1. 논문관련 분야의 소개, 동향, 전망을 설명

A main goal of neurobiology is to understand how the brain develops to from functional circuits that underlie behaviors. In order to study circuit formation, it is important to be able to specifically label and identify the individual subtypes of neurons. Methods to label such neurons have thus far largely lacking. Accordingly, neuroscientists have longed for novel methods to label distinct type of cells that allow us to study their morphological, functional specification, and selective wiring with other neurons.

Here, we used genetic methods to label a single set of nerve cells in the mouse eye with a fluorescent marker that reveals their structure. These neurons were initially identified by their specific expression of the cell adhesion molecule, JAM-B. The cells in the eye studied thus far extend their dendrites radially in all directions, but the neurons we discovered point their dendrites in a single direction-from top to the bottom. Its sole and peculiar morphology led us to hypothesize that these cells in the eye might functionally respond to moving objects in a unique direction. Such cells are said to be "directionally selective." We recorded electrical signals from these cells, and confirmed that these cells were not only directionally selective, but also responded to objects moving in the same direction that the dendrites pointed. Because the eye's lens reverse images (like a camera), these pointy cells will respond to objects moving up in the real world. The beauty of the current work is that the cell's function was predicted by examining its structure. It is unusual to be able to predict what a cell does just by looking at it - but that is exactly what we were able to do in this case.

The potential of the current work is that our strategy can now be applied throughout the brain because it provides a powerful technique to dissect distinct types of neurons in the midst of strikingly complex neural circuit that comprise the brain. Recent studies indicate that either malfunction or miswiring of particular types of neurons may lead to altered behaviors observed in disorders such as autism or schizophrenia. There is also a rapidly growing number of mouse models of these disorders in which to test the idea. We hope our method helps us gain insight on neuronal function and selective wiring in the normal brain and their changes in animal models of neurological diseases.

2. 연구를 진행했던 소속기관 또는 연구소에 대해 소개 부탁 드립니다.

I am working in the Department of Molecular and Cellular Biology at Harvard University. As our laboratory focuses on study of nervous system during development, we are also the part of Center for Brain Science, which is headed by Dr. Joshua Sanes (a corresponding author of the current paper). This environment provides inspiring intellectual interactions as well as excellent technological resources including a large imaging facility. The present research is the product of the department's efforts that emphasize the importance of collaboration among different research fields.

3. 연구활동 하시면서 평소 느끼신 점 또는 자부심, 보람

When I started this project, I was unfamiliar with every subject I faced (e.g. retina, transgenic techniques) since my background was slightly different. The first time when I saw unique shape of these directionally selective neurons, I knew that I found something very interesting. Last summer, I had a chance to give a talk about my work at Gordon Research Conference. After my talk, many people including Dr. Richard Axel came to me and said, "a good job". It was one of those moments that motivated me to keep working on challenging scientific questions. The lesson I learned from performing this project is "don't give up things too soon even if they don't work well. It takes time to get great rewards".

4. 이 분야로 진학하려는 후배들 또는 유학준비생들에게 도움이 되는 말씀을 해 주신다면?

The first thing you want to figure out is why you want to study biology and the second is what you are interested in among various topics. I hope that people will choose their scientific careers wisely, not just because something sounds cool or looks promising, but because it genuinely interests them. In science, one may more often be disappointed than excited in many cases over time because things often do not work well. However, if your motivation to study biology is solid, you will find a way out and eventually get answers. Dr. Eric Kandel once said, "we do research because it is amusing." I encourage people to seek opportunities to study outside Korea. You will be able to experience lots of new exciting subjects and broaden your knowledge. Of course, you should work hard to get to the point you are aiming for.

5. 연구활동과 관련된 앞으로의 계획이 있으시다면?

Currently, I am examining mechanisms that regulate morphological and functional differentiation of a novel retinal cell type described in the paper, and how it is integrated into the circuits that process visual information. I expect that this work will enhance our understanding of retinal connectivity and the underlying mechanisms of visual processing. My long-term research goal is to understand how neural circuits are formed, modified by experience in the brain, and possibly altered in animal models of neurological diseases. I hope that studying the retina during my postdoctoral period will help me design new tools to further understand neuronal development in the brain, where the circuitry is more complex.