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PubMed2003

Vestibular influences on CA1 neurons in the rat hippocampus: an electrophysiological study in vivo.

Vestibular information is known to be important for accurate spatial orientation and navigation. Hippocampal place cells, which appear to encode an animal's location within the environment, are also thought to play an essential role in spatial orientation. Therefore, it can be hypothesized that vestibular information may influence cornu ammonis region 1 (CA1) hippocampal neuronal activity. To explore this possibility, the effects of electrical stimulation of the medial vestibular nucleus (MVN) on the firing rates of hippocampal CA1 neurons in the urethane-anesthetized rat were investigated using extracellular single unit recordings. The firing rates of CA1 complex spike cells (n=29), which most likely correspond to place cells, consistently increased during electrical stimulation of the MVN in a current intensity dependent manner. Stimulation applied adjacent to the MVN failed to elicit a response. Overall, the firing rates of non-complex spike cells (n=22) did not show a consistent response to vestibular stimulation, although in some cells clear responses to the stimulation were observed. These findings suggest that vestibular inputs may contribute to spatial information processing in the hippocampus.

Animals↗
PubMed1987

Effects of cognitive training on primary mental ability structure.

We report results of the first empirical test, as far as we know, of the assumption of structural invariance of latent constructs from pretest to posttest in cognitive training research on the elderly. In all, 401 participants in the Seattle Longitudinal Study, over 62 years old, received a 5-hr test battery at pre- and posttest that included 16 ability tests, marking the five primary abilities of Spatial Orientation, Inductive Reasoning, Numerical Ability, Verbal Ability, and Perceptual Speed. A total of 229 of our subjects received 5 hr of individual training on either Spatial Orientation or Inductive Reasoning. Restricted factor analysis with the LISREL algorithm tested the hypothesis of measurement equivalence across test occasions, separately for the control subjects and for each of the training groups. When ability-specific cognitive training intervenes, no structural change is observed for abilities not subject to intervention. However, slight shifts occurred in the optimal regression weights for the different markers for the training target abilities.

Aged↗
PubMed1990

[Dynamic stereoscopy and parallactoscopy and their importance for the 3-dimensional perception of moving objects].

The three-dimensional perception of moving objects plays an important role in professional and everyday tasks. Nevertheless, to date it has remained relatively unnoticed in the practice of ophthalmological and occupational medicine, although in 1984 the WHO also recommended testing dynamic vision. To determine dynamic stereoscopic visual acuity, the binocular prism rotation device was constructed and to determine dynamic parallactoscopy, the parallactoscopometer. The visual acuity found via dynamic stereoscopy decreased relatively quickly with increasing velocity (n = 103) and differed from stereoscopy determined at rest. Dynamic stereoscopy led to very precise fine spatial orientation, but it failed with average velocities; dynamic parallactoscopy had coarser visual powers, but it was relatively independent of speed and thus rendered essentially better spatial orientation possible at rapid velocities. It is possible that at slow pedestrian speed the two were equal. Under much-reduced light densities and reduced visual acuities, dynamic parallactoscopy remained intact in contrast to dynamic stereoscopy.

Depth Perception↗
PubMed1998

Cochleo- and tonotopic organization of the second auditory cortical area in the cat.

The cochleo- and tonotopic organization of the second auditory area (AII) was investigated in cats anaesthetized with pentobarbital using a combination of macro- and microelectrode recording technique. The results obtained following electrical stimulation of the neural fibres innervating different regions of the organ of Corti indicate the existence of two complete representations of the cochlea in area AII: one in the dorsocaudal portion, the other in its ventrorostral portion. These two cortical representations of the cochlea differ in size and spatial orientation. The dorsocaudal projection area extends over a distance of 2.6-3.2 mm from the basal to the apical focus and is arc-shaped. The spatial orientation of cochlea representation within the dorsocaudal region of AII is similar to that described in AI, in that stimulation of the cochlea base results in maximal responses in the more rostral portion of AII and stimulation of the apex evokes cortical responses more caudally. The ventrorostral region within AII is smaller (1.4-2.5 mm length), and has the opposite cochleotopic orientation (base and apex stimulation represented caudally and rostrally, respectively). In both AII zones, there was a proportionally greater cortical representation of basilar membrane than of middle and apical portions. Although two distinct zones with the overall cochleotopic pattern described above were noted in all cats, their precise size and location considerably varied in different animals. Using microelectrode recordings, a cortical tonotopic organization can be observed that was consistent with and expanded on the earlier cochleotopic data. Within the dorsocaudal region of AII, neurons with higher best frequency responses were located in more rostral regions, while those with lower best frequencies were located caudally. An orderly progression of best frequency responses was noted as serial recordings carried out along the full extent of the representation. Neurons within the ventrorostral region of AII also displayed an orderly progression of best frequencies, but in the opposite direction, with higher best frequencies noted more caudally and lower best frequencies more rostrally.

Acoustic Stimulation↗
PubMed1998

Detection of object orientation and spatial changes by mice: importance of local views.

This study examines the types of information used by mice to detect changes in their environment. After a period of habituation to an open field containing three bicolored cube-shaped objects, we modified the spatial configuration of the objects or rotated the objects 180 degrees, or both. We noted that whatever the modification, mice reexplored the objects. This shows that mice are able to detect both topological changes and, in particular, changes in the orientation of objects. This is possible only if mice can establish a local view of the objects in relation to a stable element of their environment. A second experiment showed that this stable element is in fact a pattern within the open field and not an element of the distal environment. These two experiments demonstrate the importance of local views in spatial representation for rodents.

Animals↗
PubMedDate not supplied

Behavioral and growth effects induced by low dose methamphetamine administration during the neonatal period in rats.

The investigation of methamphetamine exposure during neonatal development in rats has demonstrated that long-term spatial learning deficits are induced. A previous dose-response study showed that administration of 5 mg/kg methamphetamine, four times daily from postnatal days 11 to 20 produced these deficits, although the effects were not as severe as at higher doses of 10 or 15 mg/kg. This study examined concentrations of methamphetamine at or below 5mg/kg given over the same period of time. Five different concentrations of methamphetamine (i.e., 5, 2.5, 1.25, 0.625, or 0) were administered every 2 h four times daily from postnatal days 11 to 20. Body weights, zero maze performance, and Morris water maze learning were examined. A dose-dependent decrease in body weight was observed during the period of methamphetamine administration and these lower weights continued throughout adulthood for the 5, 2.5, and 1.25 mg/kg concentrations, although the adult decreases were negligible. No differences were noted in the zero maze. In the Morris water maze during the acquisition period, dose-dependent differences in spatial orientation were seen, however non-dose related deficits were observed for other parameters. During the shifted platform phase ("reversal"), a similar dose-dependent difference in spatial orientation was observed, although no other effects were noted during this phase. Females performed worse than males regardless of treatment or the phase of learning in the Morris water maze. These data suggest that even lower doses of methamphetamine can alter learning and memory in adulthood, although with less consistent results than with doses higher than 5 mg/kg/dose. These data would caution against even casual use of methamphetamine by women during pregnancy since even low doses could alter the ability of the child to learn.

Aging↗
PubMed1989

Perceptual speed in adulthood: cross-sectional and longitudinal studies.

Cross-sectional data on age differences in perceptual speed are presented from the Seattle Longitudinal Study for the age range 22-91 years (N = 1,620, first assessed in 1977; N = 628, first assessed in 1984). In addition, 838 subjects were followed over the 7-year interval. Markers of perceptual speed were the Identical Pictures and Finding A's tests from the ETS Kit of Factor-Referenced Tests. Significant age differences, age changes, and cohort differences were found at both observed variable and latent construct levels. Cross-lagged correlations examine the role of perceptual speed in predicting later performance on other abilities (Verbal Meaning, Inductive Reasoning, Spatial Orientation, Number, and Word Fluency). When perceptual speed is partialled out of scores for these abilities, aging effects are reduced markedly for all abilities, but least for Spatial Orientation and Inductive Reasoning.

Adult↗
PubMed1980

Spatial anatomy of facial nerve fibers--a preliminary report.

Horseradish peroxidase (HRP) was used to tag axons to the orbicularis oculi muscle in eight adult cats. Retrograde axonal transport in some animals resulted in fiber labelling such that the spatial anatomy of fibers was determined. In those few animals in which labelling occurred, a definite spatial orientation was retained in the extra-temporal nerve. Problems with the HRP technique are discussed in the paper, and the literature is reviewed with regard to spatial orientation of facial nerve axons. This technique, previously used to label neurons in the facial nucleus, appears to be of value in labelling of the peripheral fibers as well.

Animals↗
PubMed1992

Effect of 12-hour infusion of naloxone on mood and cognition in normal male volunteers.

The effects of a 12-hour naloxone infusion on mood, cognition, and plasma cortisol levels were evaluated in eight normal subjects. The dosage used was a 10 mg dose plus 7 mg/hr (total = 94 mg). Naloxone induced a significant rise in serum cortisol and also induced cognitive impairment, as shown by increased choice reaction time, reduced ability to recall the order of letters and numbers, and reduced accuracy of spatial orientation. The rise in cortisol induced by naloxone was significantly correlated with the rise in the Profile of Mood Scale (POMS) score, indicative of dysphoria. Finally, performance on the spatial orientation task was highly negatively correlated with the peak POMS score after naloxone. From these data and previous studies it is concluded that opioid receptors of low sensitivity to naloxone may mediate a common mechanism regulating the pituitary-adrenal axis' mood, and cognitive function during stress. Personality traits may account for the large individual variability reported in previous studies.

Adult↗
PubMed1988

Structural three-dimensional constitutive law for the passive myocardium.

A three-dimensional constitutive law is proposed for the myocardium. Its formulation is based on a structural approach in which the total strain energy of the tissue is the sum of the strain energies of its constituents: the muscle fibers, the collagen fibers and the fluid matrix which embeds them. The ensuing material law expresses the specific structural and mechanical properties of the tissue, namely, the spatial orientation of the comprising fibers, their waviness in the unstressed state and their stress-strain behavior when stretched. Having assumed specific functional forms for the distribution of the fibers spatial orientation and waviness, the results of biaxial mechanical tests serve for the estimation of the material constants appearing in the constitutive equations. A very good fit is obtained between the measured and the calculated stresses, indicating the suitability of the proposed model for describing the mechanical behavior of the passive myocardium. Moreover, the results provide general conclusions concerning the structural basis for the tissue overall mechanical properties, the main of which is that the collagen matrix, though comprising a relatively small fraction of the whole tissue volume, is the dominant component accounting for its stiffness.

Animals↗
PubMed2000

The dynamics of shifting visuospatial attention revealed by event-related potentials.

We developed a behavioral task for spatial orienting of attention in which the same physical stimulus cued covert peripheral shifts of attention to either the left or the right visual fields in different conditions. The design enabled us to record the brain activity engaged during spatial shifts of covert attention that was independent from the physical characteristics of the cueing stimulus using event-related potentials (ERPs). ERPs elicited by foveal cues differed according to the predicted target location starting ca. 160 ms, and differences persisted until the occurrence of the target stimuli. Multiple processes were linked to shifting spatial attention during the cue-target interval. The earliest effects consisted of enhanced negative potentials over the posterior scalp contralateral to the cued location. Later effects were concentrated over the right anterior scalp sites, where activity associated with shifts to the right visual field elicited larger positive potentials. The results extend our understanding of the neural system that orients spatial attention by providing valuable information about the temporal dynamics and hemispheric asymmetries of activity within its posterior and anterior regions.

Adult↗
PubMed1992

Motion sickness and equilibrium ataxia.

In order to know the relationship between motion sickness and equilibrium ataxia, we performed Graybiel's ataxia test battery on 10 normal subjects: 1) before donning goggles which reversed the optical image horizontally and vertically; 2) while wearing the goggles and walking; and 3) after walking as long as possible up to 90 min. Horizontal reversal of vision resulted in a statistically significant decrease in the score for all the closed-eyes tests and one open-eyes test performed during walking and after walking, respectively. In contrast, walking while wearing vertical reversing goggles produced a significant but very small change for one of the closed-eyes tests alone. The present study indicates that failure to detect spatial orientation, which evokes autonomic nervous symptoms as an alarm sign, produces equilibrium ataxia by impairing the top-down regulation of body balance, and that vertically reversed vision does not impair spatial orientation needed to maintain upright posture or to execute locomotion.

Adult↗
PubMed1998

Study of stereospecificity in mushroom tyrosinase.

This paper reports experiments on the stereospecificity observed in the monophenolase and diphenolase activities of mushroom tyrosinase. Several enantiomorphs of monophenols and o-diphenols were assayed: L-tyrosine, D,L-tyrosine, D-tyrosine; L-alpha-methyltyrosine, D,L-alpha-methyltyrosine; L-dopa, D,L-dopa, D-dopa; L-alpha-methyldopa, D,L-alpha-methyldopa; L-isoprenaline, D,L-isoprenaline and D-isoprenaline. The Vmax values obtained for each series were the same. The electronic densities on the carbon atoms in the meta (C-3) and the para (C-4) positions of the benzene ring were determined by NMR assays. This value is related to the nucleophilic power of the oxygen atom belonging to the hydroxy group, which could explain the Vmax values experimentally obtained for the monophenolase and diphenolase activities of mushroom tyrosinase. The spatial orientation of the ring substituents led to lower Km values for L-isomers than for D-isomers. However, the Vmax values were the same for each series of isomers because spatial orientation did not affect the NMR value of C-4. Therefore mushroom tyrosinase showed stereospecificity in its affinity towards its substrates (Km) but not in the transformation reaction rate (Vmax) of these substrates.

Basidiomycota↗
PubMed1997

Effects of metrifonate on radial arm maze acquisition in middle-aged rats.

The efficacy of metrifonate, a well-tolerated cholinesterase (ChE) inhibitor, in attenuating the normal aging- and corticosterone-induced impairments of radial maze performance of rats was compared. Middle-aged Fischer 344 rats were screened for their spatial orientation performance in the Morris water escape task. Good and bad performers were selected: good performers (N= 22) were treated with subcutaneous sustained-release corticosterone pellets, resulting in hippocampal cell damage and impaired spatial orientation in the radial maze; age-induced bad performers (N = 20) were tested without additional pharmacological intervention. Metrifonate (MFT), administered daily during radial maze testing, 30 min before training, at a dose of 15 mg/kg p.o., facilitated the acquisition of the task in age-impaired rats, but not in corticosterone-impaired rats.

Age Factors↗
PubMed2005

Detection of geometric, but not topological, spatial transformations in 6- to 12-month-old infants in a visual exploration paradigm.

Several theories of spatial orientation propose that the geometry of an environment plays a privileged role in reorientation, relative to relations between individual landmarks. Infants (N = 90) in three age groups (6, 8 1/2, and 12 months) experienced three conditions: topological, geometric, and control. A round room contained four distinctive objects in a rectangular arrangement on the inside periphery. Infants were familiarized to the array prior to a 2-min test period. In the topological condition, two objects were switched. In the geometric condition, the objects were moved to form an irregular quadrilateral. In the control condition, the array remained unchanged. Infants of 8 1/2 months and over visually explored significantly more in the geometric condition only. An initial study with adults found greater visual exploration in both geometric and topological conditions. These results are discussed in the context of current theories of spatial orientation.

Adult↗
PubMed2006

A comparison of two solder registration materials: a three-dimensional analysis.

STATEMENT OF PROBLEM: Use of a segmental indexing/soldering approach for assembly of complete arch implant frameworks has been advocated by some clinicians to achieve a passively fitting framework. To the authors' knowledge, a mathematical assessment using a 3-dimensional (3-D) distortion analysis has not been performed comparing segmental framework assembly to reassembly of 1-piece complete arch frameworks that required sectioning, indexing, and soldering. PURPOSE: The present study compared the use of 2 indexing materials, autopolymerizing acrylic resin and light-polymerized composite resin, for use in solder registration of complete-arch implant frameworks using 3 framework/indexing material combinations: gold/light-polymerized composite resin, silver palladium/autopolymerizing acrylic resin, and silver palladium/light-polymerized composite resin. MATERIAL AND METHODS: Five frameworks for each alloy/index combination were fabricated, for a total of 15 frameworks. Each framework was fitted to 5 implant abutments. Measurements were made of the initial gold cylinder/abutment positions for each of the 5 sites for the 15 frameworks. The 3-D spatial orientation of each gold cylinder/abutment was calculated prior to the gold cylinders being incorporated into the framework casting and served as the control against which all measurements were compared. After the indexing/soldering procedures, the 3-D spatial orientations of the cylinders were measured, first as 2- and 3-unit solder assembled framework segments and, finally, for complete-arch frameworks. These measurements were recorded in micrometers for linear distortions and degrees for angular distortions using a coordinate measurement machine (CMM). These data were compared and statistically assessed using a 1-way analysis of variance (ANOVA). A Student-Newman-Keuls test was used to determine significance between cylinders within each indexing combination. A repeated-measures ANOVA and a Student-Newman-Keuls test were used to determine significance between alloy/index group and cylinders for each of the measurement variables with statistical significance at alpha=.05 for all statistical analyses. RESULTS: Mean differences and SDs of total linear change for all groups found dR (total linear change) to be 33.56 +/- 27.70 mum for gold/light-polymerized composite resin, 34.87 +/- 27.99 mum for silver palladium/autopolymerizing acrylic resin, and 31.56 +/- 24.37 mum for silver palladium/light-polymerized composite resin. Total angular change, dtheta(R), was calculated to be 0.47 +/- 0.13 degrees for gold/light-polymerized composite resin, 0.46 +/- 0.17 degrees for silver palladium/autopolymerizing acrylic resin, and 0.52 +/- 0.15 degrees for silver palladium/light-polymerizing composite resin. CONCLUSIONS: No significant differences were found between alloy/index combinations, except for the measured variable dtheta(y), angular change about the Y axis.

Acrylic Resins↗
PubMed1976

Visual orientational anisotropy and stimulus surround effects in discrimination of spatial numerosity.

Visual spatial numerosity perception was investigated as a function of spatial orientation and surround conditions. 3 to 13 dots arranged linearly in horizontal, vertical, or oblique orientations were presented for 200 msec. in either a square or circular stimulus field. For patterns with small numbers of dots (3 to 7), surround and orientation conditions did not substantially alter perceived number except vertical arrangements were judged as having reliably more dots than identical horizontal arrangements. For large dot-number patterns (8 to 13), surround significantly altered perceived number and left oblique linear arrangements were judged to have reliably more dots than equivalent arrangements in all other orientations.

Discrimination, Psychological↗