2013 |
Ruta, Vanessa |
DP2Activity Code Description: To support highly innovative research projects by new investigators in all areas of biomedical and behavioral research. |
Connecting Neural Plasticity to Learning and Memory
DESCRIPTION (provided by applicant): A fundamental challenge of modern neuroscience is to define how memories are encoded within the brain. Classically, long-lasting plasticity in synaptic transmission has been proposed to be the cellular substrate for memory, shaping the flow of information through neural pathways. However, the sparse distributed neural networks thought to encode a memory trace have, until now, defied delineation. Consequently, the link between synaptic plasticity, sensory ensembles and learned behaviors remains elusive. Here I propose to use the olfactory system of the fruit fly, Drosophila melanogaster, as a unique paradigm to bridge the critical interface between synapses and behavior. I present a novel neural tracing technique that uses photoconvertible fluorophores and precise electroporation of dyes to label synaptically connected neurons for anatomic and functional analysis. I propose to apply this innovative tracing approach to map the associative olfactory circuits in the fly brain and discern how odor associations are encoded by synaptic connections and neural ensembles. I will then use in-vivo functional imaging and electrophysiolgical recordings in a tethered fly preparation to directly correlate the plasticity of individual synapses with learned olfactory behaviors. As a complement to these high-resolution circuit-mapping techniques, I propose genetic strategies to catalog the transcriptional changes selectively induced in neurons participating in a memory trace and provide insight into the molecular machinery that mediates experience-dependent changes in neural circuit function. Together, these experiments will offer an integrative understanding of neural plasticity mechanisms, from molecules and synapses to circuits and behavior, and lay the foundation for the development of rational therapeutic treatments to treat dementias and other memory disorders with molecular precision.
|
1 |
2014 — 2021 |
Ruta, Vanessa |
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. |
Molecular Mechanisms Underlying Insect Odorant Receptor Function and Modulation
DESCRIPTION (provided by applicant): Insects are the primary vectors for many deadly diseases. Mosquitoes and other blood-feeding insects are attracted to their human hosts via volatile olfactory cues. Consequently, the transmission of insect-borne diseases could be effectively controlled through strategies that target insect odorant receptors, disrupt the initial detection of human volatiles and prevent mosquitoes and other vectors from locating their human hosts. Insect odorant receptors are thought to form a novel class of heteromeric ion channels comprised of two distinct subunits-a highly divergent odorant receptor (OR) subunit that confers odorant specificity and a common Orco subunit, that is virtually invariant amongst diverse insect species, reflecting an absolutely essential role in olfactory transduction. Unfortunately as these receptors lack any structural homologs, many of their most fundamental structural and functional properties remain elusive, precluding sufficient mechanistic understanding to guide drug design. The objective of this proposal is to bring much-needed molecular insight to insect odorant receptors. We plan to perform X-ray crystallographic studies on Orco, alone and in complex with previously identified small-molecule agonists and antagonists, as a strategy to reveal the structural and mechanistic basis for modulation in this critical olfactory channel. In parallel, we have devised functional assays that allow us to probe the structural basis for Orco function and pharmacology, both in vitro using mutational analysis, and in vivo. Together, these studies will provide atomic insight into the mechanism by which the Orco channel functions and can be modulated, laying the foundation for the rational design of small molecule repellents that disrupt odor detection and host-seeking behavior in insect vectors of human disease.
|
1 |
2019 — 2020 |
Ruta, Vanessa |
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. |
Dissecting the Dual Role of Dopamine in Context-Dependent and Learned Behaviors
Project Summary Dopamine plays a central role in motivation and reinforcement learning, allowing animals to take advantage of their current circumstances to optimize both present and future behavior. Yet reconciling the diverse roles of dopamine has remained a challenge, in part due to the difficulty of understanding how a single neuromodulator can convey different signals to its cellular targets in distinct behavioral contexts. One prominent model is that different patterns of dopamine release engage distinct molecular pathways in downstream circuits, such that tonic fluctuations in dopamine regulate motivation while phasic bursts of dopamine convey reward prediction errors for learning. However, recent work has suggested that phasic firing patterns can both instruct learning and convey motivational signals that promote movement, challenging this simple dichotomy. Here we propose to use the Drosophila mushroom body as a powerful model to dissect dopamine?s diverse roles in modulating behavior. Recent work from our lab has shown that the same mushroom body dopaminergic neurons (DANs) responsive to rewards that instruct learning also reflect an animal?s purposive actions, underscoring how the dual representation of reward and locomotion is a conserved feature of dopaminergic systems from flies to mammals. Taking advantage of the mushroom body?s simple circuit architecture and unparalleled genetic toolkit, we will build on these observations to reveal how reward and locomotor signals are directly translated to different patterns of dopamine release and engage distinct dopamine receptor signaling cascades to shape circuit processing and behavior. In Aim 1, we will perform multicolor functional imaging as animals navigate in a virtual olfactory environment and reveal how tonic and phasic patterns of DAN activity are propagated to their post- synaptic targets. In Aim 2 we will use a suite of optical sensors to measure dopamine release and dopamine receptor signaling to understand how the same neuromodulator engages different sub-cellular cascades in different behavioral contexts. In Aim 3 we will test how animals use tonic DAN activity to regulate their ongoing behavior. Dysfunction in dopaminergic signaling is at the core of a wide array of neuropsychiatric conditions, from the severe motor deficits of Parkinsonian patients to motivational disorders like depression and drug addiction. By applying a multidisciplinary approach to interrogate the relatively simple dopaminergic circuitry of the fly, we hope to provide an integrative understanding of dopamine?s diverse actions with important implications to understanding neuromodulation in both healthy and diseased states.
|
1 |
2019 — 2021 |
Ruta, Vanessa |
R35Activity Code Description: To provide long term support to an experienced investigator with an outstanding record of research productivity. This support is intended to encourage investigators to embark on long-term projects of unusual potential. |
Using Evolutionary Variation to Probe the Neural Basis For Behavior
Animals exhibit astonishing diversity in their behavior, yet almost nothing is known about how evolutionary variation in neural circuits gives rise to species-specific behavioral variation. Here I propose to take advantage of recent advances in genome editing and develop an innovative approach to reveal how evolution sculpts brain circuits. Using CRISPR genome editing technology, we are translating neurogenetic tools from D. melanogaster to other Drosophila species, allowing for the first high-resolution anatomic and functional neural circuit mapping across species. By directly comparing the homologous sensory processing pathways in closely related drosophilids, we will precisely pinpoint where adaptive changes have occurred within the nervous system to produce species-specific mate preferences. The rapid evolution of Drosophila courtship allows us to systematically probe how parallel changes in behavior have been independently implemented in different species, shedding light on the types of changes that are permissible and preferable within brain circuits. Mapping the sites of anatomic and functional change within these pathways will further enable us to study their underlying molecular basis, using transcriptional profiling of the relevant neural populations to provide a definitive link between genetic and behavioral variation. Together, the proposed studies will transform our understanding of the molecular, cellular, and circuit-level changes that generate adaptive behavioral variation across species. As the etiology of many brain disorders is aberrant neural circuit wiring, a deeper understanding of the link between genes, neural circuits, and behavior could have profound consequences for mental health.
|
1 |