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At least 91 records · Page 5Linked to original sources
PubMed1985

Colliding targets: evidence for spatial localization within the motion system.

The ability to judge the relative location of moving targets is seriously degraded if the targets move in different directions. The vernier acuity for a target in which the two components move in the same direction is not impaired until target velocity exceeds about 4 deg/sec. If the components are moving along trajectories which differ in direction by more than 15 deg, vernier thresholds rise significantly at target speeds greater than 1 deg/sec. The conditions which affect stationary vernier acuity, i.e. separation of target components, duration, and orientation, do not account for the loss in acuity. Our results suggest that localization for moving targets depends on directionally-selective motion detectors.

Female↗
PubMed1985

Accuracy of spatial localizations near the time of saccadic eye movements.

Two-dimensional eye movements were recorded while subjects used a hammer to strike targets that were flashed-on briefly before, during or up to 750 msec after a horizontal saccade. Mean position of hammer blows was 20 min arc (SD = 67 min arc) from the target when the only cue to target location was eye position. Position of responses varied slightly with time of target exposure relative to the saccade. These results show that observers can closely monitor small changes in eye position during and near the time of saccadic eye movements.

Eye Movements↗
PubMed1993

Temporal and spatial localization of steroidogenic enzymes in premenopausal human ovaries: in situ hybridization and immunohistochemical study.

In situ hybridization and immunohistochemical localization of cytochrome P450 cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), cytochrome P450 17 alpha-hydroxylase (P450c17) and cytochrome P450 aromatase (P450arom) was performed in 50 morphologically normal human premenopausal ovaries, and correlated these findings with their endometrial phase. In general, mRNA expression of these enzymes examined by in situ hybridization were in good agreement with immunolocalization examined by immunohistochemistry. Expression of P450scc, 3 beta HSD and P450c17 was observed in large-sized preantral follicles, consisting of more than five layers of granulosa cells, preovulatory follicles, corpora lutea, and some degenerating corpora lutea and atretic follicles in all endometrial phases. Several follicles and/or corpora lutea positive for these enzymes were observed in the same ovary. Expression of P450arom was generally observed in only one follicle (antral or preovulatory follicle) or corpus luteum per case in mid proliferative to premenstrual phase, and was not observed in menstrual to early proliferative phase. These findings indicated that (1) expression of steroidogenic enzymes was associated with the continual human ovarian process including follicular development and atresia, and (2) especially, P450arom expression may occur only in a selected antral follicle and may have an important role in dominant follicular development.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Spatially localized neuronal cell lineages in the developing mammalian forebrain.

The role of cell lineage in the organization of the cerebral cortex and striatum of the developing rat forebrain was analysed using retroviral-mediated gene transfer to mark the progeny of individual progenitors. Injections around the onset of neurogenesis (embryonic day 14) produced neuronal- and glial-specific clones in the striatum and cortex. The majority of the neuronal clones were restricted to either the deep or superficial layers of the cortex and to either the striatal patch or matrix compartments of the striatum. Moreover, modeling the distributions of the neuronal clones in various ways revealed that grouping the clones into deep vs superficial cortical compartments and patch vs matrix striatal compartments best accounted for the clone distributions. These results suggest that at the onset of neurogenesis there is a heterogeneity of neuronal progenitors within the proliferative ventricular zone.

Animals↗
PubMed1990

Distinct spatial localization of specific mRNAs in cultured sympathetic neurons.

We examined the subcellular distribution of specific mRNAs in cultured sympathetic neurons. Under appropriate conditions, sympathetic neurons extend both axons and dendrites that are distinguishable by light microscopic and immunocytochemical criteria. In situ hybridization revealed a differential localization of mRNA within dendrites. mRNA encoding MAP2 was abundant in cell bodies and distributed nonhomogeneously throughout the dendritic compartment, but was not detected in axons. In contrast, mRNAs encoding GAP-43 and alpha-tubulin were restricted to the cell body and largely excluded from dendrites as well as axons. Detergent extraction revealed that most dendrite-associated mRNA encoding MAP2 was associated with the Triton X-100 insoluble fraction of the cell. The subset of mRNAs present in the dendritic compartment may encode proteins involved in the morphogenesis and remodeling of dendrites.

Animals↗
PubMed1994

Spatial localization of pre-mRNA transcription and processing within the nucleus.

The organization of transcription, processing, and transport of pre-mRNA within the nucleus is a major unsolved problem in cell biology. Several recent studies have helped to define the localization of specific DNAs, RNAs, and proteins within the nucleus and have led to various models for higher level organization of pre-mRNA metabolism.

Animals↗
PubMed1995

Lateral neck imaging for spatial localization of parathyroid tissue.

Two patients with an ectopic parathyroid adenoma are described. In both cases the lesions were clearly demonstrated in an anterior view on T1-201/Tc-99m scintigraphy, but were not identified during the first surgical exploration. Failure to identify the ectopic adenoma at surgery in the second patient led to oblique and lateral views being obtained. These views permitted correct depth localization. We, therefore, believe that lateral and oblique views can be of assistance in improving preoperative localization of an ectopic parathyroid adenoma.

Adenoma↗
PubMed1989

Ethanol and spatial localization.

Water (Exp. 1) and radial maze (Exp. 2) tasks permitted an evaluation of the relative degree of impairment imposed by ethanol (0, 0.75, 1.5, and 2.0 g/kg) on cognitive mapping vs. cued place learning. The tasks did not require working memory. A strong tendency emerged for ethanol-treated rats to persist in cognitive mapping strategies after the strategies were no longer useful, but there was no indication of a mapping impairment per se. When performance deficits appeared, they were equivalent across mapping and cued place tasks and may have reflected motivational effects of ethanol. In most instances, neither mapping nor cued place tasks were difficult for ethanol-treated animals unless the tasks required abandoning one strategy for another. The tenacity of ethanol-treated rats to use cognitive mapping strategies, particularly rats receiving the highest dose, proved consistent and theoretically decisive. The behavioral invariance of ethanol-treated rats is not caused by a cognitive mapping deficit. Rather, mapping is another domain in which ethanol reduces flexibility.

Animals↗
PubMed1992

Effects of unilateral parietal lesions on spatial localization in the rat.

In the first of two experiments, rats with left or right parietal lesions and controls were tested in place and landmark navigation in the water maize. Right parietal lesions resulted in deficits in both tasks, but especially landmark navigation. Lateralized effects appeared mainly in latency to find the platform. Experiment 2 investigated the role of the corpus callosum. Split-brain rats with unilateral parietal lesions were tested on the same two tasks. Place and landmark deficits were particularly severe, but lateralization was weaker. Callosum section had its own effect, impairing the learning of both tasks. There appear to be additive effects of unilateral cortical lesions and bisection of the hemispheres. The impairment from left lesions equaled the right-lesion deficit because of the interruption of compensatory information from the intact right hemisphere and the effect of callosum section itself.

Animals↗