- Proceedings. Biological sciences / The Royal Society
- Published over 5 years ago
The importance of exercise for health and neurogenesis is becoming increasingly clear. Wheel running is often used in the laboratory for triggering enhanced activity levels, despite the common objection that this behaviour is an artefact of captivity and merely signifies neurosis or stereotypy. If wheel running is indeed caused by captive housing, wild mice are not expected to use a running wheel in nature. This however, to our knowledge, has never been tested. Here, we show that when running wheels are placed in nature, they are frequently used by wild mice, also when no extrinsic reward is provided. Bout lengths of running wheel behaviour in the wild match those for captive mice. This finding falsifies one criterion for stereotypic behaviour, and suggests that running wheel activity is an elective behaviour. In a time when lifestyle in general and lack of exercise in particular are a major cause of disease in the modern world, research into physical activity is of utmost importance. Our findings may help alleviate the main concern regarding the use of running wheels in research on exercise.
Animals housed in impoverished cages are often labelled ‘bored’. They have also been called ‘apathetic’ or ‘depressed’, particularly when profoundly inactive. However, these terms are rarely operationally defined and validated. As a negative state caused by under-stimulation, boredom should increase interest in stimuli of all kinds. Apathy (lack of interest), by contrast, should manifest as decreased interest in all stimuli, while anhedonia (loss of pleasure, a depressive symptom) should specifically decrease interest in normally rewarding stimuli. We tested the hypotheses that mink, a model carnivore, experience more boredom, depression-like apathy, or anhedonia in non-enriched (NE) cages than in complex, enriched (E) cages. We exposed 29 subjects (13 E, 16 NE) to ten stimuli categorized a priori as aversive (e.g. air puffs), rewarding (e.g. evoking chasing) or ambiguous/neutral (e.g. candles). Interest in stimuli was assessed via latencies to contact, contact durations, and durations oriented to stimuli. NE mink contacted all stimuli faster (P = 0.003) than E mink, and spent longer oriented to/in contact with them, albeit only significantly so for ambiguous ones (treatment*type P<0.013). With stimulus category removed from statistical models, interest in all stimuli was consistently higher among NE mink (P<0.0001 for all measures). NE mink also consumed more food rewards (P = 0.037). Finally, we investigated whether lying down while awake and stereotypic behaviour (both increased by NE housing) predicted these responses. Lying awake positively co-varied with certain measures of increased exploration. In contrast, stereotypic 'scrabbling' or locomotion (e.g. pacing) did not. Overall, NE mink showed no evidence of apathy or depression, but instead a heightened investigation of diverse stimuli consistent with boredom. This state was potentially indicated by spending much time lying still but awake (although this result requires replication). Boredom can thus be operationalized and assessed empirically in non-human animals. It can also be reduced by environmental enrichment.
Wild carnivores in zoos, conservation breeding centres, and farms commonly live in relatively small, unstimulating enclosures. Under these captive conditions, in a range of species including giant pandas, black-footed ferrets, and European mink, male reproductive abilities are often poor. Such problems have long been hypothesized to be caused by these animals' housing conditions. We show for the first time that rearing under welfare-improving (i.e., highly valued and stress-reducing) environmental enrichments enhances male carnivores' copulatory performance: in mate choice competitions, enriched male American mink (Neovison vison) mated more often than non-enriched males. We screened for several potential mediators of this effect. First was physiological stress and its impact on reproductive physiology; second, stress-mediated changes in morphology and variables related to immunocompetence that could influence male attractiveness; and third, behavioural changes likely to affect social competence, particularly autistic-like excessive routine and repetition (‘perseveration’) as is reflected in the stereotypies common in captive animals. Consistent with physiological stress, excreted steroid metabolites revealed that non-enriched males had higher cortisol levels and lower androgen levels than enriched conspecifics. Their os penises (bacula) also tended to be less developed. Consistent with reduced attractiveness, non-enriched males were lighter, with comparatively small spleens and a trend to greater fluctuating asymmetry. Consistent with impaired social competence, non-enriched males performed more stereotypic behaviour (e.g., pacing) in their home cages. Of all these effects, the only significant predictor of copulation number was stereotypy (a trend suggesting that low bodyweights may also be influential): highly stereotypic males gained the fewest copulations. The neurophysiological changes underlying stereotypy thus handicap males sexually. We hypothesise that such males are abnormally perseverative when interacting with females. Investigating similar problems in other taxa would be worthwhile, since many vertebrates, wild and domestic, live in conditions that cause stereotypic behaviour and/or impair neurological development.
Stereotypic behaviours are commonly observed in captive animals and are usually interpreted as a sign of poor welfare. Stereotypies have also been linked with brain abnormalities. However, stereotypies are a heterogeneous class of behaviours and mounting evidence indicates that different stereotypies can have different causes, and can be linked to different affective states. As a consequence, the implications of a specific stereotypy in a specific species cannot be safely inferred from evidence on other stereotypies or species. Here we review what is known about pacing behaviour in laboratory rhesus macaques, a common stereotypy in this species. Our review highlights the current lack of understanding of the causal factors underlying pacing behaviour. According to current knowledge, the welfare of pacing macaques could be either better, worse or equivalent to that of non-pacing individuals. It is also unclear whether pacing results from brain abnormalities. Since rhesus macaques are widely used as a model of healthy humans in neuroscience research, determining if pacing behaviour reflects an abnormal brain and/or poor welfare is urgent.
Intensive behavioral intervention for young children diagnosed with autism can produce large gains in social, cognitive, and language development. Although several studies have identified behaviors that are possible indicators of best outcome, changes in performance are typically measured using norm-referenced standardized scores referencing overall functioning level rather than via repeated observational measures of autism-specific deficits (i.e., social behavior). In the current study, 83 children with autism (CWA), aged 1, 2 and 3 years, and 58 same-aged typically developing children (TDC) were directly observed in the areas of cognitive skills, joint attention (JA), play, and stereotypic behavior using a measure called the Early Skills Assessment Tool (ESAT; MacDonald et al., 2006). CWA were assessed at entry into an EIBI program and again after 1 year of treatment. Changes in performance were compared pre- and post-treatment as well as to the normative data by age. Results indicate significant gains on the ESAT across all age groups with the greatest gains seen in the children who entered treatment prior to their second birthday. Increases were seen on direct measures of JA, play, imitation and language while decreases were seen in stereotypy regardless of level of performance at entry into EIBI. The ESAT, a direct measurement tool, served as a sensitive tool to measure changes in autism symptomatology following EIBI treatment.
Several studies have demonstrated that auditory enrichment can reduce stereotypic behaviors in captive animals. The purpose of this study was to determine the relative effectiveness of three different types of auditory enrichment-naturalistic sounds, classical music, and rock music-in reducing stereotypic behavior displayed by Western lowland gorillas (Gorilla gorilla gorilla). Three gorillas (one adult male, two adult females) were observed at the Buffalo Zoo for a total of 24 hr per music trial. A control observation period, during which no sounds were presented, was also included. Each music trial consisted of a total of three weeks with a 1-week control period in between each music type. The results reveal a decrease in stereotypic behaviors from the control period to naturalistic sounds. The naturalistic sounds also affected patterns of several other behaviors including locomotion. In contrast, stereotypy increased in the presence of classical and rock music. These results suggest that auditory enrichment, which is not commonly used in zoos in a systematic way, can be easily utilized by keepers to help decrease stereotypic behavior, but the nature of the stimulus, as well as the differential responses of individual animals, need to be considered. Zoo Biol. XX:XX-XX, 2014. © 2014 Wiley Periodicals, Inc.
- Journal of neurology, neurosurgery, and psychiatry
- Published almost 2 years ago
To describe the phenomenology and prevalence of leg stereotypy syndrome (LSS), characterised chiefly by repetitive, rhythmical, stereotypic leg movement, especially when sitting.
Considerable evidence has shown that physical exercise could be an effective treatment in reducing stereotypical autism spectrum disorder (ASD) behaviors in children. The present study seeks to examine the underlying mechanism by considering the theoretical operant nature of stereotypy. Children with ASD (n = 30) who exhibited hand-flapping and body-rocking stereotypies were asked to participate in both control (story-time) and experimental (ball-tapping-exercise intervention) conditions. The experimental condition comprised 15 min of ball tapping during which the children were asked to tap a plastic ball as many times as they could. Results indicated that hand-flapping stereotypy was significantly reduced but body-rocking stereotypy following the ball-tapping-exercise intervention was not. These results not only confirm the positive impact of exercise intervention on stereotypic behavior as shown in many previous studies, but further suggest that physical exercise should be matched with the biomechanics of stereotypy to produce a desirable behavioral benefit.
Diverse motivational triggers, including diet, elicit stereotypic behavior. We investigated whether diets comprised of different protein levels but similar levels of energy were associated with the occurrence of locomotor stereotypies in the striped mouse Rhabdomys dilectus chakae. In a first experiment, 20 stereotypic and 20 non-stereotypic (10 subjects per sex and per group) juvenile (40 days old) subjects were placed on baseline (BP), high (HP) or low protein (LP) diet treatments (120 subjects in total). All subjects initially identified as stereotypic displayed stereotypic behavior in the BP and HP treatments on Days 60-63 and Days 80-83 compared to 35% and 12.5% of LP subjects, respectively. Moreover, LP subjects displayed lower levels of activity and stereotypic behavior than BP and HP subjects. Those identified as non-stereotypic never displayed stereotypy. In a second experiment, 48 individuals, bred and reared on LP and whose parents were stereotypic, were assigned to either HP (13 males, 12 females) or LP (12 males, 11 females) treatments at 50 days of age for 30 days. Stereotypy was three times less likely to occur in the LP than the HP treatment, and activity was greater in LP-HP individuals than LP-LP individuals. In both experiments, LP individuals had the lowest body mass. Striped mice adjusted their behaviors in response to dietary protein levels. Protein deficiency reduced activity and stereotypic behavior and prevalence, possibly related to an energy or neurological deficit.
Captive bears are housed in environments that differ greatly from their natural habitat, restricting their ability to perform normal species-specific behaviours. This may be detrimental to welfare, with disabled individuals at particular risk. The effect of physical disability on behaviour and enclosure utilisation was assessed in 12 adult Malayan sun bears (Helarctos malayanus) using 10minute interval scan sampling. Amputees spent less time performing locomotor behaviours than able-bodied bears, used their enclosures less evenly, but did not exhibit obvious stereotypies. This was possibly due to the increased energy demands of locomotion, or residual pain in amputated limbs. Amputees spent less time grooming, but did not differ in time spent climbing compared with non-amputees. Partially sighted bears did not differ from able-bodied controls in enclosure use or behaviour. Age was positively correlated with stereotypical behaviour, and negatively correlated with maintenance and resting. Medication use was associated with more resting and grooming, and reduced stereotypy. The findings suggest that enclosures for amputees can be smaller than those for able-bodied bears, but should still contain a variety of climbing structures. Partially sighted bears fare well in enclosures designed for able-bodied bears, not requiring any special provision.