Jeff Lichtman: Connectomics: Mapping the Brain | Harvard Department of Physics

Transcript

MELISSA FRANKLIN: I'm Melissa Franklin, I teach physics here. And we have a new lecture series once a month, Wednesdays, public lectures from the Harvard faculty, Harvard, including science faculty, faculty from the medical school. That's it. [LAUGHTER] And anyhow, I'm really, really glad you came. It's a terrible day. It's windy and rainy and horr... Read More

Summary

In this lecture, Professor Jeff Lickman discusses the complexity of understanding the brain's structure and function. He emphasizes the unique challenges of studying the nervous system compared to other organ systems in the body. Lickman introduces the concept of connectomics, which involves mapping out the intricate neural connections in the brain. He presents two approaches, one using light microscopy and another using genetically engineered animals with different fluorescent proteins, to visualize and study the wiring diagram of the brain.

Questions & Answers

Q: Why is there a significant amount of interest in the brain compared to other organ systems?

The nervous system receives a lot of attention due to its complexity and the numerous departments dedicated to studying the brain in medical schools. This interest stems from the fact that the brain plays a critical role in functions such as cognition, behavior, and emotion. Additionally, there is still much to be learned about the brain, making it an exciting and fruitful area of research.

Q: How does the relationship between structure and function differ between the brain and other organs?

While the relationship between structure and function is well-established in most organs, the brain presents a unique challenge. The cellular motifs in the brain are incredibly complex, with a wide variety of different types of cells. This complexity surpasses that of other organ systems. Moreover, the brain's functions are distributed to different regions and scales, unlike other organs. This complexity and distribution make it more difficult to decipher the relationship between structure and function in the brain.

Q: How does the brain's cellular complexity contribute to its challenges in understanding its structure and function?

The brain's cellular complexity presents challenges in understanding its structure and function. For example, the retina alone contains around 50 different types of cells. These different cells have specific functions and unique arrangements, adding to the overall complexity of the brain. Moreover, the brain consists of a vast variety of neuronal cell types across different regions, making it difficult to map out the complete wiring and connections between cells.

Q: What is connectomics, and why is it important in studying the brain?

Connectomics is a branch of biotechnology concerned with mapping the structural connections of neural circuits in the brain. It involves using techniques such as high-speed imaging, image acquisition, and computer-assisted analysis to map out the wiring diagram of the brain. Connectomics aims to provide a comprehensive understanding of the brain's complex network, which is crucial for studying neurological and psychiatric diseases and unraveling fundamental questions about brain functionality.

Q: How can fluorescent proteins and genetic engineering contribute to studying the brain's structure?

Through genetic engineering and the use of fluorescent proteins, researchers can introduce distinct colors into different cells in the brain. By labeling neurons with different fluorescent proteins, scientists can visualize and trace their connections in the brain. This approach allows for the visualization of individual cells and their network of connections, providing valuable insights into the brain's structure and organization.

Q: Can the structure of the brain change based on experience?

Yes, the structure of the brain can change based on experience. Learning and practicing new tasks can lead to structural changes in the brain. For example, learning to ride a bicycle as a child and then not riding for years but still being able to ride as an adult suggests that the brain can adapt and change its structure based on past experiences. These structural changes are thought to underlie the formation of memories and the acquisition of new skills.

Q: How does the brain differ from other organs in terms of genetic influence on its structure?

Unlike other organs, which are primarily structured based on genetic blueprints, the brain's structure does not solely rely on genes. While genes contribute to the initial development and organization of the brain, it is through experience, learning, and practice that the brain's structure is further shaped and modified. This unique feature highlights the complexity of understanding the brain's structure-function relationship and how it differs from other organs.

Q: What is the difference between genomics and connectomics?

Genomics focuses on studying an organism's complete set of genes or its genetic blueprint. It involves mapping and analyzing the DNA sequences to understand various biological processes. On the other hand, connectomics involves mapping and analyzing the neural connections within the brain. Connectomics aims to determine the wiring diagram of the brain's neural circuits, identifying how different regions and cells are connected to one another. While genomics provides insights into an organism's genetic makeup, connectomics helps unravel the structural underpinnings of brain function and disease.

Q: How does the complexity of the brain's wiring impact studying its wiring diagram?

The brain's wiring diagram poses significant challenges due to its immense complexity. Mapping out the connections between individual neurons and their structural motifs is a herculean task. The brain's wiring spans a vast range of resolutions, from macroscopic to microscopic levels. Researchers need to employ various techniques and technologies, such as high-speed imaging and computer-assisted analysis, to map out these connections. Additionally, the brain's intricate wiring requires an understanding of both the minute details of individual neurons and the larger network organization for a comprehensive understanding of brain functionality.

Q: In what ways can connectomics aid in understanding neurological and psychiatric diseases?

Connectomics has the potential to shed light on the underlying causes and mechanisms of various neurological and psychiatric diseases. By mapping out the wiring diagram of the brain, researchers can identify any abnormalities or disruptions in the neural connections associated with specific diseases. This could provide insights into the functional deficits observed in patients and potentially lead to the development of targeted treatments. Additionally, connectomics can aid in identifying patterns and biomarkers associated with these diseases, allowing for improved diagnosis and classification.

Q: What is the ultimate goal of connectomics?

The ultimate goal of connectomics is to create a comprehensive map of the connections and wiring diagram within the brain, often referred to as the connectome. This map would provide a detailed understanding of how different regions, circuits, and cells in the brain interact and communicate with each other. By achieving this goal, researchers hope to unravel the mysteries of brain function and develop a deeper understanding of how our thoughts, emotions, and behaviors arise from the complex network of neural connections.

Takeaways

Studying the brain presents unique challenges due to its complexity and distributed functions. Unlike other organ systems, the relationship between the brain's structure and function is not well understood. Connectomics, the study of the brain's wiring diagram, is a promising approach to unraveling the mysteries of the brain. Through techniques like light microscopy and genetic engineering, researchers can visualize and map the intricate neural connections. Connectomics has the potential to revolutionize our understanding of neurological and psychiatric diseases, improve diagnoses, and inform targeted treatments. By creating a comprehensive connectome, scientists hope to unlock the secrets of brain function and unlock its full potential.