a new time-of-flight mass spectrometer with a spiral ion trajectory.

A new time-of-flight (TOF) mass spectrometer with a corkscrew ion trajectory was designed and constructed. The spiral trajectory was realized by using four toroidal electrostatic sectors. Each had fifteen-stories made of sixteen Matsuda plates piled up inside a cylindrical electrostatic sector. The ions passed the four toroidal electrostatic sectors sequentially and revolved along a figure-eight-shaped orbit on a certain projection plane. During the multiple revolutions, each ion trajectory was shifted by 50 mm per cycle on a direction perpendicular to the projection plane, thus generating a spiral trajectory. The flight path length of one cycle was 1.308 m so that the maximum flight path length became approximately 20 m. The mass resolution, mass accuracy, and ion transmission were tested by utilizing an orthogonally coupled electron ionization source. A mass resolution of 35,000 (FWHM) for m/z greater than 300 was achieved. Even in a lower mass region, mass resolutions of more than 20,000 (FWHM) were confirmed with a doublet of (12)C(5)(1)H(5)(14)N(+) and (13)C(12)C(5)(1)H(6)(+). The mass accuracy was also improved such that it was better than 1 ppm with only one internal standard peak. An ion transmission of approximately of 100% was observed for 15 cycles.

Equipment Design↗
PubMed2004

Enhanced sampling by multiple molecular dynamics trajectories: carbonmonoxy myoglobin 10 micros A0-->A(1-3) transition from ten 400 picosecond simulations.

The utility of multiple trajectories to extend the time scale of molecular dynamics simulations is reported for the spectroscopic A-states of carbonmonoxy myoglobin (MbCO). Experimentally, the A0-->A(1-3) transition has been observed to be 10 micros at 300 K, which is beyond the time scale of standard molecular dynamics simulations. To simulate this transition, 10 short (400 ps) and two longer time (1.2 ns) molecular dynamics trajectories, starting from five different crystallographic and solution phase structures with random initial velocities centered in a 37 A radius sphere of water, have been used to sample the native-fold of MbCO. Analysis of the ensemble of structures gathered over the cumulative 5.6 ns reveals two biomolecular motions involving the side chains of His64 and Arg45 to explain the spectroscopic states of MbCO. The 10 micros A0-->A(1-3) transition involves the motion of His64, where distance between His64 and CO is found to vary up to 8.8 +/- 1.0 A during the transition of His64 from the ligand (A(1-3)) to bulk solvent (A0). The His64 motion occurs within a single trajectory only once, however the multiple trajectories populate the spectroscopic A-states fully. Consequently, multiple independent molecular dynamics simulations have been found to extend biomolecular motion from 5 ns of total simulation to experimental phenomena on the microsecond time scale.

Animals↗
PubMed2006

Motion correction properties of the shells k-space trajectory.

The feasibility of a k-space trajectory that samples data on a set of 3D shells is demonstrated with phantom and volunteer experiments. Details of an interleaved multi-shot, helical spiral pulse sequence and a gridding reconstruction algorithm that uses Voronoi diagrams are provided. The motion-correction properties of the shells k-space trajectory are described. It is shown that when used in conjunction with three point markers, k-space data acquired with the shells trajectory provide a generalization of the RINGLET method, allowing for correction of arbitrary rigid-body motion with six degrees of freedom. Use of dedicated navigator echoes or redundant acquisitions of k-space data are not required. Retrospective motion correction is demonstrated with controlled phantom experiments and with seven healthy human volunteers. The motion correction is shown to improve the images, both qualitatively and quantitatively with a metric calculated from image entropy. Advantages and challenges of the shells trajectory are discussed, with particular attention to acquisition efficiency.

Algorithms↗
PubMed2004

Visual and motor constraints on trajectory planning in pointing movements.

The aim of the present study was to show that planning and controlling the trajectory of a pointing movement is influenced not solely by physical constraints but also by visual constraints. Subjects were required to point towards different targets located at 20 degrees , 40 degrees , 60 degrees and 80 degrees of eccentricity. Movements were either constrained (i.e. two-dimensional movements) or unconstrained (i.e. three-dimensional movements). Furthermore, movements were carried out either under a direct or a remote visual control (use of a video system). Results revealed that trajectories of constrained movements were nearly straight whatever the eccentricity of the target and the type of visual control. A different pattern was revealed for unconstrained movements. Indeed, under direct vision the trajectory curvature increased as the eccentricity augmented, whereas under indirect vision, trajectories remained nearly straight whatever the eccentricity of the target. Thus, movements controlled through a remote visual feedback appear to be planned in extrinsic space as constrained movements.

Adolescent↗
PubMed2025

Premorbid functioning trajectories and the one-year course of cognitive performance in first-episode psychosis: a cluster analysis in PSYSCAN.

BACKGROUND: We examined the course of cognitive performance in first-episode psychosis (FEP) compared to healthy controls (HC), and whether this varied across subgroups of patients defined by premorbid functioning (PMF) trajectories, using a clustering approach. METHODS: Data were collected in 302 FEP and 136 HC subjects participating in PSYSCAN (HEALTH.2013.2.2.1-2-FEP). K-means clustering (Euclidean distance) was used to cluster longitudinal trajectories of different PMF domains simultaneously. Since PMF was assessed retrospectively using the Premorbid Adjustment Scale (PAS), findings should be interpreted with caution, although PAS ratings have shown reasonable validity against prospective data. RESULTS: As expected, FEP showed impaired performance across all cognitive domains compared to HC. We identified four trajectories of PMF: a normal premorbid developmental trajectory (globally-normal, 21&#xa0;%), stable intermediate PMF across domains (stable-intermediate, 29&#xa0;%), stable poor or deteriorating PMF in the academic domain (normal-social/poor-academic, 29&#xa0;%), and a globally impaired group with poor/deteriorating PMF across domains (globally-poor, 21&#xa0;%). These clusters showed distinct levels of post-onset impairments in sustained visual attention, visual working memory and emotion recognition. CONCLUSIONS: This study confirms a positive association between PMF and cognitive performance in the early years following psychosis onset. It aligns with findings that individuals later diagnosed with schizophrenia already show developmental deficits/lags from childhood to early adolescence compared to normally developing children. As PMF can be considered a proxy for cognitive reserve, our results suggest that higher reserve acts as a buffer against cognitive decline and supports better performance on sustained visual attention, complex visual working memory, and aspects of emotion recognition.

Clustering↗
PubMed2005

The predictive power of trajectory motion.

When the central region of an obliquely oriented line is bisected by a wide, vertical opaque occluder, observers misperceive the two line segments as being misaligned (the Poggendorff illusion). If the oblique line segment is replaced with a spot moving on an oblique trajectory, little if any misalignment is perceived. This accurate alignment of oblique segments depends upon the consistent motion of the dot along the oblique trajectory and not other temporal or spatial characteristics of the motion-defined segments since random plotting of the dot along each oblique segment resulted in robust misalignment. The nullification of the Poggendorff illusion was also obtained if only one of the segments was defined by a moving spot so long as the spot moved in a direction that 'pointed' to the static segment. Moreover, if the occluder boundary was defined by rows of vertically moving dots, was filled with vertically moving dots or was a real (cardboard) occluder, the motion-defined oblique segments were still perceived to be aligned with little error, consistent with the unimpaired detection of a trajectory dot in noise interrupted by similar occluders [Watamaniuk, S. N. J. & McKee, S. P. (1995). 'Seeing' motion behind occluders. Nature, 377, 729-730]. The results are interpreted as evidence that trajectory motion produces a cascade of activity in appropriately aligned motion detectors, in the direction of motion, that continues after the moving object has been occluded to produce a prediction of where the moving object should reappear.

Humans↗