 |
| A sketch of the basic structures of the brain |
Basic Anatomy of Your Brain
Your brain is where all your thinking takes place. So learning a little about the structure and operation of your brain is an appropriate beginning for a book on training your brain to think clearly.
The brain is a complex organic system for processing information fed to it by your senses. The structures of the brain contain several billion neurons with a total weight of about 1.4 kilograms (3 pounds). Those neurons require about twenty percent of the blood flow from your heart to keep them supplied with oxygen and nourishment. The brain floats in a cerebrospinal fluid that helps to support its spongy structure and protect it from mechanical shocks.
Based on knowledge derived from anatomy, evolutionary theories, and functional characteristics, the brain can be regarded as a composite of three basic substructures. According to Paul MacLean (Laboratory of Brain Evolution and Behaviour of the National Institute of Mental Health), as the human brain evolved primitive structures were successively surrounded by more advanced neural structures. The hindbrain, located at the base of the brain, is its most primitive part and is associated with autonomic functions. The midbrain complex lies above the hindbrain, is more sophisticated, and is associated with our emotions and the formation of memories. The left and right hemispheres of the forebrain form a cap over the midbrain. The forebrain is the most highly evolved component of the brain and is associated with awareness and thinking. (See for a sketch of the basic brain structures.) It is MacLean’s contention that, “We are obliged to look at ourselves and the world through the eyes of three quite different mentalities.” [The human brain] “amounts to three interconnected biological computers [each with] its own sense of time and space, its own memory, [muscle] motor control, and other functions”.
Carl Sagan adds,
“Each [of these three] brain[s] corresponds to a separate major evolutionary step. The three brains are distinguished neuro-anatomically and functionally, and contain strikingly different distributions of the neurochemicals dopamine and cholinesterase.”
Your brain is where all your thinking takes place. So learning a little about the structure and operation of your brain is an appropriate beginning for a book on training your brain to think clearly.
The brain is a complex organic system for processing information fed to it by your senses. The structures of the brain contain several billion neurons with a total weight of about 1.4 kilograms (3 pounds). Those neurons require about twenty percent of the blood flow from your heart to keep them supplied with oxygen and nourishment. The brain floats in a cerebrospinal fluid that helps to support its spongy structure and protect it from mechanical shocks.
Based on knowledge derived from anatomy, evolutionary theories, and functional characteristics, the brain can be regarded as a composite of three basic substructures. According to Paul MacLean (Laboratory of Brain Evolution and Behaviour of the National Institute of Mental Health), as the human brain evolved primitive structures were successively surrounded by more advanced neural structures. The hindbrain, located at the base of the brain, is its most primitive part and is associated with autonomic functions. The midbrain complex lies above the hindbrain, is more sophisticated, and is associated with our emotions and the formation of memories. The left and right hemispheres of the forebrain form a cap over the midbrain. The forebrain is the most highly evolved component of the brain and is associated with awareness and thinking. (See for a sketch of the basic brain structures.) It is MacLean’s contention that, “We are obliged to look at ourselves and the world through the eyes of three quite different mentalities.” [The human brain] “amounts to three interconnected biological computers [each with] its own sense of time and space, its own memory, [muscle] motor control, and other functions”.
Carl Sagan adds,
“Each [of these three] brain[s] corresponds to a separate major evolutionary step. The three brains are distinguished neuro-anatomically and functionally, and contain strikingly different distributions of the neurochemicals dopamine and cholinesterase.”
We also know that the brain has conscious and subconscious modes. While you are reading this sentence part of your brain keeps your heart beating, part keeps your eyes moving across the page, and another part wonders what is for supper tonight.
Your brain also has a sleep mode that can create dreams, and it has an unconscious mode to which it can retreat when your brain is injured. Your rational thoughts can be disrupted by emotional concerns, and your emotional concerns can be overridden by your basic needs to breathe, drink, and eat. It is no wonder that it is sometimes a challenge to think clearly.
With several levels of functioning, each with conscious and subconscious modes, it is a great advantage to be able to shift mental gears at-will to meet daily demands.
Your brain also has a sleep mode that can create dreams, and it has an unconscious mode to which it can retreat when your brain is injured. Your rational thoughts can be disrupted by emotional concerns, and your emotional concerns can be overridden by your basic needs to breathe, drink, and eat. It is no wonder that it is sometimes a challenge to think clearly.
With several levels of functioning, each with conscious and subconscious modes, it is a great advantage to be able to shift mental gears at-will to meet daily demands.
