Mark H. Lewis - US grants

Prolonged social isolation of certain species of non-human primates and rats during early development has significant and long-lasting effects on behavior. We have available a population of 17-22 year old rhesus monkeys who were socially isolated during all or most of their first year of life. Preliminary data demonstrate that this social isolation caused profound and permanent effects on the behavior of these monkeys. We propose to study the neurobiology underlying these long-term changes in both rhesus monkeys, and in rats that will be socially isolated during either the pre- or post-weaning period of development. Because other preliminary data indicate that significant changes in dopaminergic function exist in these monkeys, one thrust will be characterize changes in central dopaminergic and other monoaminergic pathways using behavioral, pharmacological and biochemical methods. Initial studies will examine how selected drugs targeted at specific receptor populations alter certain isolation-induced behaviors, including stereotyped behavior, self- aggression, polydipsia, etc. Following two years of behavioral and psychopharmacological studies, the monkeys will be sacrificed, and in vitro experiments will be conducted on post-mortem brain tissue. Neurochemical and receptor binding studies will be performed in microdissected nuclei, and alterations in the density and affinity of several populations of monoamine receptors, and the concentration of monoamines and their acidic metabolities in specific brain regions will be measured. While these studies are being conducted in monkeys, related experiments will be ongoing in Sprague-Dawley rats. These experiments will not only permit comparison across geni, but also allow the preliminary testing of other hypotheses that may be relevant to the studies in rhesus monkeys. Finally, although existing data support the initial focus on dopaminergic transmission, the in vivo and in vitro methodologies to be used will allow us to determine alterations in monaminergic and other neuronal systems attributable to early social isolation, and careful archiving of tissue will permit its use for other post hoc hypotheses.

DESCRIPTION: (Adapted From The Applicant's Abstract) Stereotyped behavior (repetitive, rhythmical, motor acts such as body rocking, head rolling or self-hitting) is highly prevalent in both children and adults with mental retardation. Little is known about the functional or neurobiological basis of such behavior, and stereotypies are typically refractory to treatment. A large body of literature and the investigators' preliminary data point to an important role of central dopamine in the expression of stereotyped and self-injurious behavior. Similarly, altered serotonergic function figures prominently in hypotheses about the neurochemical medication of these behaviors, and considerable evidence from both clinical and animal studies supports a robust interaction between central dopamine and serotonin systems. Thus, the proposed studies will compare several in vivo estimates of central dopamine (e.g., eye blink, reaction time, plasma HVA) and central serotonin (e.g., platelet imipramine binding) function in individuals with mental retardation who engage in high rates of stereotyped behavior and in matched control subjects. A second major goal of the proposed project is to test the hypothesis that the tricyclic antidepressant clomipramine will prove efficacious in the treatment of stereotyped behavior. Although clomipramine and its major metabolite clearly have actions on serotonin systems, clomipramine also has dopamine antagonist properties. Because it has proven to be highly effective in the treatment of compulsive, ritualistic behavior, the investigators will examine its efficacy in treating stereotyped and self-injurious behavior in a double-blind placebo-controlled, cross-over study. The proposed trial of clomipramine is both well justified and promising, given the similarity of stereotyped and self-injurious behavior to the compulsive, ritualistic behavior characteristic of obsessive-compulsive disorder. The data obtained from the proposed studies should provide important, new information about the pathophysiology and treatment of stereotyped behavior disorders.

The focus of this research will be important neurobiological substrates of aggressive behavior in mice, and how genetic, developmental, and experiential determinants of aggression are mediated by specific neuronal systems. To study this problem systematically, an integrated multidisciplinary approach will be used to examine the behavior and neurobiology of lines of mice, derived from ICR foundational stock, which have been selected over 21 generations for high and low levels of aggression. Alterations in aggression induced by genetic, ontogenetic, and experiential factors will be related to specific neurobiological mechanisms. Preliminary data support the hypothesis that an important mechanism for genetically-induced behavioral differences is an alteration in dopaminergic activity in specific terminal regions. Thus, the aims of the proposed studies are: (1) To determine whether alterations in brain monoamine, particularly dopamine, activity in specific terminal regions mediate behavioral differences observed in mice selectively bred for high and low levels of aggression; (2) to determine whether developmental and genetic differences in aggression are due to alterations in the magnitude or temporal development of innervation of discrete catecholamine terminal fields; (3) to determine whether social experience alters the neurobiological mechanisms mediating genetic and developmental differences in aggressive behavior. Because there are qualitative and quantitative changes in aggressive behavior changes as a function of developmental period, and as a function of social experience, the activity of dopamine and other monoamine (serotonin and norepinephrine) systems in both high and low aggressive mice will be studied during ontogeny, using behavioral, pharmacological, neurochemical, receptor, and immunocytochemical techniques. A cosibial\longitudinal design will be used that allows genetic, developmental, and experiential factors to be disentangled. Computer-supported observational methods (interactional analyses) will be used to quantify behavior, while high performance liquid chromatography (HPLC) and quantitative receptor autoradiography will be used to measure neurochemical and receptor changes in monoamine systems. Immunocytochemical techniques, using antisera to tyrosine hydroxylase (TH) and dopamine-beta-- hydroxylase (DBH), will be used to characterize the distribution of catecholaminergic fibers in specific brain regions of high and low aggressive mice. The proposed studies will provide important, new information about the neurobiology of aggression and timidity, and the brain mechanisms that mediate genetic, developmental, and experiential effects on social behavior.

The focus of this research will be important neurobiological substrates of aggressive behavior in mice, and how genetic, developmental, and experiential determinants of aggression are mediated by specific neuronal systems. To study this problem systematically, an integrated multidisciplinary approach will be used to examine the behavior and neurobiology of lines of mice, derived from ICR foundational stock, which have been selected over 21 generations for high and low levels of aggression. Alterations in aggression induced by genetic, ontogenetic, and experiential factors will be related to specific neurobiological mechanisms. Preliminary data support the hypothesis that an important mechanism for genetically-induced behavioral differences is an alteration in dopaminergic activity in specific terminal regions. Thus, the aims of the proposed studies are: (1) To determine whether alterations in brain monoamine, particularly dopamine, activity in specific terminal regions mediate behavioral differences observed in mice selectively bred for high and low levels of aggression; (2) to determine whether developmental and genetic differences in aggression are due to alterations in the magnitude or temporal development of innervation of discrete catecholamine terminal fields; (3) to determine whether social experience alters the neurobiological mechanisms mediating genetic and developmental differences in aggressive behavior. Because there are qualitative and quantitative changes in aggressive behavior changes as a function of developmental period, and as a function of social experience, the activity of dopamine and other monoamine (serotonin and norepinephrine) systems in both high and low aggressive mice will be studied during ontogeny, using behavioral, pharmacological, neurochemical, receptor, and immunocytochemical techniques. A cosibial\longitudinal design will be used that allows genetic, developmental, and experiential factors to be disentangled. Computer-supported observational methods (interactional analyses) will be used to quantify behavior, while high performance liquid chromatography (HPLC) and quantitative receptor autoradiography will be used to measure neurochemical and receptor changes in monoamine systems. Immunocytochemical techniques, using antisera to tyrosine hydroxylase (TH) and dopamine-beta-- hydroxylase (DBH), will be used to characterize the distribution of catecholaminergic fibers in specific brain regions of high and low aggressive mice. The proposed studies will provide important, new information about the neurobiology of aggression and timidity, and the brain mechanisms that mediate genetic, developmental, and experiential effects on social behavior.

DESCRIPTION: (Adapted From The Applicant's Abstract) Stereotyped behavior (repetitive, rhythmical, motor acts such as body rocking, head rolling or self-hitting) is highly prevalent in both children and adults with mental retardation. Little is known about the functional or neurobiological basis of such behavior, and stereotypies are typically refractory to treatment. A large body of literature and the investigators' preliminary data point to an important role of central dopamine in the expression of stereotyped and self-injurious behavior. Similarly, altered serotonergic function figures prominently in hypotheses about the neurochemical medication of these behaviors, and considerable evidence from both clinical and animal studies supports a robust interaction between central dopamine and serotonin systems. Thus, the proposed studies will compare several in vivo estimates of central dopamine (e.g., eye blink, reaction time, plasma HVA) and central serotonin (e.g., platelet imipramine binding) function in individuals with mental retardation who engage in high rates of stereotyped behavior and in matched control subjects. A second major goal of the proposed project is to test the hypothesis that the tricyclic antidepressant clomipramine will prove efficacious in the treatment of stereotyped behavior. Although clomipramine and its major metabolite clearly have actions on serotonin systems, clomipramine also has dopamine antagonist properties. Because it has proven to be highly effective in the treatment of compulsive, ritualistic behavior, the investigators will examine its efficacy in treating stereotyped and self-injurious behavior in a double-blind placebo-controlled, cross-over study. The proposed trial of clomipramine is both well justified and promising, given the similarity of stereotyped and self-injurious behavior to the compulsive, ritualistic behavior characteristic of obsessive-compulsive disorder. The data obtained from the proposed studies should provide important, new information about the pathophysiology and treatment of stereotyped behavior disorders.

Our overall objective is to develop nationally recognized mental health researchers in the Department of Psychiatry at the University of Florida (UF). To this end we will implement a comprehensive and coherent plan to improve the current research environment of the Department. The plan will increase the number and quality of clinical investigators, increase the scope and quality of mental health research, and provide mechanisms for research training, mentoring, and consultation for junior investigators. These outcomes will improve the competitiveness of the Department of Psychiatry faculty for NIMH and related extramural funding. Successful implementation of this development plan will require attainment of the following objectives: expand our education and training efforts to include activities critical to the development of successful clinical investigators, recruit and retain junior and senior faculty and trainees who will contribute significantly to the research environment, expand our research access to clinical populations already being served and identify new special clinical populations for study; establish research support sections that will provide direct clinical, data services, and bioanalytical support to planned and ongoing investigations, develop and conduct specific pilot research projects that have the potential to become competitive for extramural funding, and develop a multidisciplinary research environment by establishing critical linkages with relevant departments and centers and integrating clinical and services research. The clinical research focus of these activities will be mood disorders and related conditions. These studies will address a significant number of priorities relevant to public health (Healthy People 2000), and reflect a clinical research focus with a growing capacity for services research. This latter endeavor will emphasize the academic/public psychiatry interface as well as urban and rural services issues (AIDS, homeless mentally ill, early identification). Rapid growth in the Department includes active recruitment of 18 new faculty in the past 24 months, establishment of laboratory space, creation of clinical research support positions, establishment of new clinical research space, establishment of access to clinical populations for clinical and services research, and creation of new fellowship programs. Such progress, coupled with the new UF Brain Institute and the new Department of Health Policy and Epidemiology as well as a Departmental commitment of release time, equipment, and support staff will ensure successful attainment of the objectives of this application. We believe that the initial steps taken to begin the development of a major mental health research program in Psychiatry at UF makes RISP funds an investment that will yield significant dividends in increased quality and number of mental health investigators conducting clinical and services research on important diseases and related conditions of public health relevance.

DESCRIPTION:(Adapted from applicant's abstract): Stereotypy refers to behavior that is repetitive, rhythmical, topographically invariant, and without an obvious function. Although stereotypies can be observed in many species in different contexts, such behavior is typically associated, in humans, with various psychiatric, neurological, and developmental disorders, and, in animals, with adverse environmental circumstances. Although studies using pharmacological models of stereotyped behavior have identified important brain mechanisms, little is known about the neurobiological basis or function of spontaneous stereotypes in animals or humans. The investigators propose to study the development and neurobiological basis of abnormal stereotyped behavior in wild-type muroid rodents. A laboratory based rodent model offers significant advantages for these kinds of studies as much is known about the neurobiology of these species and large numbers of animals can be rapidly bred. The proposed studies will have three aims: To characterize the development of stereotyped behavior in deer mice; to prevent the development of abnormal stereotyped behavior by early environmental enrichment; and to identify important neurobiological mechanisms that mediate the development and expression of stereotyped behavior. Successful completion of the proposed studies will provide important information about the pathophysiology and treatment of stereotypic movement disorder in humans. Moreover, these studies will address basic brain mechanisms that mediate environmentally-induced stereotyped behavior, and the function of such behavior for the biological organism.

DESCRIPTION (Provided by applicant): We are in the early development stage of building an interdisciplinary team of investigators focused on both basic and clinical issues related to autism. Our goal is to establish a Center for Excellence in Autism Research made up of a highly interactive set of investigators who have a strong record of research in developmental disorders and an increasing focus on and commitment to autism. Thus, consistent with NIH goal, this developmental grant will serve to attract both young and experienced investigators to the field of autism. We have significant resources to be developed including ready access to clinical populations for study and an excellent research environment in which to plan and develop a research Center. Our multidisciplinary research team has a history of collaborative efforts. Among this group are leaders in the field of abnormal repetitive behaviors, behavior analysis/functional analysis, and clinical and basic psychopharmacology. Our focus will be on a core and defining but understudied feature of autism: restricted and repetitive behaviors. We will employ approaches with which we have considerable experience including behavior analysis, psychopharmacology, movement analysis, and animal models. The period of support of the developmental grant will allow completion of several key developmental activities. First, the organizational structure for the successful development of an autism research program will be designed and implemented. A second activity will be to attract outstanding investigators into the field. A third activity will be the development of pilot projects. This will involve development and review of clinical protocols for assessment and treatment of repetitive behaviors disorders as well as research protocols for basic animal studies. Fourth, core services that will be cost effective and support the largest number of proposed or planned projects will be designed and implemented. Fifth, the planning and development of training activities will also be a major undertaking. We will identify current resources (relevant coursework, grand rounds, journal clubs, etc.) and supplement those where necessary.

Little is known about the development of abnormal repetitive behaviors (e.g., stereotypies, rituals) in children at risk for autism and related neurodevelopmental disorders. This lack of knowledge precludes effective early intervention and prevention strategies. Appropriate animal models could provide a wealth of information about the developmental characteristics of such behavior, particularly the neurobiological mechanisms mediating the transition to persistent, fixed, and habitual behavior. Thus, the overall goal of this project will be to examine the development of repetitive motor behavior in a mouse model and identify the neurobiological mechanisms mediating the emergence and expression of habitual, persistent and inflexible motor behavior. We will test hypotheses that the development of persistent repetitive behavior is associated with alterations in corti co-basal ganglia circuitry. Specifically, we will test hypotheses that alterations in basal ganglia pathways (direct and indirect) (Aim #2) as well as striatal compartments (striosome and matrix) (Aim #3) mediate the transition to persistent repetitive behavior. Pharmacological experiments in Aim #2 will not only aid in identifying neurobiological mechanisms but will also identify potential therapeutic targets for drug development.

DESCRIPTION (provided by applicant): Autism spectrum disorders (ASD) are defined, in part, by behavior that can be characterized as restricted and inflexible. Such behavior is exemplified by the so-called "higher order" restricted repetitive behaviors characterized by their insistence on sameness or resistance to change. Behaviors characterized in this way are pervasive in children with ASD and can significantly interfere with opportunities to develop functional behaviors and more complex repertoires. Thus, restricted, inflexible behavior likely adversely impacts brain and behavioral development, and intervention directed toward such behavior should have significant positive impact on neuroplasticity and neurodevelopmental trajectories. The overall goal of the proposed project is to initiate a program of research to develop a novel treatment approach to restricted, inflexible behavior, a clinically important and highly understudied problem in neurodevelopmental disorders in general and autism in specific. Rather than target a particular compulsive, restricted, or repetitive behavior for modification, our proposed strategy is to promote the development of flexibility and variability using age appropriate, functional activities. As such, the proposed project is highly translational as our approach to intervention is based on a body of animal and human laboratory studies that have established the empirical foundation for such an approach. Effective interventions are hypothesized to have generalizable effects on development and will be highly translatable to other neurodevelopmental disorders. Thus, we propose to assess restricted, inflexible behavior in children with ASD and typically developing controls and then pilot test an experiential intervention to determine if it will directly promote variable and flexible adaptive responding in children with ASD. This project is highly innovative in targeting flexibility and variability as goals of the intervention. No systematic efforts have been made to develop effective methods for the behavioral treatment of the general rigidity/inflexibility that is most characteristic of autism and common in related neurodevelopmental disorders. Finally, the proposed project represents a translational effort to take laboratory-based animal and human studies and apply them to a focused intervention directed at restricted, inflexible behavior that can ultimately be conducted in a community setting. If successful, the proposed treatment approach should have considerable potential for becoming a widely used, cost effective treatment approach. PUBLIC HEALTH RELEVANCE: Autism spectrum disorders (ASD) are defined, in part, by behavior that can be characterized as restricted and inflexible. No systematic attempts have been made to develop effective methods for the behavioral/educational treatment of the higher-order ritualistic repetitive behaviors and general rigidity/inflexibility that are most characteristic of autism. Establishing assessment methods for restricted, inflexible behavior and interventions to increase variability and flexibility in responding will be of significant benefit to individuals with autism and their families.

Project Summary Restricted, repetitive behavior refers to multiple behavioral categories that include stereotyped movements, compulsions, and rituals. Repetitive behavior is diagnostic for autism spectrum disorders (ASD), highly prevalent in syndromic and non-syndromic intellectual and developmental disability (IDD), and common in certain neurological disorders (e.g. Tourette syndrome, fronto-temporal dementia). Despite its clinical importance, effective interventions for repetitive behavior are lacking owing, at least in part, to only a rudimentary understanding of the relevant neural circuitry mediating such behavior. Identifying discrete neural pathways controlling repetitive behaviors is key to determining neurobiological mechanisms and developing effective treatments. Our prior work, using two mouse models of repetitive behavior, has identified cortico- basal ganglia circuitry dysregulation, specifically decreased neuronal activation in brain areas associated with the indirect basal ganglia pathway. What is lacking, however, is direct evidence of discrete basal ganglia projections that control the expression of repetitive behavior. Thus, the overall goal of this project is to determine specific cortical basal ganglia pathways that control repetitive behavior. We will test two hypotheses: activation of the indirect basal ganglia pathway via disinhibition of the subthalamic nucleus (STN) will significantly and rapidly reduce repetitive behavior and inhibition of the hyperdirect pathway will exacerbate repetitive behavior. To test these hypotheses, we will employ in vivo optogenetics to manipulate, with the requisite temporal and spatial resolution, the critical functional circuitry hypothesized to mediate the expression of repetitive behavior. Using this approach, we propose to test directly the importance of the indirect and the hyperdirect basal ganglia pathways in mediating repetitive behavior. This will be done using an inbred mouse strain (C58) that exhibits a well-characterized, robust repetitive behavior phenotype. Dissecting the basal ganglia circuitry controlling the expression of repetitive behavior will be innovative and impactful and guide the development of novel treatments in disorders involving aberrant repetitive behavior.