Yevgenia Kozorovitskiy, Ph.D. - US grants

[unreadable] DESCRIPTION (provided by applicant): Prior research in rodents suggests that living without exposure to environmental complexity leads to physiological changes in the brain that carry heavy functional costs. In comparison to rats, non-human primates are characterized by complex social behavior and cognitive capacity. They interact with their environment in intricate ways and are therefore likely to have greater requirements with respect to environment for optimal functioning. Housing monkeys in standard laboratory cages may have an even greater negative impact on their brain than the decreased neuronal survival shown by my prior work in rats. Our laboratory has built a new marmoset facility and my general intent for the next several years is to characterize experiential influences on neurogenesis and dendritic architecture in adult marmosets. The proposed experiments will correlate several indices of brain plasticity in this species with the level of environmental complexity and determine whether the effect is graded. If living in an enriched environment alters brain structure in the adult marmoset, then individual variables responsible for the effect will be identified. This work will begin to characterize the effects of living in different environments on structural plasticity in adult primates, and it will create the basis for studying animals in laboratory conditions that are free of the potential confounds of variable housing. [unreadable] [unreadable]

PROJECT SUMMARY Dendritic spines are the remarkable, highly specialized membrane compartments on neurons that house the postsynaptic, receiving end of many excitatory, glutamatergic synapses in the brain. They are highly plastic and change with learning, in development, and in disease. Dendritic spine and synapse changes have been linked to therapeutic responses to rapidly acting antidepressant drugs, but our understanding of the consequences of these treatments in specific neuronal classes are limited. This proposal relies on 2-photon multilaser assays to induce and evaluate the formation of new synapses, in order to measure how major depression and rapidly acting therapies regulate plasticity rules in specific neuronal groups. We will complement these focused assays with a new platform for genetically targeted proteomics in the cell classes implicated in major depressive disorder and its symptomatic amelioration by rapidly acting antidepressants. This work will provide the basis for a deep and broad understanding of synaptic and cellular changes induced by depressive state and rapidly acting antidepressant drugs. The unique synthesis of novel optical microscopy approaches, molecular tools, and proteomics chemistry represents a significant advance over canonical approaches to studying plasticity of neural circuits. The goal is to build a conceptual framework to enable harnessing the genesis of new synapses and the regulation of plasticity for mental health therapeutics. In addition, this work will help resolve fundamental mysteries surrounding the genesis of synapses and will develop useful tools for the neuroscience community.

Dendritic spines are the remarkable, specialized membrane compartments on neurons that house the postsynaptic, receiving end of most excitatory, glutamatergic synapses in the brain. They are highly plastic and change during development, learning, and in disease. This proposal relies on multi-laser 2-photon imaging and photostimulation approaches to generate and evaluate new connections on genetically targeted striatal neurons, dissecting interacting variables of sex, age, and neuromodulatory state. The proposal builds on preliminary observations of sex differences in spinogenesis, which may interact with other convergent signaling cascades to control dendritic spine formation and sensitivity to therapeutic agents. Further, the earliest stages of nascent synapses in striatal neurons will be defined functionally and ultrastructurally, using newly developed molecular tools and imaging approaches to assist this objective. The proposed work would yield valuable insights into new spine and synapse genesis, early-stage function, and stability, impacting basic research relevant to synaptic development and rules that guide plasticity. The resulting platform will help to drive technical innovation that would allow researchers to design therapies to augment reconstruction of neuronal architecture or deconstruct aberrant connectivity.

The brain is composed of intricate circuits of neurons communicating via fast electrical signals created by the coordinated actions of excitatory and inhibitory neurotransmission. Overlaid on this broad structure is a diverse set of slower instructive chemical signaling, referred to collectively as neuromodulation, which critically regulate fast transmission and neuronal function. This proposal brings together molecular-genetic tools, expertise in manipulating and interrogating neuromodulatory neuronal circuits, imaging and electrophysiology to decipher neurohypophyseal regulation of dopaminergic neurons. Dopamine is an essential modulator, required for vertebrate life. Dopamine dysregulation, best studied in degenerative disease, is also associated with anxiety and mood disorders, as well as neurodevelopmental diseases and addiction. Oxytocin, a neurohypophyseal hormone and neuromodulator implicated in social affect and reproductive behaviors, interacts with reward systems indirectly, and also by directly regulating the tonic activity of dopamine neurons, as work from our laboratory has recently demonstrated. The control of dopamine signaling by neurohypophyseal peptides represents a powerful regulation of essential adaptive behaviors, which both emphasizes the central importance of these endogenous peptides in development and establishes them as therapeutic targets for ameliorating disease states. The objective for this proposal is to build on our preliminary data in order to better understand the mechanisms and context of direct neurohypophyseal control over DA neuron function. The major overall premise of this proposal is that neurohypophyseal peptides act centrally in midbrain dopaminergic regions regulating cellular activity, synaptic transmission, as well as plasticity, and that this regulation is sex-independent and important in early development. To address several hypotheses deriving from this premise, we synthesize anatomical, electrophysiological, and behavioral assays, with technical innovations ranging from new light-sheet imaging technologies to promoter-driven viruses for orthogonal control of multiple modulatory systems. Carrying out the proposed experiments would advance our conceptual understanding of the complex neuromodulatory systems regulating affect and reward, and it is relevant to numerous mental health, neurodevelopmental and neurodegenerative disorders characterized by dysfunctional neuromodulation.

Project Summary Neuroscience has been revolutionized by the widespread adoption of two experimental methods: optogenetics, where light is used to control neural activity, and calcium imaging, where light is used to monitor neural activity. ?Sculpted Light in the Brain? refers to the optical process of changing the shape of light to be more useful for both imaging and stimulation purposes, and is a fundamental theme of this conference. With the advent of these approaches conventional electrical recording and stimulation tools are being progressively complemented and sometimes replaced by these light-based approaches. However, progress is still needed for these optical techniques to reach the speed, specificity, and range necessary to understand neural activity. This meeting is timely since this new generation of advanced light-based biological tools is fundamentally transforming how neuroscientists interrogate the nervous system, relying on the fusion of computational and optical methods with neuroscience. The success of the 2017 meeting highlights the timely nature of this topic. Sculpted Light in the Brain 2017 was originally designed as a brief (1 day) local conference at University of California at Berkeley. However, due to overwhelming interest as well as the engagement and commitment of the organizers, the 2017 meeting was rapidly expanded to 11 speakers (3 international) supported by funding from 14 entities. Feedback was overwhelmingly positive, and the conference was highlighted in Neurophotonics (Shanker et al 2017). The programs for the 2019 Sculpted Light in the Brain meeting was designed by an interdisciplinary, international committee guided by suggestions from the field. The organizers include 3 scientists from the 2017 organization committee, and 3 new members, including 2 women and 2 international representatives. This meeting will generate future collaboration opportunities by gathering established scientists and the next generation of researchers from the fields of optics, computer science, and neuroscience in a discussion focused on developing future light-based technologies that will enable real time communication with the living brain. This forward-looking unique new conference satisfies an urgent need in the scientific community that is currently completely unmet, since there are no other stand alone meetings directly dedicated to this rapidly growing scientific area.

PROJECT SUMMARY Dendritic spines are the remarkable, specialized membrane compartments on neurons that house the postsynaptic, receiving end of most excitatory, glutamatergic synapses in the brain. They are highly plastic and change during development, learning, and in disease. This proposal relies on multi-laser 2-photon imaging and photostimulation approaches to generate and evaluate new connections on genetically targeted striatal neurons, dissecting interacting variables of sex, age, and neuromodulatory state. The proposal builds on preliminary observations of sex differences in spinogenesis, which may interact with other convergent signaling cascades to control dendritic spine formation and sensitivity to therapeutic agents. The proposed work would yield valuable insights into new spine and synapse genesis, early-stage function, and stability, impacting basic research relevant to synaptic development and rules that guide plasticity. The resulting platform will help to drive technical innovation that would allow researchers to design therapies to augment reconstruction of neuronal architecture or deconstruct aberrant connectivity. The current supplement introduces a new form of imaging to the project, while supporting a promising undergraduate student in research and career development.