The central nervous system (CNS) of our body consists of the brain and the spinal cord. Together they control most our basic functions like movements, speech, cognition, vision, etc. The human brain is a very complex system. It is made up of nerve cells called neurons. There are an estimated 50-100 billion neurons are present in an average human brain which weighs approximately about 1.5 kg. The brain is considered to consist of three main constituents:
- The forebrain,
- The hindbrain; and
- The limbic system.
The cerebrum or cortex is the largest part of the brain and is considered to be responsible for functions like thought and action. The cerebral cortex is divided into four sections or lobes.
- The frontal lobe-responsible for logical reasoning, emotions, planning, some types of movement, part of speech, empathy and altruism, problem solving judgment and impulse control. It is fully developed when we are young adults. It also manages our higher emotions.
- Parietal lobe-responsible for some types of movement, recognition, orientation, perception of stimuli like pain, touch, speech and cognition.
- Occipital lobe-responsible for vision.
- Temporal lobe-responsible for perception and recognition of auditory stimuli, memory and speech.
The cerebral cortex is symmetric with two parts called the left and right hemispheres. Both the hemispheres are connected by a bundle of cells called the corpus callosum. The cerebral cortex is folded such that it allows a large surface area to fit within the skull. In terms of size, it is about two-thirds of the human brain. This is the most advanced region of the brain only found in advanced mammals and it gives us the intellectual superiority. The right hemisphere is considered to be responsible for artistic, spatial and musical qualities and the left hemisphere is responsible for rational and verbal qualities.
This is the primitive part of the brain and is responsible for basic instincts of survival, mating, dominance, etc. The hindbrain consists of:
- The spinal cord-is a set of nerve cells which runs vertically through our vertebral column. It is responsible for transmitting the instructions of the brain to other body parts.
- The medulla oblongata-is responsible for involuntary actions like respiration, digestion and heart rate. It also acts as a relay station.
- The pons-It is responsible for arousal and sleep.
- The cerebellum-It is responsible for regulation and coordination of movement, posture and balance.
The Limbic System
The limbic system is buried deep within the cerebrum. It is also called the emotional brain as emotions and memory are associated with this structure. It is also associated with unconscious value judgments, creativity and spontaneity.
It consists of:
- The amygdale-it is responsible for classifying emotionally charged memories. It is responsible for the emotion fear and is considered to trigger responses such as sweaty palms; increased heartbeat and stress hormone release.
- The hippocampus-this structure is primarily responsible for memory.
- The hypothalamus-it is responsible for some of the involuntary actions of our body.
- The thalamus-it is responsible for relay of nerve signals.
As is clear from the structure of the brain, that some decisions mostly falling under the category of rational, logical and analytical nature are processed in the forebrain frontal lobe, whereas some decisions based on emotional considerations may use the limbic system. Thus, clearly, different areas of the brain are activated for different types of decision-making.
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