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PubMed1998

On the perception of objects and their orientations.

A novel paradigm, description-depiction classification (DDC), was used to test whether knowledge of object orientation in the picture plane precedes or follows object identification. Undergraduate students were asked to verify the identities and orientations of depicted objects against preceding descriptions, e.g. 'UPRIGHT CAR'. The results showed that identity mismatches were verified faster and more accurately than orientation mismatches, regardless of whether subjects had to discriminate small (90 deg) or large (180 deg) differences in orientation. These findings suggest there is primacy for identity information in that (a) subjects determine object identity before they determine object orientation, and (b) even when orientation is determined, identity information tends to dominate the response. This is the signature of a perceptual-cognitive system that has evolved to rapidly identify objects, not their orientations, contra to theories of recognition that assume orientation is determined before an object has been classified at the basic level.

Adult↗
PubMed1989

Visual feedback and anticipatory hand orientation during infants' reaching.

Infants 5, 7, and 9 mo. of age were videorecorded while reaching for a dowel that either was stationary or changed orientation after initiation of a reach. Visual fixation and hand orientation were monitored throughout each reach, as was the efficiency with which infants contacted the stimulus. In reaching for the stationary stimulus, the 5-mo.-olds showed significantly poorer hand orientation adjustment throughout their reach than 9-mo.-olds. The 7-mo.-olds began a reach with the hand poorly oriented as did 5-mo.-olds, but just before object contact their performance matched that of the 9-mo.-olds. On change-orientation trials, the 5-mo.-olds' reaching was disrupted. They missed, stopped, or withdrew their reach on over half of these trials, and hand orientation on contact was significantly worse than on no-change trials. By contrast, older infants were more skilled in using visual feedback to make corrective adjustments in hand orientation during execution of the reach to secure a smooth contact with the stimulus. These infants showed no difference in hand orientation on contact for change in comparison to no-change trials. The 9-mo.-olds' performance surpassed that of the 7-mo.-olds only in the efficiency with which they contacted the stimulus and the incidence of grasps on first contact.

Attention↗
PubMed1999

Role of memorization conditions in the haptic processing of orientations and the 'oblique effect'.

The haptic processing of vertical, horizontal, 45 degrees and 135 degrees oblique orientations was studied in blindfolded sighted adults in an exploration-reproduction task. The purpose was to determine whether the variations of the memorization conditions between the exploration and reproduction phases would influence the global performance and the oblique effect (lower performance in oblique orientations than in vertical-horizontal orientations). If orientation coding depended on attentional resources, the increase in memory constraints would affect the haptic processing of orientations and the oblique effect. Memory constraints were therefore varied by changing the length and the nature of the delay in two tasks in which previous research has shown that the availability of gravitational cues affected orientation coding. Blindfolded adults were asked to explore haptically a rod with minimal (Expt 1) or natural (Expt 2) gravitational cues and then to reproduce the orientation of this rod ipsilaterally after one of four memorization conditions: with 5 s or 30 s unfilled delays, and 30 s delays filled with verbal or haptic interpolated tasks. When the delay was unfilled, whatever its length (5 s or 30 s), the performance depended on the conditions of manual exploration: the oblique effect was absent when the gravitational cues were minimal (Expt 1) and was present when these cues were natural (Expt 2). By contrast, when the delay was filled with interpolated tasks, the haptic oblique effect was present whatever the conditions of manual exploration. Taken together, these results showed that memorization conditions played a role in the haptic processing of orientations and in the oblique effect when the gravitational cues were minimal during manual exploration.

Adult↗
PubMed1999

Modulation frequency and orientation tuning of second-order texture mechanisms.

Modulation frequency and orientation tuning of second-order mechanisms underlying the detection of modulation in local spatial-frequency information are assessed by using an oblique-masking paradigm. Stimuli were Gabor-filtered noise patterns in which the local carrier spatial frequency was modulated about an average value of 4.7 cycles per degree (cpd) according to sinusoidal function. Thresholds were determined for spatial-frequency modulated test patterns (0.2 and 0.8 cpd) with fixed vertical carrier and modulation orientations presented alone and in the presence of spatiotemporally superimposed masks. Mask modulation frequency (0.1, 0.2, 0.4, 0.8, or 1.6 cpd), modulation orientation (0 degree, 45 degrees, or 90 degrees relative to vertical), and carrier orientation (18.5 degrees or 90 degrees relative to vertical) were manipulated independently while the mask modulation amplitude remained fixed at 0.25. Manipulating the modulation frequency of the mask revealed some modulation frequency specificity, particularly at lower test modulation frequencies. Spatial-frequency modulated masks produced threshold elevations regardless of the local carrier orientation. However, there was no evidence of threshold elevation when the mask modulation orientation was orthogonal to that of the test pattern. These results suggest a second-order texture mechanism that is tuned to both modulation frequency and modulation orientation but is not selective in terms of the orientation of first-order inputs.

Contrast Sensitivity↗
PubMed1985

Postadaptation orientation discrimination.

An orientational difference of only 0.3-0.5 deg can be discriminated between two gratings or two lines, although psychophysical channels and cortical cells both have comparatively broad orientation bandwidths of 10-25 deg. One proposed explanation for the fineness of orientation discrimination is that, while detection is determined by the most excited orientation-tuned neural elements, superthreshold orientation discrimination is determined by difference signals between these elements [Westheimer et al., J. Opt. Soc. Am. 66, 332 (1976)]. This implies that, if stimulus orientation is changed slightly, the most important elements for discriminating this change will be those whose relative activity changes most, even though the excitation of these elements may be comparatively weak. In accord with this prediction, we found that adapting to a high-contrast grating degraded discrimination for test gratings inclined at about 10-20 deg to the adapting grating while having little effect on the detection of these inclined gratings. For test gratings parallel to the adapting grating, discrimination was improved, but detection was degraded. Either an opponent-process or a line-element model can account for these effects of adaptation. An opponent model can also explain our findings that subjects do not confound orientation change with contrast change and that suprathreshold orientation discrimination is almost independent of contrast, varying by only +/- 10% from about 3 to about 25 times contrast threshold. A discrimination model must incorporate reliable storage of spatial frequency, because discrimination was not affected by increasing the interval between grating presentations from 1 to 10 sec.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Ocular↗
PubMed2000

Orientation specificity in biological motion perception.

We addressed the issue of how display orientation affects the perception of biological motion. In Experiment 1, spontaneous recognition of a point-light walker improved abruptly with image-plane display rotation from inverted to upright orientation. Within a range of orientations from 180 degrees to 90 degrees, it was dramatically impeded. Using ROC analysis, we showed (Experiments 2 and 3) that despite prior familiarization with a point-light figure at all orientations, its detectability within a mask decreased with a change in orientation from upright to a range of 90 degrees-180 degrees. In Experiment 4, a priming effect in biological motion was observed only if a prime corresponded to a range of deviations from upright orientation within which the display was spontaneously recognizable. The findings indicate that display orientation nonmonotonically affects the perception of biological motion. Moreover, top-down influence on the perception of biological motion is limited by display orientation.

Adolescent↗
PubMed2006

Instruction in mastery goal orientation: developing problem solving and persistence for clinical settings.

Individuals with a mastery orientation are more motivated to persist and increase their competence. Although studies have demonstrated the usefulness of explicitly teaching mastery goal orientation, no interventions have been used in nursing education. The purpose of this study was to determine whether mastery goal orientation could be rapidly acquired by nursing students via a short-term educational intervention. Nursing students from five programs participated in a 3-week intervention. Participants were matched by demographic profile and pretest goal orientation scores before being randomly assigned to experimental and control groups. Goal orientation was measured before and after the intervention. Students in the experimental group increased their mastery orientation significantly, while reducing their performance orientation somewhat. They persisted to solve problems, while students in the control group gave up more easily when faced with a difficult task. Early development of mastery goal orientation that promotes problem solving and persistence for clinical settings can be a powerful adjunct to undergraduate nursing education.

Adaptation, Psychological↗
PubMed1975

[Disturbances of orientation with functional psychoses (author's transl)].

It was supposed by clinical impressions that disturbances of orientation do not appear only in severe degrees of a transit-syndrome, but also in the light stadium of such a physically founded psychosis. In order to verify these impressions, a questionnaire was developed which permitted an objective scoring. This Q-Test consists of 37 questions (items), which measure the orientations of time, space, situation, and person. On the base of this questionnaire two samples were tested, the one consisting of 50 patients with functional psychoses (reversible physically founded psychoses), the other consisting of 50 patients with only neurological disturbances. The degree of the functional psychoses was determined by the "Syndrome-Test" (F. Bocker, 1959). The range of the scores corresponded with the clinical categories from a low degree of the transit-syndrome to a medium degree of disturbances of consciousness. The scoring was based on an standard system derived from the results of the control group (patients with only neurological disturbances). The clinical impressions could be verified by empirical and statistical methods. According to the test results, disturbances of orientation already appear during the light stadium of the transit-syndrome. Furthermore there is a high significant correlation (p. less than 001) between the degree of the functional psychoses and the degree of the disturbances of orientation. This applies to all categories of orientation. The orientation concerning time, space and situation proved to be more susceptible to disturbances than the orientation concerning the person. The very close correlation between the degrees of the functional psychoses and the degrees of the disturbances of orientation make it possible to determine the stadium of the functional psychoses promptly. The complete and very handy "short-time-test" will be published in a special paper.

Consciousness Disorders↗
PubMedDate not supplied

[Vector systems and rhythms in movements and orientation of elk (Alces alces L.) and other wild animals (Mammalia)].

The orientation of elk and other mammals studied in fields with visual and instrumental tracing has obviously hierarchical organization. Animals usually choose general direction headed for distant markers and then select short-distance landmarks. Movements of animals to distant and close landmarks is characterized by almost constant or regularly changing angles between main direction and movement vector. Fragments of trajectories represent left-side or right-side spirals with decreasing or increasing curvature according to the main direction. Three types of spirals differed by average values of initial angles are considered. Orientation to distant landmarks or along direction of movement possesses discrete reaction on the given landmarks and has some characters of iteration process. Special rhythms of activity (rhythms of orientation changing) participate in regulation of changing of movement directions and orientation reactions. They take part in formation of sinusoid, spiral and other trajectories. Rhythmic regulation involves great statistical variability of parameters (lengths, angles, time periods between consecutive orientations) that can be adaptive meaning. Lengths of orientation vectors and trajectory fragments are similar to some linear elements of landscape. Angular parameters of orientation are more variable. The main ones are similar to the angular parameters of Earth rotation. It looks, that orientation parameters evolved under the influence of Sun-Earth compass in inertial field of Earth rotation.

Animals↗
PubMed1987

[Selectivity of the neuronal responses of the human brain to different angular orientations of visual stimuli].

In parkinsonic patients with long-term intracerebral electrodes implanted into different nuclei of the thalamus and striopallidar complex the neuronal impulse activity was recorded during visual testing for orientation sensitivity. Visual testing revealed significant responses in multiple unit activity of studied neuronal populations to the angular orientations of the presented stimuli differing from background stimulus orientation. This responses were spatially specific and were not the result of modulation of the activity of these units by the common afferent signal. Neuronal populations differently responding to stimuli which differ only in the angular orientation were observed. These findings might be interpreted as an orientation sensitivity. Such orientation sensitivity of various units differs both in optimal orientation angle and sharpness of responses, some unit groups responding to the definite orientation of the stimuli only. It is suggested that the neuronal populations with significant responses to the visual stimuli used are the elements of thalamostriopallidar system which plays an important role in the maintenance of motor functions. The convergence of motor and visual information within this system probably enables their comparison and interaction, related to the visual perception constancy.

Brain Mapping↗
PubMed1986

Orientation selectivity of synaptic potentials in neurons of cat primary visual cortex.

Neurons of the visual cortex of the cat were penetrated with intracellular electrodes and postsynaptic potentials evoked by visual stimuli recorded. By alternately polarizing the cell with steady current injected through the recording electrode, IPSPs and EPSPs could be recorded and analyzed independently. Hyperpolarizing current suppressed IPSPs and enhanced EPSPs by moving the membrane potential toward the IPSP equilibrium potential. Depolarizing the cell toward the EPSP equilibrium potential enhanced IPSP. The responses to electrical stimulation of the LGN, where EPSPs and IPSPs could be distinguished easily by virtue of their characteristic latencies and shapes, were used to set the current injection to the appropriate level to view the two types of synaptic potential. EPSPs were found to be well oriented in that maximal depolarizing responses could be evoked at only one stimulus orientation; rotating the stimulus orientation in either direction produced a fall in the EPSP response. IPSPs were also well tuned to orientation, and invariably the preferred orientations of EPSPs and IPSPs in any one cell were identical. In addition, no systematic difference in the width of tuning of the two types of potential was seen. This result has been obtained from penetrations of over 30 cortical cells, including those with simple and complex receptive fields. It is concluded that orientation of cortical receptive fields is neither created nor sharpened by inhibition between neurons with different orientation preference. The function of inhibition evoked simultaneously with excitation by optimally oriented stimuli has yet to be determined, though it is likely to be the mechanism underlying other cortical receptive field properties, such as direction selectivity and end-stopping.

Animals↗
PubMed1986

[Differences in the properties of 2 groups of orientation detectors of the visual cortex in the cat].

Functional properties of 149 neurons in field 17 of the visual cortex were studied in immobilized cats. They were divided into two groups. In 37% of neurons the initial and peak latencies of responses changed not more than by 10 ms in the orientation range. They were named "timer"-neurons. 63% of neurons were called "scanners". "Timers" reliably differed from "scanners" in shorter latencies, time of the discharge frequency increase, duration of the response and higher discharge frequency in all stimuli orientations. Scanners had a higher orientation selectivity, they considerably more often scanned the range of orientations in time. Neurons of the two groups had contraphase dynamics of the width of tuning orientation during response while distribution of their preferential orientations supplemented each other. In orientation columns of the visual cortex, both timers and scanners were most often found with a predominance of the latter. The columns consisting of only timers or only scanners were more seldom. The role of differences in properties of two neuronal groups in the cat visual cortex for orientation detection is discussed.

Animals↗
PubMed1995

[Neurons in monkey parietal association cortex sensitive to axis orientation].

Patients with parietal lesions may fail to adjust the orientation of the hand to that of the target object or may make errors in judging the orientation of the bar. This suggests that the parietal cortex functions to discriminate the orientation of objects. Therefore, we studied orientation selectivity of the visual neurons of the posterior parietal association cortex of alert behaving monkeys. We recorded 23 neurons that showed selectivity in the axis orientation of visual stimulus in the lateral bank and fundus of the caudal part of the intraparietal sulcus (IPS). Almost all the neurons tested with a slit on the screen responded better to a longer or narrower stimulus. There were also neurons which responded only to three dimensional objects, such as a bar presented in the sagittal orientation tilted forward or backward. The majority of these neurons had wide receptive fields and their responses were position-invariant. These results suggest that the axis orientation selective neurons of the parietal cortex represent orientation of the longitudinal axis of objects in 3-dimensional space.

Animals↗
PubMed1999

Distribution map of collagen fiber orientation in a whole calf skin.

It is important to obtain information about the collagen fiber orientation in biological fibrous tissues such as human and animal skins because the collagen fiber orientation in the skins may closely relate to the motional functions of the body. However, no reports are yet available on the distribution of collagen fiber orientation in a whole skin. The microwave method recently developed by the author was applied for giving the distribution of collagen fiber orientation. A map representing the distribution of collagen fiber orientation was obtained for a leather sheet prepared from the entire skin of a calf. It was found that the direction of collagen fiber orientation was, on an average, parallel to the calf's spinal column and limbs, corresponding to the direction perpendicular to that of skin motions due to eating and walking, and that the degree of orientation was large in the parts where the skin motions were marked. These findings suggest that the distribution map of fiber orientation in calf leather significantly affects the motional functions of its different parts and also hopefully gives useful information for performing an appropriate transplant of skins.

Animals↗
PubMed1998

A novel nozzle for more efficient sperm orientation to improve sorting efficiency of X and Y chromosome-bearing sperm.

Efficient high-resolution detection of DNA for flow cytometric sorting of X and Y chromosome-bearing sperm is dependent on effectively orientating the sperm head to the laser beam in orthogonally configured flow systems. Normally, a beveled needle is required to enlarge the fraction of properly orientated sperm (flat side facing the laser beam). In this report, a modification to a standard jet-in-air nozzle for improved sperm orientation is presented. Inside the modified nozzle (novel nozzle), orientation forces are applied lower in the nozzle than in the current beveled injection needle system. The nozzle was tested with sperm heads from several species. This study shows that use of the nozzle to orientate cattle, swine, rabbit, mouse, and human sperm effectively improves the percentage of sperm that are properly oriented. The percentage of sperm heads oriented by use of the former system (beveled needle) ranges around 30% for most species. With the newly designed nozzle, that percentage ranges around 60%. At least a twofold increase in analysis is achieved. It was found that, unlike results with the beveled needle, the percentage of properly oriented sperm was independent of the sample rate. The introduced nozzle is a significant improvement over the beveled needle system for the analysis and sorting of sperm on the basis of DNA content. In addition to the improvement in sorted sperm production brought about by the novel nozzle when fitted to standard-speed cell sorters, it clearly also has significant potential for improving the efficiency of the Beltsville Sperm Sexing Technology for separating X and Y chromosome-bearing sperm when adapted to high-speed cell-sorting systems.

Animals↗
PubMed1987

Effect of the surface geometry of smooth and porous-coated titanium alloy on the orientation of fibroblasts in vitro.

The migration and orientation of human gingival fibroblasts in relation to the rim of smooth-surfaced and porous-coated titanium discs placed on multilayers in vitro was investigated. Samples were examined after 6 h, 24 h, 3 days, and 7 days of culture using phase-contrast and scanning electron microscopy. The cells migrated from the multilayer onto the smooth-surfaced discs forming bridges between them, and orientated along parallel circumferential grooves in the rim of the discs. This resulted in the cellular bridges orientating at an acute angle to the rim of the disc, and adjacent cells in the multilayer orientating parallel to the rim. Cellular bridges were also formed between the porous-coated discs and the multilayer but, because the cells that migrated onto, and between, the spheres of the porous-coat showed no preferred orientation, the bridges retained their orientation at right angles to the surface of the rim. This in turn resulted in the cells of the adjacent multilayer becoming similarly orientated. These observations suggest that the geometrical configuration of the surface of implants could influence whether a capsule or an orientated fibrous attachment is developed in relation to implants in vivo.

Alloys↗
PubMed2003

Relationship between damage accumulation and mechanical property degradation in cortical bone: microcrack orientation is important.

The accumulation of damage and the associated degradation of the mechanical properties of cortical bone are postulated to contribute to age-, disease-, overuse-, and disuse-related skeletal fragilities. Therefore, gaining insight into the relationship between damage and degradation processes is essential in understanding the etiology of skeletal fractures. In investigating this relationship, the damage measure ideally needs to account for the size, the distribution density, and the orientation of microcracks. Existing measures of damage address the size and distribution density of microcracks; however, the orientation of cracks has not been well-investigated. Because the overall orientation of microcracks determines the material axis along which the greatest degradation will be experienced, we hypothesized that the incorporation of the relative orientation between microcracks and loading direction will improve the significance of the relationship between damage accumulation and material property degradation. A three-cycle damage protocol was used to induce tensile damage and to quantify the degradation of the elastic modulus of specimens from human donor femoral cortical bone (a 24-year-old and a 72-year-old man). Microcracks were evaluated by en bloc basic fuchsin staining of specimens after testing. The length (L(i)) and the orientation with respect to the loading direction (beta(i)) of each crack were quantified by a video microscopy system. Three damage measures were quantified for each specimen: the number of linear microcracks (Cr #), the sum of the crack lengths (SigmaL(i)) accounting for the microcrack size alone, and the sum of the projected crack length [SigmaL(Pi) = SigmaL(i)cos(beta(i))] accounting for both crack size and orientation. Inclusion of the orientation parameter improved the coefficient of determination between damage accumulation and the degradation of the elastic modulus: the coefficient of determination of the sum of the projected crack length (R(2) = 0.239) was 60% greater than that of the sum the projected crack length (R(2) = 0.149) and 33% greater than that of the number of linear microcracks (R(2) = 0.180). We conclude that microcrack orientation is an essential physical variable in the relationship between damage accumulation and degradation of mechanical properties of cortical bone tissue.

Adult↗
PubMed2004

Effects of titanium-coated micromachined grooved substrata on orienting layers of osteoblast-like cells and collagen fibers in culture.

Osteogenic cells from newborn rat calvariae were cultured on titanium surfaces on which cell orientation could be manipulated. Substrata included smooth surfaces and substrata with smooth regions (gaps) flanked by grooves of 47-microm pitch and 3-, 10-, or 30-microm depth. Orientation angles of the cells were measured over time using propidium-iodide staining and confocal laser scanning microscopy. In addition, collagen fibers were identified using picro-sirius staining and reflected light polarization microscopy. Grooves proved effective in orienting cells, but their orienting ability decreased above the ridge level. Cells on the smooth surface showed no preferred orientation. Cells in the gaps became oriented as a result of cell-cell interactions with the cells on the flanking grooves. Cells in grooves produced oriented collagen fibers, but in the gaps, fibers could be parallel, perpendicular, or diagonal to the grooves. Collagen fibers on the smooth surfaces formed arrays of parallel fibers in a crisscross pattern. In long-term cultures, bone-like nodules were formed, but mostly above the ridge level. These data demonstrate that grooved surfaces can influence cell orientation both in cell populations above the cells in contact with the grooves and in cell populations adjacent to the grooves.

Animals↗