Karen Gale - US grants

bicuculline; anticonvulsants; prosencephalon; basal ganglia; superior colliculus; morphine; gamma aminobutyrate; substantia nigra; neurotransmitter receptor; neurochemistry; neural information processing; serotonin; neuroanatomy; generalized seizures; convulsions; neural transmission; histology; electroencephalography; laboratory rat; Primates; brain electrical activity;

The effect of chronic treatment with antipsychotic drugs will be examined in rats with respect to alterations in neurochemical parameters in selected brain regions. An attempt will be made to discriminate changes which are related to behavioral alterations induced by the drugs. In particular, dopamine-containing, GABA-containing and Substance-P-containing pathways within the basal ganglia and GABA-containing outputs from the basal ganglia will be manipulated pharmacologically and the resulting neurochemical and behavioral effects will be compared. Neurochemical parameters to be examined include GABA receptor binding, GABA turnover, and enzymes associated with GABA synthesis and degradation. Behavioral parameters under study include stereotyped hyperactivity induced by dopamine stimulants or intranigral application of GABA agonists, and catalepsy induced by antipsychotic drugs. Both acute and chronic drug treatments will be compared in order to distinguish between short-term and long-term influences of the drugs on the neural circuits of interest. In certain cases, a neural pathway and its target region will be characterized neurochemically and anatomically before examining the influence of antipsychotic drug treatment on the pathway. Emphasis will be placed on research, on expanding the existing methodological and technical capabilities of the laboratory, and on developing additional techniques applicable to the proposed area of investigation. Skills to be expanded and developed include quantitative histochemical procedures for neurotransmitter-associated enzymes, neuroanatomical tracing techniques, high pressure liquid chromatography, procedures for monitoring neurotransmitter synthesis and release in brain slices, methods for transplantation of fetal rat brain nuclei or adrenal chromaffin cells into adult rat brain, radiolabelling of GABA-transaminase for purposes of examining its activity and transport in vivo, and radioimmunoassay procedures for analysis of pepetides.

The effects of chronic administration of cocaine will be measured with respect to 1) changes in GABA-related neurochemical parameters in the nigrostriatal system, 2) changes in stereotyped hyperactivity produced by cocaine, apomorphine and other psychomotor stimulants, and 3) changes in the ability of cocaine and apomorphine to antagonize neurochemical and behavioral responses induced by dopamine-receptor antagonists. The neurochemical mechanisms responsible for the development of these changes, and the persistence of these changes following drug withdrawal will be examined. Pharmacological (dopamine agonist and antagonists, GABA agonists) and surgical (lesions of neural pathways containing dopamine, serotoin) manipulations will be evaluated for their ability to prevent the changes induced by chronic cocaine treatment. In the process we will determine whether the neurochemical mechanisms involved in a) the development of sensitization to cocaine and/or b) the development of tolerance to apomorphine, are similar to those mechanisms responsible for the changes in GABA synthesis and receptor function following chronic exposure to cocaine. These studies will help to a) determine how GABAergic dopaminergic, and possibly serotonergic pathways interact in the basal ganglia, b) identify the neural circuits which are involved in the psychomotor stimulant actions of drugs such as cocaine, and c) determine how these neural circuits can be altered by repeated, prolong exposure to psychomotor stimulants. The results will contribute to an understanding of the neurochemical basis for some of the toxic and pathological snydromes induced by chronic abuse of psychomotor stimulants. At the same time, this information may aid in the design and development of effective antidotes and therapy for disorders associated with stimulant abuse.

The proposed research will employ focal intracerebral microinfusions of drugs stereotaxically directed at specific regions of the medial temporal lobe: perirhinal piriform cortex, entorhinal cortex, parahippocampal gyrus, and amygdala. These microinfusions will be administered to awake, behaving monkeys via chronically indwelling cappulas, immediately prior to evaluating performance on a visual recognition memory task. The drugs to be used for the intracerebral infusions are selected for their effects on specific amino acid neurotransmitter receptors: 1) drugs which block excitatory transmission mediated via glutamate receptors (NMDA and non-NMDA subtypes) and 2) drugs which enhance inhibitory transmission mediated via GABAA receptors. The brain regions to be investigated have been selected on the basis of studies in the literature which have demonstrated significant deficits in visual recognition memory following individual or conjoint lesions of those regions. In the experiments proposed, each subject will be repeatedly tested under drug and control conditions so that each subject serves as its own control and different drugs and infusions into various brain areas can be compared within the same subject. Once one or more brain areas (alone or in combination) have been identified in which the drug treatments impair performance on the recognition memory task, the anatomic site-specificity of the drug effect will be evaluated. It is expected that blockade of excitatory transmission in perirhinal and entorhinal cortex, as accomplished by the focal application of glutamate antagonists in GABA agonists, will rapidly and reversibly impair performance on a visual recognition memory task. Furthermore, it is expected that this acute impairment will require only unilateral drug application, in contrast to the bilateral damage required in chronic ablation studies. It is hoped that the results of these studies will: (1) provide the basis for a more detailed investigation of the neurochemical and neuroanatomic substrates of memory functions subserved by neural networks in the limbic cortex; and (2) provoke additional studies in the nonhuman primate using focally applied chemical agents to probe brain regions crucial for cognitive function. The use of reversibility-acting intracerebral focal drug infusions is expected to offer several advantages in studying the role of specific brain regions for memory functions in non-human primates. In particular, a) the ability to use each subject as its own control reduces experimental variability and decreases the number of monkeys needed to generate interpretable data; b) the ability to test the same subject repeatedly using different drugs or different anatomical sites of infusion, maximizes the amount of experimental data that can be generated from a single monkey and increases the anatomical resolution that can be obtained; c) the ability to avoid damage to fibers of passage and problems with secondary degeneration which complicate the interpretation of lesion studies; and d) the ability to avoid permanent damage to the monkeys allows for non-terminal experiments in which the animals can be used subsequently for other studies. These advantages could greatly enhance the feasibility and utility of pursuing this important field of research in monkeys. The project furthers VPW program objectives to provide opportunities for women to advance their careers in science or engineering through research, and to encourage other women to pursue careers in these areas through the investigator's enhanced visibility as a role model on the host campus. The proposed activities which contribute to the second objective include: training and mentoring graduate and undergraduate students by involving them in the experiments proposed; teaching a graduate elective course in Psychology (also open to undergraduates); leading a workshop for Women in Science through the Department of Women's Studies; presenting research accomplishments in lectures/colloquia sponsored by the Psychology Department and also in a forum sponsored by the Northwest Center for Research on Women; regularly attending student-faculty journal clubs in the Psychology Department, as well as weekly Student Research Seminars in physiological psychology.

The substantia nigra (SN) is a critical site at which GABA agonist drugs act to exert anticonvulsant actions in a variety of experimental seizure models in the rodent. The anticonvulsant actions evoked from SN have been shown to be mediated via disinhibition of the deep superior colliculus (DSC). The goal of the research in the present proposal is to extend our knowledge of the functional neuroanatomy of the nigral circuitry with respect to seizure control in several important respects: 1) To determine the role of serotonin (5HT) in SN for regulation of seizure susceptibility and to examine interactions between manipulations of 5HT and GABA-mediated transmission in SN in seizure control. These studies, which are an outgrowth of our recent findings that intranigral 5HT agonists exert anticonvulsant actions, will test the hypothesis that 5HT activity can compensate for a loss of GABA function in SN with respect to maintaining seizure control; 2) To determine whether intranigral GABA agonist treatment can attenuate neuronal damage induced by prolonged seizure activity in the rat. These studies (prompted by our recent evidence that unilateral GABA agonist treatment in SN attenuates the seizure-evoked increase in regional glucose utilization without attenuating the seizures) will test the hypothesis that GABA-mediated inhibition of the SN in one hemisphere will protect against seizure-induced neuronal damage in the same hemisphere even though the seizures themselves are not suppressed; 3) To determine whether the anticonvulsant action of GABA-mediated inhibition in SN can be extended to the primate brain. By using an acute focally- evoked seizure model which we have developed in the nonhuman primate, we will test the hypothesis that enhancing GABA-mediated transmission bilaterally in the SN of the monkey will be anticonvulsant; 4) To determine whether the anticonvulsant action of GABA receptor blockade in the DSC can be extended to the primate brain, using the same seizure model as in (3) above; 5) To evaluate the influence of the DSC on the initiation and propagation of seizure discharge in the limbic system of the rat. These studies will use depth EEG recording to test the hypothesis that blockade of GABA in the DSC interrupts the development of seizure discharge throughout the limbic circuitry; 6) To determine whether excitatory inputs to SN from the subthalamic nucleus (STN) play an important role in regulating seizure susceptibility. These studies will test the hypothesis that inhibition of the STN bilaterally will exert an anticonvulsant effect by reducing excitatory inputs (mediated via excitatory amino acids) to SN: The results of the proposed studies will advance our understanding of the neurotransmitter receptor interactions in SN and interconnections with other regions such as DSC and STN which are important for seizure control. At the same time, the proposed experiments will verify the extent to which the basic findings with rodent models are applicable to the primate brain, thereby allowing for clinically relevant conclusions to be formulated. It is expected that novel therapeutic strategies for the control of seizure disorders may emerge from these investigations, and in addition, insights into sources of pathology that may contribute to the etiology of certain forms of human epilepsy may be generated.

[unreadable] DESCRIPTION (provided by applicant): A fascination with disorders of the brain draws students to pursue Ph.D. training in neuroscience. However, although we have one of the most successful Ph.D. training programs in integrative neuroscience, our current curriculum divorces the basic neuroscience taught in the core curriculum from the clinical neuroscience incorporated in a handful of elective offerings. Furthermore, many of the elective offerings address clinical neuroscience in an abstract manner, with little or no first hand exposure to the disorders themselves in a clinical context. The goal of this application is to develop a course in which a clinical understanding of neurological and psychiatric disorders inform, enrich, and contextualize basic neuroscience education throughout the first year of the predoctoral training period. To achieve this goal, the following specific aims will be pursued: 1) Design, develop and introduce a first year core course in the Neurobiology of Disease to incorporate interactive disease-oriented problem-solving as an organizing and assessment principle in the classroom, introducing both clinical case presentations and clinical research literature in the context of the basic science topics that the students are learning concurrently in the basic neuroscience core course. 2) Use the repetition and recurrence of selected disease-oriented themes (e.g., Autism, Stroke, Epilepsy, Alzheimer's, Schizophrenia, Spinal Cord Injury, Addiction. Parkinson's) as a mechanism for cutting across and integrating the various levels of analysis: from genes to systems, channels to cognition, and circuits to emotions. 3) Develop joint presentations on selected topics by clinicians and basic scientists in order to integrate the basic science with the clinical etiological, diagnostic and therapeutic features, 4) Develop an archive of web-based interactive video-demonstrations of patient presentations and 5) Introduce discussions of clinical 'neuroethics' into the Skills and Ethics course. Outcomes will be evaluated by determining impact on student performance in comprehensive exams, undergraduate teaching, research seminars, individual predoctoral fellowship applications, publications, and dissertations. The application will utilize the translational programs and clinical faculty from the Georgetown Hospital, the VA Medical Center (Center For Schizophrenia and Neuroscience Research), National Rehabilitation Hospital, and Children's National Medical Center. We expect that by integrating clinical neuroscience into the first year predoctoral curriculum, our graduates will gain an appreciation for the clinical context for their research, ideas for novel research questions, and a facility for establishing clinical collaborations. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): The Interdisciplinary Program in Neurosciences (IPN) at Georgetown University is a broad-based, transdisciplinary, non-departmental program leading to a Ph.D. in Neuroscience. The program, established in 1994, trains students in the scholarly pursuit of research in integrative neuroscience, from the cell to the intact behaving organism. The 32 core training faculty and 17 supporting faculty are drawn from 12 clinical and basic science departments on the Main Campus and Medical Center;they span a breadth of inquiry, ranging from neurotransmitter receptors and signal transduction, to behavior and human disease. Areas of research strengths include 1) neural injury, degeneration, and plasticity;2) synaptic modulation and signal transduction;4) neural substrates of autism, epilepsy, and addiction;and 5) telencephalic neural networks subserving sensory processing, memory and language. Students gain training in a range of approaches, including molecular, genetic, neurophysiological, cognitive testing, and imaging techniques. Training Grant funds support prethesis training (8 slots during the first 2 years);research grants and individual fellowships support thesis research. The program enrolls 40-50 thesis and prethesis students. Aggressive recruitment of underrepresented racial and ethnic applicants continues to be a top priority. The training environment fosters interactive, pandisciplinary research of both faculty and trainees. Over 40% of the core training faculty are in close proximity in the Research Building, with state-of-the-art core facilities and custom designed laboratory and office space. Faculty are highly collaborative;students are encouraged to seek co-mentorship between faculty with interfacing interests and complementary approaches. All core training faculty have research grant support and fully equipped facilities for training pre-and postdoctoral students. The recent recruitment of several neuroscience faculty into the Department of Pharmacology, and the growth of the Department of Neuroscience, has expanded the equipment, facilities and faculty expertise available to the training program. The training program includes broad-based didactic coursework, as well as rotations in laboratories of the training faculty. The trainees participate in a seminar series, national professional meetings, journal clubs, intensive laboratory research, and training in several essential professional skills (writing and reviewing manuscripts, grantsmanship, mentorship, teaching, conflict resolution, career choices, oral presentations) and their ethical dimensions. Opportunities for gaining practical teaching experience at the undergraduate and secondary school levels are abundant and encouraged.

DESCRIPTION (provided by applicant): The Interdisciplinary Program in Neurosciences (IPN) at Georgetown University is a broad-based, transdisciplinary, non-departmental program leading to a Ph.D. in Neuroscience. The program, established in 1994, trains students in the scholarly pursuit of research in integrative neuroscience, from the cell to the intact behaving organism. The 32 core training faculty and 20 supporting faculty are drawn from 14 clinical and basic science departments on the Main Campus and Medical Center;they span a breadth of inquiry, ranging from neurotransmitter receptors and signal transduction, to behavior and human disease. Areas of research strengths include 1) neural injury, degeneration, and plasticity;2) synaptic modulation and signal transduction;4) neural substrates of autism, epilepsy, schizophrenia, dementias, and addiction;and 5) telencephalic neural networks subserving sensory processing, memory and language. Students gain training in a range of approaches, including molecular, genetic, neurophysiological, cognitive testing, computational and imaging techniques. Training Grant funds support prethesis training (8 slots during the first 2 years);research grants and individual fellowships support thesis research. The program enrolls 40-50 thesis and prethesis students. Aggressive recruitment of underrepresented racial and ethnic applicants continues to be a top priority. The training environment fosters interactive, pandisciplinary research of both faculty and trainees. Over 40% of the core training faculty are in close proximity in the Research Building, with state-of-the-art core facilities and custom designed laboratory and office space. Faculty are highly collaborative;students are encouraged to seek co-mentorship between faculty with interfacing interests and complementary approaches. All core training faculty have research grant support and fully equipped facilities for training pre-and postdoctoral students. The recent recruitment of several neuroscience faculty into the Departments of Pharmacology, Psychology and Neuroscience, has expanded the equipment, facilities and faculty expertise available to the training program. The training program includes broad-based didactic coursework, as well as rotations in laboratories of the training faculty. The trainees participate in a seminar series, national professional meetings, journal clubs, intensive laboratory research, and training in several essential professional skills (writing and reviewing manuscripts, grantsmanship, mentorship, teaching, conflict resolution, career choices, oral presentations) and their ethical dimensions. Opportunities for gaining practical teaching experience at the undergraduate and secondary school levels are abundant and encouraged. PUBLIC HEALTH RELEVANCE: The goal of the proposed training program is to prepare future scientists for a career as highly creative, inquisitive and productive biomedical researchers. We seek to provide the trainees, who are pursuing their Ph.D. in neuroscience, with broad-based interdisciplinary training relevant to understanding a variety of diseases and disorders of the nervous system. Through didactic coursework, laboratory research, career development skills training, and instruction in the responsible conduct of research, the students supported through this training mechanism will be poised to make important discoveries aimed at preventing and curing a spectrum of neurological and psychiatric disorders, such as autism, epilepsy, schizophrenia, dementias, communicative disorders, and addiction.

DESCRIPTION (provided by applicant): The proposal aims to identify the neural substrates in the primate brain that are responsible for abnormal socio-emotional behavior. This understanding is vital for developing both diagnostic and therapeutic approaches to identify and treat the abnormal brain circuitry in neuropsychiatric conditions such as affective and anxiety disorders. The field of social behavior research still lacks appropriate animal models for social pathology that leads to inappropriate aggression, social anxiety/phobias, social withdrawal/detachment, impulsivity, or defensiveness. The study of the neurobiology of social behavior in the nonhuman primate is especially promising since the impairment in social interactions and emotional processing generates symptomatology that resembles psychopathology observed in human patients. The proposed research seeks to investigate the novel components of the amygdala-based network that regulate socioemotional responses in nonhuman primates in order to account for imbalances that can give rise to psychopathology in the absence of structural lesions. We have determined that reversible pharmacological manipulations of specific sites within the amygdala result in profound changes in social interactions and emotional behavior in macaque monkeys. Further, we have discovered that the activation of the intermediate and deep layers of the superior colliculus (DLSC; a midbrain structure) by focal infusions of GABAA antagonist bicuculline, has a profound impact on emotional reactivity and defensive responses. In the proposed experiments, we will use the method of intracerebral focal drug infusions of either the GABA agonist muscimol or the GABA antagonist bicuculline aimed at various sites within either amygdala or DLSC to test further the role of these structures in socioemotional behavior. Specific Aim 1 will define specific nuclei within the amygdala responsible for GABA- mediated regulation of socioemotional responses. Aim 2 will test the hypothesis that disinhibition of DLSC will evoke aggressive behavior and emotional hyperactivity. Aim 3 will assess the role of DLSC and amygdala in fear-potentiated startle, a conditioning paradigm that is altered in human patients with PTSD. Social interactions will be assessed in dyads, each infused animal will be paired with a familiar non-infused partner; videotaped behaviors will be analyzed by two independent observers using a standardized behavioral categorization. Special attention will be paid to reciprocal social interactions, aggressive behavior, and emergence of any abnormal behaviors (e.g., stereotypies, self-directed behaviors). Emotional reactivity will be tested by presenting the animals with a standard set of stimuli (neutral, positive, and negative). An understanding of the functional relationship between the amygdala-derived and colliculus-derived regulation of social interactions and emotional tone is expected to reveal novel targets for both etiology and therapeutic intervention for affective and anxiety disorders.