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PubMed1994

Training in a novel environment improves the appetitive learning performance of the snail, Lymnaea stagnalis.

The effect of novelty, an environmental background variable affecting feeding and appetitive learning performance, was examined in a behavioral study of the pond snail Lymnaea stagnalis. Transfer of snails into a novel aquatic environment (clean water) evoked exploratory behavior which manifested itself in an increased number of spontaneous rasping movements of the mouth over the second to fifth minute after exposure to the novel environment. The intensity of this behavior was much weaker in a familiar environment (used water from the home tank). Similarly, sucrose-induced feeding rates were highest when the snails were given the sucrose stimulus in a novel environment. The effectiveness of appetitive conditioning using tactile stimulus paired with food (Kemenes & Benjamin, 1989a) improved when the snails were subjected to conditioning in a novel environment. Satiety, an internal variable, suppressed the stimulating effects of the novel environment on the spontaneous, unconditioned, and conditioned feeding alike. After training in the novel environment, the conditioned response was retained for up to 12 days and thus provided a robust behavioral paradigm for the extension of the analysis to the neurophysiological mechanisms of factors affecting appetitive learning in molluscs.

Animals↗

PubMed1992

Brief exposure to an enriched environment improves performance on the Morris water task and increases hippocampal cytosolic protein kinase C activity in young rats.

This study was designed to determine whether brief exposure to an enriched environment around the time of weaning would affect learning and memory processes in young rats. In addition, this study sought to determine if experience in an enriched environment would alter hippocampal protein kinase C (PKC) which is thought to be a possible neural substrate that underlies learning and memory processes. Animals were either reared in an enriched environment or standard laboratory cages starting at 15 days old. After 6 (21 days old) or 12 (27 days old) days subjects were either tested in the Morris water task, or had the hippocampus removed for biochemical analysis of PKC activity. Morris water task results showed that compared to laboratory reared controls, the performance of subjects reared in the enriched environment for 12 days, but not 6 days, was improved. In addition, 12 days of exposure to the enriched environment, but not 6 days, produced more cytosolic hippocampal PKC activity. The particulate fraction appeared not to be affected by rearing in the enriched environment. Brief exposure to an enriched environment around weaning, therefore, both improved Morris water task performance and increased hippocampal PKC activity. These outcomes suggest that performance in the Morris water task and hippocampal PKC may be functionally related.

Animals↗

PubMed1997

Subicular cells generate similar spatial firing patterns in two geometrically and visually distinctive environments: comparison with hippocampal place cells.

Cells in both the hippocampus and the subiculum show location related firing patterns, so that the momentary firing rate of a cell is related to the spatial location of a freely moving rat as it navigates in an environment. Since the subiculum receives a strong anatomical projection from the hippocampus, it seems possible that the subicular cell spatial patterns are simply driven by the spatial signals from hippocampal place cells. Data presented here, however, suggest that the two areas code space in fundamentally different ways. Here, spatial firing patterns of individual hippocampal and subicular cells were studied as rats navigated in two different environments. The two chambers were a cylinder and a square, of equal area. For some rats the two chambers were painted to have similar visual stimulus characteristics, while for others, the two were very different. The subicular cells showed very similar firing patterns in the two chambers, regardless of whether they were visually similar or different. In contrast, as predicted based on the findings of earlier studies, hippocampal place cells showed different patterns in the two (again, regardless of their visual similarity). These results suggest that the subicular cells have the ability to transfer a single, abstract spatial representation from one environment to another. This pattern is stretched to fit within the boundaries of the current environment. Thus, the subicular cells seem to provide a generic representation of the geometric relationships between different locations in an environment. It seems possible that this representation may contribute to some navigational abilities exhibited by animals, such as dead reckoning, and novel route generation in unfamiliar environments. In contrast, it appears that hippocampal place cells provide a spatial representation-which is unique for each environment and which is strongly influenced by the exact details and overall context of the situation.

Animals↗

PubMed2001

Effects of early environment on granule cell morphology in the dentate gyrus of the guinea-pig.

The aim of the present study was to determine whether early environment affects the morphology of the dentate gyrus granule cells in the guinea-pig, a rodent whose brain is at an advanced stage of maturation at birth. Male and female guinea-pigs were assigned at six to seven days of age to either a control (social) or an isolated environment where they remained for 80-90 days. The dendritic tree and somata of the granule cells were quantified in Golgi-Cox-stained brains. The granule cells of isolated males had fewer dendritic branches and a shorter dendritic length than those of control males in the inner two-thirds of the dendritic tree, but a larger number of branches and a larger dendritic length in the distal one-fourth. In contrast, the granule cells of isolated females had a larger number of branches and a larger dendritic length than control females in the inner one-half of the dendritic tree and a reduced number of branches and a shorter dendritic length in the distal one-fourth. The granule cell somata were smaller in isolated than in control males. No such difference was observed in females. Sex differences were found in the granule cell morphology. In the control environment, the granule cells of males had more branches and a greater dendritic length in the inner one-half of the dendritic tree than those of females but fewer dendritic branches and a shorter dendritic length in the distal one-fourth. In the isolated environment, the granule cells of males had fewer branches and a shorter dendritic length in the inner two-thirds of the dendritic tree than females, but more dendritic branches and a greater dendritic length in the distal one-fourth. In the control environment male granule cells had a larger soma than those of females. The opposite occurred in the isolated environment. The results of this study indicate that early isolation induces remarkable structural changes in the granule cells of the dentate gyrus in a rodent whose brain is at an advanced stage of maturation at birth. They also indicate that the effects of environment are different at different levels of the dendritic tree and in the two sexes.

Animals↗

PubMed2002

Effects of early environment on field CA3a pyramidal neuron morphology in the guinea-pig.

There is evidence that early environmental conditions have profound effects on the morphology of the dentate granule cells. The aim of the present study was to obtain information about the effects of early environment on neuron morphology in the hippocampal field CA3, a structure closely linked to the dentate gyrus. The dendritic trees and the somata of field CA3a pyramidal neurons were quantified in Golgi-stained brains of guinea-pigs of both sexes raised in either a social or an isolated environment. Two pyramidal neuron types were found in CA3a, characterized by either a long or a short shaft. Environment affected the apical tree of the long-shaft neurons only in males and that of the short-shaft neurons in both sexes. In isolated males the long-shaft neurons had a decrease in the number of dendritic intersections (62-82%), branching points (76%) and length (71%) in the middle third of the apical tree. The short-shaft neurons had a decrease in the number of intersections at two distal levels only in both isolated males (26, 83%) and females (77, 82%). The shaft spine density was affected by environment in the long-shaft neurons of males only, with a density increase (110%) in isolated males. In both sexes the basal tree of only the long-shaft neurons was affected by environment. Isolated males had a decrease in the number of dendritic intersections (65-88%), primary dendrites (80%) and dendritic length (88%) and isolated females had a decrease in the number of intersections (51-89%), branching points (77%) and dendritic length (85%). The soma major axis of only the long-shaft neurons was affected by environment with a reduction in isolated males (90%) but an increase in isolated females (111%). These results demonstrate dendritic atrophy of CA3a pyramidal neurons following early isolation and a different reactivity to environment of the two CA3a pyramidal neuron types, their apical and basal trees and the two sexes. The dendritic atrophy of CA3a neurons caused by isolation is likely to be associated with an impairment in the physiology of the hippocampal formation and in the forms of memory in which the hippocampal formation plays a major role.

Aging↗

PubMed2003

The impact of intrauterine exposure versus postnatal environment in neurodevelopmental toxicity: long-term neurobehavioral studies in children at risk for developmental disorders.

Various investigators have shown that enriched environment may positively affect the early brain development of experimental animals. Environment was also shown to positively affect the development of young children born to mothers of low socio-economic class (low SES). It is unknown, however, to what extent can an enriched environment improve the developmental outcome of children born with slight brain damage. We studied the development of preschool and early school age children born to heroin dependent parents raised at home or adopted in comparison to children suffering only from environmental deprivation (low parental SES) and to controls. They were examined by several professionals, using standard, age appropriate, neurological and psychological tests. Similar evaluations were performed on a group of early school age children born to mothers with pregestational or with gestational diabetes and on a group of children born prematurely, with a birth weight of less than 1500 g using various developmental tests. Young children born to heroin dependent mothers and fathers raised at home and children of low SES had, in comparison to controls, lower intellectual skills and a higher rate of inattention. This persisted at school age, too. Children born to heroin dependent mothers adopted at a young age and hence being raised in a good environment had normal intellectual function but a high rate of inattention and behavioral problems. We also examined the school age children for possible presence of ADHD and found a high rate of ADHD among all children born to heroin dependent parents including those adopted, as well as in the children with low parental SES. Similar findings regarding the strong positive influence of an enriched environment were observed in children born to diabetic mothers, where the intellectual abilities of the children were directly related with parental education. The cognitive abilities of the children born prematurely were also strongly associated with parental education and not with the degree of perinatal complications. In conclusion, in all groups of children at high risk for developmental problems was found that the environment has a strong influence on their intellectual abilities but not on motor skills or attention span. A good environment (high parental SES) may significantly improve the outcome.

Child↗

PubMed2002

How the built environment affects physical activity: views from urban planning.

The link between the built environment and human behavior has long been of interest to the field of urban planning, but direct assessments of the links between the built environment and physical activity as it influences personal health are still rare in the field. Yet the concepts, theories, and methods used by urban planners provide a foundation for an emerging body of research on the relationship between the built environment and physical activity. Recent research efforts in urban planning have focused on the idea that land use and design policies can be used to increase transit use as well as walking and bicycling. The development of appropriate measures for the built environment and for travel behavior is an essential element of this research. The link between the built environment and travel behavior is then made using theoretical frameworks borrowed from economics, and in particular, the concept of travel as a derived demand. The available evidence lends itself to the argument that a combination of urban design, land use patterns, and transportation systems that promotes walking and bicycling will help create active, healthier, and more livable communities. To provide more conclusive evidence, however, researchers must address the following issues: An alternative to the derived-demand framework must be developed for walking, measures of the built environment must be refined, and more-complete data on walking must be developed. In addition, detailed data on the built environment must be spatially matched to detailed data on travel behavior.

Choice Behavior↗

PubMed2000

Estimation of distribution functions using data from different environments.

Suppose that when a unit operates in a certain environment, its lifetime has distribution G, and when the unit operates in another environment, its lifetime has a different distribution, say F. Moreover, suppose the unit is operated for a certain period of time in the first environment and is then transferred to the second environment. Thus we observe a censored lifetime in the first environment and a failure time of a "used" unit in the second environment. We propose an EM algorithm approach for obtaining a self-consistent estimator of F using observations from both environments. The case where failure times are subject to right censoring is considered as well. We also establish the maximum likelihood estimator of F when the unit is repairable. Application and simulation studies are presented to illustrate the methods derived.

Algorithms↗

PubMed2001

Intra- and extra-familial influences on alcohol and drug misuse: a twin study of gene-environment correlation.

AIMS: Genotype-environment correlation refers to the extent to which individuals are exposed to environments as a function of their genetic propensities. These correlations are important in the study of psychopathology because they identify environments that may maintain the expression of underlying genetic liabilities for a disorder. The present study examined the correlation between genetic liabilities for alcohol and drug misuse with perceptions of the social environments of the family of origin and the classroom. DESIGN: Postal survey data were collected from monozygotic and dizygotic twin pairs. SETTING: Twin pairs were recruited from Vancouver, British Columbia, Canada using newspaper advertisements and media stories. PARTICIPANTS: Eighty-five monozygotic and 77 dizygotic twin pairs were recruited from the general population. MEASUREMENTS: Twin pairs completed self-report measures of alcohol and drug misuse contained in the Dimensional Assessment of Personality Pathology, the Family Environment Scale, the Classroom Environment Scale, and the Traumatic Events Questionnaire. FINDINGS: Genetically indexed alcohol and drug misuse scores were regressed on the environmentally indexed FES and CES scales. Genetic liabilities for alcohol and drug misuse were associated with decreased perceived family moral-religious emphases, family cohesion and classroom task orientation and increased perceptions of classroom order and organization (strictness). CONCLUSIONS: Genotype-environment correlations, in particular, moral-religious emphases in the home, appear to be important in the development of substance misuse.

Adolescent↗

PubMed1998

Exposure to a dry environment enhances epidermal permeability barrier function.

Previous studies have suggested that transepidermal water movement may play an important role in epidermal homeostasis and barrier repair. Here we analyzed cutaneous barrier function, epidermal morphology, and lipid content of the stratum corneum in hairless mice maintained in a high relative humidity (RH > 80%) versus low humidity (RH < 10%) environment for 2 wk. Basal transepidermal water loss was reduced by 31% in animals maintained in a dry versus humid environment. Moreover, the number of lamellar bodies in stratum granulosum cells, the extent of lamellar body exocytosis, and the number of layers of stratum corneum increased in animals kept in a dry environment. Furthermore, the dry weight of the stratum corneum and the thickness of the epidermis also increased in a dry environment. In addition, total stratum corneum lipids increased but lipid analysis revealed no significant differences in lipid distribution. Lastly, barrier recovery following either acetone treatment or tape stripping was accelerated after prolonged prior exposure to a dry environment, while conversely, it was delayed by prior exposure to a humid environment. These studies demonstrate that environmental conditions markedly influence epidermal structure and function, and suggest mechanisms by which the environment could induce or exacerbate various cutaneous disorders.

Animals↗

PubMed2004

Students' perceptions of educational environment: a comparison of academic achievers and under-achievers at kasturba medical college, India.

CONTEXT: No country, least of all poorly resourced countries such as India, can afford to lose too many medical students in their undergraduate years. It would be useful to have an instrument to identify those students who are vulnerable to academic failure at this level of training and to identify the features of the educational environment that they perceive differently from students who are succeeding academically in order to design intervention strategies. Gender differences in perceptions of the educational environment might well emerge in particular academic or cultural contexts, with particular curricula. The present study was motivated by this concern and focused on comparisons between academic achievers and under-achievers and male and female students of Kasturba Medical College, India. OBJECTIVES: (1) To compare the perceptions of the educational environment of academic achievers and under-achievers and to identify problem areas that should be remediated. (2) To identify whether there is any gender difference in the perceptions. METHODS: The Dundee Ready Educational Environment Measure (DREEM) was administered to 508 medical students studying in the clinical years at the Kasturba Medical College in India. Item as well as scale scores were compared between academic achievers and under-achievers. FINDINGS: Overall sample of the present study rated educational environment in this institution as average. The overall mean DREEM score was significantly higher for academic achievers. Compared to under-achievers, academic achievers scored significantly higher on perceptions regarding teachers, academic atmosphere and social self-perceptions. In addition to this, the overall rating (total DREEM score) of female students was significantly less compared to males in the academically vulnerable group. CONCLUSIONS: Perceptions of poor performers are significantly different from those of better performers in the same institution. More importance should be given to the perceptions of students to improve the educational environment, as perceptions are associated positively with learning outcome, learning approach and attitude toward studying. Use of the DREEM as a monitoring tool might permit timely interventions to remediate problematic educational environments.

Achievement↗

PubMed2000

A mixed-model approach to mapping quantitative trait loci in barley on the basis of multiple environment data.

In this article, I propose a mixed-model method to detect QTL with significant mean effect across environments and to characterize the stability of effects across multiple environments. I demonstrate the method using the barley dataset by the North American Barley Genome Mapping Project. The analysis raises the need for mixed modeling in two different ways. First, it is reasonable to regard environments as a random sample from a population of target environments. Thus, environmental main effects and QTL-by-environment interaction effects are regarded as random. Second, I expect a genetic correlation among pairs of environments caused by undetected QTL. I show how random QTL-by-environment effects as well as genetic correlations are straightforwardly handled in a mixed-model framework. The main advantage of this method is the ability to assess the stability of QTL effects. Moreover, the method allows valid statistical inferences regarding average QTL effects.

Crosses, Genetic↗

PubMed2006

Assessing and comparing physical environments for nursing home residents: using new tools for greater research specificity.

PURPOSE: We developed and tested theoretically derived procedures to observe physical environments experienced by nursing home residents at three nested levels: their rooms, the nursing unit, and the overall facility. Illustrating with selected descriptive results, in this article we discuss the development of the approach. DESIGN AND METHODS: On the basis of published literature, existing instruments, and expert opinion about environmental elements that might affect quality of life, we developed separate observational checklists for the room and bath environment, unit environment, and facility environment. We trained 40 interviewers without specialized design experience to high interrater reliability with the room-level assessment. We used the three checklists to assess 1,988 resident room and bath environments, 131 nursing units, and 40 facilities in five states. From the data elements, we developed quantitative indices to describe the facilities according to environmentally relevant constructs such as function-enhancing features, life-enriching features, resident environmental controls, and personalization. RESULTS: We reliably gathered data on a large number of environmental items at three environmental levels. Environments varied within and across facilities, and we noted many environmental deficits potentially relevant to resident quality of life. IMPLICATIONS: This research permits resident-specific data collection on physical environments and resident-level research using hierarchical analysis to examine the effects of specific environmental constellations. We describe practice and research implications for this approach.

Aged↗

PubMed2006

Association of twelve immune-related genes with performance of three broiler lines in two different hygiene environments.

Elite populations of farm animals under genetic selection are often maintained in high hygiene conditions, yet the commercial populations may be raised in, and are expected to perform well in, environments of varied hygiene levels. This presents special challenges to genetically improve those traits for which genotype by environment interactions are important. Twelve immune-related genes were studied for associations with general mortality and other performance traits in 3 elite commercial broiler chicken lines raised in high and low hygiene environments. The genes were toll-like receptor 4, MD-2 (accessory' protein of TLR4), interferon-gamma, transforming growth factor-beta3, inducible nitric oxide synthase, macrophage migration inhibitory factor, interleukin-2, caspase-1, inhibitor of apoptosis protein-1, tumor necrosis factor-related apoptosis-inducing ligand, chicken B-cell marker, and bone morphogenetic protein-7. From a total of 56 identified single-nucleotide polymorphisms (SNP) in 12 genes, 14 SNP that had moderate allelic frequencies in at least 2 of the 3 lines were typed in about 100 progeny-tested sires from each of 3 elite commercial broiler chicken lines using restriction fragment length polymorphism techniques and then used in association analysis. The traits measured on the progeny (total progeny = 145,467) were: mortality from hatching to 14 d and from 14 to 40 d of age, BW at 7 and 40 d of age, feed conversion, ultrasound breast depth, percentage of breast, eviscerated carcass weight, twisted legs or evident tibial dyschondroplasia, x-ray-inspection-based subclinical or incipient development of tibial dyschondroplasia, curly or crooked toes or bowed legs, oxygen content of blood, and female's antibody titer to infectious bursal disease virus at 27 wk. Association analyses were conducted with allele and haplotype substitution effect models using progeny mean data adjusted for fixed and mate effects as sire trait records. Ten of the 12 genes had SNP associations with at least 1 trait. Most detected effects were with mortality and growth traits. Most gene-SNP trait associations varied by genetic line or with environment. These results indicate that associations of candidate genes with important broiler traits can be identified in multiple environments, and they offer a potential for the implementation of marker-assisted selection for traits expressed in the environment in which the commercial broiler needs to perform. The effects of these immune-related candidate genes, however, are complex and affected by genetic background and environment.

Animal Husbandry↗

PubMed1991

Hearing aid benefit in everyday environments.

Hearing aid benefit was measured for three matched groups of eleven hearing-impaired subjects, each serving in one typical listening environment. Benefit was quantified in terms of improvement in intelligibility score for the Connected Speech Test. Each subject was individually fitted with three hearing aids, differing in nominal frequency response slope by a total of 8 dB/octave. Research questions centered on the amount of benefit typically realized in everyday environments and the interactions of this benefit with frequency response and/or visual cues. Results revealed: (1) mean benefit in a living-room type setting was about 24% and significantly greater than in a reverberant setting (7%) and a noisy setting (-1%); (2) despite the relatively large mean difference in benefit between the reverberant and noisy environments, the difference was not statistically significant (p greater than 0.05); (3) the addition of visual cues did not change hearing aid benefit in any tested environment; (4) there was no significant overall trend for any of the three different frequency-response slopes to give superior benefit in any environment; (5) 76% of the subjects achieved significantly different benefit (p less than 0.05) in at least one hearing aid condition when data were considered on an individual basis; and (6) articulation indices in the aided conditions did not successfully predict the observed within-subject benefit differences. Benefit was significantly related to speech reception threshold in the living-room environment. However, in the less favorable environments, benefit and hearing loss were not related despite the fact that benefit varied considerably across subjects.

Acoustics↗

PubMed2005

Assessment of the work environment of multidisciplinary hospital staff.

PURPOSE: The purpose of this article is to investigate the performance of scales to assess the work environment of hospital professional staff, other than nurses or physicians. DESIGN/METHODOLOGY/APPROACH: A survey was conducted among professional (non-nursing or medical) staff at a 300-bed urban, university-affiliated Canadian hospital. A total of 24 work environment items were adapted from a scale previously validated among nursing staff. Scales were developed based on a principal components analysis, and were compared among four groups of staff. The relationships between the scales and the following measures were then explored using univariate and multivariate analyses: satisfaction with the work environment, perceived quality of patient care, perceived frequency of patient/family complaints, work-related injuries, and verbal abuse of staff. FINDINGS: The survey response rate was 154/200 (76.6 percent). Four scales were identified (with corresponding Cronbach's alpha), assessing the following aspects of the work environment: supervisory support (0.88), team-work (0.84), professionalism (0.77), and interdisciplinary relations (0.64). In multivariate analyses, there were significant differences between the job groups in all four scales. One or more of the scales was significantly associated with overall satisfaction, perceived quality, and adverse incidents, even after adjustment for other staff characteristics. RESEARCH LIMITATIONS/IMPLICATIONS: Limitations include: the cross-sectional design, subjective measurement of quality of care, small sample sizes in some groups of staff, and the single study site. PRACTICAL IMPLICATIONS: The scales developed in this study may be used by managers to assess hospital staff perceptions of the work environment. ORIGINALITY/VALUE: The four proposed scales appear to measure meaningful aspects of the working environment that are important in determining overall satisfaction with the work environment and are related to quality of care.

Cross-Sectional Studies↗

PubMed2003

The extended genotype: the heritability of personality accounts for the heritability of recalled family environments in twins reared apart.

How are retrospective accounts of family rearing environments linked to adult personality? We addressed this question by measuring both domains in a sample of 180 reared-apart twins. Twins completed extensive measures of rearing environments (the Minnesota-Briggs History Record, the Block Environmental Questionnaire, the Family Environment Scale, and the Physical Facilities Questionnaire) and an omnibus measure of adult personality (the Multidimensional Personality Questionnaire). Retrospective accounts of family environments were partially heritable and all the heritable variance in environmental measures could be accounted for by heritable variance in personality. In addition, differences between twins in their accounts of their rearing environments (nonshared environmental factors) were not significantly linked to differences between twins in their personalities. Hence, family environmental measures appear to be heritable because personality genes influence the way people shape and recall their rearing environments. In addition, differences in reared-apart twins' retrospectively recalled rearing environments appear to have little impact on differences in their personalities in adulthood.

Adult↗

PubMed2003

Divergent environments and population bottlenecks fail to generate premating isolation in Drosophila pseudoobscura.

While the feasibility of bottleneck-induced speciation is in doubt, population bottlenecks may still affect the speciation process by interacting with divergent selection. To explore this possibility, I conducted a laboratory speciation experiment using Drosophila pseudoobscura involving 78 replicate populations assigned in a two-way factorial design to both bottleneck (present vs. absent) and environment (ancestral vs. novel) treatments. Populations independently evolved under these treatments and were then tested for assortative mating and male mating success against their common ancestor. Bottlenecks alone did not generate any premating isolation, despite an experimental design that was conducive to bottleneck-induced speciation. Premating isolation also did not evolve in the novel environment treatment, neither in the presence nor absence of bottlenecks. However, male mating success was significantly reduced in the novel environment treatment, both as a plastic response to this environment and as a result of environment-dependent inbreeding effects in the bottlenecked populations. Reduced mating success of derived males will hamper speciation by enhancing the mating success of immigrant, ancestral males. Novel environments are generally thought to promote ecological speciation by generating divergent natural selection. In the current experiment, however, the novel environment did not cause the evolution of any premating isolation and it reduced the likelihood of speciation through its effects on male mating success.

Animals↗