What does a rat's brain look like? - briefly
A rat brain is about the size of a grape, featuring a smooth, elongated cerebral hemispheres, prominent anterior olfactory bulbs, and a comparatively large cerebellum beneath the cortex. Its surface is soft, pinkish‑gray, and the overall shape is slightly oval with a tapered posterior region.
What does a rat's brain look like? - in detail
The rat brain is a compact organ weighing approximately 2 g in an adult specimen. Its overall shape resembles a small, elongated oval with a distinct dorsal convexity and a flatter ventral surface. The cerebrum occupies the majority of the mass, forming two hemispheres that are separated by a shallow interhemispheric fissure. Each hemisphere displays a smooth cortical surface; gyrification is absent, unlike in primates.
Key anatomical regions include:
- Cerebral cortex: thin, layered structure (six layers) covering the hemispheric surface; primary sensory and motor areas are localized in the rostral and lateral zones.
- Olfactory bulb: prominent, anterior protrusion that accounts for a substantial portion of the brain volume; highly vascularized and densely packed with mitral and granule cells.
- Hippocampus: curved formation situated medially, extending from the dorsal to the ventral aspect; composed of the dentate gyrus, CA1–CA3 fields, and subiculum.
- Striatum: large, subcortical mass comprising the caudate‑putamen; involved in motor control and reward processing.
- Thalamus and hypothalamus: centrally located nuclei that serve as relay stations and autonomic regulators.
- Midbrain, pons, and medulla: form the brainstem, maintaining vital functions such as respiration and cardiovascular regulation.
- Cerebellum: positioned posteriorly, with a foliated surface of parallel lobules; responsible for coordination and balance.
Externally, the brain exhibits a light gray to pinkish hue, reflecting the underlying vasculature and myelin distribution. The meninges—dura mater, arachnoid, and pia mater—envelop the tissue, with the subarachnoid space containing cerebrospinal fluid.
In comparison to larger mammals, the rat brain lacks cortical folds, has a proportionally larger olfactory system, and presents a more pronounced hippocampal formation relative to total brain volume. These features make it a valuable model for neurobiological research, allowing direct observation of structural organization and functional mapping.