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PubMed1975

[Role of the principal and accessory eyes in the photomenotactic orientation of the funnel spider Agelena labyrinthica (CL.)].

The photomenotactic orientation of funnel spiders (Agelena labyrinthica [Cl.]) returning to their retreat was studied by measuring the direction of their course on the horizontal webs. 1. If a lamp was shifted 90 degrees just before the spider caught its prey the mean return course deviated less than 90 degrees from the direction of the retreat. This deviation was not only a function of the azimuth of the light and of the amount it had been moved, but also varied with the course taken when approaching the prey, the duration of the interval without light stimulation while the lamps were changed, the light stimulation experienced while at the retreat, the extent to which vision was experimentally reduced, and the light intensity. 2. Elimination of the principal or of the accessory eyes had little or no significant effect on the photomenotactic orientation. Spiders able to use only the median eye or one principal eye could no longer use the lamp to orient by. 3. Animals with full vision showed an increased (decreased) deviation from the direction of the retreat if the light intensity was abruptly increased (decreased), as did animals without principal eyes or without accessory eyes. The mean return directions were, however, not dependent upon light intensity changes before reaching the prey or after an interruption of web contact. The threshold for photomenotactic orientation using the accessory eyes is 0.366-10(-4) sb; the corresponding value for the principal eyes is 100 times larger. 4. If the lamp was not visible on the outward run the spiders were unable to perform correct return runs by light orientation without optical information from previous runs. If they could see a lamp while at the retreat their return course was shifted in the direction away from the light. Animals without principal eyes did not show this effect. 5. Spiders that had not performed an outward run did not keep to a straight course. Animals with full vision spontaneously showed negative phototactic orientation, those without principal eyes were usually positively phototactic. 6. Animals, whose web contact had been interrupted or animals without principal eyes showed a similar deviation from the correct return direction as did unmanipulated animals.

Animals↗
PubMedDate not supplied

[Shape recognition and image orientation in young children].

A comparison was made of recognition of images in the direct and inverse "top-bottom" orientation. A child two and a half years old was to find the test image on the response card or to give a verbal reply. The verbal responses have shown that the child identifies well both the shape and orientation of the images. In experiments with the response card, the presentation of images in inverse orientation did not result in any mistakes in recognizing the shape nor did it prolong the latency of the reaction, and no correlation was found between the orientation of the presented and the response figures. A child trained to find images of both similar shape and orientation is incapable of indicating properly the orientation of an image presented for a limited time period. These facts are interpreted in terms of the hypothesis of multichannel transfer of information about the pattern in the visual system.

Form Perception↗
PubMed1975

The orientation of night-migrating passerines without the directional influence of the starry sky and/or the earth magnetic field.

During four seasons in 1972-73 a total of 598 orientation experiments -- including 157 displacements -- was carried out. The purpose of the experiments was to investigate the orientation under an overcast sky and/or when the earth magnetic field was screened by a strong artificial magnetic field. These experiments were compared with experiments carried out under the presumed maximum condition, i.e. under a starry sky and without magnetic disturbances. In general, little or no "reduction" of the sample mean vector, was observed under the "deprived" conditions. However, the concentration of the individual mean vectors and the activity were lowered. Clear compensation for a displacement was found in the absence of the stars and in a disturbed magnetic field. This means that directing cues from other sources than the stars and the earth magnetic field were involved. It is guessed that inertial orientation plays an important role. Reverse orientation -- including reverse compensation -- was found fairly frequently. It is supposed to be correlated with overcast, and perhaps in general stress conditions. In conclusion, simple one-direction orientation models are not thought to be sufficient to "explain" the observed orientations.

Animals↗
PubMed2003

Disparity-based coding of three-dimensional surface orientation by macaque middle temporal neurons.

Gradients of binocular disparity across the visual field provide a potent cue to the three-dimensional (3-D) orientation of surfaces in a scene. Neurons selective for 3-D surface orientation defined by disparity gradients have recently been described in parietal cortex, but little is known about where and how this selectivity arises within the visual pathways. Because the middle temporal area (MT) has previously been implicated in depth perception, we tested whether MT neurons could signal the 3-D orientation (as parameterized by tilt and slant) of planar surfaces that were depicted by random-dot stereograms containing a linear gradient of horizontal disparities. We find that many MT neurons are tuned for 3-D surface orientation, and that tilt and slant generally have independent effects on MT responses. This separable coding of tilt and slant is reminiscent of the joint coding of variables in other areas (e.g., orientation and spatial frequency in V1). We show that tilt tuning remains unchanged when all coherent motion is removed from the visual stimuli, indicating that tilt selectivity is not a byproduct of 3-D velocity coding. Moreover, tilt tuning is typically insensitive to changes in the mean disparity (depth) of gradient stimuli, indicating that tilt tuning cannot be explained by conventional tuning for frontoparallel disparities. Finally, we explore the receptive field mechanisms underlying selectivity for 3-D surface orientation, and we show that tilt tuning arises through heterogeneous disparity tuning within the receptive fields of MT neurons. Our findings show that MT neurons carry high-level signals about 3-D surface structure, in addition to coding retinal image velocities.

Animals↗
PubMed1991

Effect of light adaptation on the orientation acuity of human cone vision.

At the detection threshold, a line orientation is identified by the accuracy of 15-20 deg. Deviations from this rule are observed for short lines presented on a dim background. We checked up for one possible source of deviation: the substitution for foveal cone vision by peripheral rod vision. Long wavelength (red) light was used for the test line. In a control experiment such light did not stimulate rods. The test line was 4 min of arc long. It was presented for 20 ms on a white background of 1 or 1000 trolands and was viewed foveally. In a 2-alternative forced-choice experiment the psychometric functions for detection and orientation identification (vertical v. horizontal) were compared. In another experiment, the line was presented randomly in one of 18 orientations in the range 0-180 deg and the subject was asked to determine the orientation. In both experiments orientation perception was impaired at the dim background in comparison with the results at the bright background. This suggests that light-adaptational changes of the mechanisms responsible for orientation perception exist within the photopic vision.

Adaptation, Ocular↗
PubMed1990

How well do response changes of striate neurons signal differences in orientation: a study in the discriminating monkey.

Just-noticeable differences (JNDs) in orientation were measured in 2 monkeys using a temporal same-different task, with stationary rectangular gratings as stimuli, and compared to those of humans tested in the same setup. The JNDs of one monkey (1.5 degree) were similar to those of humans; those of the other monkey were larger (5.8 degrees). We recorded from V1 neurons in these monkeys while they were performing the orientation discrimination with the same stimuli and under the same conditions as used in the behavioral testing. In order to determine how small a difference in orientation the V1 neurons can, in these conditions, signal reliably by small changes in firing rate, we performed 2 different receiver-operating characteristic (ROC) analyses. One ROC analysis was performed on the number of spikes evoked by the first of the 2 stimulus presentations as a function of the orientation of this stimulus. Neural JNDs derived from the neurometric curve were obtained in this way for 50 cells. In the second ROC analysis, the difference in the number of spikes evoked by the 2 stimuli presented in succession during 1 trial was analyzed as a function of orientation difference between the 2 stimuli. Neural JNDs were obtained by this procedure for 21 cells. These 2 complementary ROC analyses yielded very similar results. Also, the results were similar for the 2 monkeys. A minor fraction of V1 cells can reliably signal difference in orientation as small as 2.5 degrees, but none could signal differences smaller than 2 degrees. Our results also showed that the neural JND obtained by the ROC analysis depends on the duration of the interval during which spikes are counted. In these experiments, this duration could be chosen rather precisely, because the reaction times of the 2 monkeys were measured. Also, our results showed that the neural JND depends on the point of the tuning curve at which the measurement is made and is smallest when this is done on the steepest part of the tuning curve. Finally, our results show that the discriminative capacity of V1 neurons does not depend so much on each of the tuning characteristics--bandwidth, response strength, and variability--as on the combination of these factors.

Analysis of Variance↗
PubMed1989

[The effect of sombrevin on the orientation adjustment of the visual cortex neurons in the cat].

Change in the orientation tuning of 58 visual cortex neurons, evoked by light sombrevine anaesthesia were studied in acute experiments on immobilized cats. After the sombrevine injection a reliable change of the preferable orientation by 47.6 +/- 5.6 degrees took place in 60% of cells, while in the remaining cells it was stable in all stages of anaesthesia. Stable neurons preferred the horizontal and vertical orientations, in the unstable ones this preference was less expressed. The stable neurons possessed higher qualities of orientation detection than the unstable ones. The width of the orientation tuning changed reliably by 65.2 +/- 6.7 degrees on the average in 55% of neurons, while in 31% of neurons the tuning acuteness was worse, but in 24% it was sharper. The frequency of background discharges under anaesthesia in 2/3 of investigated neurons was reduced by 58% and that of the evoked discharges by 35%. The preferable orientation, the width of the tuning and the frequency of the neuron discharge as a rule recovered in 30 min after the beginning of the anaesthesia.

Animals↗
PubMed1984

The strength of the orienting response during Pavlovian conditioning.

The strength of orienting toward a light that signaled food was studied in five experiments. Experiment 1 demonstrated that this response declined in strength during conditioning but was temporarily restored during extinction. In Experiment 2 the light was again paired immediately with the unconditioned stimulus (US), whereas in Experiments 3 and 4 it signaled a tone which in turn signaled the US. In these three experiments we again found that continuous reinforcement resulted in a decline in the strength of light orientation. These studies also revealed that under conditions of partial reinforcement, orientation to the light was sustained. Experiment 5 demonstrated that the decline in light orientation with a continuous reinforcement procedure can be retarded either by preexposing the light for a number of trials prior to conditioning or by intermixing reinforced light trials with nonreinforced presentations of a tone. This experiment also revealed that reversing the reinforcement contingency associated with the tone restored orientation to the light. This pattern of results can be most readily explained by the proposal that the strength of orientation toward the light is inversely related to the predictive accuracy of this stimulus.

Acoustic Stimulation↗
PubMed1980

Temporal characteristics of the recognition of short lines orientation.

The influence of the number of orientations (3 and 8) and of the magnitude of the angle for identification (45 and 22.5 degrees) on the temporal characteristics of orientation recognition with test lines of different lengths (5.5, 10 and 22') was studied. The time for recognition was shorter for longer stimuli. Both the number of stimuli and the magnitude of the angle influenced the percentage of correct responses. The effects of the number of orientations were weaker than expected for a sequential type of recognition. Therefore, it is assumed that the mechanism of orientation recognition is basically of the detector type even when there is influence of the angle, i.e. under conditions of insufficient orientational selectivity. The distribution of the responses was asymmetric. The degree of asymmetry of the frequencies of the errors depended on the length of the test stimuli and on the number of orientations.

Form Perception↗
PubMed1996

Development of orientation preference maps in ferret primary visual cortex.

The development of orientation preference maps was studied in ferret primary visual cortex using chronic optical imaging of intrinsic signals. The emergence and maturation of the maps were examined over time in single animals. The earliest age at which cortical domains selectively responsive to particular stimulus orientations were observed varied considerably between individuals, from postnatal day 31 to 36. In all cases, the earliest maps seen were low-contrast, with regions of orientation-specific activity that were difficult to distinguish from noise. These early maps matured over a period of several days into the high-contrast, patchy maps typical of adult animals. The structure of the orientation maps was remarkably constant over time. The indistinct features in the earliest maps were always patches of the same sizes and shapes and at the same locations as in the maps obtained in subsequent recording sessions. Details of the more mature maps, including the relative intensities of individual iso-orientation domains, were also constant from one recording session to another over periods of several weeks. The patterning of iso-orientation domains in ferret primary visual cortex thus is established early in development and remains stable over time, unaffected by either normal visual experience or the anatomical rearrangements of geniculocortical afferents into eye-specific domains.

Age Distribution↗
PubMed1996

[Topographic relationship of orientation sensitive relay cells in lateral geniculate nucleus (LGN) of dark-reared cats].

The orientation sensitivity of the LGNd neurons of dark-reared cats were investigated. As in normal cats, most of the cells studied were significantly sensitive to the orientations of grating stimuli (Bias > 0.1), and preferred horizontal and/or radial orientations. Also the adjacent cells tended to assume similar preferred orientations. These results indicate that visual deprivation in cats neither affect the distribution properties of preferred orientations, nor the clustering of cells with similar preferred orientations in the LGN.

Animals↗
PubMed1998

Effects of map orientation during learning on airport identification.

BACKGROUND: If an observer first learns to recognize an object in a specific orientation, a significant increase in processing time usually occurs when the object is subsequently seen in a different orientation; this phenomenon is called the "misorientation effect." The present study examines how quickly and how accurately human observers discriminate between airport maps that are viewed in orientations other than those in which they were initially learned. METHOD: Participants were trained to discriminate between two navigation maps that were seen in only one orientation; they subsequently were tested with maps and aerial photographs of the same airports that were presented in various orientations. RESULTS AND CONCLUSIONS: There were three principal findings: a) discriminative responses to maps of airports were most rapid when the maps were seen in the same orientation as that in which they were initially learned; b) a significant reduction in reaction time (RT) occurred with repeated presentations of the misoriented stimuli; and c) information learned from navigation maps was not sufficient for all observers to recognize aerial photographs of the same airports.

Adult↗
PubMedDate not supplied

[Digit span, automatic speech and orientation: amplified norms of the Barcelona Test].

BACKGROUND: Digit span, automatic speech and orientation are screening tests of interest in neurology due to their high sensitivity in cerebral pathologies and easy applicability. These tasks assess attention, concentration, mental control, orientation and short-term memory. OBJECTIVES: To analyze the impact of age and education on the results of the following subtest included in the Barcelona Test: digit span, automatic speech and orientation. PATIENTS AND METHODS: 275 normal subjects were evaluated. Mean (SD) age: 52 (17.7), range (18-19). Mean education: 9 (5.5) years, range (0-25). Subjects were stratified into 7 groups by age and education. Nine items of Barcelona Test were used: digits span forward and backward, automatic speech, forward and backward, with and without time, and person, time and place orientation. RESULTS: Statistical description, parametric and non parametric test. The Kruskal Wallis test was used, showing that aged and education are significant difference in the automatic speech forward or backward, with or without time, while it did not showed a significant difference in the different groups in the orientation tests. Analysis of Variance for group of age and education showed significant differences in the digit span forward and backward (F = 19.92; p < 0.001; F = 18.44, p < 0.001), respectively. CONCLUSIONS: Both age (inversely) and education (directly) influenced on the scores of the analyzed items, except to person, place and time orientation that are not affected for them.

Adolescent↗
PubMed1999

Effects of attention on orientation-tuning functions of single neurons in macaque cortical area V4.

We examined how attention affected the orientation tuning of 262 isolated neurons in extrastriate area V4 and 135 neurons in area V1 of two rhesus monkeys. The animals were trained to perform a delayed match-to-sample task in which oriented stimuli were presented in the receptive field of the neuron being recorded. On some trials the animals were instructed to pay attention to those stimuli, and on other trials they were instructed to pay attention to other stimuli outside the receptive field. In this way, orientation-tuning curves could be constructed from neuronal responses collected in two behavioral states: one in which those stimuli were attended by the animal and one in which those stimuli were ignored by the animal. We fit Gaussians to the neuronal responses to twelve different orientations for each behavioral state. Although attention enhanced the responses of V4 neurons (median 26% increase) and V1 neurons (median 8% increase), selectivity, as measured by the width of its orientation-tuning curve, was not systematically altered by attention. The effects of attention were consistent with a multiplicative scaling of the driven response to all orientations. We also found that attention did not cause systematic changes in the undriven activity of the neurons.

Animals↗
PubMed2006

Nondisclosure of sexual orientation to a physician among a sample of gay, lesbian, and bisexual youth.

BACKGROUND: The American Medical Association, the American Academy of Pediatrics, and the Society for Adolescent Medicine recommend discussing sexual orientation as part of the health supervision of all adolescents. Little is known about whether lesbian, gay, and bisexual (LGB) youth hide their orientation from health care providers, which can potentially lead to missed opportunities in identifying individual health risks and provide appropriate screening and counseling. OBJECTIVES: To describe the health care experiences of a nonclinical sample of LGB youth and identify factors associated with disclosure and nondisclosure of orientation to physicians. DESIGN: Community-based participatory study using a self-administered questionnaire. SETTING: Los Angeles youth empowerment conference held in October 2003 targeting high school-aged LGB youth. PARTICIPANTS: One hundred thirty-one youth aged 14 to 18 years who identified themselves as LGB. Main Outcome Measure Physician's knowledge of participant's sexual orientation. RESULTS: Thirty-five percent of the sample reported that their physician knew they were LGB. Bisexual youth were less likely than gay and lesbian youth to have disclosed. The strongest predictor of disclosure was having discussed sex or sexual health of any kind with a physician (odds ratio, 15.47; 95% confidence interval, 4.34-55.18). When asked what a physician could do to make talking about being LGB more comfortable, 64% of participants chose the survey response, "Just ask me." CONCLUSIONS: Even among a nonclinical sample of LGB youth who were open enough about their orientation to attend a conference on the subject, only 35% reported that their physician knew their orientation. The results indicate that physicians had not discussed sexuality with most LGB youth in the study and that most youth would welcome such a discussion.

Adolescent↗
PubMed1999

Microtubules in Xenopus oocytes are oriented with their minus-ends towards the cortex.

Despite lacking centrosomes, stage VI Xenopus oocytes contain extensive networks of cytoplasmic microtubules (MTs). To gain additional insight into the factors regulating MT organization during oogenesis, we have used electron microscopy and "hook decoration" to examine the distribution and orientation of MTs in Xenopus oocytes. A limited survey of two "undecorated" stage VI oocytes revealed 218 MTs in images covering approximately 2,500 microm(2), and indicated that the MT number density of the animal cytoplasm was greater than that of the vegetal cytoplasm. Examination of five "decorated" stage VI oocytes (three animal and five vegetal hemispheres) revealed 653 MTs. Of these, 76% could be scored as having exclusively counterclockwise (CCW) or clockwise (CW) hooks. In the animal hemispheres, 93% of the scored MTs exhibited CCW hooks when viewed from the direction of the cortex, indicating that most MTs were oriented with their minus-ends out. MT orientation appeared relatively uniform throughout the animal cytoplasm: more than 90% of the scored MTs in the cortical (90%), subcortical (96%), or perinuclear (98%) cytoplasm were oriented with their minus-ends out. In the vegetal hemispheres, approximately 80% of the scored MTs exhibited CCW hooks, and thus were oriented with their minus-ends out; 96% of the scored MTs in stage III oocytes were oriented minus-end out. These observations support a model in which the cortex plays a significant role in MT nucleation and organization in Xenopus oocytes, and have significant implications for the MT-dependent transport and localization of cytoplasmic organelles and RNAs during oogenesis.

Animals↗
PubMed1998

Psychotherapy training and theoretical orientation in clinical psychology programs: a national survey.

A survey of the instructors of the initial psychotherapy course in APA accredited clinical psychology programs investigated the relationship between theoretical orientation and 33 items assessing metatheoretical assumptions, operating constructs, and active components emphasized in psychotherapy instruction. Factor analysis of the 33 items yielded the following factors: Professional Behaviors/Attending Skills, Problem Focused, and Dynamic Constructs. Analysis of variance of the three factors by orientation revealed that only Factor 3 (Dynamic Constructs) was significant with regard to orientation. Significant differences were found between teachers with dynamic and cognitive behavioral orientations and between those with dynamic and behavioral orientations. With the exception of Dynamic Constructs, the assumptions, constructs and components emphasized in psychotherapy training in these courses appear to be similar regardless of the orientation of the instructor.

Attitude↗
PubMed2000

The effects of emotion-oriented approaches in the care for persons suffering from dementia: a review of the literature.

OBJECTIVE: This article presents an overview of the results of intervention studies in various emotion-oriented approaches in the care for people suffering from dementia. Recommendations are made with regard to clinical practice and future research. DATA SOURCES: We searched for references (1990-99) in several bibliographical databases, i.e. Medline, PsycLit, Embase, Sociofile and Current Contents. The terms 'dementia' and 'Alzheimer's disease' were linked separately to the search terms: emotion-oriented, validation (therapy), sensory integration/sensory stimulation/snoezelen, simulated presence therapy and reminiscence (therapy)/life-review. Based on references in the articles found, other publications were traced. STUDY SELECTION: We started from the 'emotion-oriented' approaches used in 24-hour care distinguished by the American Psychiatric Association (1997) i.e. validation, sensory stimulation/integration, simulated presence therapy and reminiscence. We selected research articles that describe intervention, design, measuring instruments and results. DATA EXTRACTION: The articles were analyzed with regard to research group, setting, design, effect variables, intervention, measuring instruments, statistical analyses and results. DATA SYNTHESIS: It is shown that mainly positive results (including increased social interaction and decrease of behavior problems) are achieved with these emotion-oriented approaches. Unfortunately many studies have methodological limitations and are done independently, which makes comparison difficult. CONCLUSIONS: Despite the limited cogency of the studies we traced, the results are promising. Emotion-oriented care approaches offer the opportunity to tailor the care to the individual needs of dementing elderly and can be complemented with other psychosocial approaches (e.g. psychomotor therapy and music therapy) when necessary. The challenge for the care sector is to develop guidelines to determine which approach should be applied to whom and when. Scientific research can contribute by examining which emotion-oriented approaches, possibly in combination with each other or with psychosocial therapies, effect an increase in the well-being and improve functioning in which patients.

Aged↗