Largest-ever 3D map of human brain created by Harvard and Google

Researchers from Harvard University and Google Research have achieved a remarkable feat. They created the largest-ever 3D map reconstruction of a human brain fragment at synaptic resolution. 

This breakthrough in connectomics, the study of neural connections within the brain, offers an unparalleled view into the intricate architecture that underlies our thoughts, memories, and consciousness.

Complexity in creating 3D map of human brain

While a cubic millimeter of brain tissue may seem insignificant, it harbors a staggering network of elements:

• 57,000 cells: These include a variety of neurons and glial cells that carry out essential functions like processing information, supporting neural health, and maintaining homeostasis within the brain.
• 230 millimeters of blood vessels: A dense network of capillaries ensures a steady supply of oxygen and nutrients to keep these cells functioning optimally, highlighting the brain’s intensive metabolic demands.
• 150 million synapses: Synapses are the junctions where neurons communicate, and this small tissue fragment contains a massive web of these connections, forming the basis for thoughts, memories, and all brain activity.
• 1,400 terabytes of data: The sheer volume of information captured by imaging this fragment is astounding. This data provides a comprehensive look at the brain’s wiring diagram, revealing the intricate patterns that underpin cognition and behavior.

Understanding this intricate system holds immense potential for neuroscience. It can unravel mysteries of brain diseases, inspire new therapies, and shed light on the fundamental principles of brain function.

Why map the human brain?

A comprehensive brain map, akin to a detailed atlas of neural pathways, could revolutionize our understanding of:

Cognition

Comprehensive brain maps have the potential to revolutionize our understanding of how the brain gives rise to thought and behavior. These maps would reveal the intricate organization of neural circuits.

They underlie cognitive processes like learning, memory formation, and complex decision-making. Understanding these circuits is crucial for grasping how the brain functions.

By observing how neural connections and activity change during different mental states, scientists could unlock the physical basis of thought.

This would provide an unprecedented look into the biological mechanisms of the mind. It could reveal how the brain organizes and processes information. Understanding these processes could revolutionize our grasp of cognition and behavior.

Neurological disorders

Detailed brain maps hold tremendous promise in the fight against neurological disorders. 

By comparing maps of healthy brains to those of individuals with conditions like Alzheimer’s, epilepsy, and schizophrenia, scientists can identify specific structural abnormalities. They can also spot unusual connectivity patterns linked to each disease.

This knowledge could be crucial for developing targeted therapies that address the root causes. Such therapies would go beyond just managing symptoms.

Instead, they could lead to more effective and personalized treatments. This approach has the potential to revolutionize how we understand and treat brain disorders.

Artificial intelligence

The human brain serves as a potential model for the future of artificial intelligence. Analyzing detailed brain maps could inspire new designs for AI systems that are less energy-intensive and more adaptive. 

Understanding the brain’s network organization could lead to advancements in artificial neural networks, resulting in AI systems capable of more sophisticated learning and problem-solving abilities.

Harvard-Google collaboration

This cutting-edge research is driven by a collaboration between neuroscientists led by Dr. Jeff Lichtman at Harvard, and AI experts at Google Research. The process involves:

Imaging: Electron microscopy

Electron microscopy employs beams of electrons instead of light to visualize objects. This allows for significantly higher magnification and resolution compared to traditional light microscopy, making it possible to capture the intricate details of brain tissue down to individual synapses.

Electron microscopy generates images that meticulously map the intricate structures in the brain. It captures neurons (nerve cells), their axons and dendrites, and the tiny junctions where neurons communicate. These detailed maps help scientists understand the brain’s complex architecture.

AI analysis

The vast amount of data from human brain map collected through electron microscopy requires sophisticated analysis. Google’s advanced algorithms are specifically designed to process these complex images, identifying and color-coding distinct elements like neurons, blood vessels, and synapses.

The algorithms don’t just analyze individual images. They piece together sequences of images to create a comprehensive reconstruction. This results in a detailed three-dimensional model of the brain tissue. This 3D map represents the complex network of connections and interactions within the brain.

“A fragment of a human brain – just a minuscule bit – is still thousands of terabytes. The scale of this endeavor highlights the vast complexity of the human brain.” noted Dr. Jeff Lichtman from Harvard.

“Our priority was to ensure that the results of this significant project could be widely accessible and leveraged by the scientific community,” added Viren Jain from Google Research.

Early insights from human brain map

The discovery of neurons with an abnormally high number of synapses highlights the potential existence of centralized hubs within the brain’s network. These highly connected neurons might play a crucial role in coordinating and integrating information across different brain regions.

Further investigation of these neural hubs in the map of human brain could reveal how they contribute to complex cognitive processes like decision-making, attention, and overall brain efficiency.

Moreover, the observation of axons forming peculiar loops deviates from the expected patterns of neural wiring. This raises questions about the prevalence of these formations and whether they represent normal variations within the brain’s architecture.

If these unusual axon configurations are found to be consistently associated with the brain tissue of individuals with specific neurological disorders, they could serve as potential markers for early diagnosis or provide clues about the underlying disease mechanisms.

Future directions: Towards a whole brain map of humans

Fuelled by the success of this study, the team’s ambitious goal is to map an entire mouse brain – a task requiring roughly 1,000 times the current data volume.

The researchers have made their dataset of human brain map and analysis tools publicly available. This underscores their commitment to open science. Now, the global neuroscience community can contribute to this monumental effort. Sharing this information encourages collaboration and accelerates discovery.

This work represents a major stride towards deciphering the intricate wiring of the human brain. As connectomics continues to advance, we can anticipate groundbreaking discoveries that deepen our understanding of the very essence of what makes us human.

The study is published in the journal Science.

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