An in-depth neurobehavioral characterization shows anxiety-like traits, impaired habituation behavior, and restlessness in male Cryptochrome-deficient mice.

Many psychiatric disorders, for example, anxiety, are accompanied by disturbances of circadian rhythms, including disturbed sleep/wake cycles, changes in locomotor activity, and abnormal endocrine function. Conversely, alternations of circadian rhythms are a risk factor for the development of psychiatric disorders. This assumption is supported by animals with clock gene mutations which often display behaviors that resemble human psychiatric disorders. In this study, we performed an in-depth behavioral analysis with male mice lacking the central clock genes Cryptochrome 1 and 2 (Cry1/2-/- ), which are thus unable to express endogenous circadian rhythms. With wild-type and Cry1/2-/- mice, we performed an extensive behavioral analysis to study their cognitive abilities, social behavior, and their expression of depression-like and anxiety-like behavior. While Cry1/2-/- mice showed only mild abnormalities at cognitive and social behavioral levels, they were consistently more anxious than wildtype mice. Anxiety-like behavior was particularly evident in reduced mobility in new environments, altered ability to habituate, compensatory behavior, and consistent restless behavior across many behavioral tests. In line with their anxiety-like behavioral phenotype, Cry1/2-/- mice have higher c-Fos activity in the amygdala after exposure to an anxiogenic stressor than wild-type mice. In our study, we identified Cry1/2-/- mice as animals that qualify as a translational mouse model for anxiety disorder in humans because of its consistent behavior of restlessness, increased immobility, and dysfunctional habituation in new environments.

PsyCoP - A Platform for Systematic Semi-Automated Behavioral and Cognitive Profiling Reveals Gene and Environment Dependent Impairments of Tcf4 Transgenic Mice Subjected to Social Defeat.

Recently, hundreds of risk genes associated with psychiatric disorders have been identified. These are thought to interact with environmental stress factors in precipitating pathological behaviors. However, the individual phenotypes resulting from specific genotype by environment (G×E) interactions remain to be determined. Toward a more systematic approach, we developed a novel standardized and partially automatized platform for systematic behavioral and cognitive profiling (PsyCoP). Here, we assessed the behavioral and cognitive disturbances in Tcf4 transgenic mice (Tcf4tg) exposed to psychosocial stress by social defeat during adolescence using a "two-hit" G×E mouse model. Notably, TCF4 has been repeatedly identified as a candidate risk gene for different psychiatric diseases and Tcf4tg mice display behavioral endophenotypes such as fear memory impairment and hyperactivity. We use the Research Domain Criteria (RDoC) concept as framework to categorize phenotyping results in a translational approach. We propose two methods of dimension reduction, clustering, and visualization of behavioral phenotypes to retain statistical power and clarity of the overview. Taken together, our results reveal that sensorimotor gating is disturbed by Tcf4 overexpression whereas both negative and positive valence systems are primarily influenced by psychosocial stress. Moreover, we confirm previous reports showing that deficits in the cognitive domain are largely dependent on the interaction between Tcf4 and psychosocial stress. We recommend that the standardized analysis and visualization strategies described here should be applied to other two-hit mouse models of psychiatric diseases and anticipate that this will help directing future preclinical treatment trials.

Assessing behavior and cognition in rodents, nonhuman primates, and humans: where are the limits of translation?
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New psychopharmacological treatments are needed for affective and nonaffective psychoses, especially for the associated negative and cognitive symptoms. Earlier developments mostly failed, probably partly because of limitations in behavioral models used for validation. Now, deeper understanding of the genetics underlying disease pathogenesis and progress in genetic engineering will generate many rodent models with increased construct validity. To improve these models' translational value, we need complementary data from nonhuman primates. We also have to improve and streamline behavioral test systems to cope with increased demand. Here, we propose a comprehensive neurocognitive test battery that should overcome the disadvantages of single tests and yield cognitive/behavioral profiles for modeling subsets of patient symptoms. Further, we delineate a concept for classifying disease-relevant cognitive endophenotypes to balance between face and construct validity and clinical diagnostics. In summary, this review discusses new concepts and the limitations and future potential of translational research on cognition in psychiatry.
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Se requiere de nuevos tratamientos psicofarmacológicos para las psicosis afectivas y no afectivas, especialmente para los síntomas negativos y cognitivos asociados. La mayoría de los desarrollos anteriores fallaron; en parte debido, probablemente, a las limitaciones en los modelos conductuales empleados para la validación. Ahora, una comprensión más profunda de la genética subyacente a la patogénesis de la enfermedad y el progreso en la ingeniería genética generará muchos modelos de roedores con una mayor validez de constructo. Para mejorar el valor de estos modelos translacionales se requiere de datos complementarios de primates no humanos. También hay que mejorar y racionalizar los sistemas de pruebas conductuales para hacer frente a una mayor demanda. En este artículo se propone una batería completa de pruebas neurocognitivas que debería superar las desventajas de las pruebas individuales y generar perfiles cognitivo-conductuales para modelar subconjuntos de síntomas del paciente. Además, se plantea un concepto para clasificar los endofenotipos cognitivos relevantes para la enfermedad a fin de equilibrar la validez aparente y de constructo con el diagnóstico clínico. En resumen, esta revisión analiza nuevos conceptos, y las limitaciones y el potencial futuro de la investigación translacional sobre la cognición en psiquiatría.

De nouveaux traitements psychopharmacologiques sont nécessaires pour les psychoses dysthymiques ou non, surtout pour les symptômes associés négatifs et cognitifs. Par le passé, la plupart des développements ont échoué, probablement en partie en raison des limites des modèles comportementaux utilisés pour la validation. Aujourd'hui, une meilleure compréhension de la génétique de la pathogenèse de la maladie et les progrès du génie génétique vont produire de nombreux modèles de rongeurs mieux construits. Des données supplémentaires issues de primates non humains sont nécessaires pour améliorer la valeur traductive de ces modèles. Afin de satisfaire une demande croissante, nous devons aussi améliorer et rationaliser les systèmes de tests comportementaux. Nous proposons ici une batterie complète de tests neurocognitifs susceptible de palier les inconvénients des tests isolés et de fournir des profils cognitifs/comportementaux pour des sous-groupes de modélisation des symptômes des patients. En outre, nous définissons un concept pour classer les endophénotypes cognitifs pertinents pour la maladie afin de trouver un équilibre entre une validité de façade et de construit et les diagnostics cliniques. En résumé, cet article analyse de nouveaux concepts ainsi que les limites et les futures possibilités de la recherche translationnelle sur la cognition en psychiatrie.