1985 |
Malenka, Robert C |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
Cellular Actions of Dopamine On Neurons @ University of California San Francisco |
0.954 |
1989 — 2012 |
Malenka, Robert C |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. R29Activity Code Description: Undocumented code - click on the grant title for more information. R37Activity Code Description: To provide long-term grant support to investigators whose research competence and productivity are distinctly superior and who are highly likely to continue to perform in an outstanding manner. Investigators may not apply for a MERIT award. Program staff and/or members of the cognizant National Advisory Council/Board will identify candidates for the MERIT award during the course of review of competing research grant applications prepared and submitted in accordance with regular PHS requirements. |
Mechanisms of Synaptic Plasticity in the Hippocampus
DESCRIPTION (provided by applicant): The ability of the mammalian brain to undergo long-lasting, activity-dependent changes in synaptic function and structure importantly contributes to the neural circuit modifications that underlie many forms of adaptive and pathological experience-dependent plasticity, including learning and memory. A leading model for such synaptic plasticity is NMDA receptor-dependent long-term potentiation (LTP). Although progress has been made in understanding the mechanisms underlying LTP, much remains unknown. This proposal tests the novel hypothesis that postsynaptic complexins play a mandatory role in the trafficking of AMPA receptors to the plasma membrane during LTP and also in the growth of dendritic spines that accompanies LTP. Complexins are critical for the calcium-dependent regulation of transmitter release via direct interactions with the SNARE proteins that are required for presynaptic vesicle fusion. This project will perform experiments that for the first time examine the synaptic functions of postsynaptic complexin. The experiments use a "molecular replacement" strategy, which incorporates the simultaneous, viral-mediated expression of multiple shRNAs to knockdown complexin levels as well as express a "replacement" version of wildtype or mutant complexin in single hippocampal pyramidal cells in vivo or in vitro. Electrophysiological assays in acute hippocampal slices and cell biological assays in cultured neurons will be performed to determine the consequences of the complexin manipulations on basal synaptic responses, LTP, long-term depression and AMPA receptor exocytosis and endocytosis. The role of postsynaptic complexin on the spine growth that accompanies LTP will also be examined. These experiments will elucidate novel molecular mechanisms by which excitatory synapses in the mammalian brain are likely modified during various forms of experience-dependent plasticity, including learning and memory. The results will also open up new, innovative areas of research on the postsynaptic membrane trafficking underlying LTP. In addition, this research will provide information that is critical for the development of agents that modify synaptic transmission in ways that promote cognitive function and alleviate psychiatric symptoms. PUBLIC HEALTH RELEVANCE: Learning and memory involves long-lasting modification of the communication between nerve cells at their physical connections, which are termed synapses. This project will use sophisticated experimental techniques to elucidate some of the key molecular mechanisms underlying how this modification happens. The information that will be collected is essential for developing more effective treatments for the deterioration of cognitive function that accompanies many forms of mental illness.
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1 |
1991 — 1993 |
Malenka, Robert C |
K02Activity Code Description: Undocumented code - click on the grant title for more information. |
Modulation of Synaptic Transmission in the Hippocampus @ University of California San Francisco
This proposal for an ADAMHA Research Scientist Development Award (RSDA) outlines a series of experiments which address fundamentally important questions about the mechanisms underlying long-term potentiation (LTP). LTP is along-lasting increase in the strength of synaptic transmission produced by brief, repetitive activation of excitatory pathways. It is the most compelling model in the mammalian brain for a neural mechanism related to learning and memory. Using cellular electrophysiological and biochemical techniques, the proposed experiments will examine the intracellular factors which are required for the induction and maintenance of LTP in the CA1 region of the hippocampal slice preparation. Collaboration with several neurochemists and molecular biologists will permit the utilization of biochemical methodology to test the effectiveness of experimental manipulations. This will not only make the experimental results more meaningful but also will foster my scientific growth and facilitate the development of techniques and approaches not presently used in my laboratory. The induction of LTP in the CA1 region of the hippocampus requires activation of postsynaptic NMDA (N-methyl-D-aspartate) receptors and concomitant postsynaptic depolarization leading to the influx of calcium, the presumptive critical trigger for LTP. It has been proposed that this rise in calcium may activate specific protein kinases. An initial set of experiments will examine the effects on basal synaptic transmission of non- specific kinase inhibitors, specific peptide inhibitors of calcium/calmodulin-dependent protein kinase II or protein C, and okadaic acid, a phosphatase inhibitor. Whether these compounds act primarily pre- or postsynaptically also will be determined. Biochemical assays of in situ substrate phosphorylation will be performed to determine directly the efficacy of the various kinase or phosphatase inhibitors. Intracellular biochemical pathways potentially involved in LTP will be examined by: (1) determining whether kinase inhibitors depress previously established LTP to a greater degree than basal synaptic transmission, (2) determining the effects on LTP of GTP-binding protein inhibitors or lithium, and (3) monitoring ionic conductances known to be modulated by second messenger systems. The involvement of de novo protein synthesis or RNA synthesis in LTP will be examined using specific protein synthesis and RNA synthesis inhibitors. Biochemical assays will determine the effectiveness of these compounds. Preliminary results indicate that it is possible to generate two distinct forms of NMDA receptor-dependent synaptic enhancement; LTP and a decremental short-term synaptic potentiation (STP). Experiments will be performed to determine the factors which control the duration of synaptic potentiation and the events responsible for converting STP to LTP. A final section will describe novel experimental approaches which eventually may permit more specific and potent manipulation of neuronal biochemical pathways. A detailed understanding of the mechanisms underlying synaptic transmission and LTP will yield important insights into the cellular and molecular properties underlying synaptic plasticity and thus human memory. This in turn may eventually lead to pharmacological interventions which either promote the ability to learn and remember or retard the deterioration of this ability.
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0.954 |
1994 — 1995 |
Malenka, Robert C |
K02Activity Code Description: Undocumented code - click on the grant title for more information. |
Modulation of Synaptic Transmission in Hippocampus @ University of California San Francisco
This proposal for an ADAMHA Research Scientist Development Award (RSDA) outlines a series of experiments which address fundamentally important questions about the mechanisms underlying long-term potentiation (LTP). LTP is along-lasting increase in the strength of synaptic transmission produced by brief, repetitive activation of excitatory pathways. It is the most compelling model in the mammalian brain for a neural mechanism related to learning and memory. Using cellular electrophysiological and biochemical techniques, the proposed experiments will examine the intracellular factors which are required for the induction and maintenance of LTP in the CA1 region of the hippocampal slice preparation. Collaboration with several neurochemists and molecular biologists will permit the utilization of biochemical methodology to test the effectiveness of experimental manipulations. This will not only make the experimental results more meaningful but also will foster my scientific growth and facilitate the development of techniques and approaches not presently used in my laboratory. The induction of LTP in the CA1 region of the hippocampus requires activation of postsynaptic NMDA (N-methyl-D-aspartate) receptors and concomitant postsynaptic depolarization leading to the influx of calcium, the presumptive critical trigger for LTP. It has been proposed that this rise in calcium may activate specific protein kinases. An initial set of experiments will examine the effects on basal synaptic transmission of non- specific kinase inhibitors, specific peptide inhibitors of calcium/calmodulin-dependent protein kinase II or protein C, and okadaic acid, a phosphatase inhibitor. Whether these compounds act primarily pre- or postsynaptically also will be determined. Biochemical assays of in situ substrate phosphorylation will be performed to determine directly the efficacy of the various kinase or phosphatase inhibitors. Intracellular biochemical pathways potentially involved in LTP will be examined by: (1) determining whether kinase inhibitors depress previously established LTP to a greater degree than basal synaptic transmission, (2) determining the effects on LTP of GTP-binding protein inhibitors or lithium, and (3) monitoring ionic conductances known to be modulated by second messenger systems. The involvement of de novo protein synthesis or RNA synthesis in LTP will be examined using specific protein synthesis and RNA synthesis inhibitors. Biochemical assays will determine the effectiveness of these compounds. Preliminary results indicate that it is possible to generate two distinct forms of NMDA receptor-dependent synaptic enhancement; LTP and a decremental short-term synaptic potentiation (STP). Experiments will be performed to determine the factors which control the duration of synaptic potentiation and the events responsible for converting STP to LTP. A final section will describe novel experimental approaches which eventually may permit more specific and potent manipulation of neuronal biochemical pathways. A detailed understanding of the mechanisms underlying synaptic transmission and LTP will yield important insights into the cellular and molecular properties underlying synaptic plasticity and thus human memory. This in turn may eventually lead to pharmacological interventions which either promote the ability to learn and remember or retard the deterioration of this ability.
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0.954 |
1995 — 1997 |
Malenka, Robert C |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Drugs of Abuse &Synaptic Processes in Nucleus Accumbens @ University of California San Francisco
Drug abuse and addiction are major societal problems with devastating medical and economic consequences. The development of more effective treatment regimens requires a detailed understanding of the neural mechanisms which mediate the effects of drugs of abuse. This proposal outlines an extensive series of experiments which address fundamentally important questions about the mechanism of action of the psychostimulant drugs, cocaine and amphetamine, in the nucleus accumbens. The nucleus accumbens is part of the mesolimbic dopamine system and is considered a fundamental component of the neural circuits which mediate many of the behavioral and reinforcing actions of drugs of abuse. Despite the clear importance of the nucleus accumbens in mediating many of the behavioral effects of drugs of abuse, relatively little is known about synaptic processes within this structure and how these are modified by acute and chronic exposure to such drugs. An initial goal of the proposed experiments is to examine excitatory synaptic transmission and the different forms of synaptic plasticity which can be generated at the synapse between prelimbic cortical afferents and cells in the core region of the nucleus accumbens. This will be accomplished using an in vitro rat brain slice preparation and single cell electrophysiological recording techniques. The occurrence and mechanisms of both long-term potentiation (LTP) and long-term depression (LTD) will be examined. Because a major action of psychostimulant drugs such as cocaine and amphetamine is to block the re-uptake of the neurotransmitter, dopamine (DA), a second series of experiments will examine the actions of DA on synaptic transmission and pharmacologically characterize the DA receptor subtype mediating the observed effect(s) using subtype specific agonists and antagonists. Whether endogenous DA or exogenously applied DA influences the generation of LTP or LTD will also be examined and if so, the DA receptor subtype(s) responsible for these effects will be determined. After elucidating the actions of DA on synaptic physiology and plasticity, the effects of acute application of cocaine and amphetamine will be determined. Two related questions will be addressed: (1) do these psychostimulants closely mimic the actions of DA on synaptic physiology and synaptic plasticity? and (2) do they exert their actions via the same receptor mechanisms as DA? In a final extensive series of experiments, cocaine or amphetamine will be chronically administered to animals for 2 weeks at which point the effects of DA, cocaine, and amphetamine on synaptic physiology and synaptic plasticity in the nucleus accumbens will be examined and compared to those observed in control tissue. Whether modifications in the function of DA receptors or the DA transporter contribute to any observed changes will also be examined. The experiments in this proposal should provide fundamental information about the mechanisms by which cocaine and amphetamine modify synaptic processes in the nucleus accumbens. Such information is critical for a detailed understanding of the neural mechanisms which lead to drug abuse and drug addiction and will eventually lead to the development of pharmacological agents which modify these mechanisms so as to promote abstinence and retard the development of addiction.
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0.954 |
1996 — 2006 |
Malenka, Robert C |
K02Activity Code Description: Undocumented code - click on the grant title for more information. P41Activity Code Description: Undocumented code - click on the grant title for more information. |
Synaptic Plasticity in the Mammalian Brain @ University of California San Francisco
DESCRIPTION (Adapted from applicant's abstract): This proposal is a competing continuation application for an Independent Scientist Award (K02). Such an award will provide the scientific freedom and institutional support that are required to pursue my career goal of elucidating the cellular and biochemical mechanisms underlying synaptic plasticity in the mammalian brain. Long-lasting, activity-dependent changes in the strength of synaptic transmission play a critical role in the development of neural circuits and in the storage of information. Such changes occur in brain regions that are involved in the pathophysiology of many neuropsychiatric disorders including schizophrenia, drug addiction and Alzheimer's disease. Thus the proposed examination of synaptic plasticity in several different brain regions will lead to a better understanding of the etiology of brain disorders and to the development of drugs that alleviate psychiatric symptoms and prevent the deterioration of cognitive function that accompanies mental illness, drug addiction and aging. The most well-understood models of synaptic plasticity are the forms of long-term potentiation (LTP) and long-term depression (LTD) that occur in the hippocampus. An extensive series of experiments will examine some of the critical issues concerning the mechanisms responsible for LTP and LTD. The role of changes in postsynaptic calcium concentration and the modification of glutamate receptor function by protein kinases and protein phosphatases will be a major focus. Via collaborations, I will have the opportunity to interact with and learn from preeminent investigators studying these issues. I will also learn about techniques and approaches not presently used in my laboratory. A second project will examine the mechanisms of synaptic plasticity in the nucleus accumbens, a region of brain implicated in drug abuse and addiction. The basic mechanisms of LTP and LTD in this region will be defined and the modulation of synaptic plasticity by dopamine and the psychostimulants, cocaine and amphetamine, will be examined. This represents a new area of research and provides an opportunity for learning about and contributing to the current understanding of the biological basis of drug abuse and addiction. A final project will examine the development and mechanisms of synaptic plasticity at thalamocortical synapses in somatosensory cortex. These experiments will provide important information about the mechanisms that control the development of cortical circuitry and will expand my potential to make significant contributions to an area of research with broad clinical implications.
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1 |
1997 — 2001 |
Malenka, Robert C |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Cellular &Biochemical Mechanisms Underlying Mossy Fiber Long Term Potentiation @ University of California San Francisco
Long-lasting, activity-dependent changes in the strength of synaptic transmission play a critical role in the development of neural circuits and in the storage of information. Such changes also appear to play an important role in the recovery of the brain from a variety of pathological insults. The most compelling and extensively studied model for such changes has been that form of long-term potentiation (LTP) observed in hippocampal CAl pyramidal cells. It is clear, however, that there are many forms of synaptic plasticity and that their underlying mechanisms differ. The primary goal of this project is to elucidate the molecular mechanisms underlying the novel form of LTP observed at the synapses between mossy fibers and hippocampal CA3 pyramidal cells (MF LTP). Unlike the LTP in CAl cells, MF LTP does not require activation of NMDA receptors but appears to be induced by presynaptic activation of the cAMP-dependent protein kinase (PKA) resulting in a long-lasting increase in neurotransmitter release. A number of different physiological and biochemical approaches will be used to examine MF LTP. Because MF LTP can be generated in single cell cultures of dentate granule cells, it will be possible to directly monitor changes in synaptic vesicle exocytosis and endocytosis using the fluorescent dye FMl-43. Biochemical assays will be used to monitor the time course of changes in cAMP levels and PKA activity during MF LIP as well as to determine whether specific presynaptic phosphoproteins, in particular rabphilin 3A, may be involved in this form of plasticity. A complementary set of experiments will examine MF LTP in a line of mutant mice which is lacking the specific presynaptic protein, rab3A. Because neurotrophins appear to play an important role in experience-dependent cortical plasticity and also cause long-lasting increases in neurotransmitter release, their synaptic actions will be examined and compared to MF LTP. An examination and comparison of MF LIP and the synaptic actions of neurotrophins will markedly enhance our understanding of the basic mechanisms of synaptic plasticity in the mammalian brain. This in turn will facilitate the development of interventions that will either prevent or promote recovery from the pathological insults accompanying a number of neurologic disorders such as stroke and epilepsy.
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0.954 |
1999 — 2009 |
Malenka, Robert C |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Drugs of Abuse &Synaptic Processes in Dopamine Systems
DESCRIPTION: (Applicant's Abstract) A major component of the neural circuit that is thought to mediate "incentive-motivation" and "reinforcement" is the mesolimbic dopamine (DA) system, which consists of the ventral tegmental area (VTA) and the nucleus accumbens (Nac) along with their afferent and efferent connections. The great clinical importance of developing a sophisticated understanding of this brain system has been emphasized because of is importance in mediating many of the behavioral actions of drugs of abuse as well as is role in mental illnesses such as schizophrenia. Although much is known about the anatomy of the NAc and VTA and some of the cellular and molecular changes that occur within these structures following exposure to therapeutic drugs as well as drugs of abuse, surprisingly little is known about basic synaptic processes in these structures and how they might be modified by normal and pathological experience. A well characterized behavioral response that involves modifications within the mesolimbic DA system is the behavioral sensitization that occurs in response to psychomotor stimulants as well as other drugs of abuse. The overriding hypothesis underlying this proposal is that synaptic plasticity at excitatory inputs to both the NAc and VTA is critically important for mediating both behavioral sensitizaton to psychomotor stimultants and for the functioning of the mesolimbic DA system during normal behavior. The major goals of the proposed experiments re to elucidate the basic properties and mechanism of synaptic plasticity at excitator synapses in the NAc an TA. This will be accomplished using whole cell patch clamp recording techniques and in vitro brain slice preparations. Specific studies will include detailed analysis of long-term depression (LTD) in the Nac and long-term potentiation (LTP) in the VTA. The effects of dopamine (DA) and psychomotor stimulants (cocaine and amphetamine) on these phenomena will also be examined. Finally whether prolonged in vivo exposure to amphetamine modifies excitatory synaptic transmission in the NAc and VTA will be determined. These experiments will provide important information about the mechanisms by which synaptic transmission in the mesolimbic DA system is modified both during normal behavior and following prolonged exposure to psychomotor stimulants. Such information is critical for a detailed understanding of the neural mechanism which contribute to the development of drug addiction as well as the development of severe mental illness such as schizophrenia.
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1 |
2006 — 2010 |
Malenka, Robert C |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Electrophysiologic Analysis of Rim Function in Presynaptic Plasticity
Project #2: Electrophysiologic Analysis of RIM Function in Presynaptic Plasticity Elucidating the molecular basis and physiological significance of synaptic plasticity will lead to a more sophisticated understanding of the neural circuit modifications which underlie experience-dependent olasticity in both health and disease. Much is known about the mechanisms of postsynaptic forms of long asting plasticity. By comparison, however, relatively little is known about the underlying mechanisms of long lasting forms of presynaptic plasticity. In this proposal we focus on understanding the synaptic functions of a class of presynaptic, active zone proteins, RIMs, because of their required involvement in a prominent form of presynaptic LTP and their additional roles in basal neuretransmitter release and short-term plasticity. RIMs have several protein binding domains that interact with key components of synaptic vesicles and active zones. In Aim 1, we will evaluate the physiologic significance of RIM's diverse protein interactions by attempting to rescue the synaptic abnormalities of autaptic cultured hippocampal neurons lacking RIMs with mutant RIMs that disrupt individual protein interactions. In Aim 2, we will evaluate the functional roles of several different RIM isoforms by examining synaptic function in autaptic cultured neurons in which these are absent or overexpressed. In Aim 3, using a knockin mouse model, we will test the functional significance of mutating a key serine residue (S413A) hypothesized to be required for presynaptic LTP by evaluating synaptic function in autaptic cultured neurons and acute hippocampal and cerebellar slices prepared from these mutant mice. In Aim 4, we will further characterize several features of presynaptic LTP in the cerebellum in the context of Project 4 which examines its postulated contribution to motor learning. Taken together, these studies will help elucidate the molecular basis of multiple forms of presynaptic plasticity and enable the generation of tools that will facilitate the examination of their functional significance at the behavioral level. By defining RIMs' molecular interactions that mediate synaptic plasticity and behavior, we will generate information that will be critical for targeting these proteins as needed for the treatment of a wide range of neuropsychiatric diseases.
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1 |
2006 — 2007 |
Malenka, Robert C |
R13Activity Code Description: To support recipient sponsored and directed international, national or regional meetings, conferences and workshops. |
Conference On Excitatory Amino Acids &Brain Function @ Gordon Research Conferences
DESCRIPTION (provided by applicant): The third Gordon Research Conference on Excitatory Amino Acids and Brain Function will be held in July 2003 at Mount Holyoke College in South Hadley, Massachusetts. This meeting has established itself as one of the most important forums for discussing progress in this rapidly moving field. The conference will bring together approximately 130 active investigators, post-doctoral fellows and students for discussion of recent advances in the area of excitatory amino acids (EAAs) and brain function. The science discussed will be highly interdisciplinary, encompassing genetic, molecular, cellular, biophysical, structural, and behavioral approaches to understanding brain function. Specific topics which will be covered at the conference include, structure and function of excitatory amino acid (EAA) receptors, genetic approaches to EAA receptor function using invertebrate and vertebrate systems, membrane trafficking of EAA receptors, presynaptic function at excitatory synapses, regulation of dendritic and spine structure, EAAs and neuronal development and synaptic plasticity. The chosen speakers include the major leaders in the field as well as promising young scientists near the beginning of their careers. This proposal requests funds to provide partial support for travel and registration fees for participants from North America and overseas. This conference is timely and important, as it will bring together investigators from many scientific disciplines whose common link is the elucidation of the role of EAAs in brain function. The unique Gordon Conference format, which encourages informal and open discussion among the participants, provides an ideal environment for the development of new ideas/approaches, and initiation of new collaborative efforts, which will help shape the future directions of this critical field. EAAs play important roles in most higher brain function and are relevant to affective and behavioral disorders, mental health and drug addiction as well as brain development and plasticity. EAAs also are involved in several neurological disorders and diseases of aging such as Alzheimer's and Parkinson's, and other neurodegenerative diseases. The conference should be of interest to the missions of several institutes at NIH including NIMH, NINDS, NICHD, NIA, NIDA and NIAAA.
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0.903 |
2006 — 2010 |
Malenka, Robert C |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Animal Core
Core B: Animal Core Genetically modified mice offer many advantages for the multidisciplinary analysis of the mechanisms and functions of synaptic plasticity. They provide a renewable, reproducible and reliable resource that can be analyzed at multiple levels by multiple investigators with complementary expertise. Thus, a critical component of this program project is the use of the same lines of RIM mutant mice by all investigators. This will allow exploration of RIM function at multiple levels simultaneously, an approachwhich should synergistically lead to a more sophisticated understanding of the role of RIM proteins in active zone function and various forms of presynaptic plasticity. Importantly, by examining these mice behaviorally in well- defined assays of experience-dependent plasticity, we will also be able to probe the specific functional role of presynaptic LTP and the other forms of synaptic plasticity in which RIMs are involved. To accomplish this ambitious multidisciplinary approach will require a stable supply of correctly genotyped RIM mutant mice that can be used simulaneously by all members of the program project. The critical purpose of this animal core is to provide such animals. This Core will have two components, one at the Sudhof laboratory at UT Southwestern and one at Stanford. The UT Southwestern core will be responsible for the generation and initial characterization of the various mutant mice at the anatomical and biochemical levels. Mice will then be shipped to the Stanford Mouse Core B in which colonies will be established so that they can be examined in the cell biological, electrophysiological and behavioral assays described in Projects 2-4. Centralizing this function will achieve maximal efficiency both in terms of costs and labor and thus will greatly facilitate the overall progress of this program project.
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1 |
2007 |
Malenka, Robert C |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Neurophysiological &Synaptic Actions of Drugs of Abuse @ University of Texas SW Med Ctr/Dallas |
0.954 |
2009 — 2010 |
Malenka, Robert C Sudhof, Thomas C [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
A Systematic Test of the Relation of Asd Heterogeneity to Synaptic Function
DESCRIPTION (provided by applicant): Although autism spectrum disorders (ASDs) are highly heritable, ASDs are heterogeneous, and no single genetic cause contributes to ASDs in a large proportion of patients. Instead, heterogeneous genetic changes, including many single gene mutations and copy-number variations (CNVs) are found in ASDs. Thus, a key question is whether different genetic changes contribute to ASDs via multiple, independent, pathogenic pathways, or whether the various genetic changes in ASDs converge onto a single pathogenic pathway. Several independent mutations in genes encoding synaptic proteins, such as neurexin-1, neuroligins, and SHANK3, suggested that ASDs may generally involve an impairment of synaptic communication between neurons. However, most of the other genetic changes observed in ASDs have no known effect on synapses in fact, have no known effect on any brain function. Thus, the major goal of the present proposal is to conduct a large scale, systematic analysis of the synaptic effects of genetic changes in ASDs. The approach will be to over express (to mimic gene duplications) or knock down (to mimic gene inactivations) mRNAs corresponding to 81 ASD candidate genes, and to test the effect of these manipulations on synapses using standardized assays. Cell viability, neuronal development, synapse density and synapse function will be assessed in cultured mouse neurons using optical and electro-physiological assays that are well established in the PI's laboratories. Genes that were found to affect neuronal development, synapse formation, or synapse function in cultured neurons will be studied by the same manipulations in vivo after stereotaxic injection of lentiviruses into the mouse hippocampus, or after in utero electroporation. Changes in synapse function and plasticity will then be examined in acute slices from these mice using standard electrophysiological techniques well established in the PI's laboratories. All results from this project will be posted on a dedicated public website, and all reagents generated will be made readily available to the scientific community. The results of this project will provide a standardized reference point for the function of ASD candidate genes, and provide an initial test of the hypothesis that despite their clinical and genetic heterogenity, ASDs involve a common, if diverse, pathway acting on synaptic communication in the brain. PUBLIC HEALTH RELEVANCE: Autism spectrum disorders are known to be clinically and genetically heterogeneous, but it is unclear whether these two types of heterogeneity are related, and how specifically the various genetic changes affect brain function. This project will address these issues by studying the changes in neuron-to-neuron communication caused by the genes associated with autism.
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1 |
2009 — 2019 |
Malenka, Robert C |
P50Activity Code Description: To support any part of the full range of research and development from very basic to clinical; may involve ancillary supportive activities such as protracted patient care necessary to the primary research or R&D effort. The spectrum of activities comprises a multidisciplinary attack on a specific disease entity or biomedical problem area. These grants differ from program project grants in that they are usually developed in response to an announcement of the programmatic needs of an Institute or Division and subsequently receive continuous attention from its staff. Centers may also serve as regional or national resources for special research purposes. |
Activity-Dependent Synaptic and Circuit Plasticity
DESCRIPTION (provided by applicant): The brain processes information and generates behavior by transmitting signals at its synapses, which connect neurons into vast networks of communicating cells. These networks, known as neural circuits, are not static but are modified throughout life by experience. Such neural circuit plasticity is critical for the brain to develop normally and perform all of its important functions, including learning and memory. When brain plasticity mechanisms function abnormally, however, devastating mental illnesses often ensue. Thus, a major goal of neuroscience research is to understand the detailed mechanisms by which the brain activity generated by experiences modifies neural circuit behavior. This occurs in large part because neural activity continually adjusts the efficiency or strength of synaptic communication between neurons, a process known as synaptic plasticity. Despite the importance of synaptic plasticity for brain development and higher brain functions, relatively little is known about its molecular mechanisms other than it is commonly triggered by activity-dependent changes in intracellular calcium levels. This Conte Center will bring together four leading investigators who will use an innovative molecular screening approach combined with sophisticated biochemical, electrophysiological, and imaging assays to elucidate novel intracellular signaling pathways that underlie different forms of synaptic plasticity and how these forms of synaptic plasticity modify circuit function. The new Insights into synaptic plasticity mechanisms generated by this Conte Center will influence a broad array of neuroscientists working on a wide range of topics related to normal and pathological brain function. The Conte Center will also provide the research community with novel genetic tools that can be used to manipulate intracellular signaling pathways throughout the brain as well as novel transgenic mouse models that can be used to explore the roles of different signaling pathways and forms of synaptic plasticity in normal and pathological behaviors. Thus the Conte Center will provide both technological and intellectual innovations to one of the most important areas of neuroscience research with far ranging implications for our understanding of normal and diseased brain function. RELEVANCE: The effectiveness of communication between nerve cells is modified by experience and these modifications are crucial for all normal brain functions including learning and memory. The goal of this project is to determine the molecular mechanisms that are responsible for these modifications. Such information will lead to a better understanding of the causes of mental illness and eventually to the development of more efficacious treatments.
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1 |
2011 — 2014 |
Chen, Lu (co-PI) [⬀] Malenka, Robert C Sudhof, Thomas C. [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Large-Scale Molecular Interrogation of Synaptic Transmission
DESCRIPTION (provided by applicant): This application proposes development of an integrated array of assays to quantitatively measure synaptic function in cultured neurons and acute brain slices, with the potential for scaling up these assays for high- throughput screens. As suggested by RFA-MH-11-40 Scalable Assays for Unbiased Analysis of Neurobiological Function, this grant does not address a specific biological question, but describes new tools for large-scale analysis of neuronal function. Specifically, our applications proposes in eight specific aims a series of related but independent new assay systems, including new methods of achieving controlled expression of neuronal genes in mice, and new techniques for measuring properties of synaptic function in neurons, ranging from pre- and postsynaptic calcium-signaling over analysis of glutamate receptor trafficking to imaging of neuronal excitation or silencing and various forms of neuronal stress. With these assays, our overall goal is to develop tools to meet the increasingly obvious need for better approaches to study neuro-psychiatric disorders such as autism and schizophrenia. A growing human genetics literature describes many candidate pathogenic genes for these disorders, with a synaptic function likely for some of the implicated genes such as neurexins, suggesting that synapses could represent a pathogenetic hotspot for at least a subset of cases in these diseases. Analyzing candidate disease genes, however, has proven difficult with current approaches that require long-term studies of single genes in time-consuming and expensive experiments. Thus, new approaches that can be scaled up and quantitated without enormous investments in time and effort are needed. The tools we describe here are meant to address this need, at least in part, and are based on a series of technical innovations. The tools can be applied to cultured neurons, acute slices, or in vivo experiments in mice, and primarily use optical detection methods as readout to allow scalability. All of the tools developed under the auspices of this application will be freely and immediately distributed to the community, with the hope that they will become standardized approaches for large-scale interrogation of synaptic function in projects performed throughout the country. This application attempts to address an urgent need for scalable assay systems for analysis of neuronal function, as enunciated by the RFA-MH-11-40. The proposed new assay systems focus on synaptic transmission because neuropharmacology and human genetics identified synaptic transmission as a possible site of impairment in many important brain diseases, including autism and schizophrenia.
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1 |
2011 — 2012 |
Malenka, Robert C |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Cell Type-Specific Role of Homer Proteins in Synaptic Plasticity
DESCRIPTION (provided by applicant): Activity-dependent changes in excitatory synaptic function and structure importantly contribute to the modifications in neural circuitry that underli many forms of adaptive and pathological experience-dependent plasticity. Indeed, maladaptive or dysfunctional synaptic plasticity has been proposed to play a critical role in a variety of brai disorders including drug addiction. Thus understanding the molecular mechanisms contributing to synaptic and experience-dependent plasticity will provide important insights into normal circuit function as well as the maladaptive circuit modifications that underlie brain disorders. The mammalian brain expresses several different forms of synaptic plasticity with distinct triggering and expression mechanisms. Several of these, which have been specifically implicated in disease states, are triggered by activation of group I metabotropic glutamate receptors (mGluRs). Like most G-protein coupled receptors, group I mGluRs are tightly regulated by a macromolecular protein complex, a key component of which is the scaffolding protein Homer. Homer proteins regulate the expression and function of group I mGluRs at multiple levels including targeting, surface expression, clustering, and physical linkage to other synaptic and subsynaptic complexes. In this collaborative project involving a US laboratory at Stanford University and an Indian laboratory at the Indian Institute of Science Education and Research in Mohali , experiments will be performed to address the hypothesis that Homers regulate the function of the specific group I mGluR, mGluR5, in an isoform- and cell type-specific manner. Specifically, the functional significance of Homer in regulating mGluR5 trafficking and mGluR5-triggered synaptic plasticity in hippocampal CA1 pyramidal cells and nucleus accumbens medium spiny neurons using molecular manipulations combined with electrophysiological and imaging assays will be explored. The long-term goal of this project is to test the roles of Homer modulation of mGluR5 signaling in drug-evoked forms of behavioral plasticity of relevance to the development and maintenance of addiction. The results will open up new, innovative areas of research on the brain mechanisms underlying brain disorders such as addiction and will provide findings that are critical for the development of more effective treatments. Relevance Drug addiction involves long-lasting modification of the communication between nerve cells at their physical connections, which are termed synapses, in certain key brain areas. This project will use sophisticated experimental techniques to elucidate some of the key molecular mechanisms by which these modifications of synapses occur. The information that will be collected is essential for the development of more effective treatments for addiction and other related brain disorders. PUBLIC HEALTH RELEVANCE: Drug addiction involves long-lasting modification of the communication between nerve cells at their physical connections, which are termed synapses, in certain key brain areas. This project will use sophisticated experimental techniques to elucidate some of the key molecular mechanisms by which these modifications of synapses occur. The information that will be collected is essential for the development of more effective treatments for addiction and other related brain disorders.
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2013 — 2014 |
Dong, Yan [⬀] Malenka, Robert C Schlueter, Oliver |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Homeostatic Plasticity in Nucleus Accumbens @ University of Pittsburgh At Pittsburgh
DESCRIPTION (provided by applicant): Cues associated with prior cocaine use are powerful triggers of relapse in abstinent cocaine users and of drug seeking in cocaine-experienced rodents. Rodent studies show that cue-induced cocaine craving progressively intensifies over the course of withdrawal from extended access cocaine self-administration. This phenomenon, known as incubation of cocaine craving, may contribute to the difficulty of maintaining abstinence from cocaine use. Growing evidence supports the relevance of incubation to drug craving in humans. A key feature of the incubation process is that, once initiated, it continues to exacerbate automatically during the withdrawal period, without apparent external stimulation. This suggests the involvement of homeostatic rather than Hebbian forms of neuronal plasticity. Using a mouse model, this proposal aims to determine the role of homeostatic plasticity in the nucleus accumbens (NAc), a key brain region for addiction, in the incubation of cocaine craving. Ho- meostatic plasticity is a physiological self-correcting mechanism through which neurons compensate for 'unde- sirable' cellular alterations, thus stabilizing their functional output. Are there any forms of homeostatic neural plasticity in NAc neurons that may help these neurons regain normal function following cocaine exposure? We previously demonstrated a form of homeostatic crosstalk between excitatory synaptic input and intrinsic mem- brane excitability in NAc neurons. This phenomenon, termed homeostatic synapse-membrane crosstalk (HSMC), enables NAc neurons to adjust their intrinsic membrane excitability to functionally offset alterations in excitatory synaptic strength. As a consequence, the optimal output of NAc neurons may be stably maintained. However, if misled by false homeostatic signals, HSMC may be erroneously engaged, triggering cascades of homeostatic dysregulation that progressively shift neuronal output further and further from the normal set-point. In previous work, we showed that cocaine exposure increases synaptic levels of NR2B-containing NMDA re- ceptors in the NAc. Our central hypothesis, based on extensive preliminary results, is that this constitutes a false homeostatic signal that triggers HSMC and subsequent homeostatic dysregulation cascades, ultimately resulting in a persistent decrease in membrane excitability and an increase in synaptic strength. Together, these changes are hypothesized to magnify the response of NAc neurons to cocaine-associated cues and the- reby elicit incubation of cocaine craving. To test this hypothesis, this proposal will characterize key molecular substrates for HSMC-based dysregulation cascades (e.g., glutamate receptors and SK-type potassium chan- nels), examine the role of dopamine in modulating these cascades, and develop a HSMC-based approach to attenuate incubation of cocaine craving. To achieve these goals, we will use a multidisciplinary approach com- bining in vivo molecular/pharmacological manipulations, biochemistry, slice electrophysiology, and behavioral tests. Our results will set the stage for translational studies aimed at developing a homeostasis-based pharma- cological strategy to restore normal NAc function in cocaine users.
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0.954 |
2015 — 2019 |
Malenka, Robert C |
P50Activity Code Description: To support any part of the full range of research and development from very basic to clinical; may involve ancillary supportive activities such as protracted patient care necessary to the primary research or R&D effort. The spectrum of activities comprises a multidisciplinary attack on a specific disease entity or biomedical problem area. These grants differ from program project grants in that they are usually developed in response to an announcement of the programmatic needs of an Institute or Division and subsequently receive continuous attention from its staff. Centers may also serve as regional or national resources for special research purposes. |
Administrative Core
Center PI: Malenka, Robert C. Principal Investigator: Malenka, Robert C. Administrative Core Summary The Administrative Core will oversee and provide administrative support for all Conte Center activities. It will be run by the Conte Center director (Malenka) and consist of one full time Conte Center administrator who will be assisted by a departmental administrator with expertise in financial grants management. The administrators will manage budgets, order supplies, monitor inventory, arrange travel and meetings for Center investigators and the External Scientific Advisory Board, maintain the web site, assist in the dissemination of reagents and findings generated by the Conte Center, and provide general administrative and secretarial support. The Administrative Core will be located in the office suite shared by Dr.'s Malenka and Sudhof. Relevance To achieve its stated goals in the most efficient and cost-effective manner, the Conte Center will require an Administrative Core that will provide administrative support to all Center investigators and assist in the dissemination of reagents and findings generated by the Center.
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1 |
2015 — 2019 |
Malenka, Robert C |
P50Activity Code Description: To support any part of the full range of research and development from very basic to clinical; may involve ancillary supportive activities such as protracted patient care necessary to the primary research or R&D effort. The spectrum of activities comprises a multidisciplinary attack on a specific disease entity or biomedical problem area. These grants differ from program project grants in that they are usually developed in response to an announcement of the programmatic needs of an Institute or Division and subsequently receive continuous attention from its staff. Centers may also serve as regional or national resources for special research purposes. |
Role of Postsynaptic Synaptotagmins in Synaptic Plasticity
Center PI: Malenka, Robert C. Principal Investigator (Project 1): Malenka, Robert C./Südhof, Thomas Project Summary The ability of the mammalian brain to undergo long-lasting, activity-dependent changes in synaptic function and structure importantly contributes to the neural circuit modifications that underlie many forms of adaptive and pathological experience-dependent plasticity, including learning and memory. A leading model for such synaptic plasticity is NMDA receptor-dependent long-term potentiation (LTP). Although progress has been made in understanding the mechanisms underlying LTP, much remains unknown. This project will perform experiments that for the first time examine the novel hypothesis that postsynaptic synaptotagmins (Syts) are critical for the trafficking of AMPA receptors to the plasma membrane during LTP and also in the growth of dendritic spines that accompanies LTP. Syts are known to trigger the presynaptic release of neurotransmitter in response to calcium but their potential postsynaptic functions are largely unknown. The experiments will use a ?molecular replacement? strategy, which incorporates the simultaneous knockdown or genetic deletion of Syts with expression of a ?replacement? version of wildtype or mutant Syt in single hippocampal pyramidal cells in vivo or in vitro. Electrophysiological assays in acute hippocampal slices and cell biological assays in cultured neurons will be performed to determine the consequences of Syt manipulations on basal synaptic responses, LTP, long-term depression and AMPA receptor exocytosis and endocytosis. The role of postsynaptic Syts on the spine growth that accompanies LTP will also be examined. Preliminary evidence supports a role specifically for postsynaptic Syt1 and 7 in LTP. We will focus on molecular manipulations of these proteins for which conditional knockout mice are already available. These experiments will elucidate novel molecular mechanisms by which excitatory synapses in the mammalian brain are likely modified during various forms of experience-dependent plasticity, including learning and memory. The results will also open up new, innovative areas of research on the postsynaptic membrane trafficking underlying synaptic plasticity. In addition, this research will provide information that is critical for the development of agents that modify synaptic transmission in ways that promote cognitive function and alleviate psychiatric symptoms. Relevance Learning and memory involve long-lasting modification of the communication between nerve cells at their physical connections, which are termed synapses. This project will use sophisticated experimental techniques to elucidate some of the key molecular mechanisms underlying how this modification happens. The information that will be collected is essential for developing more effective treatments for the deterioration of cognitive function that accompanies many forms of mental illness.
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1 |
2017 — 2021 |
Malenka, Robert C |
P50Activity Code Description: To support any part of the full range of research and development from very basic to clinical; may involve ancillary supportive activities such as protracted patient care necessary to the primary research or R&D effort. The spectrum of activities comprises a multidisciplinary attack on a specific disease entity or biomedical problem area. These grants differ from program project grants in that they are usually developed in response to an announcement of the programmatic needs of an Institute or Division and subsequently receive continuous attention from its staff. Centers may also serve as regional or national resources for special research purposes. |
Project 3
Center PI:Deisseroth,Karl. Principal Investigator (Project 3): Malenka, Robert C. Project Summary/Abstract MDMA is a drug that has addictive liability yet at modest doses it enhances feelings of trust and empathy. These prosocial effects of MDMA contrast with the closely related and extensively abused psychostimulant methamphetamine (MA). To decrease the abuse liability of both drugs, it is critical to define the synaptic and circuit adaptations that mediate the prosocial effects of MDMA and distinguish those from the mechanisms responsible for MA?s high addictive liability. As a first step, we will combine in vivo and ex vivo approaches to define how MDMA and MA modifies the functioning of mesolimbic dopamine (DA) and dorsal raphe serotonin (DR 5-HT) circuits at doses that have distinct behavioral effects. Initially, we will establish an MDMA dose that is prosocial but not reinforcing and an MA dose that is reinforcing but not prosocial. We will then determine how chronic administration of these drugs influences their behavioral effects. Once dosing regimens are established, we will use pharmacological manipulations and a conditional knockout mouse line to define key molecular targets mediating these behavioral effects as well as their critical brain locations focusing on serotonin and DA transporters (SERT, DAT) and specific subtypes of 5-HT receptors. In a third series of experiments, we will define how acute MDMA and MA application influences synaptic transmission in D1- and D2 medium spiny neurons (MSNs) in the NAc as well as their intrinsic excitability. We will next define the input-specific adaptations at excitatory synapses on NAc MSNs as well as on VTA DA neurons caused by acute and chronic in vivo MDMA and MA administration. This will involve combining recordings from ex vivo slices and in vivo expression of optogenetic reagents (e.g. ChR2) in areas projecting to NAc or VTA and that are shown to be influenced by these drugs in Project 1. In final experiments we address two critical questions focusing on the 5-HTergic system. Does activation of DR inputs to the NAc mimic the behavioral effects of MDMA? Does endogenous activity within these identified circuits correlate with these same behaviors? To address these questions we will use molecular interventions to bidirectionally control activity in 5-HT inputs to NAc and determine the behavioral effects. To enhance understanding of these circuit elements in the context of the Center?s overall goals, we will also collaborate with the Technology core to use viral tracing techniques combined with CLARITY/COLM to define the input-output connectivity relationships of DR 5-HT neurons. Finally, we will collaborate with the Deisseroth lab and Technology core to elucidate the brainwide activity responses to DR 5-HT neuron stimulation using FIP. This extensive series of experiments will be prioritized and modified appropriately as Center results accumulate. By integrating the results from this project with those from other Center projects, we will facilitate elucidation of the circuit dynamics that mediate the prosocial versus reinforcing actions of MDMA and MA and how changes in these circuit dynamics contribute to the therapeutic and addictive liability of these drugs.
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1 |
2019 — 2020 |
Halpern, Casey Harrison [⬀] Lock, James D (co-PI) [⬀] Malenka, Robert C Skarpaas, Tara L |
UH3Activity Code Description: The UH3 award is to provide a second phase for the support for innovative exploratory and development research activities initiated under the UH2 mechanism. Although only UH2 awardees are generally eligible to apply for UH3 support, specific program initiatives may establish eligibility criteria under which applications could be accepted from applicants demonstrating progress equivalent to that expected under UH2. |
Responsive Neurostimulation For Loss of Control Eating
Project Abstract Background/Description. Given our mutual interest in direct brain stimulation as an effective treatment for non-adherent eating disorders associated with refractory obesity, our multidisciplinary team at Stanford University has developed a collaboration with NeuroPace, Inc, a company that recently received FDA approval for a responsive neurostimulator. We previously found that electrically stimulating the nucleus accumbens (NAc) of mice attenuates binge-like eating. In addition, increased power in low frequency oscillations appears to temporally correlate with anticipation of food reward and predict the onset of a binge. There is increasing awareness that obese individuals frequently lose control over food, which leads to binge-like eating. We hypothesize that a responsive neurostimulator could be used to identify low frequency oscillations that represent loss of control over eating and deliver responsive stimulation to the NAc to prevent a binge. Objective. To test stimulation parameters and detection algorithms for responsive neurostimulation in humans in an Early Feasibility Study. Methods. All needed regulatory avenues will be pursued, and an Early Feasibility Study will be performed in human subjects with refractory obesity due to loss of control eating. We will primarily assess device function and safety, but will utilize multimodal controlled and ambulatory measures to test the potential of this clinical program for LOC eating in obesity.
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