Early Environmental Enrichment Research Articles

Current Understanding of the Roles of Gut-Brain Axis in the Cognitive Deficits Caused by Perinatal Stress Exposure.

The term 'perinatal environment' refers to the period surrounding birth, which plays a crucial role in brain development. It has been suggested that dynamic communication between the neuro-immune system and gut microbiota is essential in maintaining adequate brain function. This interaction depends on the mother's status during pregnancy and/or the newborn environment. Here, we show experimental and clinical evidence that indicates that the perinatal period is a critical window in which stress-induced immune activation and altered microbiota compositions produce lasting behavioral consequences, although a clear causative relationship has not yet been established. In addition, we discuss potential early treatments for preventing the deleterious effect of perinatal stress exposure. In this sense, early environmental enrichment exposure (including exercise) and melatonin use in the perinatal period could be valuable in improving the negative consequences of early adversities. The evidence presented in this review encourages the realization of studies investigating the beneficial role of melatonin administration and environmental enrichment exposure in mitigating cognitive alteration in offspring under perinatal stress exposure. On the other hand, direct evidence of microbiota restoration as the main mechanism behind the beneficial effects of this treatment has not been fully demonstrated and should be explored in future studies.

Very early environmental enrichment protects against apoptosis and improves functional recovery from hypoxic-ischemic brain injury.

Appropriate rehabilitation of stroke patients at a very early phase results in favorable outcomes. However, the optimal strategy for very early rehabilitation is at present unclear due to the limited knowledge on the effects of very early initiation of rehabilitation based on voluntary exercise (VE). Environmental enrichment (EE) is a therapeutic paradigm for laboratory animals that involves complex combinations of physical, cognitive, and social stimuli, as well as VE. Few studies delineated the effect of EE on apoptosis in very early stroke in an experimental model. Although a minimal benefit of early rehabilitation in stroke models has been claimed in previous studies, these were based on a forced exercise paradigm. The aim of this study is to determine whether very early exposure to EE can effectively regulate Fas/FasL-mediated apoptosis following hypoxic-ischemic (HI) brain injury and improve neurobehavioral function. C57Bl/6 mice were housed for 2 weeks in either cages with EE or standard cages (SC) 3 h or 72 h after HI brain injury. Very early exposure to EE was associated with greater improvement in motor function and cognitive ability, reduced volume of the infarcted area, decreased mitochondria-mediated apoptosis, and decreased oxidative stress. Very early exposure to EE significantly downregulated Fas/FasL-mediated apoptosis, decreased expression of Fas, Fas-associated death domain, cleaved caspase-8/caspase-8, cleaved caspase-3/caspase-3, as well as Bax and Bcl-2, in the cerebral cortex and the hippocampus. Delayed exposure to EE, on the other hand, failed to inhibit the extrinsic pathway of apoptosis. This study demonstrates that very early exposure to EE is a potentially useful therapeutic translation for stroke rehabilitation through effective inhibition of the extrinsic and intrinsic apoptotic pathways.

Preweaning environmental enrichment alters neonatal ultrasonic vocalisations in a rat model for prenatal infections.

Maternal infections are a well-known risk factor for neurodevelopmental defects. Such defects are associated with a range of symptoms, and environmental enrichment (EE) could be a promising approach to rehabilitate these. We used the well-established prenatal poly I:C (polyinosinic-polycytidylic acid) model in rats to examine the effects of preweaning EE on rat pups' ultrasonic vocalisations (USVs) when separated from their mothers. USVs are one of the earliest indicators of a pup's functional level and, thus, well-suited as a marker of neurodevelopmental abnormalities. We used a two-by-two factorial design in which pregnant Sprague-Dawley rats received either saline or the viral mimic poly I:C, and one group of pups was exposed to preweaning enrichment. We measured maternal separation-induced USVs both before postnatal day (PND) 7 and after preweaning enrichment on PND 14. Poly I:C significantly reduced the number of USVs on PND 7. EE interacted with the poly I:C treatment in that poly I:C pups in the enrichment group called more, whereas saline pups in the enriched environment called less on PND 14 than the respective controls. We showed that the effects of maternal poly I:C on the offspring's USVs could be reduced by early EE. If replicated, it could open novel and safe avenues for treating children of mothers who were exposed to infections during pregnancy.

Altered genome-wide hippocampal gene expression profiles following early life lead exposure and their potential for reversal by environmental enrichment

Early life lead (Pb) exposure is detrimental to neurobehavioral development. The quality of the environment can modify negative influences from Pb exposure, impacting the developmental trajectory following Pb exposure. Little is known about the molecular underpinnings in the brain of the interaction between Pb and the quality of the environment. We examined relationships between early life Pb exposure and living in an enriched versus a non-enriched postnatal environment on genome-wide transcription profiles in hippocampus CA1. RNA-seq identified differences in the transcriptome of enriched vs. non-enriched Pb-exposed animals. Most of the gene expression changes associated with Pb exposure were reversed by enrichment. This was also true for changes in upstream regulators, splicing events and long noncoding RNAs. Non-enriched rats also had memory impairments; enriched rats had no deficits. The results demonstrate that an enriched environment has a profound impact on behavior and the Pb-modified CA1 transcriptome. These findings show the potential for interactions between Pb exposure and the environment to result in significant transcriptional changes in the brain and, to the extent that this may occur in Pb-exposed children, could influence neuropsychological/educational outcomes, underscoring the importance for early intervention and environmental enrichment for Pb-exposed children.

Early environmental enrichment for autism spectrum disorder Fmr1 mice models has positive behavioral and molecular effects

Autism spectrum disorder is a complex neurodevelopmental condition with genetic and phenotypic heterogeneity characterized by hallmark impairments in social functioning and repetitive behaviors. Fragile X syndrome (FXS), the leading single-gene form of autism spectrum disorder, is the most common form of inherited intellectual disability. Environmental enrichment has been shown to improve several aspects of brain development and affect histopathological, cognitive, and behavioral outcomes. However, the optimal time window to initiate it and improve cognitive and emotional development is largely unexplored. In the current study, we determined the longitudinal trends of BDNF-TrkB expression and dendritic development in FXS mice. Additionally, FXS mice were housed in an enriched environment when they showed significantly different BDNF-TrkB pathways and the phenotype of dendritic spines on postnatal day 10 (P10) until P60. The environmental enrichment delayed and attenuated some neurological alterations in FXS mice and prevented the development of cognitive and anxiety-related abnormalities and repetitive stereotyped behaviors. The correlation between neurotrophin-related pathways and multiple autistic-like behaviors was confirmed. Transcriptional profiling indicates that environmental enrichment increases the differences in the prefrontal cortex and hippocampal gene expression associated with the neural system and behavioral development. Our results provide novel evidence on the usefulness of early intervention for neurodevelopmental disorders as a strategy to facilitate positive effects on neural development and behaviors by acting on the BDNF/TrkB-PLCγ1-CaMKII pathway.

Regional Differences in BDNF Expression and Behavior as a Function of Sex and Enrichment Type: Oxytocin Matters.

The early environment is critical to brain development, but the relative contribution of physical versus social stimulation is unclear. Here, we investigated in male and female rats the response to early physical and social environmental enrichment in relation to oxytocin (OT) and brain-derived neurotrophic factor (BDNF) expression. The findings show that males and females respond differently to prolonged sensorimotor stimulation from postnatal days 21-110 in terms of functional, structural, and molecular changes in the hippocampus versus medial prefrontal cortex (mPFC). Physical enrichment promoted motor and cognitive functions and hippocampal BDNF mRNA and protein expression in both sexes. Combined physical and social enrichment, however, promoted functional and structural gain in females. These changes were accompanied by elevated plasma oxytocin (OT) levels and BDNF mRNA expression in the mPFC, while the hippocampus was not affected. Administration of an OT antagonist in females blocked the beneficial effects of enrichment and led to reduced cortical BDNF signaling. These findings suggest that an OT-based mechanism selectively stimulates a region-specific BDNF response which is dependent on the type of experience.

Effect of prenatal different auditory environment on learning ability and fearfulness in chicks.

ObjectiveEarly environmental enrichment in life can improve cognition in animals. The effect of prenatal auditory stimulation on learning ability and fear level in chick embryos remained unexplored. Therefore, this study investigated the effect of prenatal auditory stimulation on the learning ability and fear level of chicks.MethodsA total of 450 fertilized eggs were randomly divided into 5 groups, including control group (C), low-sound intensity music group (LM), low-sound intensity noise group (LN), high-sound intensity noise group (HN) and high-sound intensity music group (HM). From the 10th day of embryonic development until hatching, group LM and group LN received 65 to 75 dB of music and noise stimulation. Group HN and group HM received 85 to 95 dB of noise and music stimulation, and group C received no additional sound. At the end of incubation, the one-trial passive avoidance learning (PAL) task and tonic immobility (TI) tests were carried out, and the serum corticosterone (CORT) and serotonin (5-HT) concentrations were determined.ResultsThe results showed that compared with the group C, 65 to 75 dB of music and noise stimulation did not affect the PAL avoidance rate (p>0.05), duration of TI (p>0.05) and the concentration of CORT (p>0.05) and 5-HT (p>0.05) in chicks. However, 85 to 95 dB of music and noise stimulation could reduce duration of TI (p<0.05) and the concentration of CORT (p<0.05), but no significant effect was observed on the concentration of 5-HT (p>0.05) and PAL avoidance rate (p>0.05).ConclusionTherefore, the prenatal auditory stimulation of 85 to 95 dB can effectively reduce the fear level of chicks while it does not affect the learning ability.

Early environmental enrichment prevents cognitive impairments and developing addictive behaviours in a mouse model of prenatal psychological and physical stress.

Environmental enrichment (EE) has shown remarkable effects in improving cognition and addictive behaviour. We tested whether EE could help recover from prenatal stress exposure. Mature Swiss Webster male and virgin female mice were placed together until vaginal plugs were detectable. Next, pregnant rodents were randomized into the control, physically and psychologically stressed groups. The application of stress was initiated on the 10th day of pregnancy and persisted for a week to induce stress in the mice. Open field and elevated plus-maze (EPM) tests were utilized as explorative and anxiety assays, respectively. A passive avoidance shuttle-box test was carried out to check anxiety-modulated behaviour. Morris water maze (MWM) test was undertaken to evaluate spatial learning and memory. Conditioned place preference (CPP) test was selected for evaluation of tendency to morphine consumption. Our results showed that prenatal stress elevated anxiety-like behaviour in the offspring which EE could significantly alleviate after weaning. We also found a higher preference for morphine use in the physical stress and psychological stress offspring group. However, no difference was observed among the genders. Application of EE for the stress group improved several parameters of the cognitive behaviour significantly. Although prenatal stress can lead to detrimental behavioural and cognitive outcomes, it can in part be relieved by early exposure to EE. However, some outcomes linked to prenatal stress exposure may not be diminished by EE therapy. In light of such irreversible effects, large-scale preventive actions promoting avoidance from stress during pregnancy should be advised.

Early environmental enrichment and impoverishment differentially affect addiction-related behavioral traits, cocaine-taking, and dopamine D2/3 receptor signaling in a rat model of vulnerability to drug abuse

RationaleRisk factors for drug addiction include genetics, environment, and behavioral traits such as impulsivity and novelty preference (NP), which have been related to deficits in striatal dopamine (DA) D2/3-receptors (D2/3R) and heightened amphetamine (AMPH)-induced DA release. However, the influence of the early rearing environment on these behavioral and neurochemical variables is not clear.ObjectivesWe investigated the influence of early rearing environment on striatal D2/3R availabilities and AMPH-induced DA release in relation to impulsivity, NP, and propensity to drug self-administration (SA) in “addiction-prone” Roman high- (RHA) and “addiction-resistant” Roman low-avoidance (RLA) rats.MethodsAnimals were reared post-weaning in either environmental enrichment (EE) or impoverishment (EI) and were assessed at adulthood for impulsivity, NP, and propensity to cocaine SA. EE and EI rats were also scanned using single-photon emission computed tomography to concurrently measure in vivo striatal D2/3R availability and AMPH-induced DA release.ResultsEE vs. EI was associated with heightened impulsivity and a lack of NP in both rat lines. Higher dorsal striatal D2/3R densities were found in RHA EE and higher AMPH-induced DA release in RLA EE. Both impulsivity and NP were negatively correlated to dorsal striatal D2/3R availabilities and positively correlated with AMPH-induced DA release in EI but not in EE. EE vs. EI was related to a faster rate of cocaine intake and elevated active timeout responses in RHAs.ConclusionOur results suggest non-monotonic, environment-dependent, relationships between impulsivity, NP, and D2/3R-mediated signaling, and suggest that EI vs. EE may decrease the reinforcing effects of psychostimulants in predisposed individuals.

Early environmental enrichment rescues memory impairments provoked by mild neonatal hypoxia-ischemia in adolescent mice

Hypoxia-ischemia (HI) is a consequence of a lack of oxygen and glucose support to the developing brain, which causes several neurodevelopmental impairments. Environmental enrichment (EE) is considered an option to recover the alterations observed in rodents exposed to HI. The aim of this study was to investigate the impact of early EE on memory, hippocampal volume and brain-derived neurotrophic factor (Bbnf) and glucocorticoid receptor (Nr3c1) gene expression of mice exposed to HI. At P10, pups underwent right carotid artery permanent occlusion followed by 35 min of 8% O2 hypoxic environment. Starting at P11, animals were reared in EE or in standard cage (HI-SC or SHAM-SC) conditions until behavioral testing (P45). SHAM pups did not undergo carotid ligation and hypoxic exposure. Memory performance was assessed in the Y-maze, Novel object recognition, and Barnes maze. Animals were then sacrificed for analysis of hippocampal volume and Bdnf and Nr3c1 gene expression. We observed that animals exposed to HI performed worse in all three tests compared to SHAM animals. Furthermore, HI animals exposed to EE did not differ from SHAM animals in all tasks. Moreover, HI decreased hippocampal volume, while animals reared in early EE were not different compared to SHAM animals. Animals exposed to HI also showed upregulated hippocampal Bdnf expression compared to SHAM animals. We conclude that early EE from P11 to P45 proved to be effective in recovering memory impairments and hippocampal volume loss elicited by HI. Nevertheless, Bdnf expression was not associated with the improvements in memory performance observed in animals exposed to EE after a hypoxic-ischemic event.

Early socialization and environmental enrichment of lactating piglets affects the caecal microbiota and metabolomic response after weaning

The aim of this study was to determine the possible impact of early socialization and an enriched neonatal environment to improve adaptation of piglets to weaning. We hypothesized that changes in the microbiota colonization process and in their metabolic response and intestinal functionality could help the animals face weaning stress. A total of 48 sows and their litters were allotted into a control (CTR) or an enriched treatment (ENR), in which piglets from two adjacent pens were combined and enriched with toys. The pattern of caecal microbial colonization, the jejunal gene expression, the serum metabolome and the intestinal physiology of the piglets were assessed before (-2 d) and after weaning (+ 3d). A differential ordination of caecal microbiota was observed after weaning. Serum metabolome suggested a reduced energetic metabolism in ENR animals, as evidenced by shifts in triglycerides and fatty acids, VLDL/LDL and creatine regions. The TLR2 gene showed to be downregulated in the jejunum of ENR pigs after weaning. The integration of gene expression, metabolome and microbiota datasets confirmed that differences between barren and enriched neonatal environments were evident only after weaning. Our results suggest that improvements in adaptation to weaning could be mediated by a better response to the post-weaning stress.

Short communication: Preweaning socialization and environmental enrichment affect short-term performance after regrouping in commercially reared pigs

On-farm practices like premature weaning and frequent regrouping induce stress to pigs. Early socialization or environmental enrichment in piglets reduce weaning stress, as suggested in previous studies. Little research with both effects and in commercial settings was found. The aim was to investigate the effects of preweaning socialization and environmental enrichment on life-long performance in 661 Danbred pigs. Two treatments were distinguished during the suckling period: control (CON, 24 litters) and enriched (ENR, 24 litters). Control piglets were raised in barren farrowing pens; ENR piglets were provided with six enrichment objects from birth, and two neighboring litters were socialized from Day (D) 14. Pigs were regrouped on D25 (weaning) and D71 (fattening), while keeping the same treatment. Individual body weight was recorded on D1, 14, 23, 27, 31, 38, 69, 79, and after slaughter (carcass weight, CW). Pigs were slaughtered in six batches. Estimated slaughter weight (ESW) was calculated by CW × 1.25. Body weight, CW, and average daily gain (ADG) were analyzed by linear mixed models. Slaughter age was analyzed by Wilcox Rank-Sum test. Body weight and ESW were adjusted to non-linear models to obtain the predicted growth curves of CON and ENR, from birth to the targeted market weight (TMW, 105 kg). Average daily gain during the suckling, nursery, and fattening periods, and from birth to slaughter, did not differ between treatments. However, ADG of ENR when moving pigs from farrowing to nursery (4-day period) and from nursery to fattening (10-day period), revealed a better performance than CON (+20.6 g/day, P = 0.02; +53 g/day, P = 0.03, respectively). Enriched pigs tended to be slaughtered 2.8 days earlier than CON (P = 0.08). On the other hand, the predicted growth curves showed a non-significant 2-day window of reaching TMW between treatments (P = 0.23). Results suggested that enriching the neonatal environment improved the short-term performance after regrouping, and may benefit the life-long performance by reducing time to reach TMW.

Pre- and early postnatal enriched environmental experiences prevent neonatal hypoxia-ischemia late neurodegeneration via metabolic and neuroplastic mechanisms.

Prenatal and early postnatal periods are important for brain development and neural function. Neonatal insults such as hypoxia-ischemia (HI) causes prolonged neural and metabolic dysregulation, affecting central nervous system maturation. There is evidence that brain hypometabolism could increase the risk of adult-onset neurodegenerative diseases. However, the impact of non-pharmacologic strategies to attenuate HI-induced brain glucose dysfunction is still underexplored. This study investigated the long-term effects of early environmental enrichment in metabolic, cell, and functional responses after neonatal HI. Thereby, male Wistar rats were divided according to surgical procedure, sham, and HI (performed at postnatal day 3), and the allocation to standard (SC) or enriched condition (EC) during gestation and lactation periods. In-vivo cerebral metabolism was assessed by means of [18 F]-FDG micro-positron emission tomography, and cognitive, biochemical, and histological analyses were performed in adulthood. Our findings reveal that HI causes a reduction in glucose metabolism and glucose transporter levels as well as hyposynchronicity in metabolic brain networks. However, EC during prenatal or early postnatal period attenuated these metabolic disturbances. A positive correlation was observed between [18 F]-FDG values and volume ratios in adulthood, indicating that preserved tissue by EC is metabolically active. EC promotes better cognitive scores, as well as down-regulation of amyloid precursor protein in the parietal cortex and hippocampus of HI animals. Furthermore, growth-associated protein 43 was up-regulated in the cortex of EC animals. Altogether, results presented support that EC during gestation and lactation period can reduce HI-induced impairments that may contribute to functional decline and progressive late neurodegeneration.

Effects of Early and Current Environmental Enrichment on Behavior and Growth in Pigs.

Enriched environments are known to beneficially affect the behavior of pigs, as compared with barren pens. The influence of enrichment may, however, depend on pigs' early life housing experiences. The aim of this study was to investigate the long-term effects of early and later life environmental enrichment on behavior and growth in pigs with different coping styles. Pigs were housed in either barren pens or in larger pens enriched with rooting substrates from birth, and half of them experienced a housing switch, i.e., a loss or gain of enrichment, at 7 weeks of age, creating four treatment groups. Home pen behavior and body weight were recorded until 19 weeks of age. Pigs were classified as reactive or proactive based on a backtest at 2 weeks of age. Enrichment increased time spent exploring, chewing, and play and decreased oral manipulation of penmates and pen-directed exploring and chewing. Behavior of pigs that switched from barren to enriched pens or vice versa reflected not only their actual environment, but also their early life housing. As early and later life enrichment affected most behaviors in opposite directions, effects of enrichment, or lack thereof, after the switch were more pronounced in pigs that had experienced a different early life condition. For instance, pigs experiencing an upgrade from barren to enriched pens seemed to “catch-up” by showing more exploration and play. Conversely, pigs exposed to a downgrade displayed more oral manipulation of penmates than ones kept barren throughout, which particularly held for pigs with a reactive coping style. Effects of early life and current housing on several other behaviors depended on coping style too. Pigs housed in enriched conditions appeared better able to cope with weaning than barren housed pigs, as they gained more weight and had higher feed intake post-weaning. Barren housed pigs had a lower body weight than enriched pigs just before the switch, after which growth was mainly determined by actual housing, with enriched kept pigs having a higher feed intake and body weight. Thus, not only current housing conditions, but also a (mis)match with the early life environment may affect behavior and growth of pigs.

Environmental enrichment ameliorates perinatal brain injury and promotes functional white matter recovery

Hypoxic damage to the developing brain due to preterm birth causes many anatomical changes, including damage to the periventricular white matter. This results in the loss of glial cells, significant disruptions in myelination, and thereby cognitive and behavioral disabilities seen throughout life. Encouragingly, these neurological morbidities can be improved by environmental factors; however, the underlying cellular mechanisms remain unknown. We found that early and continuous environmental enrichment selectively enhances endogenous repair of the developing white matter by promoting oligodendroglial maturation, myelination, and functional recovery after perinatal brain injury. These effects require increased exposure to socialization, physical activity, and cognitive enhancement of surroundings—a complete enriched environment. Using RNA-sequencing, we identified oligodendroglial-specific responses to hypoxic brain injury, and uncovered molecular mechanisms involved in enrichment-induced recovery. Together, these results indicate that myelin plasticity induced by modulation of the neonatal environment can be targeted as a therapeutic strategy for preterm birth.

Early and later life environmental enrichment affect specific antibody responses and blood leukocyte subpopulations in pigs

This study addressed the impact of early and later life environmental enrichment, and their combination, on specific antibody responses and peripheral blood leukocyte subpopulations in pigs. Pigs were kept in either barren (B1) or enriched (E1) housing from birth, and half of the pigs switched to barren or enriched housing on day 47, resulting in four treatment combinations: B1B2, B1E2, E1B2, E1E2). Pigs were immunized with keyhole limpet hemocyanin-conjugated trinitrophenyl (KLH-TNP) on day 74 and 109 to induce primary and secondary antibody responses. Blood samples were taken weekly until day 130, and IgM and IgG antibody responses were measured. Leukocyte subpopulations were measured on day 74 and 130. Time course of the antibody responses was not affected by housing. Early life enrichment increased the IgG response to KLH, particularly the primary one. At day 74 the relative frequency of lymphocytes, DC and SLA-II expression on monocytes were higher in E1 pigs, whereas the percentage of granulocytes tended to be lower in E1 pigs at day 74. Early life enrichment increased the SLA-II expression on monocytes, the granulocyte to lymphocyte ratio, and tended to increase the percentage of granulocytes, but tended to decrease the percentage of monocytes at day 130. Later life enrichment reduced percentages of CD4+CD8α+ T cells before and after immunization and the SLA-II expression on monocytes at day 74, the percentage of granulocytes and the granulocyte to lymphocyte ratio at day 130. Notably, early and later life housing interacted in their effects on several immune parameters. KLH-IgM responses (both primary and secondary) were affected by the interaction between early and later life housing. IgM titers were higher for B1B2 than for E1E2, with the switched animals (B1E2 and E1B2) moving towards the titers of the animals kept in their later life environment from birth onwards. At day 130 the percentage of gamma delta T cells, CD8α+ cytotoxic T cells and DC were not different between pigs kept in B1B2 and E1E2, but there was a clear impact of the switch in housing conditions, particularly for the pigs that changed from barren to enriched housing. We also found effects of coping style (personality) and sex on some immune parameters. In conclusion, both early life and later life enrichment, and, notably a switch in housing conditions influenced specific antibodies and leukocyte subpopulations in pigs. The current study implies that the early life history of animals and the (mis)match with their current environment could thus be of major importance for their immune system. Further research is needed to investigate potential consequences for the pigs’ health.

Behavioral and Neurodevelopmental Effects of Early Interventions in Adult Wistar Rats.

Interventions performed in the early period of life are associated with cognitive and behavioral changes in adulthood. The effects of interventions such as exposure to an early stressful life event or environmental enrichment on cognitive and behavioral development are studied. The aim of this study is to develop a new intervention method, to investigate the effects of early interventions on social interaction, memory anxiety levels and NR2B levels in prefrontal and hippocampus in adulthood. The hypothesis of the study is that exposure to the ambivalent mother will affect the behavioral performance of rats at least as much as one hour apart from the mother in the adult period and cause changes in the prefrontal cortex and hippocampus in the NR2B levels. In the study, the Wistar rats were divided into four groups as control group (12), group that remained 15 minutes apart from mother (Mild Stress) (12), group that remained 60 minutes apart from mother (Severe Stress) (14) and ambivalent mother group (13). In adulthood, the social interaction test, elevated plus maze and new object recognition test performances of rats were evaluated. ELISA method was used to evaluate the effect of interventions on the prefrontal cortex and hippocampus NMDA R2B levels. The important findings of the study were that in the new object recognition test, separation from the mother did not affect the recognition memory regardless of gender, while the short-term recognition memory of the females of the ambivalent mothers' group was better than the females in the other groups and the long-term memory performance of the mild stress groups men was better than the man in the other groups. In addition, in the social interaction test, the males of the ambivalent group and the mild stress group showed more aggressive behavior. It was determined that the prefrontal cortex NR2B level was higher in the mild stress and ambivalent mother group compared to the severe stress group, and NR2B level was increased in all intervention groups compared to the control group. In contrast to the hypothesis, the results of this study support that the ambivalent mother's group rats are not more adversely affected than the severe group rats and that the model created may be an environmental enrichment model rather than an early stressful life event exposure.

Effects of early and later life environmental enrichment and personality on attention bias in pigs (Sus scrofa domesticus)

We investigated effects of early and later life housing on attention bias, as an indicator of affective state, in pigs differing in coping style [reactive (LR) vs. proactive (HR)]. Pigs (n = 128) in barren or enriched housing from birth (B1 vs. E1) that experienced either a switch in housing at 7 weeks of age or not (creating B1B2, B1E2, E1E2, and E1B2 treatments), were studied in a 180-s attention bias test at 11 weeks. Pigs exposed to a 10-s-auditory-and-sudden-motion threat in the test arena paid more attention to the location of the threat, were more vigilant, showed less eating, more walking and were more likely to utter high-pitched vocalisations than non-threat pigs. During threat presence, HR pigs from post-switch enriched housing (E2-HR, i.e., B1E2 + E1E2) showed more vigilance but less exploration than others. After threat removal, no effects were found on time spent paying attention to the threat, vigilance, and eating, but E2-HR pigs paid attention to the threat more frequently, were more likely to utter high-pitched vocalisations and walked more compared to (part of) other groups, suggesting the most negative affective state in these animals. E2 pigs grunted more than B2 pigs. Thus, current housing, but not early life housing, affected behaviour in a personality-dependent manner in this attention bias test. Housing effects were opposite to expectation, possibly due to the short-term effect of the relative contrast between the home pens of the pigs and the test room. This potentially overruled putative long-term effects of environmental conditions on attention bias.

Environmental Enrichment and Brain Neuroplasticity in the Kainate Rat Model of Temporal Lobe Epilepsy.

Background and PurposeEnvironmental enrichment (EE) improves brain function and ameliorates cognitive impairments; however, whether EE can reverse the learning and memory deficits seen following seizures remains unknown.MethodsWe tested the hypothesis that EE augments neurogenesis and attenuates the learning and memory deficits in rats subjected to kainate-induced seizures in hippocampus, amygdala and motor cortex. EE consisted of daily exposures immediately after KA lesioning (early EE) and after a 60-day period (late EE). Morphometric counting of neuron numbers (NN), dendritic branch-points and intersections (DDBPI) were performed. Spatial learning in a T-maze test was described as percent correct responses and memory in a passive-avoidance test was calculated as time spent in the small compartment where they were previously exposed to an aversive stimulus.ResultsEE increased NN and DDBPI in the normal control and in the KA-lesioned rats in all brain areas studied, after both early and late exposure to EE. Late EE resulted in significantly fewer surviving neurons than early EE in all brain areas (p < 0.0001). EE increased the percent correct responses and decreased time spent in the small compartment, after both early and late EE. The timing of EE (early vs. late) had no effect on the behavioral measurements.ConclusionsThese findings demonstrate that, after temporal lobe and motor cortex epileptic seizures in rats, EE improves neural plasticity in areas of the brain involved with emotional regulation and motor coordination, even if the EE treatment is delayed for 60 days. Future studies should determine whether EE is a useful therapeutic strategy for patients affected by seizures.

Neuroprocessing Mechanisms of Music during Fetal and Neonatal Development: A Role in Neuroplasticity and Neurodevelopment.

The primary aim of this viewpoint article is to examine recent literature on fetal and neonatal processing of music. In particular, we examine the behavioral, neurophysiological, and neuroimaging literature describing fetal and neonatal music perception and processing to the first days of term equivalent life. Secondly, in light of the recent systematic reviews published on this topic, we discuss the impact of music interventions on the potential neuroplasticity pathways through which the early exposure to music, live or recorded, may impact the fetal, preterm, and full-term infant brain. We conclude with recommendations for music stimuli selection and its role within the framework of early socioemotional development and environmental enrichment.