[Show abstract][Hide abstract] ABSTRACT: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized, in part, by an inability to adequately respond to social cues. Patients diagnosed with ASD are often devoid of empathy and impaired in understanding other people's emotional perspective. The neuronal correlates of this impairment are not fully understood. Replicating such a behavioral phenotype in a mouse model of autism would allow us insight into the neuronal background of the problem. Here we tested BTBR T(+)Itpr3(tf)/J (BTBR) and c57BL/6J (B6) mice in two behavioral paradigms: the Transfer of Emotional Information test and the Social Proximity test. In both tests BTBR mice displayed asocial behavior. We analyzed c-Fos protein expression in several brain regions after each of these tests, and found that, unlike B6 mice, BTBR mice react to a stressed cagemate exposure in the Transfer of Emotional Information test with no increase of c-Fos expression in either the prefrontal cortex or the amygdala. However, after Social Proximity exposure we observed a strong increase in c-Fos expression in the CA3 field of the hippocampus and two hypothalamic regions of BTBR brains. This response was accompanied by a strong activation of periaqueductal regions related to defensiveness, which suggests that BTBR mice find unavoidable social interaction highly aversive.
[Show abstract][Hide abstract] ABSTRACT: Step-in latencies and the proportion of time spent outside the shock situation were measured for three groups of rats. One group had received shock on stepping into the shock chamber, and had been allowed to escape the shock chamber. A yoked control group received the same number of shocks after being placed directly into the shock chamber. Escape was not permitted for these Ss. The final group had received no shock. Both shock groups differed reliably from the nonshocked group on both response measures. Differences between the two shocked groups were not significant. The results were interpreted as indicating that punishment of specific responses is not necessary for step-in passive avoidance performance.
[Show abstract][Hide abstract] ABSTRACT: Seven days after receiving unavoidable shock, rats were placed in the shock chamber, or in an adjacent chamber. Free access between the chambers was permitted, and latency to cross was measured. Latency to cross into the shocked chamber was an increasing function of shock intensity, while latency to escape the shock chamber was not related to the intensity of prior shock. The results were interpreted as supporting the hypothesis that situations associated with shock produce competing tendencies in the rat to escape and to remain immobile.
[Show abstract][Hide abstract] ABSTRACT: Two groups of rats were given seven brief foot shocks at 1 h intervals. The Ss who had been placed in the shock situations 24 h before shock crouched less after the second and all succeeding shocks than the group which had only 1/2 h habituation to the shock situation, thus indicating that the cues of the shock situation influence postshock crouching.
[Show abstract][Hide abstract] ABSTRACT: A time-sampling procedure was used to study the behavior of rats following a single foot shock. The Ss who received a 2 sec, 1.3 mA shock crouched more, lay down less, and were initially less active, than nonshocked controls. Crouching differences were greatest during the first 30 min after shock, and declined systematically over a 3 h period. The results were interpreted as indicating that foot shock produces gross behavioral changes which may affect the dependent variables of experiments involving such shock.
[Show abstract][Hide abstract] ABSTRACT: Corticotropin-releasing factor (CRF) plays an essential role in coordinating the autonomic, endocrine and behavioral responses to stressors. In this study, we investigated the role of CRF within the medial prefrontal cortex (mPFC) in modulating unconditioned defensive behaviors, by examining the effects of microinfusing cortagine a selective type-1 CRF receptor (CRF1) agonist, or acidic-astressin a preferential CRF1 antagonist, into the mPFC in male CD-1 mice exposed to a live predator (rat exposure test-RET). Cortagine microinfusions significantly reduced several indices of defense, including avoidance and freezing, suggesting a specific role for CRF1 within the infralimbic and prelimbic regions of the mPFC in modulating unconditioned behavioral responsivity to a predator. In contrast, microinfusions of acidic-astressin failed to alter defensive behaviors during predator exposure in the RET. Cortagine microinfusions also reduced Fos protein production in the medial, central and basomedial, but not basolateral subnuclei of the amygdala in mice exposed to the rat predatory threat stimulus. These results suggest that CRF1 activation within the mPFC attenuates predator-induced unconditioned anxiety-like defensive behaviors, likely via inhibition of specific amygdalar nuclei. Furthermore, the present findings suggest that the mPFC represents a unique neural region whereby activation of CRF1 produces behavioral effects that contrast with those elicited following systemic administration of CRF1 agonists.
Hormones and Behavior 07/2013; 64(3). DOI:10.1016/j.yhbeh.2013.06.008 · 4.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Female rats received shock through objects varying in discriminability. Poorly discriminable objects elicited rapid avoidance acquisition, with suppression of activity and subsequent avoidance of the shock chamber (increased entry latencies). Highly discriminable shock objects also elicited rapid acquisition of avoidance, but without activity suppression or chamber avoidance. This pattern of findings suggests dual mechanisms for passive avoidance, with discriminated avoidance underlying failure to contact highly discriminable shock objects, and response suppression (immobility) underlying avoidance of poorly discriminable sources of threat.
[Show abstract][Hide abstract] ABSTRACT: The history of science has frequently included a problem-based impetus toward research that can be translated expeditiously into solutions. A current problem is that psychopathologies, typically chronic, contribute hugely to the economic and social burden of medical care, especially in the United States. For behavioral neuroscientists a psychopathology-aimed translational research emphasis particularly involves animal models to facilitate the experimental and invasive work necessary to an understanding of the biology of normal and aberrant behavior. When the etiology of a particular psychopathology is unknown, and there are no specific biomarkers, behavioral parallels between the focal disorder and its putative models become crucial elements in assessing model validity. Evaluation of these parallels is frequently neglected, reflecting in part the lack of a systematic conceptualization of the organization of behavior and how this may be conserved across species. Recent work specifically attempting to bridge this gap suggests that analysis of behaviors that are functional - adaptive in crucial situations such as danger or social contexts - can facilitate an understanding of the parallels between behaviors of human and nonhuman species, including the dysfunctional behaviors of psycho-pathologies. As research with animal models comes to provide a more systematic analysis of particular behaviors and their adaptive functions, cross-talk between model and focal psychopathology may be advantageous to understanding both.
[Show abstract][Hide abstract] ABSTRACT: Abnormal cellular growth and organization have been characterized in postmortem tissue from brains of autistic individuals, suggestive of pathology in a critical neurogenic niche, the subventricular zone (SVZ) of the brain lateral ventricles (LV). We examined cellular organization, cell proliferation, and constituents of the extracellular matrix such as N-sulfated heparan sulfate (HS) and laminin (LAM) in postmortem brain tissue from the LV-SVZ of young to elderly individuals with autism (n=4) and age-matched typically developing (TD) individuals (n=4) using immunofluorescence techniques. Strong and systematic reductions in HS immunofluorescence were observed in the LV-SVZ of the TD individuals with increasing age. For young through mature, but not elderly, autistic pair members, HS was reduced compared to their matched TDs. Cellular proliferation (Ki67+) was higher in the autistic individual of the youngest age-matched pair. These preliminary data suggesting that HS may be reduced in young to mature autistic individuals are in agreement with previous findings from the BTBR T+tf/J mouse, an animal model of autism; from mice with genetic modifications reducing HS; and with genetic variants in HS-related genes in autism. They suggest that aberrant extracellular matrix glycosaminoglycan function localized to the subventricular zone of the lateral ventricles may be a biomarker for autism, and potentially involved in the etiology of the disorder.
Behavioural brain research 01/2013; 243(1). DOI:10.1016/j.bbr.2012.12.062 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The development of tasks measuring behaviors specific to the three major symptom categories for autism makes it possible to differentiate mouse models of autism spectrum disorders (ASD) in terms of changes in these specific categories. Prior studies indicate that BTBR T+tf/J mice, the strain that has been evaluated most extensively, show autism-relevant changes in all three symptom categories; reciprocal social interactions; communication; and repetitive, ritualized behaviors. This report reviews the behaviors of oxytocin receptor (Oxtr) and Mecp2308/Y wild-type (WT) and knockout (KO) mice, in a number of tests specifically designed to provide information on behaviors that may show functional parallels to the core symptoms of ASD. Oxtr KO mice show robust decreases in reciprocal social interactions, and reduced levels of communication, but no changes in repetitive, ritualized behaviors; whereas Mecp2308/Y KO mice show a slight but consistent enhancement of social behavior and communication, and no changes in repetitive, ritualized behaviors. This data base, although small, strongly indicates that mouse models can sort the diagnostic symptoms of autism, and suggests that biological and physiological analyses of these strains may be capable of providing differential information on the brain systems involved in particular symptoms of this disorder. Profiles of behavioral changes in other mouse models of ASD should provide additional specificity in the search for biomarkers associated with particular ASD symptoms and symptom clusters.
[Show abstract][Hide abstract] ABSTRACT: Autism spectrum disorders (ASD) form a common group of neurodevelopmental disorders appearing to be under polygenic control, but also strongly influenced by multiple environmental factors. The brain mechanisms responsible for ASD are not understood and animal models paralleling related emotional and cognitive impairments may prove helpful in unraveling them. BTBR T(+)tf/J (BTBR) mice display behaviors consistent with the three diagnostic categories for ASD. They show impaired social interaction and communication as well as increased repetitive behaviors. This review covers much of the data available to date on BTBR behavior, neuroanatomy and physiology in search for candidate biomarkers, which could both serve as diagnostic tools and help to design effective treatments for the behavioral symptoms of ASD.
Behavioural brain research 08/2012; 251. DOI:10.1016/j.bbr.2012.07.021 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A major goal of translation research in autism is to characterize the physiological and psychological processes underlying behavioral abnormalities. Since autism reflects impairments in social motivation, we modified the mouse three-chamber social approach apparatus for use as a social conditioned place preference arena. We paired one of two unique contexts with social interactions in juvenile mice for five or ten conditioning sessions in BTBR T+tf/J mice and a control strain with normal approach behaviors (C57BL/6J) since the BTBR T+tf/J inbred mouse strain displays a variety of behavioral alterations analogous to symptoms of autism spectrum disorders. While C57BL/6J mice formed a conditioned place preference to the context associated with social interactions, particularly those receiving ten days of conditioning, BTBR T+tf/J mice did not. Neither absence of social proximity nor avoidance due to high rates of autogrooming appeared to underlie the impaired positive incentive value of the unconditioned social stimulus in the BTBR T+tf/J strain. These data contribute to a growing body of evidence suggesting that the BTBR T+tf/J strain shows impairments in all diagnostic domains of autism including social motivation. Additionally, social conditioning testing might provide an important social motivation measure in other rodent models of neuropsychiatric disorders characterized by social abnormalities.
Behavioural brain research 04/2012; 233(1):99-104. DOI:10.1016/j.bbr.2012.04.040 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Clinical studies have shown that children diagnosed with autism show abnormal sulfate chemistry, which is critical for cellular and metabolic processes. To determine if the inbred BTBR T+tf/J mouse shows autism-relevant aberrations in sulfate chemistry, the present study examined plasma sulfate concentrations in BTBR T+tf/J, inbred C57BL/6J, and outbred CD-1 mice. Results showed that the BTBR T+tf/J mouse exhibits significantly lower plasma sulfate concentrations in comparison to both C57BL/6J and CD-1 mice. These results suggest that the BTBR mouse shows autism-relevant abnormalities in sulfate chemistry and may serve additional utility in examining the role of sulfate and sulfate-dependent systems in relation to autism-relevant behavioral aberrations.
[Show abstract][Hide abstract] ABSTRACT: Some animals display a variety of context dependent facial expressions. Previous studies have shown that rodents display a facial grimace while in pain. To determine if the facial expressions of mice extend beyond pain, facial expressions were analyzed in the presence of non-social, social and predator stimuli. In a vibrissae contact test, the whiskers of mice were stroked by the bristles of a brush. In a social proximity test, two mice were placed together in a small chamber where contact was virtually unavoidable. In a resident-intruder test of aggression, an unknown mouse was placed into the homecage of another mouse. In a cat odor exposure test and in a live rat exposure test, mice were presented with the respective stimuli. Results from this study indicated that mice showed two patterns of expression, either a full display of changes in the measured facial components, characterized by tightened eyes, flattened ears, nose swells and cheek swells; or a more limited display of these facial changes. The full display of changes occurred in the vibrissae contact test, the social proximity test, and in resident mice in the resident-intruder test. The more limited display of facial changes occurred in the cat odor exposure test, the rat exposure test and in intruder mice in the resident-intruder test. The differential display of facial changes across conditions indicated that mice showed tightened eyes and flattened ears in situations that provided the immediate potential for contact, suggesting that such changes are involved in protection of sensitive and/or vulnerable body parts. Furthermore, the display of facial expressions by mice indicates that these expressions are widely distributed across evolution.
[Show abstract][Hide abstract] ABSTRACT: BTBR T+tf/J (BTBR) mice show abnormal social, communicatory, and repetitive/stereotyped behaviors paralleling many of the symptoms of autism spectrum disorders. BTBR also show agenesis of the corpus callosum (CC) suggesting major perturbations of growth or guidance factors in the dorsal forebrain . Heparan sulfate (HS) is a polysaccaride found in the brain and other animal tissues. It binds to a wide variety of ligands and through these ligands modulates a number of biological processes, including cell proliferation and differentiation, migration and guidance. It is aggregated on fractal-like structures (fractones) in the subventricular zone (SVZ), that may be visualized by laminin immunoreactivity (LAM-ir), as well as by HS immunoreactivity (HS-ir). We report that the lateral ventricles of BTBR mice were drastically reduced in area compared to C57BL/6J (B6) mice while the BTBR SVZ was significantly shorter than that of B6. In addition to much smaller fractones for BTBR, both HS and LAM-ir associated with fractones were significantly reduced in BTBR, and their anterior-posterior distributions were also altered. Finally, the ratio of HS to LAM in individual fractones was significantly higher in BTBR than in B6 mice. These data, in agreement with other findings linking HS to callosal development, suggest that variations in the quantity and distribution of HS in the SVZ of the lateral ventricles may be important modulators of the brain structural abnormalities of BTBR mice, and, potentially, contribute to the behavioral pathologies of these animals.
Behavioural brain research 11/2011; 228(2):247-53. DOI:10.1016/j.bbr.2011.11.004 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A wealth of studies has implicated oxytocin (Oxt) and its receptors (Oxtr) in the mediation of social behaviors and social memory in rodents. It has been suggested that failures in this system contribute to deficits in social interaction that characterize autism spectrum disorders (ASD). In the current analyses, we investigated the expression of autism-related behaviors in mice that lack the ability to synthesize the oxytocin receptor itself, Oxtr knockout (KO) mice, as compared to their wild-type (WT) littermates. In the visible burrow system, Oxtr KO mice showed robust reductions in frontal approach, huddling, allo-grooming, and flight, with more time spent alone, and in self-grooming, as compared to WT. These results were corroborated in the three-chambered test: unlike WT, Oxtr KO mice failed to spend more time in the side of the test box containing an unfamiliar CD-1 mouse. In the social proximity test, Oxtr KO mice showed clear reductions in nose to nose and anogenital sniff behaviors oriented to an unfamiliar C57BL/6J (B6) mouse. In addition, our study revealed no differences between Oxtr WT and KO genotypes in the occurrence of motor and cognitive stereotyped behaviors. A significant genotype effect was found in the scent marking analysis, with Oxtr KO mice showing a decreased number of scent marks, as compared to WT. Overall, the present data indicate that the profile for Oxtr KO mice, including consistent social deficits, and reduced levels of communication, models multiple components of the ASD phenotype. This article is part of a Special Issue entitled Oxytocin, Vasopressin, and Social Behavior.
Hormones and Behavior 11/2011; 61(3):436-44. DOI:10.1016/j.yhbeh.2011.10.010 · 4.63 Impact Factor