2000 — 2003 |
Levitt, Jonathan B |
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. |
Mechanisms of Visual Context Effects in Visual Cortex @ City College of New York
Visual stimuli at locations beyond the classical receptive field (the area of the visual field from which responses can be evoked) can have profound effects on the selectivity and magnitude of neuronal responses in the visual cortex, even when these stimuli do not themselves evoke responses. It is generally assumed that intrinsic anatomical connections underlie these modulatory effects. Understanding how cortical neuron responses are shaped by such modulatory effects is important for understanding the role of cortical organization in determining cortical function, and in how the visual areas of the brain process complex real- world scenes. In this study we will clarify how neuronal responses in visual cortex are shaped by the spatial distribution of visual stimuli, and we will elucidate the anatomical substrates that link different points on the cortex (and therefore different spatial locations). This will therefore permit a direct test of whether local cortical connections do in fact underlie these modulatory surround effects. 1) In electrophysiological and neuroanatomical experiments in adult monkeys and ferrets, we will test whether the spatial extent and topography of response suppression or enhancement from beyond the classical receptive field can be accounted for by the distribution of local horizontal or cortical feedback connections within primary visual cortex (V1) and V2. 2) In electrophysiological studies in adult monkeys and ferrets, we will explore the stimulus specificity of response modulation from beyond the classical receptive field in V1 and V2. We will focus on V1 as the gateway to other cortical visual areas, but will also examine V2 to illuminate how general the properties and function of these modulatory effects are to all cortical visual areas. 3) In developmental studies in ferrets, we will systematically compare, across a large range of postnatal ages, the development of the modulatory surround effects to that of the responses in the classical receptive field, and to the refinement of intrinsic and extrinsic connections in V1. This will allow us to compare the developmental refinement of the modulatory effects to classical receptive field properties, and to further test whether intrinsic connections can underlie surround modulation. Comparison of details of the selectivity and spatial extent of different anatomical circuits with similar details from physiological investigations will provide information critical to an understanding of which anatomical circuits underlie particular functions, and in how neuronal function and connectivity underlie visual performance. This is a fundamental question in understanding how the cerebral cortex works, both in vision and in higher cognitive function.
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0.958 |
2006 — 2011 |
Levitt, Jonathan |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Functional Properties of Neurons Providing Feedback to Visual Cortex
Neurons in the mammalian visual cortex are intensively studied, making them perhaps the best understood cells in the brain. Research now shows that the modulatory effect of visual stimuli presented outside the classical receptive field (CRF), the area of the visual field from which responses to visual stimuli can be evoked, is not well understood and can be profound. Previous anatomical studies characterizing feedback circuits to primary visual cortex (V1) describe which cortical areas provide feedback to V1, and show that feedback links cells with nonoverlapping receptive fields. These results sugest that V1 cannot be understood purely on the basis of inputs from the eyes or local anatomical connections within V1. Therefore, understanding feedback signals to V1 is crucial to understanding how V1 works.
The research develops a comprehensive physiological characterization of fundamental brain circuits to understand better how they are organized, and to discover their contribution to the functional properties of their targets. Multiple areas of cerebral cortex provide feedback to V1 and the hypothesis that different feedback signals are provided to V1 by different cortical areas will be tested. Electrical stimulation will be used to identify neurons in areas 18 and 19 projecting to V1 using adult ferret cerebral cortex. The spatial extent and stimulus selectivity of the CRF, and the modulatory surround field of single neurons, will be studied. The functional properties of cells providing feedback to V1 from each area will be compared. In each area, the properties of cells projecting to V1 will also be compared to those of cells not providing feedback. This will permit a direct test of how different areas of cerebral cortex contribute information to V1.
The proposed work will provide critical knowledge about the mammalian cerebral cortex thereby improving understanding of mental functions. The results of this work will be published in journals, and presented at scientific meetings and academic institutions. The proposed work will enhance interactions among the burgeoning neuroscience community at City College, and will enhance research training by funding one doctoral student. Resources will enable motivated undergraduate students from underrepresented groups, which make up the majority of the student body at the City College of New York, to become involved in research in neuroscience.
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0.975 |
2006 — 2021 |
Levitt, Jonathan B |
T34Activity Code Description: To enhance the undergraduate research training of individuals from groups underrepresented in biomedical, behavioral, clinical and social sciences through Institutional National Research Service Award Training Grants, in preparation for research doctorate degree programs. |
Marc Honors Undergraduate Research Training Program @ City College of New York
DESCRIPTION (provided by applicant): The goal of the proposed MARC U*STAR program is to further increase the number of qualified URM undergraduates who continue their education at the Ph.D. level in the biomedical sciences. The project will consist of activities that represent a coordinated program that includes undergraduate recruitment, extensive research experience, and graduate school preparation. These activities are centered around the College Honors Sequence, coupled with specific courses for the MARC trainees to prepare them for the rigors of postgraduate training. In the previous funding period we made significant progress in implementing a more stringent student recruitment and selection process to screen out candidates interested in pursuing careers in medicine or fields unrelated to biomedical research; increasing numbers of MARC trainees from City College are now being admitted to doctoral programs in the biomedical sciences. Core goals of our program remain student recruitment and selection, and advisement and preparation for graduate school. Students will be placed in the laboratories of faculty in the departments of Biology, Chemistry, Earth Science, and Physics. We will expand the pool of appropriate mentors and trainees with faculty and students from the Sophie Davis School of Biomedical Education, Biomedical Engineering, and Psychology. We will also take advantage of the initiative by the City University of New York to expand science infrastructure; for example trainees interested in working on projects in structural biology will have access to state-of-the-art instrumentation for structural analyses of biomolecules at the newly constructed New York Structural Biology Center, and trainees interested in cancer research will be able to take advantage of opportunities created by City College's partnership with Memorial Sloan Kettering Cancer Center. The implementation of the new MARC U*STAR program will benefit top science students, both trainees as well as non-trainees, thereby meeting the goals of strengthening the capability of the college to train students in the sciences, and enhancing their research training experience at City College. PUBLIC HEALTH RELEVANCE: The goal of the proposed MARC U*STAR program is to further increase the number of qualified URM undergraduates who continue their education at the Ph.D. level in the biomedical sciences. This will enhance public health by increasing the pool of biomedical scientists working to study the underlying bases of biological phenomena and diseases.
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0.958 |
2011 |
Levitt, Jonathan B |
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. |
Role of Vision in Etiology of Axial Myopia @ City College of New York
DESCRIPTION (provided by applicant): It is becoming increasingly accepted that myopia is not a disease but a regulatory failure of the guidance of eye-growth. The eyes of children and most animals studied are born myopic or hyperopic (far-sighted) and adjust their growth during the postnatal period to correct their vision (emmetropization). It is clear that in animals this adjustment process is under visual control: Having animals wear positive or negative spectacle lenses causes a rapid compensation for the defocus, returning the eye to its previous refractive state. Understanding emmetropization requires finding out both how the eye can distinguish an image focused in back of the retina (which requires the eye to increase its rate of elongation) from an image focused in front of the retina (which requires the eye to slow its elongation) and how this information in the retina gets transformed into a signal that modulates eye-growth. With respect to the first problem, there is evidence that the eye uses the fact that blue light is focused in front of red light (longitudinal chromatic aberration) to guide its growth. Experiments are proposed to test whether the eye can be shifted toward or away from myopia by manipulations of the chromatic properties of stimuli. With respect to the second problem, two molecular signals change in opposite directions when the eye is exposed to opposite directions of defocus, suggesting that they might be part of the signal cascade that connects the visual signal in the retina to the growth-controlling machinery of the eye. Experiments are proposed in both birds and mammals to discover whether the particular conditions of timing of lens-wear that determine whether or not the eye compensates for lenses also determine whether or not these molecular signals change in the appropriate direction to be controlling the compensatory eye growth. Because the rules controlling how defocus leads to compensatory eye-growth appear to be similar across many different species, it seems likely that the same processes are at work in humans. Because myopia is a widespread condition that seems associated with visual experience, especially reading, it is important to understand how these visually mediated growth control processes work. Such knowledge provides our best opportunity to understand what makes some children develop myopia.
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0.958 |
2013 — 2016 |
Levitt, Jonathan Li, Christine |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Reu Site: Research Opportunities in Biology
A Research Experience for Undergraduates (REU) Sites award has been made to the City College of New York, which is part of the City University of New York. This grant will provide research training for 36 early-stage students for 10 weeks during the summers of 2013-2015. The Department of Biology has a dynamic group of 22 research-active faculty members who will serve as research mentors. Their research interests span the biological spectrum, ranging from molecular biology to population biology; some representative research projects include host-parasite interactions, modification of genes to modulate behavior, mechanisms underlying bacterial division, and molecular pathways in blood cell formation. In addition, students will attend research seminars, where they will be exposed to the diversity of research projects being conducted in the department, and various workshops, where training in responsible conduct in research, scientific writing, and scientific communication will occur and where panels will inform students about different career opportunities in industry and academia. Students will also take field trips to local industries, such as biotechnology companies, and research institutes, such as the American Museum of Natural History, Cold Spring Harbor Laboratories, and the Memorial Sloan-Kettering Cancer Center, with which the City College has a partnership agreement. The program's multi-phase recruitment effort within City College and among City University community colleges will consist of traditional "hard copy" formats, digital-based advertising, and campus recruitments. Students will be selected based on academic record, research performance, motivation, and potential for outstanding research in biology. Students will be tracked to determine their continued interest in their academic field of study, their career paths, and the lasting influences of the research experience. Information about the program will be assessed by various means, including use of an REU common assessment tool. More information is available by visiting www.sci.ccny.cuny.edu/biology/REU or by contacting the PI (Dr. Chris Li at cli@ccny.cuny.edu) or the co-PI (Dr. Jonathan Levitt at jlevitt@ccny.cuny.edu).
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0.975 |