What Are the Real Colors of a Human Brain?
Beyond the uniform grey of textbooks, the brain's true coloration is a complex palette shaped by its living state and internal structures.
Many popular depictions present a simplified image of a uniformly grey organ, but this portrayal doesn’t capture the varied palette of a living brain. The brain’s coloration is not static; it changes significantly after death and varies between its distinct structural components.
The Hue of a Living Brain
Observed during surgery, a living brain is a multi-toned organ. It appears primarily pinkish due to the immense network of blood vessels carrying a rich supply of oxygenated blood through its tissues, which gives the entire structure a fleshy cast.
Beyond the dominant pink, other colors are visible on the surface. There are areas with a yellowish tint and sections that appear off-white, corresponding to different types of tissues. The overall impression is a mix of pink, tan, and yellow, interwoven with the bright red of arteries and the darker red of veins.
Why Preserved Brains Look Different
The familiar image of a uniformly grey or beige brain comes from specimens chemically preserved for study. After death, blood circulation ceases, and the brain tissue loses its pinkish color. To prevent decay and harden the soft tissue, brains are submerged in chemical fixatives like formaldehyde.
This solution causes proteins within the brain to cross-link, which stops decomposition and firms the structure. This process also alters the brain’s natural coloration, washing out the remaining pinks, yellows, and reds, leaving the organ with its well-known greyish-tan appearance.
A Spectrum of Tissues: Colors Inside the Brain
A cross-section of the brain reveals that its internal landscape is a mosaic of different tissues with distinct hues. The most well-known of these are grey matter and white matter. The grey matter contains a high concentration of neuronal cell bodies and has a pinkish-brown or greyish appearance in its natural state. This tissue is where the brain’s computational work, such as thinking and processing information, occurs.
In contrast, white matter is composed mainly of long, myelinated nerve fibers, or axons, that transmit signals between different brain regions. The pale, whitish color is due to the high lipid content of the myelin sheaths that insulate these axons. This fatty substance acts much like the plastic coating on an electrical wire, allowing nerve impulses to travel quickly.
Beyond the prominent grey and white matter, other specialized areas have unique colors. The substantia nigra, a structure in the midbrain involved in reward and movement, is notable for its dark, blackish pigmentation. This color comes from a high concentration of neuromelanin, a pigment produced as a byproduct of dopamine synthesis.