Fluorescently colored and reminiscent of a pin art toy, a new 3D map that illuminates the intricate wiring within brain tissue could provide exciting opportunities for researchers and students, according to a neuroscience educator in the School of Molecular & Cellular Biology.

In a recent article in Science, researchers from Harvard University and Google Research outlined their efforts to create the largest dataset ever of neural connections.  We spoke with neuroscience lecturer Jeremy Toma, PhD, about the resource, its impact and what it could mean for students. Toma developed and teaches MCB 460: Neuroanatomy Lab, an advanced course for Illinois neuroscience majors that explores the structure and function of connections between different parts of the human nervous system.

“It’s very difficult to collect human brain tissue, preserve it properly, and sample it,” Toma said. “Sections of the human brain have been generated for years, but at lower resolution than what’s been achieved here. These researchers were able to preserve all the connections between the different cells, resulting in a very high-resolution dataset.”

One unique aspect of the brain map is the collaborative effort between technology companies and biologists. Harvard researchers obtained 1,400 terabytes of data from the tissue sample, which was smaller than a grain of rice. This called for unprecedented storage capabilities, leading to their partnership with Google.

After uploading the data, Google scientists then relied on AI processing techniques to automatically detect and label different parts of each cell.

“AI is becoming increasingly common as a means to save on human labor when identifying cell types in a large amount of data,” Toma said. “These computer vision tools allow researchers to score and analyze large quantities of data that would be difficult for a human to do and can minimize potential bias.”

A critical component of the project was its release as open access. Data obtained from the tissue sample was too numerous to encapsulate in one study; instead, the team of scientists elected to share their findings with the public and other researchers.

To create a map of this depth, researchers began by finely slicing the tissue sample, which was then stained with heavy metals and embedded in resin. Next, the samples were imaged using electron microscopy, which produces high resolution visualizations. Finally, the images were amalgamated into a map depicting the vast cellular connections within a portion of the brain.

The tool will provide biologists with more detailed information about how neurons connect to each other in the brain, Toma said. If expanded, it could lead to greater understanding of which neural networks are involved in various functions of the brain.

“This updates our understanding of the connections between different parts of the brain at a level of detail that has not previously been obtainable,” he said. “It improves our understanding of neuroanatomy and provides insight into all the non-neuronal brain cells and how they are interacting with neurons in ways that promote health and survival.”

Creating a human whole-brain map will prove extremely challenging due to ethical concerns and the difficulty of preserving brain tissue. That makes this current iteration a valuable tool for scientists and students because it can improve our understanding of neuronal complexity, which has historically been ascertained from animal brains and isolated human case studies.

“This will lead to many educational opportunities,” Toma said. “Providing information for other researchers, and also creating opportunities for students to get involved and ask their own questions.”

Main image courtesy of Fred Zwicky