Repetitive behavior profile and supersensitivity to amphetamine in the C58/J mouse model of autism.

Restricted repetitive behaviors are core symptoms of autism spectrum disorders (ASDs). The range of symptoms encompassed by the repetitive behavior domain includes lower-order stereotypy and self-injury, and higher-order indices of circumscribed interests and cognitive rigidity. Heterogeneity in clinical ASD profiles suggests that specific manifestations of repetitive behavior reflect differential neuropathology. The present studies utilized a set of phenotyping tasks to determine a repetitive behavior profile for the C58/J mouse strain, a model of ASD core symptoms. In an observational screen, C58/J demonstrated overt motor stereotypy, but not over-grooming, a commonly-used measure for mouse repetitive behavior. Amphetamine did not exacerbate motor stereotypy, but had enhanced stimulant effects on locomotion and rearing in C58/J, compared to C57BL/6J. Both C58/J and Grin1 knockdown mice, another model of ASD-like behavior, had marked deficits in marble-burying. In a nose poke task for higher-order repetitive behavior, C58/J had reduced holeboard exploration and preference for non-social, versus social, olfactory stimuli, but did not demonstrate cognitive rigidity following familiarization to an appetitive stimulus. Analysis of available high-density genotype data indicated specific regions of divergence between C58/J and two highly-sociable strains with common genetic lineage. Strain genome comparisons identified autism candidate genes, including Cntnap2 and Slc6a4, located within regions divergent in C58/J. However, Grin1, Nlgn1, Sapap3, and Slitrk5, genes linked to repetitive over-grooming, were not in regions of divergence. These studies suggest that specific repetitive phenotypes can be used to distinguish ASD mouse models, with implications for divergent underlying mechanisms for different repetitive behavior profiles.

Liberating health data for clinical research applications.

Global investments in health information technology (HIT) in the form of electronic health record systems represent important new strategies to improve the quality and efficiency of health care. These potential benefits of HIT will not be achieved without direct attention to the use of health care information for clinical research purposes. To support clinical research effectively, the systems put in place in the next few years must implement appropriate interoperability, information-sharing policies, and infrastructure that can liberate health data from clinical records.

Social approach and repetitive behavior in eleven inbred mouse strains.

Core symptoms of autism include deficits in social interaction, impaired communication, and restricted, repetitive behaviors. The repetitive behavior domain encompasses abnormal motoric stereotypy, an inflexible insistence on sameness, and resistance to change. In recent years, many genetic mouse models of autism and related disorders have been developed, based on candidate genes for disease susceptibility. The present studies are part of an ongoing initiative to develop appropriate behavioral tasks for the evaluation of mouse models relevant to autism. We have previously reported profiles for sociability, preference for social novelty, and resistance to changes in a learned pattern of behavior, as well as other functional domains, for 10 inbred mouse strains of divergent genetic backgrounds. The present studies extend this multi-component behavioral characterization to several additional strains: C58/J, NOD/LtJ, NZB/B1NJ, PL/J, SJL/J, SWR/J, and the wild-derived PERA/EiJ. C58/J, NOD/LtJ, NZB/B1NJ, SJL/J, and PERA/EiJ demonstrated low sociability, measured by time spent in proximity to an unfamiliar conspecific, with 30-60% of mice from these strains showing social avoidance. In the Morris water maze, NZB/B1NJ had a persistent bias for the quadrant where the hidden platform was located during acquisition, even after 9 days of reversal training. A particularly interesting profile was found for C58/J, which had low social preference, poor performance in the T-maze, and overt motoric stereotypy. Overall, this set of tasks and observational methods provides a strategy for evaluating novel mouse models in behavioral domains relevant to the autism phenotype.

Development of a mouse test for repetitive, restricted behaviors: relevance to autism.

Repetitive behavior, a core symptom of autism, encompasses stereotyped responses, restricted interests, and resistance to change. These studies investigated whether different components of the repetitive behavior domain could be modeled in the exploratory hole-board task in mice. Four inbred mouse strains, C57BL/6J, BALB/cByJ, BTBR T+tf/J, and FVB/NJ, and mice with reduced expression of Grin1, leading to NMDA receptor hypofunction (NR1neo/neo mice), were tested for exploration and preference for olfactory stimuli in an activity chamber with a 16-hole floor-board. Reduced exploration and high preference for holes located in the corners of the chamber were observed in BALB/cByJ and BTBR T+tf/J mice. All inbred strains had initial high preference for a familiar olfactory stimulus (clean cage bedding). BTBR T+tf/J was the only strain that did not demonstrate a shift in hole preference towards an appetitive olfactory stimulus (cereal or a chocolate chip), following home cage exposure to the food. The NR1neo/neo mice showed lower hole selectivity and aberrant olfactory stimulus preference, in comparison to wildtype controls. The results indicate that NR1neo/neo mice have repetitive nose poke responses that are less modified by environmental contingencies than responses in wildtype mice. 25-30% of NMDA receptor hypomorphic mice also show self-injurious responses. Findings from the olfactory studies suggest that resistance to change and restricted interests might be modeled in mice by a failure to alter patterns of hole preference following familiarization with an appetitive stimulus, and by high preference persistently demonstrated for one particular olfactory stimulus. Further work is required to determine the characteristics of optimal mouse social stimuli in the olfactory hole-board test.

Social approach behaviors in oxytocin knockout mice: comparison of two independent lines tested in different laboratory environments.

Oxytocin mediates social affiliation behaviors and social memory in rodents. It has been suggested that disruptions in oxytocin contribute to the deficits in reciprocal social interactions that characterize autism. The present experiments employed a new social approach task for mice which is designed to detect low levels of sociability, representing the first diagnostic criterion for autism. Two lines of oxytocin knockout mice were tested, the National Institute of Mental Health line in Bethesda, and the Baylor/Emory line at the University of North Carolina in Chapel Hill. Similar methods were used for each line to evaluate tendencies to spend time with a stranger mouse versus with an inanimate novel object with no social valence. Adult C57BL/6J males were tested identically, as controls to confirm the robustness of the methods used in the social task. Comprehensive phenotyping of general health, neurological reflexes, olfactory and other sensory abilities, and motor functions was employed to assess both lines. No genotype differences were detected in any of the control measures for either line. Normal sociability, measured as time spent with a novel stranger mouse as compared to time spent with a novel object, was seen in both the NIMH and the Baylor/Emory lines of oxytocin null mutants, heterozygotes, and wild-type littermate controls. Normal preference for social novelty, measured as time spent with a second novel stranger as compared to time spent with a more familiar mouse, was seen in both the NIMH and the Baylor/Emory lines of oxytocin null mutants, heterozygotes, and wild-type littermate controls, with minor exceptions. Similar behavioral results from two independent targeted gene mutations, generated with different targeting vectors, bred on different genetic backgrounds, and tested in different laboratory environments, corroborates the negative findings on sociability in oxytocin mutant mice. Intact tendencies to spend time with another mouse versus with a novel object, in both lines of oxytocin knockouts, supports an interpretation that oxytocin plays a highly specific role in social memory, but is not essential for general spontaneous social approach in mice.

Mouse behavioral tasks relevant to autism: phenotypes of 10 inbred strains.

Three defining clinical symptoms of autism are aberrant reciprocal social interactions, deficits in social communication, and repetitive behaviors, including motor stereotypies and insistence on sameness. We developed a set of behavioral tasks designed to model components of these core symptoms in mice. Male mice from 10 inbred strains were characterized in assays for sociability, preference for social novelty, and reversal of the spatial location of the reinforcer in T-maze and Morris water maze tasks. Six strains, C57BL/6J, C57L/J, DBA/2J, FVB/NJ, C3H/HeJ, and AKR/J, showed significant levels of sociability, while A/J, BALB/cByJ, BTBR T(+)tf/J, and 129S1/SvImJ mice did not. C57BL/6J, C57L/J, DBA/2J, FVB/NJ, BALB/cByJ, and BTBR T(+)tf/J showed significant preference for social novelty, while C3H/HeJ, AKR/J, A/J, and 129S1/SvImJ did not. Normal scores on relevant control measures confirmed general health and physical abilities in all strains, ruling out artifactual explanations for social deficits. Elevated plus maze scores confirmed high anxiety-like behaviors in A/J, BALB/cByJ, and 129S1/SvImJ, which could underlie components of their low social approach. Strains that showed high levels of performance on acquisition of a T-maze task were also able to reach criterion for reversal learning. On the Morris water maze task, DBA/2J, AKR/J, BTBR T(+)tf/J, and 129S1/SvImJ failed to show significant quadrant preference during the reversal probe trial. These results highlight a dissociation between social task performance and reversal learning. BTBR T(+)tf/J is a particularly interesting strain, displaying both low social approach and resistance to change in routine on the water maze, consistent with an autism-like phenotype. Our multitask strategy for modeling symptoms of autism will be useful for investigating targeted and random gene mutations, QTLs, and microarray analyses.

Large-scale gene expression differences across brain regions and inbred strains correlate with a behavioral phenotype.

Behaviors are often highly heritable, polygenic traits. To investigate molecular mediators of behavior, we analyzed gene expression patterns across seven brain regions (amygdala, basal ganglia, cerebellum, frontal cortex, hippocampus, cingulate cortex, and olfactory bulb) of 10 different inbred mouse strains (129S1/SvImJ, A/J, AKR/J, BALB/cByJ, BTBR T+ tf/J, C3H/HeJ, C57BL/6J, C57L/J, DBA/2J, and FVB/NJ). Extensive variation was observed across both strain and brain region. These data provide potential transcriptional intermediates linking polygenic variation to differences in behavior. For example, mice from different strains had variable performance on the rotarod task, which correlated with the expression of >2000 transcripts in the cerebellum. Correlation with this task was also found in the amygdala and hippocampus, but not in other regions examined, indicating the potential complexity of motor coordination. Thus we can begin to identify expression profiles contributing to behavioral phenotypes through variation in gene expression.

Mouse models of autism spectrum disorders: the challenge for behavioral genetics.

Autism is a severe neurodevelopmental disorder, which typically emerges early in childhood. The core symptoms of autism include deficits in social interaction, impaired communication, and aberrant repetitive behavior, including self-injury. Despite the strong genetic component for the disease, most cases of autism have not been linked to mutations in a specific gene, and the etiology of the disorder has yet to be established. At the present time, there is no generally accepted therapeutic strategy to treat the core symptoms of autism, and there remains a critical need for appropriate animal models and relevant behavioral assays to promote the understanding and treatment of the clinical syndrome. Challenges for the development of valid mouse models include complex genetic interactions underlying the high heritability of the disease in humans, diagnosis based on deficits in social interaction and communication, and the lack of confirmatory neuropathological markers to provide validation for genetic models of the disorder. Research focusing on genes that mediate social behavior in mice may help identify neural circuitry essential for normal social interaction, and lead to novel genetic animal models of the autism behavioral phenotype.