Long-term continuous, but not daily, environmental enrichment reduces spatial memory decline in aged male mice

Although environmental enrichment improves spatial memory and alters synaptic plasticity in aged rodents, it is unclear whether all types of enrichment treatments yield similar benefits. The present study examined the effects in aged male mice of three types of enrichment on spatial memory in Morris water maze and radial arm maze tasks, and on levels of the presynaptic protein synaptophysin in several brain regions. Non-enriched young and aged males were compared with males exposed to one of the following treatments for 10 weeks: 5 min of daily handling, 3 h of daily basic enrichment, or 24 h of continuous complex enrichment. Young controls outperformed aged controls in both tasks. Neither daily handling nor daily enrichment affected spatial memory or synaptophysin levels. In contrast, continuous enrichment significantly reduced age-related spatial memory decline in both tasks, such that this group was statistically indistinguishable from young controls in most measures of performance. Continuously enriched mice were also significantly better than other aged mice in several spatial memory measures. Despite these improvements, synaptophysin levels in the continuous enrichment group were significantly lower than those of young and aged controls in the frontoparietal cortex, hippocampus, and striatum, suggesting a negative relationship between synaptophysin levels and spatial memory in aged males. These data demonstrate that different types of enrichment in aged male mice have disparate effects on spatial memory, and that the relationship between enrichment-induced changes in synaptophysin levels and spatial memory in aged males differs from that we have previously reported in aged female mice.     

Free-operant comparisons of wild and domestic Norway rats.

Wild and domestic rats (Rattus norvegicus) were compared on nondifferential appetitive variable interval responding, discrimination, and discrimination reversal procedures. The effects of strain, sex, deprivation, preexperimental handling, and sessions on response rate were examined. Performances during the 60 days of variable interval training showed prolonged increases over that period for all strain-sex groupings, with domestic subjects responding at higher rates than wild. Males also tended to respond at higher rates than females. During the discrimination procedure wild subjects showed more resistance to extinction than did the domestic subjects, although these differences generally diminished after the 30 days of training. During the discrimination reversal procedure domestic subjects reversed their responding pattern more readily than did the wild subjects, and domestic females reached criterion significantly sooner than domestic males. The effects of deprivation and handling were not significant during the experimental procedures.     

Short-term effects of postnatal manipulation on central beta-adrenoceptor transmission

Neonatal handling is known to induce long-lasting changes in behavioral and neuroendocrine responses to stress. Since the central noradrenergic system participates in the adaptive responses to stressful conditions we have analyzed the effects of postnatal handling on beta-adrenoceptor binding sites and isoprenaline- and forskolin-stimulated cyclic AMP accumulation in cerebral cortex, hippocampus and cerebellum of rats at 1 and 3 months of age. Handled animals showed reduced emotional reactivity and lower ACTH and corticosterone secretion after stress. Binding studies using [(3) H]CGP12-177 revealed increased beta-adrenoceptor binding sites in handled rats in cerebellum and cerebral cortex with no changes in hippocampus, and decreased affinity in all cerebral regions. Handling reduced basal levels of cyclic AMP in hippocampus and cerebellum but not in cerebral cortex. The concentration-response curves of cyclic AMP to isoprenaline were displaced to the right in cerebellum of handled rats without differences in Emax; however, Emax was significantly reduced in cerebral cortex and hippocampus. Direct stimulation of the catalytic subunit of adenylyl cyclase by forskolin reduced the efficiency in hippocampus and cerebellum, but not in cerebral cortex of handled animals. It is concluded that neonatal handling reduces the binding properties of beta-adrenoceptor and its primary biochemical responses in the young rat brain, which may account for the reduced responsiveness to stress attained in the handled rats, and may explain the persistence of the effect. The present study emphasizes the role of the central noradrenergic system in modulating the behavioral and neurendocrine responses to neonatal handling.     

AN ANALOGUE EVALUATION OF ENVIRONMENTAL ENRICHMENT: THE ROLE OF STIMULUS PREFERENCE

To evaluate the effects of environmental enrichment on stereotypic self-injurious behavior (SIB), we conducted an assessment of preference for manipulating alternative stimuli rather than engaging in SIB. First, for each of 3 participants, a functional analysis of SIB was conducted in Phase 1. Participants were selected for Phase 2 if the functional analysis showed that SIB persisted in the absence of social consequences. In Phase 2, a preference assessment was conducted in which participants were observed manipulating preferred stimuli in a free-operant format. A measure was taken of time spent manipulating each stimulus and time spent engaging in SIB. In Phase 3, environmental enrichment was evaluated using stimuli that were preferred over the target response, and alternative treatments were evaluated in the event of environmental enrichment failure. Results suggested that the free-operant preference assessment (a) predicted the efficacy or inefficacy of an environmental enrichment procedure and (b) suggested possible treatment alternatives when environmental enrichment was ineffective. Collectively, the results may provide a basis for interpreting the idiosyncratic effects of environmental enrichment and a rationale for treatment selection when behavioral function is unknown.     

Enhanced spatial ability in aged dogs following dietary and behavioural enrichment

We examined the benefits of a broad spectrum antioxidant diet and enrichment comprised of physical exercise, environmental stimulants and cognitive testing, on spatial memory performance in beagle dogs. Both aged (N=48) and young (N=16) beagle dogs (Canus familiaris) were tested yearly on a three-component delayed non-match to position spatial task for three consecutive years. The results showed that young enriched animals acquired the task in fewer sessions, made fewer errors, responded slower and made fewer positional responses, compared to aged enriched animals. An analysis restricted to aged animals revealed that antioxidant administration and enrichment resulted in fewer errors, slower responses and decreased positional responses, particularly in Year 3. Finally, cohort differences emerged, which exemplify the significance of early environmental intervention. Aged dogs that were housed with other animals and exposed to an outdoor environment in early development displayed greater benefits from both interventions. These findings indicate that long-term dietary intervention and enrichment can buffer age-associated cognitive decline.     

Effect of color in rearing and testing environment on the behavior of young domestic chicks.

Young domestic chicks were reared individually in compartments of four different colors and then tested either in a color-preference test with stationary objects (N equals 128) or with a moving stimulus (N equals 128). For each type of test we used four background colors in the test arena. The dependent variables included color preferences, following behavior and emotional responses of the young chicks. The results showed no significant effects of the color of the arena-background in either test situation. The color of the rearing compartment was a significant factor affecting color preferences in the test with stationary objects. In both test situations the colors red, and then green, were the most potent in affecting the color preferences and emotional responses exhibited by the chicks.     

Chronic stress and environmental enrichment as opposite factors affecting the immune response in Japanese quail (Coturnix coturnix japonica)

Procedures in the commercial production of animals involve stressful situations which lessen the animal's welfare. This study on Japanese quail evaluated whether an environmental enrichment manipulation can affect avian immune responses and if combined with a chronic stressor exposure can help to counteract the negative effects of stress on the immune system. Potential gender effects were also considered. After hatch, half of the birds were housed in non-enriched boxes and half were housed in environmentally enriched boxes. From day 33 to 42 of age, all birds within half of the non-enriched and enriched boxes remained undisturbed while the other half were daily exposed to a 15 min restraint stressor (chronic stressor). The inflammatory response (lymphoproliferation after phytohemagglutinin-p), percentage of lymphocytes, heterophil/lymphocyte (H/L) ratio and primary antibody response against sheep red blood cells were assessed. The chronic stressor application and the enrichment procedure, respectively, either increased or reduced the four immunological parameters evaluated and always in opposite directions. Males consistently showed lower antibody titres than females and presented the highest H/L ratio in response to the stressor when reared in the non-enriched environment. The findings indicate that submitting these animals to an enriched environment can be effectively used to improve their immune response and to reduce the detrimental effects of a stressor exposure.     

Preoperative enrichment and behavioral recovery in rats with septal lesions

To assess the behavioral effects of preoperative differential housing male rats were placed in either enriched or isolated environments at weaning prior to receiving either sham operations or septal lesions when 57 days of age. Rats with septal lesions showed reduced habituation of ambulation and initially made fewer rears in an empty open field but made more object-contacts coupled with a lack of habituation in the object-filled field. Septal rats also showed severe impairments when tested in a 12-arm radial maze with 7 arms baited and 5 arms unbaited. Preoperative enrichment did not significantly affect these lesion-induced changes. Nevertheless, enrichment significantly lowered ambulation (but did not affect habituation) in the open field and increased the number of manipulatory relative to nonmanipulatory contacts. However, preoperatively enriched septal rats showed a deficit in spontaneous alternation (45%) in contrast to the high levels (83%) shown by intact enriched rats, whereas both intact and septal isolated rats showed similar levels of spontaneous alternation (68%). These results conflict with earlier reports that preoperative enrichment "protects" rats against the deficits produced by septal lesions.     

An Environmental Enrichment Programme to Promote Adaptive Responding in Two Children with Multiple Disabilities

Abstract

An environmental enrichment programme was used for two passive children who had visual and hearing impairments and profound intellectual disabilities. The enrichment items, selected through stimulus preference assessments, were accessible contingent on simple adaptive responses. Data showed that both children increased their adaptive responding (thus reducing their passivity) during the programme. Implications of the findings are discussed.     

Environmental variables and releasing-valence transfer in stimulus-directed pecking of chicks

Releasing valence transfer occurs when the power or valence to release responses is transferred from a primary releasing stimulus to a second, initially neutral, stimulus. In the exemplar, pecking responses by neonatal chicks are released and directed by a pointed object operated to make pecking movements. Stimuli attached to or pecked by the arrow thereby acquire enhanced releasing valence. Chicks peck at matching stimuli in preference to comparable but unenhanced stimuli. Research reported here shows that primary and transferred releasing valences are differentially affected by environmental variables. Specific findings were Pecking by chicks occurs only within a narrow range of ambient temperature. Outside of this range, pecking is low in frequency and insensitive to valence-enhanced release. Pecking by chicks appears to be finely tuned to arrow peck rates between 120 and 180 pecks per minute. Within this range, frequency of pecks by chicks is low whereas the percentage of pecks to the valence-enhanced stimulus is maximal. The maternal food call was a weak releaser of pecking by chicks with no valence-enhancing properties.     

Autoshaping as a function of prior food presentations

Young chickens were given 1, 10, 100, or 1000 presentations of grain in a hopper. Subsequently, the key was illuminated before each presentation of grain to study autoshaping of the key-peck response. The number of keylight-grain pairings before a bird first pecked the lighted key was found to be a U-shaped function of the number of prior food-only presentations, with pecks occurring significantly sooner after 100 food-only trials than after any of the other values. Two of five chicks at the 100-trial value pecked on the first illumination of the key. Experiment II showed further that when a series of food-only trials (no keylight) preceded keylight-only trials (no food) 30% of the chicks pecked the illuminated key. Experiment III extended the generality of first-trial pecking to pigeons. After preliminary training with food-only, two of five pigeons pecked on the first illumination of a key. The results suggest a close relationship between autoshaping and pseudo-conditioning.     

Immobility reactions: A modified classification

This theoretical paper sets the stage for subsequent experimental reports on mobility and immobility in the Arkansas Line of Nervous Pointer dogs as contrasted with kennel mates of the normal line. Exactly opposite to the normal animals, the nervous dogs show marked inhibition of heart rate and musculoskeletal responses to man, including reduced ambulation and durable immobility following inversion and brief manual restraint in an open sling. The sling immobility of the nervous dogs (which may not differ basically from their freezing in upright position) might be designated as “tonic immobility” (TI). We hypothesize that such immobility, common in laboratory and natural conditions in many species, should be divided into two classes: hypotonic (cataleptic) and hypertonic (catatonic). We provide examples of such behaviors, particularly in man and dog, and cursorily review TI studies of other species. Neurophysiologic and neurochemical studies which bear on possible immobility mechanisms are briefly noted. We suggest that inconsistencies in reported concommitants of TI might result from failure to discriminate between types of behavioral responses.     

Mother knows best: functionally referential alarm calling in white-tailed ptarmigan

Functionally referential alarm calls have stimulus specificity, distinct acoustic structure, and elicit different escape responses that are appropriate to the threat. The mechanisms by which escape responses are evoked are not fully understood and may range from eliciting innate responses to conveying representational information. White-tailed ptarmigan (Lagopus leucurus) are a long-lived alpine tundra grouse, which are preyed upon by aerial and terrestrial predators. We investigated the hypothesis that alarm calls of ptarmigan hens with chicks are functionally referential. We recorded hens’ alarm calls in response to naturally occurring and model predators in California’s Sierra Nevada alpine tundra for two summer seasons. We conducted playback experiments in the field to determine chick responses to alarm calls. Alarm calls commenced with an extended ‘alerting’ note followed by a series of staccato notes grouped into elements. Fundamental and dominant frequencies in element notes were significantly higher in terrestrial compared to aerial threat alarm calls. Playbacks of terrestrial threat alarm calls elicited an upright/alert position by chicks (75 % of responses). In response to aerial threat alarm call playbacks, chicks flattened to the ground and froze (80 % of responses). To our knowledge, this study provides the first empirical evidence of functionally referential alarm calling, including the responses of the receivers, in an avian species in the wild.     

Family‐Based HIV and Sexually Transmitted Infection Risk Reduction for Drug‐Involved Young Offenders: 42‐Month Outcomes

This study tested a family‐based human immunodeficiency virus (HIV)/sexually transmitted infection (STI) prevention approach integrated within an empirically supported treatment for drug‐involved young offenders, Multidimensional Family Therapy (MDFT). A randomized, controlled, two‐site community‐based trial was conducted with 154 youth and their parents. Drug‐involved adolescents were recruited in detention, randomly assigned to either MDFT or Enhanced Services as Usual (ESAU), and assessed at intake, 3, 6, 9, 18, 24, 36, and 42‐month follow‐ups. Youth in both conditions received structured HIV/STI prevention in detention and those in MDFT also received family‐based HIV/STI prevention as part of ongoing treatment following detention release. Youth in both conditions and sites significantly reduced rates of unprotected sex acts and STI incidence from intake to 9 months. They remained below baseline levels of STI incidence (10%) over the 42‐month follow‐up period. At Site A, adolescents who were sexually active at intake and received MDFT showed greater reduction in overall frequency of sexual acts and number of unprotected sexual acts than youth in ESAU between intake and 9‐month follow‐ups. These intervention differences were evident through the 42‐month follow‐up. Intervention effects were not found for STI incidence or unprotected sex acts at Site B. Intensive group‐based and family intervention in detention and following release may reduce sexual risk among substance‐involved young offenders, and a family‐based approach may enhance effects among those at highest risk. Site differences in intervention effects, study limitations, clinical implications, and future research directions are discussed.     

The effects of environmental change on chicks' responses to a familiar stimulus

The purpose of the present experiments was to explore chicks' proximity seeking behaviour in relation to imprinting objects in unfamiliar settings. Experiment I showed that chicks, which were individually imprinted on a stationary imprinting object, displayed reduced proximity seeking behaviour when tested in a pen smaller than the rearing pen. This finding confirmed earlier work on the effects of changed pen size. Experiment II used continuous and intermittent noise rearing and testing conditions, in all possible combinations, and a stationary imprinting object. Increased proximity seeking was found in conditions where the auditory environment was changed from rearing to testing, a result apparently opposite to that obtained in earlier work. It is suggested that the effect of environmental change on proximity seeking may vary with the modality in which change occurs and the salience of the imprinting object.     

The Nootropic Properties of Ginseng Saponin Rb1 are Linked to Effects on Anxiety

Previous studies have shown that crude ginseng extracts enhance performance on shock-motivated tasks. Whether such performance enhancements are due to memory-enhancing (nootropic) properties of ginseng, or to other non-specific effects such as an influence on anxiety has not been determined. In the present study, we evaluated both the nootropic and anxiolytic effects of the ginseng saponin Rb1. In the first experiment, 80 five-day-old male chicks received intraperitoneal injections of 0, 0.25, 2.5 or 5.0 mg/kg Rb1. Performance on a visual discrimination task was evaluated 15 minutes, 24 and 72 hours later. Acquisition of a visual discrimination task was unaffected by drug treatment, but the number of errors was significantly reduced in the 0.25 mg/kg group during retention trials completed 24 and 72 hours after injection. Animals receiving higher dosages showed trends towards enhancement initially, but demonstrated impaired performance when tested 72 hours later. Rb1 had no effect on response rates or body weight. In the second experiment, 64 five-day-old male chicks received similar injections of Rb1 (0, 0.25, 2.5 or 5.0 mg/kg) and separation distress was evaluated 15 minutes, 24 and 72 hours later. Rb1 produced a change in separation distress that depended on the dose and environmental condition under which distress was recorded. These data suggest that Rb1 can improve memory for a visual discrimination task and that the nootropic effect may be related to changes in anxiety.     

Divergent selection for duration of tonic immobility and social reinstatement behavior in Japanese quail (Coturnix coturnix japonica) chicks

Japanese quail (Coturnix coturnix japonica) were selected over 8 generations for long or short duration of tonic immobility (TI) weighted for independence from social reinstatement (SR) behavior (as measured in a treadmill) and for high or low levels of SR behavior weighted for independence from duration of TI. Divergent selection for long or short duration of TI and for high or low levels of SR behavior resulted in immediate and significant responses that continued throughout the 8 generations. There was no evidence of a plateau in the response to selection in any of the lines. SR responses did not vary in lines selected for duration of TI and vice versa. Selection for short duration of TI led to in an increase in the number of inductions required to induce TI. Selection for low levels of SR behavior led to a decrease in the tendency to move toward conspecifics but not to an increase in the tendency to move away from conspecifics.     

The nootropic properties of ginseng saponin Rb<Subscript>1</Subscript> are linked to effects on anxiety

Previous studies have shown that crude ginseng extracts enhance performance on shock-motivated tasks. Whether such performance enhancements are due to memory-enhancing (nootropic) properties of ginseng, or to other non-specific effects such as an influence on anxiety has not been determined. In the present study, we evaluated both the nootropic and anxiolytic effects of the ginseng saponin Rb₁. In the first experiment, 80 five-day-old male chicks received intraperitoneal injections of 0, 0.25, 2.5 or 5.0 mg/kg Rb₁. Performance on a visual discrimination task was uvaluted 15 minutes, 24 and 72 hours later. Acquisition of a visual discrimination task was unaffected by drug treatment, but the number of errors was significantly reduced in the 0.25 mg/kg group during retention trials completed 24 and 72 hours after injection. Animals receiving higher dosages showed trends towards enhancement initially, but demonstrated impaired performance when tested 72 hours later. Rb₁ had no effect on response rates or body weight. In the second experiment, 64 five-day-old male chicks received similar injections of Rb₁ (0, 0.25, 2.5 or 5.0 mg/kg) and separation distress was evaluated 15 minutes, 24 and 72 hours later. Rb₁ produced a change in separation distress that depended on the dose and environmental condition under which distress was recorded. These data suggest that Rb₁ can improve memory for a visual discrimination task and that the nootropic effect may be related to changes in anxiety.     

Effects of environmental enrichment on spatial memory and neurochemistry in middle-aged mice

The present study compared the effects of environmental enrichment on spatial memory, glutamic acid decarboxylase (GAD) activity, and synaptophysin levels in middle-aged male and female mice. Prior to testing, a subset of 18-month-old male and female C57BL/6 mice was housed with two to three toys and a running wheel in the home cage for up to 29 d. Adult mice (7 mo) of both sexes and the remaining middle-aged mice were group (social) housed, but not exposed to enriching objects. After the enrichment period, all mice were tested in a 1-day version of the Morris water maze, in which both spatial and nonspatial memory were assessed. Immediately after testing, the hippocampus and frontoparietal cortex were dissected, and GAD activity and synaptophysin levels were measured. Environmental enrichment reduced the age-related impairment in spatial acquisition and retention; relative to adult social controls, middle-aged enriched mice were unimpaired, whereas middle-aged social controls were impaired. This reduction was similar in middle-aged males and females. Enrichment did not affect cued memory in either sex. Although hippocampal GAD activity was increased by enrichment in males, all other neurochemical measurements were unaffected by enrichment or aging in either sex. These data suggest that environmental enrichment initiated at middle age can reduce age-related impairments in spatial memory in males and females, although the underlying neurobiological mechanisms of this effect remain unknown.     

Similarity of approach and pecking preferences for spectral stimuli in domestic chicks: absence of a mirror-image relation.

The results of Schaefer and Hess showing that White Rock chicks described mirror-image response functions to spectral stimuli in approach and pecking behavior could not be replicated using Cornish-Cross chicks under more controlled conditions. Our results showed similar blue-orange bimodal functions for both behavioral responses, resembling the approach data of Schaefer and Hess and the earlier pecking data of Hess and others, but not the pecking data reported by Schaefer and Hess.