Lihie Kalfa
Research Mentor: Dawen Cai
Mentor Department: Cell and Developmental Biology; Biophysics; Neuroscience Graduate Program, Medicine
Author(s): Mou-Chi Cheg
Session: Session 3 (11:00 AM – 11:50 AM)
Presentation Type: Poster 63
Abstract
Neurons in the human brain form highly complex networks by extending processes over millimeter-scale distances to communicate with other neurons. Understanding these networks is essential for studying brain structure, connectivity, and overall function. One method, fluorescence imaging, is a powerful tool for visualizing neuronal morphology. However, its application to intact brain tissue is limited by strong light scattering arising from refractive index mismatches between cellular components: lipids, membranes, and the aqueous components of brain cells. As a result, conventional imaging techniques can typically penetrate only a few hundred microns into brain tissue, thereby preventing complete visualization of neuronal circuits. This research is conducted to overcome these limitations by developing optical clearing methods that increase tissue transparency while preserving fluorescence signals and structural integrity. Previous literature has demonstrated that chemical and biological clearing approaches, such as tissue permeabilization, lipid removal, enzymatic treatments, and refractive index matching, can significantly extend imaging depth and, in some cases, allow whole-brain imaging at cellular resolution. However, many existing protocols involve trade-offs among clearing efficiency, structural preservation, tissue damage, and other factors, highlighting the need for continued optimization. This project builds on established optical clearing strategies by systematically evaluating and refining chemical and biological protocols for intact mouse brains. The key concepts include optical clearing, which reduces light scattering within tissue, and refractive index matching, which minimizes optical distortion during imaging. By improving these methods, this research aims to enable higher-resolution fluorescence imaging, advancing large-scale mapping of neuronal connectivity.
