The feline nervous system is made up of three components: the central nervous system, the peripheral nervous system, and the autonomic nervous system. This entire arrangement works harmoniously to enable and control vital processes within a cat’s body and to allow it to function effectively. It allows the felie to react instantaneously to external stimuli.
Central Nervous System
The central nervous system is composed of the brain, the brain stem, and spinal cord. It is protected by the skeletal system (the skull and vertebrae), meninges (special connective tissue membranes), and cerebrospinal fluid. This acts as a shock absorber that helps to prevent concussions when the head suffers a trauma. The blood-brain barrier also keeps certain chemicals and microorganisms from entering the brain. However, it also means that very few medications can cross the barrier, limiting treatment options for some brain diseases.
A cat’s brain is only the size of a golf ball. But it is just as complex and capable as a human’s brain, though it addresses needs and desires different than ours. The brain governs various behaviors through learning, motivation, and perception. It produces nerve impulses to make muscles move, to send signals throughout the body, and to control numerous automatic bodily function. The brain also receives and registers sensory impulses. It consists of billions of neurons, each with up to 10,000 connections to other cells. The cat’s brain, like the human’s, can be anatomically divided by the cerebrum, cerebellum, and brain stem.
The cerebrum, which forms the bulk of the brain, is divided into parts: the right and left cerebral hemispheres. The hemispheres are divided by a narrow slit or cleft called the cerebral longitudinal fissure. At the bottom, the two sides of the brain are connected by the corpus callosum, which delivers messages from one side to the other. In the cerebrum, there are four lobes: the frontal (controls voluntary movement), the parietal (interprets information from senses), the occipital (interprets visual and sensory stimuli), and the temporal lobe (controls behavior and memory).
It is responsible for memory, learning, and decision making. Early social interaction between mother and littermates teach kittens how to be a cat and increases their physical coordination, social skills, and learning. Studies have shown that kittens who are handled 15-40 minutes a day during the first seven weeks are more likely to develop larger brains, are more exploratory and playful, and are better learners.
The cerebellum is located at the back of the brain, attached to the brain stem and cerebrum. It functions to coordinate movement and posture.
Located at the base of the brain, the brain stem connects the cerebellum to the spinal cord. Almost all the cranial nerves, nerves that control various functions on the head, arise from the brain stem. It controls many basic life functions.
Other parts of the brain include the pituitary gland, which coordinates and controls other glands, olfactory bulb, which processes scents, hypothalamus, which secretes hormones and governs autonomic nervous system, and the pineal gland, which produces melatonin.
The Spinal Cord
As the second half of the central nervous system, the spinal cord is responsible for carrying information between the brain and the body. It is an elongated structure made up of the major bundle of nerve tracts which carries nerve impulses. The spinal cord is connected to all areas of the body by nerves that leave and enter the spinal column through the gaps between the vertebrae. It acts to coordinate movement and muscular activity as wella s govern both automatic and voluntary reflexes.
Peripheral Nervous System
The peripheral nervous system is comprised of the cranial , spinal, and other nerves that control motor skills. This includes all motor and sensory tissue in the body except of the brain and spinal cord. Nerves that are from the brain are called motor nerves and sensory nerves are nerves that return to the brain. The main peripheral system components are the twelve pairs of cranial nerves and spinal nerves.
Cranial nerves control some sense recognition and motions of the head and neck. Some examples of cranial nerves are the facial nerves that control facial motion and the optic nerve that controls vision.
Spinal nerves branch out from the spinal cord and control functions from the neck down to the toes. Examples of important spinal nerves are the radial nerve that controls the forelimb and the femoral nerve that controls the hind limb.
Autonomic Nervous System
The autonomic nervous system functions similarly to the peripheral nervous system. Except, it contains nerves which control involuntary movement of organs. Within the autonomic nervous system are two subdivisions.
The first is the sympathetic nervous system, also known as the “fight and flight” response. When this system is in control, pupils dilate, heart rate elevates, intestines quiet down, and external blood vessels dilate.
The second is the parasympathetic system. It controls body responses in a relaxed state. For example, normal food movement through the digestive system occurs under parasympathetic system.
All nervous systems contain billions of cells known as neurons. Neurons connect with each other to form neurological circuits. Information travels along these circuits via electrical signals.
Each neuron has a center portion called a cell body with two extensions called dendrites and axons. Dendrites receive signals from other neurons and transmit electrical charges to the cell body. Axons transmit the electrical charges away from the cell body. When the electrical current reaches the end of the axon, the axon releases chemicals called neurotransmitters. These neurotransmitters pass the signal to the dendrites of other neurons, muscles, or glands.
There are several types of neurons depending on the information it sends and receives. Sensory and motor neurons are some examples of neurons found in the body.
Sensory neurons carry information from the body to the spinal cord or to the brain stem. Then, it moves on to the cerebellum and cerebrum for interpretation. Sensory information includes sensations of pain, position, touch, temperature, taste, hearing, balance, vision, and smell.
Motor neurons carry responses to the sensory information from the spinal cord and the brain to the rest of the body. Inside of the spinal cord, the axons of motor neurons form bundles known as tracts, which transmit information to motor peripheral nerves going to muscles in the limbs. They are important for voluntary movements and muscle control.
There are also specialized set of neurons that controls and regulates basic, unconscious bodily functions that support life such as pumping of the heart and digestions. These neurons make up the autonomic nervous system.
Development of the Nervous System
Like all species, no kitten is born with a fully developed nervous system. Though the brain, spinal cord, and associated nerves are present at birth, they lack the capacity to adequately transmit electrical impulses in a coordinated fashion.
During the first week of life, kittens do little else other than eat or sleep. There is very little motor activity, even during sleep. By the second week, a kitten will have fewer body movements during sleep.
In the third week, most kittens are able to maintain an upright posture and begin to spend more time awake. They attempt to move by pushing or sliding, but they are still unable to stand and walk.
As time continues to progress, muscle development will continue as the kitten develops the ability to stand. Eventually, the kitten will become fully mobile and is able to walk.
Kittens are also born blind and deaf. The eyelids open by fourteen days of age, exposing the eyeball, as do the ear canals. At this age, they are easily started by sharp noises. Most kittens will gain vision by three to four weeks of age, but it will not be fully developed until after ten weeks.
Some examples of brain and spinal diseases that occur in cats are listed below:
- Cerebellar hypoplasia: A congenital disorder having occurred before birth, it is the underdevelopment of the cerebellum. It occurs usually due to infection of the pregnant mother with the feline panleukopenia virus. Cerebellar hypoplasia results in difficulty or abnormal walking in the kitten.
- Lysosomal storage diseases: A group of disorders, they interrupt normal metabolic processes in the brain because of abnormal enzymes or deficiencies in enzymes.
- Peripheral vestibular disease: A condition that affects both the brain and nerves that control equilibrium. Cats with this disease have difficulty with balance and orientation. Symptoms include head tilts and falling over. Cause is unknown, but may be due to the migration of a particular parasite.
- Infectious encephalitis: It is inflammation of brain tissue caused by infectious organisms. In cats, it may be caused by viral diseases, parasitic infestations, protozoal infections, nervous bacteria, and fungal infections.
- Seizures: It is an abnormal brain activity that may result in convulsions that manifest as odd behaviors, tremors, muscle contractions, salivation, and defecation. There are many causes such as epilepsy, which is a rare condition characterized by recurrent seizures. Seizures occur more often from exposure to toxins, such as those found in certain flea and tick products.
- Brain tumors may be primary and arise from brain tissues, or they may be secondary and develop from either surrounding or distant tissues.
- Head trauma which can cause permanent damage to the brain and depending on the severity, can cause abnormal behavior
- Sacral caudal dysgenesis: It is the malformation of the vertebrae of the lower back and tail. Mostly seen in the Manx cat as an inherited condition, they show various neurologic deficits in the hind legs, rear end, and the bladder.
- Infectious meningitis: It is the inflammation of the meninges of the brain or spinal cord, typically due to some sort of infection. The most common causes are bacterial infections, feline infectious peritonitis infection, and systemic fungal infections.
- Spinal tumors can occur in the vertebrae, the meninges, nerve roots, and/or the spinal cord itself. Tumors that arise from cells within or covering the spinal cord are primary tumors. Secondary tumors are referred to tumors arising from nearby tissues that invade or the spinal cord.
- Cats’ brains can analyze the differences between the sounds reaching the right and left ear, enabling the cat to pinpoint the source.
- Areas of the domestic cat’s brain devoted to processing visual and tactile signals are similarly mapped and adjacent to one another. This suggests that sight and touch act in a coordinated way to enable the cat to navigate.
- Cats do dream while they sleep. They undergo both REM (rapid eye movement) and non-REM sleep. Like us, it is during REM sleep that your cat will dream.
References + For More Reading
Smithsonian’s Answer Book: Cats by John Seidensticker
Cats (Eyewitness Companions) by Dr. Bruce Fogle
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