Welcome to your baby’s control center! Take a tour of your newborn’s brain and learn just what’s going on in that little head.
Your baby’s brain is made up of pinkish-gray, jelly-like tissue and controls all aspects of her central nervous system. The brain weighs about three pounds for an adult and just a few ounces for a premature baby. It transmits and receives signals in fractions of a second from all parts of the body and also from your baby’s environment. The brain regulates movement, sleep, hunger, and breathing, and processes emotions and thoughts.
Coverings of the Brain
Three membranes (meninges) provide a protective cushion between the brain and the cranium:
- Dura mater, the layer closest to the skull, is the thickest and most durable of the three membranes.
- Arachnoid layer is the middle layer.
- Pia mater, the membrane closest to the brain, contains many small blood vessels that supply the surface of the brain with oxygen and nutrition.
Sometimes these meninges get infected. Meningitis (infection of the meninges) does not occur very often, but when it does, it injures the underlying brain tissue, which can lead to long-term problems with development. The only way to diagnose meningitis is to perform a spinal tap. This permits the doctor to obtain a sample of cerebrospinal fluid (CSF) to look for signs of infection.
Parts of the Brain
The cerebrum controls the high-level brain functions, such as thinking and imagining. It looks somewhat like a giant walnut with two halves. These halves are referred to as the right hemisphere and the left hemisphere of the cerebrum. The right hemisphere controls the left side of your body and the left hemisphere controls the right side of your body. This crossover occurs because the nerves connecting the brain to the spinal column cross sides on their way to the spinal column. If you are right-handed, your left hemisphere dominates your brain, whereas left-handers are right hemisphere-dominant.
The corpus callosum connects the two cerebral hemispheres to each other. Some babies are born with an absent or incompletely formed corpus callosum. Absence of the corpus callosum is associated with handicaps, but not in all cases. Amazingly, some babies born without this part of their brain do very well.
The outside layer of the cerebrum is the gray matter or cerebral cortex. It is within the cerebral cortex that activities like talking and walking are controlled. The cerebrum also allows us to feel pain, learn new things, and process our emotions. The inside layer of the cerebral hemispheres is called the white matter.
Within the center of our brain are four small fluid-filled spaces called ventricles. The ventricles are connected to each other and to the spinal column. Within the two largest ventricles, which lie in the right and left sides of the cerebrum, the brain manufactures a clear, watery fluid called cerebrospinal fluid (CSF). The CSF circulates through the brain and spinal cord, creating a protective cushion for the nervous system. Adults produce approximately one pint or more of CSF per day. Most of this fluid is reabsorbed.
The area of the brain just outside the ventricles is the germinal matrix, a tissue made up of immature nerve cells and fragile blood vessels. As the preterm baby matures, either in the womb or after premature delivery, these nerve cells and blood vessels mature, and the germinal matrix becomes incorporated into the developing brain. The germinal matrix is a common site of bleeding within the brain of premature infants. The more premature an infant is, the more likely this bleeding will occur.
The cerebellum, the second largest part of your brain, is located just below the cerebrum in the lower back of the brain. The cerebellum looks a bit like a ball of yarn. The cerebellum coordinates movement and helps us maintain our posture and balance. Coordinated muscle activities, such as hitting a baseball or playing the piano, depend on the cerebellum.
The brain stem sits within the central core of the brain and extends down from the center of the brain, gradually turning into the spinal cord. The brain stem controls all of the vital functions that keep us alive. For example, breathing, heart rate, and blood pressure are all regulated by the brain stem.
The spinal cord is a long cord of nerve fibers that starts at the brain stem and runs down to your lower back. The spinal cord connects your brain to the rest of your body. Like the brain, it is covered by meninges for protection, and is enclosed within the vertebrae or backbones. Nerves extend out of the spinal cord, similar to the branches of a tree. The spinal nerves carry messages to and from your tissues and brain.
Your Baby’s Brain
Your baby’s brain will eventually contain about 100 billion nerve cells that look like long, knotted pieces of thread. These bundles of nerves send and receive signals to and from your body through the spinal cord. (You can send a message from your arm to your head in five microseconds!)
Most nerve cells are present when you are born. If they are damaged, new nerves apparently do not form to replace them. However, babies appear to have the ability to form new connections within their brains as they learn or relearn tasks after an injury. Newborn babies have a remarkable ability to recover brain function after a brain injury that might be catastrophic in an older person.