The nervous system controls and regulates a cat’s body. It is made up of nerve cells (neurons) and their fibers, which transmit impulses, or electrical signals, between parts of the body.
The brain analyses information from stimuli gathered by the sensory organs, such as the cat’s eyes and ears, and from inside a cat’s body, too. It then makes changes by stimulating muscle activity or causing the release of chemical messengers called hormones that can alter body chemistry.
The anatomical structure of a cat’s brain is similar to that of other mammals. Its largest part, the cerebrum, governs behavior, learning, memory, and the interpretation of sensory information. It is divided into two halves, or cerebral hemispheres, each made up of lobes with their own functions.
The cerebellum, at the back of the brain, fine-tunes body and limb movements. Other structures within the brain include the pineal gland, hypothalamus, and pituitary body, which are also part of the endocrine system. The brainstem connects the brain to the spinal cord, which runs inside the vertebral column, or spine.
Cortical folding
A cat’s brain weighs up to about 1oz (30g), which is just under 1 percent of its total body weight. That’s relatively small compared to a human brain (2 percent of body weight) or even that of a dog (1.2 percent). The domestic cat’s brain is also about 25 percent smaller than that of its closest relative, the wildcat.
This reduction in size is mainly because the regions of a wildcat’s brain used to map an extensive hunting territory are no longer needed in the domestic cat, which gradually came to depend on humans for most of its food. The cerebrum of a cat’s brain has a higher degree of folding in its outer layer (cortex) than that of a dog.
Cortical folding significantly increases the amount of the cerebral cortex, which contains the cell bodies of neurons (also known as “gray matter”), allowing many more cells to be packed into the confined space of the skull.
A cat’s cerebral cortex contains about 300 million neurons. That is almost double the number in a dog’s cerebral cortex. A high degree of cortical folding is linked to increased brain processing and what we humans think of as intelligence.
Highly developed regions
The areas of the brain involved in interpreting sensory information are particularly well developed in cats. For example, the feline visual cortex, which receives input from the eyes, contains more neurons than the equivalent area of a human brain. Vision is a cat’s key sense when it hunts.
The regions that control paw movements and grip are also intricate, allowing cats to be surprisingly dextrous with their paws. They can use their paws almost like human hands when seizing and manipulating objects, such as items of prey and toys. This skill and other hunting behaviors, such as stalking, pouncing, and biting, appear to be hardwired into a cat’s brain.
Kittens instinctively begin to practice hunting when playing with their littermates, and indoor cats without access to wild prey will continue to hone their predatory skills on toys.
A cat’s brain has a built-in directional compass. A frontal area of the brain contains iron salts that are sensitive to the Earth’s magnetic fields. This compass helps cats navigate their territory and may also explain how some cats have managed to travel hundreds of miles back to their home after being moved away.
The cat’s brain also registers the different times of the day from the movement of the sun. From this internal clock, a cat soon learns when to appear each day for its dinner.
CNS and PNS
Together, the brain and spinal cord (which contains bundles of nerve fibers) are known as the central nervous system (CNS). The rest of the nervous system—nerve fibers branching off from the CNS and associated groups of cells called ganglia—is known as the peripheral nervous system (PNS).
The PNS connects the CNS with the limbs and body organs. Some nerve fibers of the PNS transmit electrical signals to the CNS for analysis; others carry signals in the opposite direction to cause a change in the body.
Some parts of the PNS are under voluntary, or conscious, control, such as the nerves that allow a cat to wave its tail to show annoyance or to pounce on a mouse; other parts of the PNS are involuntary, subconsciously affecting internal processes such as regulation of heartbeat or digestion.
Hormones
The nervous system works closely with the endocrine system. Hormones made by the pituitary gland in the brain control the production of many other hormones, including those regulating metabolism, response to stress, and sexual behavior.