Fig. 1: An audience at the iX Symposium in Montreal experiencing multiple brain datasets superimposed using the Neurotours bundle.
Is that what the brain really looks like?
After dome audiences experience flying through caverns of the cranium, surveying the ridges and valleys of the surface of the cerebral cortex, and dancing among the anemone-like "enchanted loom" of connectivity in the brain, that is one of the top questions kids ask me.
It’s a fantastic question! It gets at a fundamental curiosity that drives scientific inquiry. So is "that" what it looks like? If you mean just by the naked eye, then technically no. As I explain, if you cut a hole in the head and dig in with surgical tools, you would see blood and guts* (ok not guts). But what if you want to get a better idea of the actual 3D anatomy of the brain and substructures in a living brain?
Magnetic resonance imaging (MRI) produces 3D images of the brain that reflect the presence of water in tissues. It’s significantly more convenient than removing someone’s brain and tumbling it around in your hands. But what is the right color to superimpose on the resulting images? MRI doesn’t reveal color, so the color itself is added to the data afterwards.
Using a computational process called segmentation, an MRI image of the brain can be separated into anatomically well-defined sub-structures. Coloring those individually in pseudocolor provides an effective tool for teaching the non-specialist about the major roles of different components of the brain. In fact, historically, many breakthroughs in understanding the brain have emerged from patient cases in which specific regions of the brain were damaged or removed; the absence of certain components points to aspects of behavior that are either modified or lost completely.
Fig. 2: Flying through a jungle of cortical neuron dendrites.
And what about the neurons themselves? We show high-resolution imagery of single neurons, which glow yellow in our visualizations in the dome (Fig. 2). Are the neurons in the brain actually yellow? Generally no…but this is an interesting exception: yes, the neurons we imaged actually glow yellow because they were produced from a transgenic mouse that was genetically programmed to make a certain population of neurons manufacture “yellow fluorescent protein,” or YFP. This fluorescent protein is actually derived from the bioluminescent jellyfish Aequorea victoria; this sort of genetic “labeling” strategy creates a new way to see the brain, but, as with MRI, highlights structures in ways that would not normally be observable by eye.
Fig. 3: View of the Sun as seen in Ultraviolet light. Solar flares are visible as bright regions (Solar Dynamics Observatory/NASA).
Many people are not aware that the same visualization issues come up with astronomical images. When you look up at the night sky, you are seeing only the visible light spectrum. However looking at different colors of light – ones that are not visible to our eyes – reveals a multitude of information about astronomical objects. For instance sunspots are much more apparent when you view the ultraviolet wavelengths (Fig. 3).
So is that what the Sun really looks like?
- Jonathan Fisher
*P.S. Speaking of blood and guts, another question we’ve gotten more than once from the kiddies (go figure) is "What does a zombie’s brain look like?" We’ll have to work on that module for the future.
Fig. 4: Bioluminescent jellyfish on the shore at night. Photo credit: Phil Hart.