The domestic pig, Sus scrofa domesticus, has emerged as a significant model organism in neuroscience and biomedical research due to its close biological and anatomical similarities to human physiology. Its recognized intelligence and complex behavioral repertoire suggest a highly developed neurological architecture. Studying the anatomy of the pig brain provides scientists with a valuable large-animal platform for understanding human brain function, development, and disease processes.
Overall Physical Structure
The pig brain is a gyrencephalic structure, meaning its surface is characterized by prominent folds called gyri and grooves known as sulci, similar to the human brain. This convoluted surface structure indicates a large cortical surface area, typically associated with advanced cognitive functions. The average weight of an adult pig brain is approximately 127 to 180 grams, considerably larger than the brain of a typical rodent model.
The pig brain weight averages about 1:226 of the total body weight, establishing it as a large-animal model suitable for clinical imaging equipment designed for humans. The nervous tissue is protected by the cranial vault of the skull and layers of protective membranes called meninges. These meningeal layers—the dura mater, arachnoid mater, and pia mater—encase the brain and support it within the cerebrospinal fluid.
Functional Regions and Major Components
The pig brain is divided into the three fundamental regions common to all vertebrates: the forebrain, midbrain, and hindbrain. The forebrain, dominated by the cerebrum, is the largest section and integrates sensory information and coordinates voluntary activity. The cerebrum is partitioned into four major lobes, each associated with distinct functions.
The frontal lobe manages motor control and executive functions, while the parietal lobe processes sensory information like touch, temperature, and pain. The temporal lobe is involved in auditory processing and memory formation, and the occipital lobe is dedicated to processing visual input. Functional magnetic resonance imaging (fMRI) studies confirm that pigs possess homologous resting-state networks corresponding to human functions, including executive control and sensorimotor activity.
Deep within the cerebrum, the hippocampus plays a role in memory and spatial navigation, and the basal ganglia are involved in motor control and procedural learning. The hindbrain includes the cerebellum, which is positioned beneath the cerebrum and is responsible for balance, posture, and the coordination of fine motor movements. The brainstem connects the cerebrum and cerebellum to the spinal cord, regulating involuntary actions like heart rate and respiration.
Comparative Anatomy: Pig vs. Human Brain
Structural and physiological similarities make the pig brain a valuable translational model. Both species possess a high white-to-gray matter ratio, and the organization of the white matter tracts is highly comparable. The myelination rate also follows a similar pattern in pigs and humans.
The vascularization of the pig brain closely mirrors the human cerebral vasculature. This similarity is advantageous for research focused on stroke, trauma, and neurosurgical procedures. The volume of the pig’s prefrontal cortex, associated with complex decision-making, accounts for about 10% of its total brain volume, a percentage similar to that found in humans.
Despite these similarities, a primary difference is the relative size of the olfactory bulb, which is significantly larger and more developed in the pig. This anatomical difference reflects the pig’s reliance on its sense of smell for survival and interaction with its environment. Although the pig brain is gyrencephalic, its cerebral cortex is generally considered less complex than the human cortex, with shallower sulci and a slightly less intricate folding pattern.