A joint research team in the KAIST Institute for Health Science and Technology, led by Professor YongKeun Park of the Department of Physics and Professor Yong Jeong of the Department of Bio and Brain Engineering, has recently developed a new optical technique that can quantitatively analyze Alzheimer’s disease through holography.

     Studying the structure of the brain is crucial for studying neurological diseases, as it closely relates to how the brain functions and how diseases affect neural activity. In the case of Alzheimer’s disease, irregular structures such as amyloid plaques and neurofibrillary tangles form in the brain’s gray matter and hippocampus. The practicality of other imaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET), which are commonly used to create images of the brain, is limited when it comes to studying Alzheimer’s disease, as they cannot precisely image structures that are smaller than 100 micrometers. Histopathology methods, such as a cross-sectional analysis after a dyeing process, were used to make up for this weakness, but they were also unreliable due to distortions created during imaging from the dye. Histopathology also only provides information on whether the brain is affected, whereas accurate diagnosis uses quantitative criteria to determine the severity of the disease.

     The team worked around this with holography, using light interference to calculate the refractive index distribution of nervous tissue; this method rendered the dyeing process in histopathology unnecessary. Light was then scattered across the tissue according to the refractive index distribution to calculate the average distance and directional spread the scattered light travelled, providing a qualitative and quantitative image of the brain. This holography was tested on a sample of mice, and results showed that the average distance travelled and the directional spread of the scattered light was much lower in brains affected by Alzheimer’s disease. The hippocampus was especially affected, with a 40 percent decrease in distance travelled.

     This new technology is expected to revolutionize brain imaging technology, as it can also be applied to research for other neurological diseases such as Parkinson’s disease. The findings of this research were published in the scientific journal Scientific Reports on August 3.