The Most Complex Organ
The brain is the most complex organ in the body. It is the organ that allows us to think, have emotions, move, and even dream. Given this complexity, it should not be surprising that there are many ways to separate brain parts.
Brain parts can be separated on the basis of what they look like to the naked eye, under a microscope, or by what certain brain parts do. The brain and spinal cord make up the central nervous system and all of the nerves found in our body make up the peripheral nervous system.
When you see a picture of the brain you probably think of a wrinkled gray blob. Well, the wrinkles are called cortex and it is where the majority of brain cells or neurons reside. The cortex can be divided into four main lobes.
The frontal lobe, where you do your heavy thinking, pondering and planning your actions; temporal cortex, where you process sounds and form memories; occipital cortex, where you process all the things that you see; and parietal cortex, where you integrate or makes sense of all of the different bits of information that are bombarding your brain. Diagram of Brain.
The Cerebral and Motor Cortexes
On the top or your brain there are two special brain parts. The sensory cortex that processes all of the physical sensations that you have and the motor cortex sends signals to your body to move.
Not surprisingly, these areas are next to each other and communicate information all of the time. Much of our movements are based on the things that we feel. Imagine trying to walk if you could not feel the ground with your feet. The brain part that coordinates movement is the cerebellum. It is the wrinkled ball of nervous tissue that rests below the occipital cortex.
The Limbic System
The brain parts that you do not often see in drawings is found deep within the brain. This brain part is called the limbic system and is involved in emotions and basic drives. Some refer to the limbic system as the lower brain, not only because of where it is located, but because it handles the things about us that are a bit less civilized.
For example, the amygdala and nucleus accumbens are important for processing fear and reward. They are also involved in drug, alcohol and other addictions. The cingulate gyrus runs the day to day activities of the body that we do not directly control, like heart rate and blood pressure.
Understanding the Hippocampus
One interesting part of the limbic system that actually resides in the parietal cortex is called the hippocampus. The hippocampus is the brain part that forms memories. You have one of these on each side of the brain. If one hippocampus is injured, say by a stroke, the other one will still allow your brain to make memories.
However, if both hippocampi are removed, as was once done through surgery, then you cannot form new memories!
This horrible thing happened to a person that underwent surgery to prevent almost continuous, life-ruining seizures. After the surgery, it was found that the person could only remember things that happened prior to the surgery and could not make new memories! Each day, in fact each new moment was a confusing, perpetual question of “How did I get here?” Needless to say this surgery never happens anymore but this terribly unfortunate occurrence demonstrates the importance of the hippocampus in memory.
The thalamus is sort of the hub for all sensory information in the brain, sort of like the mailroom in a large office building. Almost all signals that go into or come out of the brain pass through the thalamus.
While the thalamus has long been thought to be just a relay station, new research suggests that it is much more complicated. For instance it is in some way related to sleep and wakefulness. Finally, the hypothalamus is the brain part that controls many hormones and regulates other important bodily functions including hunger, thirst, body temperature, and even breast feeding.
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