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Results for “Spatial orientation”

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PubMed1991

Localization of visual targets inside and outside the field of view: the effect of hearing loss.

In two experiments the eye and head localization responses of auditorially handicapped children to visual targets in a surrounding circular display were compared with the corresponding responses of age-matched controls (Experiment 1, mean age: 131 months, hearing loss of auditorially handicapped children greater than 90 dB; Experiment 2, two age groups with mean ages: 72 and 123 months, hearing loss of auditorially handicapped greater than 50 dB). It was hypothesized that an auditory deprivation results in a deficient spatial orientation to the regions outside the visual field. This in turn should affect the actual localization behaviour to visual targets situated within those regions. Differences between the auditorially handicapped and non-handicapped children were found with respect to the localization times of so-called 'reversal' responses of eye (Experiment 1) and head (Experiment 2) to targets situated outside the field of view. In the second experiment significant age-effects were present. The implications of these findings for the presence of specific differences in cognitive spatial abilities between auditorially handicapped and hearing children are discussed.

Age Factors↗

PubMed2000

Functional inactivation of dorsal hippocampus impairs active place avoidance in rats.

This paper assesses the contribution of hippocampus to the spatial orientation of Long-Evans rats in a new place avoidance task. The animals learn to avoid a mild footshock in a segment of a rotating arena. Since the punished region is defined in the coordinate system of the stationary room the subject is forced to move away from the prohibited segment even if it is immobile. After bilateral injection of tetrodotoxin (5 ng in 1 microl of saline) into the dorsal hippocampus rats were not able to avoid the punished place while a similar injection of saline did not affect performance. The results suggest the task is suitable for assessing the hippocampus-dependent spatial abilities of laboratory rodents.

Animals↗

PubMed1979

[Critical study of the morphogenesis of trunco-conal malformations].

Anatomical and angiocardiographic studies have made possible discussion of hypotheses of the development and differentiation of the conus and of the trunco-conal orientation of the septum. Three autopsy specimens and two angiocardiogrammes of intertwined great vessels with transposition and partial distortion of the great vessels were studied. The specimen of intertwined great vessels comprised a muscular sub-aortic infundibulum posterior to and greater than the pulmonary infundibulum. In the case of transposition the opposite situation was encountered with a muscular pulmonary infundibulum posterior to and greater than the sub-aortic infundibulum; the plane of the aortic valves was higher than that of the pulmonary valves. The specimen of partial distortion of the great vessels comprised a muscular sub-aortic infundibulum posterior to and greater than the pulmonary infundibulum with the aortic valve set higher and in fibrous continuity with the mitral valve. It is concluded that the relations of the great vessels between each other and with the ventricles depend on the orientation of the trunco-conal septum and on the process of incorporation of the cone. The presence or absence of a posterior muscular infundibulum is not related to the growth or differential reabsorption of the cone but to a process of cellular differentiation. There was no relation between the level of the valves and their spatial orientation and the length of the infundibulum. The continuity or discontinuity between the aortic and atrio-ventricular valves is not determined by the level of the aortic valves.

Female↗

PubMed1991

Making arm movements within different parts of space: the premotor and motor cortical representation of a coordinate system for reaching to visual targets.

The activity of 156 individual arm-related neurons was studied in the premotor cortex (area 6) while monkeys made arm movements of similar directions within different parts of 3-dimensional space. This study was aimed at describing the relationship between premotor cortical cell activity and direction of arm movement and assessing the coordinate system underlying this relationship. We found that the activity of 152 (97.4%) cells varied in an orderly fashion with the direction of movement, in at least some region of the work space. Premotor cortical cells fired most for a given preferred direction and less for other directions of movement. These preferred directions covered the directional continuum in a uniform fashion across the work space. It was found that, as movements of similar directions were made within different parts of the work space, the cells' preferred directions changed their orientation. Although these changes had different magnitudes for different cells, at the population level, they followed closely the changes in orientation of the arm necessary to move the hand from one to another part of the work space. This shift of cells' preferred direction with the orientation of the arm in space has been observed with similar characteristics in the motor cortex (see Caminiti et al., 1990). In both premotor and motor cortices, neuronal movement population vectors provide a good description of movement direction. Unlike the individual cell preferred directions upon which they are based, movement population vectors did not change their spatial orientation across the work space, suggesting that they remain good predictors of movement direction regardless of the region of space in which movements are made. The firing frequency of both premotor and motor cortical neurons varied significantly with the position occupied by the hand in space. These static positional effects were observed in 88.5% of premotor and 91.8% of motor cortical cells. In a second task, monkeys made movements from differing origins to a common end point. This task was performed within 3 different parts of space and was aimed at dissociating movement direction from movement end point. It was found that in both premotor and motor cortices virtually all cells were related to the direction and not to the end point of movement. These data suggest that premotor and motor cortices use common mechanisms for coding arm movement direction. They also provide a basis for understanding the coordinate transformation required to move the hand toward visual targets in space.

Analysis of Variance↗

PubMed1986

Behavioral effects of large and small lesions of the rat medial frontal cortex.

Rats with either sham operations, small medial frontal cortex lesions (SMF), or large medial frontal cortex lesions (LMF) were tested in the open field, for spatial alternation and for 8-arm maze learning. The behaviors of sham-operated and SMF rats were similar on the spatial learning tasks, while the LMF group performed poorly in relation to these two groups. In contrast, the two lesion groups differed from the sham group, but not from each other, on locomotor activity in the open field. The differences in performance between the SMF and LMF groups on the spatial learning measures suggest that medial frontal cortex lesion size and locus may be important factors underlying the variable results of previous studies evaluating spatially-oriented behaviors of rats with varying degrees of medial frontal cortex damage.

Animals↗

PubMed1998

Repeated blockade of mineralocorticoid receptors, but not of glucocorticoid receptors impairs food rewarded spatial learning.

Corticosteroids from the adrenal cortex influence a variety of behaviours including cognition, learning and memory. These hormones act via two intracellular receptors, the mineralo-corticoid receptor (MR) and the glucocorticoid receptor (GR). These two receptor types display a high concentration and distinct distribution in the hippocampus, a brain region which is directly involved in the regulation of spatial orientation and learning. In this study, repeated subcutaneous administration of the mineralocorticoid receptor antagonist RU28318 (1.0 mg/100 g body weight), the glucocorticoid receptor blocker RU38486 (2.5 mg/100 g body weight), or a combination of both antagonists were investigated for their effects on working--and reference memory in morning and afternoon trials during 8 subsequent days in food rewarded spatial learning in a hole board task. Each rat received one dose of either vehicle (2% ethanol in PEG 400), RU28318, RU38486 or the combination of both antagonists directly after the first trial on training days 1, 3, 5, and 7. The experiments demonstrated that repeated blockade of mineralocorticoid receptors impairs reference memory reflected in the morning--as well as in the afternoon trial, whereas blockade of glucocorticoid receptors has little effect on this type of cognitive behaviour. Furthermore, combined blockade of MRs and GRs resulted in a decrease, in both daily trials, in reference memory as well as working memory performance. These findings suggest that in this spatial learning paradigm, the impairment of working memory required blockade of both receptor types, while reference memory performance involves predominantly the mineralocorticoid receptors.

Animals↗

PubMed2005

Evidence of separable spatial representations in a virtual navigation task.

Three experiments investigated spatial orientation in a virtual navigation task. Subjects had to adjust a homing vector indicating their end position relative to the origin of the path. It was demonstrated that sparse visual flow was sufficient for accurate path integration. Moreover, subjects were found to prefer a distinct egocentric or allocentric reference frame to solve the task. "Turners" reacted as if they had taken on the new orientation during turns of the path by mentally rotating their sagittal axis (egocentric frame). "Nonturners," by contrast, tracked the new orientation without adopting it (allocentric frame). When instructed to use their nonpreferred reference frame, both groups displayed no decline in response accuracy relative to their preferred frame; even when presented with reaction formats based on either ego or allocentric coordinates, with format unpredictable on a trial, both groups responded highly accurately. These findings support the assumption of coexisting spatial representations during navigation.

Adolescent↗

PubMed2000

Mechanism of receptor-oriented intercellular calcium wave propagation in hepatocytes.

Intercellular calcium signals are propagated in multicellular hepatocyte systems as well as in the intact liver. The stimulation of connected hepatocytes by glycogenolytic agonists induces reproducible sequences of intracellular calcium concentration increases, resulting in unidirectional intercellular calcium waves. Hepatocytes are characterized by a gradient of vasopressin binding sites from the periportal to perivenous areas of the cell plate in hepatic lobules. Also, coordination of calcium signals between neighboring cells requires the presence of the agonist at each cell surface as well as gap junction permeability. We present a model based on the junctional coupling of several hepatocytes differing in sensitivity to the agonist and thus in the intrinsic period of calcium oscillations. In this model, each hepatocyte displays repetitive calcium spikes with a slight phase shift with respect to neighboring cells, giving rise to a phase wave. The orientation of the apparent calcium wave is imposed by the direction of the gradient of hormonal sensitivity. Calcium spikes are coordinated by the diffusion across junctions of small amounts of inositol 1,4, 5-trisphosphate (InsP(3)). Theoretical predictions from this model are confirmed experimentally. Thus, major physiological insights may be gained from this model for coordination and spatial orientation of intercellular signals.-Dupont, G., Tordjmann, T., Clair, C., Swillens, S., Claret, M., Combettes, L. Mechanism of receptor-oriented intercellular calcium wave propagation in hepatocytes.

Animals↗

PubMed2000

Elevation of Vernier thresholds during image motion depends on target configuration.

Previously we showed that thresholds for abutting Vernier targets are unaffected by motion, as long as the targets are processed by the same spatial-frequency channel at each velocity and remain equally detectable [Invest. Ophthalmol. Visual Sci. (Suppl.) 37, S734 (1996)]. In this study we compared Vernier thresholds for stationary and moving abutting and nonabutting targets (gaps = 0, 18, and 36 arc min) for velocities of 0-16 deg/s. The Vernier targets were spatially filtered vertical lines (peak spatial frequency = 3.3 or 6.6 c/deg), presented at contrast levels of two, four, and eight times the detection threshold of each component line. Unlike the results for abutting targets, Vernier thresholds for nonabutting targets worsen with velocity as well as gap size. The results for abutting Vernier targets are consistent with the hypothesis that thresholds are mediated by oriented spatial filters, whose responses increase proportionally with the stimulus contrast. The velocity-dependent thresholds found for nonabutting Vernier targets can be explained on the basis of local-sign comparisons if the comparison process is assumed to include a small amount of temporal noise.

Contrast Sensitivity↗

PubMed1981

Geometric figure-rotation task and face representation in dyslexia: role of spatial relations and orientation.

Two tasks tapping various kinds of spatial-relations representation were given to test the role of spatial representation in writing and reading. (1) An intentional rotation task using six geometric (Bender-Gestalt) figures was performed by 356 children (ages 8 to 15 yr.), namely, 252 normal readers and 104 dyslexic children. (2) A draw-a-person test with the face from the front was added, since previous studies showed a significant positive correlation between un- or under-developed writing and reading abilities on one hand, and the specifically distorted pictorial representation of the upper part of the human face ("neolithic faces") on the other. Compared to normal readers, the dyslexic children not only drew significantly more "neolithic faces" but also made more errors of spatial displacement (up/down or right/left) on parts of asymmetric figures, while among both groups there were similar percentages (67.06% and 65.38%, respectively) of children who made no errors in the merely global rotation of the figures. The specific difficulty in the performance of a subgroup (78.85%) of dyslexic children on the figure rotation task appears to be analogous to certain errors made with lexical signs, where the global shape is preserved, while its asymmetrical parts may be displaced: (b = d = q = p, N = Z). Analogously, the "neolithic faces," while misrepresenting (obliterating) the spatial-relationally complex and individualized bridge of the nose area, preserve merely its global configuration.

Adolescent↗

PubMed2003

Inhibition of return for the length of a line?

Inhibition of return is most often measured using an exogenous spatial cuing method. The experiments presented here follow up on a small number of studies that have examined whether a similar effect occurs for nonspatial stimulus attributes. In Experiments 1 and 2, the task was to identify a target line as either short or long. In this context, targets on valid trials were of the same length as that of a preceding cue, whereas targets on invalid trials were of a different length than that of a preceding cue. The results were similar to those in spatial orienting studies in that responses were slower for valid than for invalid targets only at stimulus onset asynchronies (SOAs) longer than 300 msec. In Experiment 3, the stimuli were the same but the task was to detect the onset of the target line. This task change resulted in slower responses for valid than for invalid targets at all SOAs. A similar result was observed in Experiment 4, in which validity was defined by color rather than line length, and the task was to identify the target color. The discussion centers on an opponent process approach to interpreting cuing effects, and consequent difficulties in distinguishing spatial and nonspatial cuing effects based on their time course.

Adult↗

PubMed1982

Spatial self-reference systems and shortest-route behavior in toddlers.

2 experiments were conducted concerning the development of spatial orientation during the second year of life. Both experiments were focused on oriented search for a hidden target object in the absence of landmarks, which can be accomplished by relating one's movements to knowledge of a target's location. In experiment 1, 18-month-olds were tested to examine the precision with which they use information for the direction and magnitude of self-movement to keep track of the target location. Although the toddlers' search behavior was imprecise, the results showed that they appropriately modulated their search behavior according to the directions and magnitudes of their previous movements away from the hidden target. Experiment 2 was designed to determine whether toddlers can go beyond the information directly experienced in previous routes of travel to infer the shortest route to a hidden target. The results indicated that the 18-month-old and the highly selected 14-month-old subjects can perform spatial inferences of this type. The mechanisms through which these spatial abilities develop are discussed.

Child Development↗

PubMed1996

A normal bias toward a pictorially defined top in line bisection.

BACKGROUND: We set out to determine whether separable visual and representational components underlie normal subjects' upward and distal biases in bisecting vertical and radial lines under visual guidance. METHODS: Thirty-four normal subjects were asked to bisect lines oriented horizontally, vertically, and radially. Human silhouette figures were placed at either end of each line. These figures were presented upright or upside down in order to pictorially define a "top" to each line independent of the actual top of the visual field. RESULTS: Although subjects erred toward the top of the visual field, they also demonstrated a significant bias toward the heads of the figures for lines in all spatial orientations. CONCLUSIONS: This result supports the existence of two biases: one toward the upper visual field, and another toward an internally represented "top" as suggested pictorially. These findings provide further support for the hypothesis that normal subjects' upward and distal biases on bisection of vertical and radial lines under visual guidance have both representational and visual-based components.

Adult↗

PubMed1989

A homing procedure for studying spatial memory in immature and adult rodents.

In this procedure, subjects learn the spatial position of one hole out of many, that allows them to escape from a large open-field into their home cage. The arena is circular and can be rotated between trials so that no proximal landmark is permanently associated with the target hole. This task is thus similar to the Morris water maze procedure, since subjects must remember the position of the escape hole relative to extra-arena cues only. In addition it allows studying the importance of olfactory cues such as scent marks in or around a hole. Since the motivation is to reach home and the motor requirement is low, this task provides a useful alternative to the Morris place navigation task for studying spatial orientation in weanling or senescent rats. Examples are given showing that various behavioural parameters provide a good estimation as how subjects learn this task.

Animals↗

PubMed1982

Spatial disorientation in right-hemisphere infarction.

Spatial orientation was tested with the rod orientation test. The subjects were 40 normal controls and 68 brain-damaged patients with cerebral infarcts. Patients in whom the lesion included the post-rolandic region of the right hemisphere performed worse than controls or patients with lesions at other sites. Patients with an exclusively postrolandic (usually occipital) lesion showed higher error rates than patients with a combined prerolandic and postrolandic lesion, but only for the visual part of the test. These patients were re-examined one year after the stroke. Most of them showed an incomplete recovery of spatial function.

Adult↗

PubMed2005

The spatial frequency and orientation selectivity of the mechanisms that extract motion-defined contours.

The human visual system can undertake a specialized form of motion integration, one that enables the presence of extended spatial contours to be disambiguated from their backgrounds. We have shown previously that the visual system can selectively integrate local motion signals when their directions are along spatial contours and its efficiency is inversely related to the curvature of the contour involved (Ledgeway, T., & Hess, R. F. (2002). Vision Research, 42, 653-659). This integration primarily involves the direction, rather than the speed, of local motion signals. In the present study, we sought to investigate both the spatial frequency and orientation tuning of this specialized contour integration process, using a path detection paradigm. The results show that the tuning for spatial frequency is very broad, in line with previous studies that have examined this issue. In contrast, the orientation selectivity of the mechanism mediating contour extraction under these conditions is relatively narrowband. Thus, spatial frequency but not orientation pooling appears to take place prior to the extraction of motion-defined contours, a situation that is different from that previously shown for spatial contours composed of static, oriented elements.

Form Perception↗

PubMed1998

Small intestinal submucosa: a substrate for in vitro cell growth.

The extracellular matrix (ECM) of the small intestinal submucosa (SIS) was harvested by removing the superficial layers of the mucosa and the external muscular layers. The remaining 80 microns thick sheet was disinfected and sterilized by methods which removed all cellular components. The SIS-ECM, retaining its native 3-dimensional microarchitecture and composition, was evaluated for its ability to support in vitro cell growth. Six separate cell types were seeded either alone or in coculture with other cells upon this matrix, grown in selected media, a examined daily for time periods ranging from 48 h to 2 weeks. The six cell types tested were NIH Swiss mouse 3T3 fibroblast, NIH 3T3/j2 fibroblasts, primary human fibroblasts, primary human keratinocytes, human microvascular endothelial cells (HMECs), and an established rat osteosarcoma (ROS) cell line. All cell types showed the ability to attach a proliferate. All fibroblast cell line and the keratinocytes proliferated and/or migrated into the 3-dimensional scaffold of the SIS matrix. The ROS cells and the HMECs were confined in their growth pattern to the surface of the matrix. Coculturing of NIH 3T3/J2 fibroblasts and primary human keratinocytes resulted in a distinctive spatial orientation of the two cell types. The fibroblast populated the mid-substance of the 3-dimensional matrix and the keratinocytes formed an epidermal structure with rete ridge-like formation and stratification when the composite was lifted to an air liquid interface in culture. In summary, SIS provides a substratum with a 3-dimensional scaffold that allows for cell migration and spatial organization. The substratum is suitable for in vitro studies of the interaction between epithelial or mesenchymal cells and a naturally occurring extracellular matrix.

3T3 Cells↗

PubMed1975

Sex-linked major-gene influences on selected types of spatial performance.

Four paper-and-pencil spatial tests, measuring two- and three-dimesional spatial visualization and spatial orientation, were administered to 2508 Caucasian high-school students. Sibling correlations and within-sex score distributions were examined for the influence of a major sex-linked gene. Sex-linked influences were most clear on the test of two-dimensional visualization and on an average of the standard scores on all the tests. For those tests best fitting the genetic model, estimates of the frequency of the recessive gene (contributing to good performance) we-re near 0.45. There was evidence of incomplete dominance in females. Environmental or non-sex-linked genetic factors influenced spatial performance but did not systematically improve performance with age.

Adolescent↗