Here we present the use of Third Harmonic Generation (THG) for the label-free imaging of myelinated axons in the murine cerebral cortex. Myelin plays an important role in the processes of learning and disease. However, much of the myelin biology research thus far has focused on white matter tracts where myelin is more visible. Much is still unknown, particularly with regard to myelin in gray matter. First, we engage in THG microscopy using an optical parametric oscillator pumped by a titanium-sapphire laser to demonstrate the utility of the technique for imaging myelin in vivo. Second, we investigate the use of a custom built low-repetition rate laser to substantially increase THG signal. We characterize the improvements and limitations of this light source with regards to THG microscopy. Lastly, we demonstrate a method for the estimation of the g-ratio from THG images by the use of a Bayesian model. The g-ratio is an important physical property relating to the thickness of the myelin sheath; modulation in the g-ratio could give clues to its underlying function. THG microscopy is uniquely adept at providing the data necessary for a g-ratio estimation.
","abstract_html":"<p>Here we present the use of Third Harmonic Generation (THG) for the label-free imaging of myelinated axons in the murine cerebral cortex. Myelin plays an important role in the processes of learning and disease. However, much of the myelin biology research thus far has focused on white matter tracts where myelin is more visible. Much is still unknown, particularly with regard to myelin in gray matter. First, we engage in THG microscopy using an optical parametric oscillator pumped by a titanium-sapphire laser to demonstrate the utility of the technique for imaging myelin in vivo. Second, we investigate the use of a custom built low-repetition rate laser to substantially increase THG signal. We characterize the improvements and limitations of this light source with regards to THG microscopy. Lastly, we demonstrate a method for the estimation of the g-ratio from THG images by the use of a Bayesian model. The g-ratio is an important physical property relating to the thickness of the myelin sheath; modulation in the g-ratio could give clues to its underlying function. THG microscopy is uniquely adept at providing the data necessary for a g-ratio estimation.</p>","abstract_has_math":false,"creators":["Redlich, Michael"],"institution":"The Graduate School and University Center of The City University of New York","degree_name":"Doctor of Philosophy","degree_level":"Doctoral","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":[],"advisors":["Hyungsik Lim"],"committee_chairs":[],"committee_members":["Ying-Chih Chen","Ye He","Ronald Koder","Min Xu"],"year":2021,"date_issued":"2021-02-01T08:00:00Z","date_published":"2021-02-01T08:00:00Z","updated_at":"2026-07-24T01:58:22Z","subjects":["Biophysics","Molecular and Cellular Neuroscience","Optics","Nonlinear optical microscopy","Label-free imaging","Myelin","Gaussian Mixture Model"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://academicworks.cuny.edu/gc_etds/4161","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Hyungsik Lim"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Ying-Chih Chen","Ye He","Ronald Koder","Min Xu"]},{"key":"dc:creator","label":"Author","values":["Redlich, Michael"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2021-01-19T08:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["The Graduate School and University Center of The City University of New York"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Biophysics","Molecular and Cellular Neuroscience","Optics","Nonlinear optical microscopy","Label-free imaging","Myelin","Gaussian Mixture Model"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://academicworks.cuny.edu/gc_etds/4161"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Here we present the use of Third Harmonic Generation (THG) for the label-free imaging of myelinated axons in the murine cerebral cortex. Myelin plays an important role in the processes of learning and disease. However, much of the myelin biology research thus far has focused on white matter tracts where myelin is more visible. Much is still unknown, particularly with regard to myelin in gray matter. First, we engage in THG microscopy using an optical parametric oscillator pumped by a titanium-sapphire laser to demonstrate the utility of the technique for imaging myelin in vivo. Second, we investigate the use of a custom built low-repetition rate laser to substantially increase THG signal. We characterize the improvements and limitations of this light source with regards to THG microscopy. Lastly, we demonstrate a method for the estimation of the g-ratio from THG images by the use of a Bayesian model. The g-ratio is an important physical property relating to the thickness of the myelin sheath; modulation in the g-ratio could give clues to its underlying function. THG microscopy is uniquely adept at providing the data necessary for a g-ratio estimation.
"]},{"key":"dc:title","label":"Title","values":["Third Harmonic Generation: A Method for Visualizing Myelin in the Murine Cerebral Cortex"]}]}],"canonical_facts":{"dc:contributor.advisor":["Hyungsik Lim"],"dc:contributor.committeemember":["Ying-Chih Chen","Ye He","Ronald Koder","Min Xu"],"dc:creator":["Redlich, Michael"],"dc:date.available":["2021-01-19T08:00:00Z"],"dc:description.abstract":["Here we present the use of Third Harmonic Generation (THG) for the label-free imaging of myelinated axons in the murine cerebral cortex. Myelin plays an important role in the processes of learning and disease. However, much of the myelin biology research thus far has focused on white matter tracts where myelin is more visible. Much is still unknown, particularly with regard to myelin in gray matter. First, we engage in THG microscopy using an optical parametric oscillator pumped by a titanium-sapphire laser to demonstrate the utility of the technique for imaging myelin in vivo. Second, we investigate the use of a custom built low-repetition rate laser to substantially increase THG signal. We characterize the improvements and limitations of this light source with regards to THG microscopy. Lastly, we demonstrate a method for the estimation of the g-ratio from THG images by the use of a Bayesian model. The g-ratio is an important physical property relating to the thickness of the myelin sheath; modulation in the g-ratio could give clues to its underlying function. THG microscopy is uniquely adept at providing the data necessary for a g-ratio estimation.
"],"dc:identifier":["https://academicworks.cuny.edu/gc_etds/4161"],"dc:subject":["Biophysics","Molecular and Cellular Neuroscience","Optics","Nonlinear optical microscopy","Label-free imaging","Myelin","Gaussian Mixture Model"],"dc:title":["Third Harmonic Generation: A Method for Visualizing Myelin in the Murine Cerebral Cortex"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["Doctor of Philosophy"],"thesis:institution_name":["The Graduate School and University Center of The City University of New York"]},"updated_at":"2026-07-24T01:58:22Z"}