Train Your BrainBuild a Framework for Clear Thinking pot

Train Your Brain
Build a Framework for Clear Thinking
Take Full Advantage of Your Brain’s Exceptional Powers
By Dr. William W. Dodd
Copyright 2012 William Dodd
Smashwords Edition
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Table of Contents
Chapter 1: Your Neurons at Work
Chapter 2: Framing Your Thoughts
Chapter 3: Putting Your Brain to Work
Chapter 4: Tools for Clear Thinking
Chapter 5: Food for Thought
Chapter 6: The Conscious Mind
Chapter 7: A Model of the Mind
Chapter 8: Solving Problems
Chapter 9: Getting it Right
Chapter 10: Managing Your Resources
Chapter 11: Clear Thinking and You
About the Author
Introduction
Clear thinking involves learning more, remembering more, making better decisions,
finding more satisfactory solutions to a variety of problems, and improving relations
with others.

The most important concept in Train Your Brain is that thinking skills can be
developed and enhanced through directed effort and practice. You can train your
brain to think better, just as you can train your muscles to perform specific tasks,
such as playing a saxophone or swimming the backstroke.
A clear thinker systematically collects data, analyzes information, and makes
considered decisions. A clear thinker also communicates effectively and strives to
work effectively with others.
Thinking clearly on a regular basis is an achievable objective. It does not require a
revolutionary approach. Every attempt at clear thinking leads to increased knowledge
and improved skills. Each success lays the foundation for more success in the future.
As you learn more and start to think more clearly, additional learning becomes easier.
With more knowledge, clear thinking becomes a habit rather than a challenge.
Over time, the cumulative effect of increased knowledge and clear thinking will lead
to systematic improvements in your own health, wealth, satisfaction, and happiness.
###
Chapter 1: Your Neurons at Work
1.1 Basic Anatomy of Your Brain
1.2 Your Body’s Communication Systems
1.3 Your Senses
Thinking is a wondrously complicated biological process.
The basic anatomy of your brain and input from your senses operate together to
determine how your mind perceives the universe, and how you think.
1.1 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 Figure #1 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.”
Figure #1: A sketch of the basic structures of the brain
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.
1.1.1 Learning about the Brain
There are a number of sources of information about the structure and operation of
the brain.
Brain injuries
Whenever someone experiences a damaging head wound and survives, there is an
opportunity to compare any resulting disability with the damaged region of the brain.
Historically, the advent of high-speed bullets in the 19th century led to many non-
fatal head wounds. Survivors had characteristic impairments when specific parts of
the brain were injured.
Animal experiments
While there are recognized ethical constraints that limit neural experiments on
humans, there are as yet few constraints limiting experiments on animals. And since
there are many parallels between the structures of human and animal brains, much
has been learned from animal studies about how our brains function. Continued
experiments on animals reflect our basic ignorance of subtle biological processes.
Brain surgery
The techniques and procedures for performing successful operations on human brains
evolved rapidly during the 20th century. There are no pain sensors in the brain itself
and patients are normally restrained but awake during brain surgery. Surgeons can
then talk to patients during an operation to confirm that incisions are having the
intended effect.
During operations to treat patients with severe epilepsy, Wilder Penfield discovered
that stimulating specific regions of the brain produced physical sensations. During the
early 1950’s, he demonstrated that the sense of touch for each part of the body’s
surface is represented on the parietal lobe (see section 1.1.4), and that adjacent
parts of the body are represented on adjacent parts of the brain. Penfield also found

that the more important and sensitive body regions have proportionally greater parts
of the brain assigned to them. He discovered, as well, that stimulation of other
regions could elicit particular memories in a patient.
In the 1960’s, a new operation was designed to ease the symptoms of severe epilepsy.
In this operation the main connection (corpus callosum) between the left and right
cerebral hemispheres of the forebrain is severed to prevent future epileptic seizures
from spreading across the whole brain. While the operation limited the damage of
epileptic seizures, it also led to characteristic deficiencies. Roger Sperry won the
Nobel Prize in 1981 for his studies of the subsequent behavioural characteristics of
these patients.
Brain scans
Non-invasive scanning techniques allow the human brain to be studied in action. A
variety of scanning techniques have been developed since 1920, when the German
physiologist, Hans Berger, first used electroencephalography to study the human
brain. Newer techniques can detect activity in smaller regions of the brain over
shorter time periods.
Here are brief descriptions of some of the common scanning techniques:
1. EEG – Electroencephalography – measures the electrical activity of the brain as
detected by electrodes on the surface of the head.
2. MEG – Magnetoencephalography – similar to EEG but it measures magnetic
signals.
3. MRI – Magnetic Resonance Imaging – uses strong magnetic fields and radio
waves to analyze soft tissue. It can be used on any part of the body, including
the brain.
4. CT – Computerized Tomography (or CAT – Computerized Axial Tomography) –
converts the information from a MRI into a three dimensional image.
5. fMRI – functional MRI – a newer version of MRI that is much faster (and much
more expensive).
6. PET – Positron Emission Topography – requires the injection of a radioactive
substance into a patient’s bloodstream. The patient is given a specific mental

task to perform and the most active areas of the brain then absorb the most
radioactive material.
7. NIRS – Near-Infra-Red Spectroscopy – can be used to assess brain function by
detecting changes in blood hemoglobin concentrations that are associated with
neural activity.
1.1.2 The Hindbrain
The hindbrain is considered the most primitive component of the brain. It is located
at the top of the spinal cord, just inside the base of the skull. Its main components
are the medulla, the pons, and the cerebellum.
The medulla is located just at the top of the spinal cord at the lower end of the
hindbrain. The medulla controls many autonomic functions including respiration,
circulation, and digestion. At the top of the medulla, just under the midbrain, is a
small region called the reticular activating system. The reticular activating system is
believed to harbour our centre of arousal and motivation. This system acts as a
primary filter on all incoming neural signals. Signals are forwarded to other parts of
the brain only if the input is deemed significant. The reticular activating system is
also involved in maintaining consciousness and regulating sleep.
The cerebellum is located at the back of the hindbrain, behind the medulla. It is
about the size of a small apple and is divided into left and right hemispheres . Its
compact structure contains about fifty percent of the brain’s neurons in only ten
percent of the brain’s volume. About 200 million input neurons from the spinal cord
pass through the cerebellum. The cerebellum also controls subconscious movements
to maintain posture, balance, and co-ordination.
The pons is a swelling around the medulla just in front of the cerebellum. It connects
the two halves of the cerebellum and manages the switching of signals from one side
of the body to the opposite side of the brain. It plays a major role in relaying sensory
information from the cerebellum to the forebrain.
Figure #2: Basic structures of the hindbrain
1.1.3 The Midbrain Complex
To simplify the discussions, the term ‘midbrain complex’ has been coined to include

the midbrain along with the thalamus and the limbic system.
The midbrain is cylinder shaped, about 2 centimetres (cm) in height and 2 cm in
diameter. It sits on top of the hindbrain in the middle of the head; approximately
level with the bridge of your nose. The midbrain is associated with the pathways for
voluntary muscle control, visual system reflexes, and hearing.
The thalamus consists of two plum sized lobes just above the midbrain. These left-
right lobes provide a system for relaying neural signals between the midbrain and the
hemispheres of the forebrain, and act as the brain’s main filter of sensory input. The
thalamus is also associated with regulating sleep, wakefulness, consciousness, and
mental arousal.
The limbic system is an important series of left-right nerve pathways located around
the midbrain and under the forebrain. The limbic system is involved in emotional
responses such as fear and aggression, mood in general, appetite, and emotional
responses to food. The limbic system is also involved in the processing and storage of
short-term memory. From an evolutionary point of view, the limbic system is an old
structure that can also be found in fish, amphibians, and reptiles – as well as
mammals. The limbic system is highly connected with the frontal lobes (see section
1.1.4) and may be the source of emotional satisfaction that can be derived from clear
thinking. There is no universal agreement on exactly which organs should be listed as
part of the limbic system, but its main components are the hypothalamus, the
hippocampus, and the amygdala.
The hypothalamus consists of two small left-right structures, each about the size of a
bean. The two parts of the hypothalamus reside under the two parts of the thalamus.
The primary function of the hypothalamus is to maintain the body’s status quo. It
regulates blood pressure, temperature, fluid levels, electrolyte balance, body weight,
and appetite. Your hypothalamus sends you a signal to let you know when you are
hungry, thirsty, tired, mad, or sad. The hypothalamus is also connected to the
pituitary gland, the master regulator of the body’s endocrine (hormone) system.
Your hypothalamus works much like the thermostat on a furnace, maintaining key
body parameters at appropriate levels. In the short run you may gain or lose a few

pounds, but the setting for body weight established in your hypothalamus will
eventually bring your body weight back to its former setting. Similar corrective
measures initiated in your hypothalamus maintain your body temperature and blood
pressure.
Figure #3: Basic structures of the midbrain complex
The amygdala has a left-right structure with almond shaped components residing just
below the hypothalamus. The amygdala is involved with the emotions of aggression,
fear, and pleasure. Persons with a large amygdala tend to be more aggressive.
Anxiety, autism, depression, narcolepsy, phobias, and schizophrenia are often linked
to a malfunctioning amygdala.
The hippocampus has a left-right structure in the shape of elongated beans curving
towards the back of the brain from the amygdala. The hippocampus plays an essential
role in our ability to create new memories of daily events and also influences our
ability to access old memories. Research also suggests that the hippocampus plays a
role in our ability to form mental maps of our surroundings and to perform spatial
tasks.
The nucleus accumbens is sometimes considered part of the basal ganglia of the
forebrain and sometimes as part of the limbic system. It has sensitive dopamine
receptors that respond to intense stimuli, novel stimuli, and pheromones. The nucleus
accumbens has been called the pleasure centre of the brain.
Many of the structures in the midbrain are connected by an extended loop called the
fornix.
1.1.4 The Forebrain
The forebrain (also known as the cerebrum) is the dominant part of the brain that you
see in most pictures of the brain. The forebrain is the most evolved portion of the
brain and is usually regarded as the seat of conscious thought. It has two basic
components, the large cerebral hemispheres, and a set of specialized nerve clusters
called the basal ganglia.
The left-right structures of the cerebral hemispheres look like the two halves of a
giant walnut, and are situated at the top of the brain. The wrinkled surface of the

cerebrum is also known as the cerebral cortex, or the neural cortex. The word
‘cortex’ simply means outer layer. The cortex has many folds that increase its surface
area by a factor of three and consists of about ten billion neurons arranged in six thin
layers. This grey matter is supported by a thicker layer of myelinated axons (white
matter). The two cerebral hemispheres are connected by a thick band of cells called
the corpus callosum. The cerebral hemispheres are essential to thought, memory, and
personality. They receive, store, and interpret information from all over the body,
and initiate voluntary actions.
The cerebral hemispheres are each divided by larger folds into four distinct lobes. See
Figure #4. By the time impulses from neurons in your body reach this portion of your
brain, they have switched sides. Lobes on the right side control processes on the left
side of the body, and visa versa.
As the name implies, the frontal lobes are located at the front of the brain, just
behind your forehead. Your most advanced thinking and decision-making occur in the
frontal lobes. Your personality and intelligence are thought to reside here. The motor
cortex in each frontal lobe controls all your voluntary muscular activity. The right
motor cortex lies in a band from the top of your head down towards your right
temple. The portion near the top controls the movement of your lower left body and
the portion near your right temple controls the muscles on the left side of your face.
The frontal lobes also contain Broca’s area devoted to generating speech, and other
regions related to understanding, learning, thinking, and planning.
The parietal lobes lie just behind the frontal lobes and extend towards the back of
your head. The parietal lobes contain the somatosensory cortex, a region that
receives sensory input from all parts of your body. A map of the surface of your body
can be traced out on the somatosensory cortex.
Figure #4: Basic structures of the forebrain
The occipital lobes are located at the very back of the head and are devoted to
vision. If you happen to get hit in the back of the head you sometimes ‘see stars’
because the occipital lobes have been jarred and spurious neural signals are
generated.

The temporal lobes are located at the side of the head, just inside the ears.
Appropriately, the temporal lobes contain the auditory cortex that is responsible for
the ears and hearing. The temporal lobes also contain Wernicke’s area; a region
devoted to understanding speech.
The basal ganglia are small and specialized clusters of cells involved with the control
of movement. They are found inside the white matter beneath the cerebral cortex.
This introduction to the anatomy of the brain has touched on the major structures at
work in your brain. There are also several large spaces in the brain, called ventricles,
that are filled with cerebral fluid. The cerebral fluid circulates through the ventricles
transporting hormones, removing waste, and helping to support the structure of the
brain.
A summary of the basic structures of the brain and their main functions is provided in
Table #1.
Table #1: A summary of basic brain components
The fundamental concept to remember is that your brain is a highly complex structure
deserving of your best efforts to use it effectively.
1.1.5 The Left Brain and the Right Brain
Most structures on the right side of the brain are duplicated by similar structures on
the left, and most components are designed to control functions on the opposite side
of the body. A massive neural link, the corpus callosum, connects the left and right
sides of the brain. This connection provides a natural backup in which most neural
control mechanisms are duplicated in the right and left sides of the brain. If one side
of the brain is damaged, there is still a good chance that an individual can survive
using the backup functionality in the other half of the brain.
There are minor differences between the right and left sides of your brain. In a
typical right-handed person, the left cerebral cortex controls language analysis and
speech production, and tends to process information one item at a time in a
sequential manner. In the same right-handed person, the right cerebral cortex tends
to process information holistically to gain an overall impression.
Most humans display a distinct preference for using the right hand, both for fine

motor activities such as writing, and for power activities such as swinging a bat or
club in sports. In fact the whole right side of a right-handed person tends to be
dominant over the left. People tend to have a dominant eye, a dominant ear, a
dominant arm, and a dominant leg – all on the same side. Since body parts are
controlled by the opposite side of the brain, in these people the left cerebral cortex
tends to dominate.
This arrangement, with each half of the brain managing the opposite side of the body,
is common across the animal kingdom. When combined with the concept of a
dominant side, the neural crossover may provide a distinct survival advantage. If a
creature were involved in a life and death struggle it would tend to turn its strongest
side towards the most immediate enemy. With the crossover brain structure, this
posture automatically moves the dominant half-brain away from the enemy. The
dominant half-brain is thus better protected and can continue to direct moves for
attack and defence even if the leading half-brain is damaged.
About 86% of the population is right-handed, and these people process language in the
left cerebral cortex. The remaining 14% can be divided into three groups:
1. About 2% are pure left-handers and process language in the right cerebral
cortex. Their brains are left-right mirror images of right-handed people.
2. About 4% process language in both sides of the brain. These people tend to be
ambidextrous and can write or play sports equally well with either hand.
3. About 8% have a mixed dominance. These people tend to perform some tasks
with their right hand and some with their left hand, and process language on
the same side as their dominant hand. Those with mixed dominance often have
difficulty distinguishing right from left, but sometimes find it easier to view a
situation holistically rather than seeing it as composed of individual
components.
The tooth-brush test for handedness
If you brush all your teeth with your right hand, your dominant side is probably on the
right.
If you brush all your teeth with your left hand, your dominant side is probably on the

left.
If you can brush all your teeth with either your right or your left hand, you may be
ambidextrous.
If you brush some of your teeth with your right hand, and the rest with your left, then
you may have a mixed dominance.
In human society, your handedness can sometimes be an advantage, and sometimes a
disadvantage. Most devices and structures are designed for the right-handed majority
– everyday items such as door handles, stair rails, and scissors are right-handed. The
left-to-right flow for reading and writing favour right-handers. Left-handed baseball
pitchers are in demand because the majority of batters are right-handed and find it
more difficult to hit pitches delivered from a pitcher’s left hand.
* * *
1.2 Your Body’s Communication Systems
The body has two major communication systems: the electro-chemical nervous
system, and the bio-chemical endocrine system. These systems gather information
about your body and your environment, process that information, and then initiate
action that will increase your chances for survival. Ultimately, all of your actions are
intended to increase your chances for survival.
1.2.1 Neurons – Building Blocks of the Nervous System
The nervous system consists of billions of specialized cells called neurons. About one
third of your neurons are organized into a complex communication network to carry
information from your sense organs to your brain and from your brain back to your
muscles. The rest of your neurons form the structures in your brain.
A neuron is a specialized and elongated cell that transmits an electro-chemical signal
from one end to the other. A neuron receives signals through delicate branching
structures called dendrites located near the cell nucleus. A nerve cell has one longer
extension, an axon. And at the far end of the axon, there are more branches. A single
neuron can receive signals though many of its dendrites and can transmit signals to
many other neurons through its axon branches. If a strong nerve impulse arrives at a
dendrite, or a weaker signal arrives at a number of dendrites, then an electro-

chemical signal is generated that propagates along the axon and then off to the
dendrites of one or more nearby neurons.
There is a tiny but important gap, called a synapse, between the dendrites and axons
of neighbouring neurons. A nerve impulse can only jump this gap with the assistance
of specialized chemicals called neurotransmitters. Neurotransmitters are created and
released at a synapse as a nerve impulse approaches the end of an axon. If enough
neurotransmitter has been generated before the nerve impulse arrives, then the
impulse can cross the synapse and continue down the dendrite of the next nerve. An
impulse has a greater chance of being transmitted if the signal in a single axon is
stronger, or if an impulse has been duplicated and is travelling along several
neighbouring neurons at the same time. A synapse can also act as a filter by blocking
weaker signals. After an impulse reaches the end of an axon, neurotransmitters are
quickly broken down so they will not interfere with the next set of nerve impulses.
Neurons outside of the brain are bundled to form nerve fibres that look like white
cords or wires. Signals typically travel from dendrites and down the axon of a nerve
fibre at speeds up to one hundred metres per second, depending on the overall
structure of the nerve bundle. Although neurons are carefully protected and
nourished by support cells, they are unable to undergo cell division or to repair any
significant damage. Any neural damage tends to be permanent.
Figure #5: The basic structure of a neuron
1.2.2 The Central Nervous System
Your nervous system has two main components: the central nervous system and the
peripheral nervous system. The central nervous system, in turn, has two main
components: the brain and the spinal cord. The spinal cord is the trunk line for
transmitting neural signals back and forth between your body and your brain. The
central nervous system is protected by the skull and the spine, and by three
membranes of fibrous tissues – the meninges. Damage to the spinal cord is very
serious and can lead to permanent disability or death.
1.2.3 The Peripheral Nervous System
The peripheral nervous system is a network of sensory neurons that branch out from

the spinal cord to reach every nook and cranny of your body. One set of sensory
neurons transmits signals towards the central nervous system and then on to your
brain, and another set of motor neurons transmits signals in the opposite direction to
activate both the voluntary and involuntary action of muscles.
The peripheral system has a right-left symmetry with forty-three pairs of major nerve
fibres. Ten of these pairs emerge from the underside of your skull to serve your head,
and the other thirty-three pairs emerge at different points along your spine to serve
the rest of your body.
The peripheral nervous system can be further divided into the somatic nervous system
and the autonomic nervous system.
The somatic nerves serve activities that are under your conscious control. They
collect information from sensory organs and transmit signals to muscles to initiate
voluntary movement.
The autonomic nervous system controls short-term actions and systems that function
without conscious control. Some autonomic neurons (sympathetic) are dedicated to
stimulating organs and muscle action, and other autonomic neurons (parasympathetic)
are dedicated to inhibiting the action of muscles and organs. The autonomic system
can transmit signals to alter the size of your pupils in response to light, change your
rate of breathing, alter your heart rate, stimulate muscular contractions in your
stomach and intestines, and cause the hairs on your skin to stand on end.
The autonomic system can also transmit signals to generate a co-ordinated set of
activities such as a response to perceived danger. The danger response includes an
increase in respiration and heart rate, the dilatation of air passages, the diversion of
blood from the skin and internal organs to muscles, and the release of extra sugar
from the liver into the bloodstream.
1.2.4 The Endocrine System
The endocrine glands secrete hormones into the blood stream to maintain chemical
balances in the body, to help prepare your body for emergency situations, and to
control longer term processes such as sexual maturation and body growth. Specific
hormones may start, stop, or inhibit a process and often participate in chemical

feedback loops to help maintain normal body conditions.
The pituitary is the master endocrine gland. It is the size of a pea and is located just
under the thalamus, surrounded by bone at the bottom of the skull. The thalamus
provides the connection between the brain and the pituitary gland.
The front portion of the pituitary produces growth hormone and other hormones that
influence the thyroid glands, the adrenal glands, the gonads, and the mammary
glands. The back portion of the pituitary produces a hormone that controls the body’s
water balance and oxytocin. Oxytocin is involved in initiating the birth process and
the production of breast milk.
The other main endocrine glands are the:
1. Adrenal glands (above each kidney) – produce adrenaline that controls the
body’s ‘fight or flight’ response.
2. Thyroid gland (front of the neck) – produces thyroxine that controls the body’s
rate of metabolism.
3. Parathyroid glands (just above the thyroid gland) – modulate the chemical
balance of calcium and phosphorous.
4. Pancreas (in front of the kidneys) – produces insulin to control the amount of
sugar in the blood. Unlike the other glands, you only have one pancreas.
5. Gonads (testicles in the male, ovaries in the female) – modulate sexual
functions.
The influence of the endocrine system is pervasive. It monitors and controls basic
body chemistry. It also provides the chemical stimulus for vital survival activities and
all stages of reproduction.
* * *
1.3 Your Senses
Your sense organs provide your brain with all of the information it possesses about
your external environment. Your sense organs are remarkable detectors, but they do
have physical limitations. Your sense organs also filter environmental information as it
is detected. The resulting information from your senses is further filtered as it flows
through diverse parts of your brain. Then your brain gets to work, using the

information that it has gathered, and constructs a model of reality in your mind.
When you listen to an orchestra play, your conscious mind hears music – not a set of
vibrations at different frequencies and intensities. When you look out the window,
you see a tree – not a set of colour intensities across your retina.
We normally think of five sets of specialized organs (tongue, nose, skin, ears, and
eyes) as providing all the information about the environment and the state of our
body, to our brains. The orientation systems in our joints and our ears should be
counted as an additional sense .
In this section, the emphasis is on the flow of information from sensory organs to your
brain.
1.3.1 Your Tongue
Your tongue is sensitive to warmth and cold, but it specializes in detecting the taste
of liquids. The tongue is coated with about 10 000 taste buds. Each bud consists of a
little pit lined with a cluster of sensory cells and the sensory cells are in contact with
peripheral nerves. The taste buds at the tip of the tongue are most sensitive to
sweetness. A little further back, the taste buds are most sensitive to saltiness. Behind
those are taste buds sensitive to sourness, and at the back are taste buds sensitive to
bitterness. Another set of taste buds is responsive to umami, a savoury taste. All
other taste sensations can be described in terms of these basic tastes.
Under constant stimulation, the taste buds lose some sensitivity. A second chocolate
is not as sweet as the first.
Taste sensations do not always provide an accurate indication of what you are eating
because there are chemicals that can alter the sensitivity of your taste buds. For
example, when monosodium glutamate is mixed with food, all four types of taste
receptors are stimulated. An Indian plant called Gymnema sylvestre contains
gymnemic acid, which reduces the sensitivity of the tongue to sweetness. A fruit from
West Africa, Synsepalum dulcificum, has the effect of making sour substances taste
sweet.
1.3.2 Your Nose
Your sense of smell is located in two small patches of specialized cells located high up

in each nasal passage, just under the brain case. The olfactory mucosa each contain
about 10 million sensory cells. These sensory cells conduct odour signals directly to
the side of the brain above them. This arrangement reflects the early evolutionary
development of the sense of smell. (The other senses conduct most signals from one
side of the body to the opposite side of the brain.)
The nose specializes in detecting airborne chemicals, which we interpret as odours. It
is the electron configuration of a chemical that stimulates a receptor. Chemicals with
similar molecular shapes tend to elicit the same odour response. It takes about 5
molecules of a chemical to excite a single receptor, and about 40 receptors must be
excited to reach the threshold of detection. When these conditions are met, a nerve
impulse is sent off to your brain. As the intensity of a smell increases (there are more
of the associated chemicals in the air you are breathing) the response also tends to
increase, up to a maximum level. After continual exposure to an odour, the response
tends to decline. When you first enter a cow barn the smell of animals tends to be
quite intense. After a few minutes the smell becomes much less noticeable.
Smells inform us about our chemical environment. Smells provide clues about what
materials are safe to eat, what is safe to keep near us, and what items may be
poisonous or contain harmful bacteria. Combined with taste, the sense of smell
enhances the pleasure of eating. In the wild, predators use smell to hunt their prey,
and prey animals use smell to avoid predators.
Smell also plays an important role in mate selection. The female gypsy moth, when it
is ready to mate, emits a scent that can attract a male moth from miles away. All
mammals, including humans, emit similar chemicals called pheromones to indicate
their sexual status. While pheromones can have a significant effect on our selection of
mates, the process occurs at a subconscious level. We sometimes use perfumes and
colognes in an effort to enhance the effect of pheromones. In the days before
ovulation, women are about a hundred times more sensitive to musk odour than men.
Other pheromones can transmit a subconscious alarm, ‘danger is near’ that we
sometimes interpret as the ‘smell of fear’.
Research has been conducted to determine if there are olfactory sensors that respond

only to specific chemicals, but the results are inconclusive. However, it has been
shown that combinations of a few basic odours can stimulate our interpretation of
most other odours.
Table #2: A list of primary odours
The olfactory sensors seem to be particularly sensitive to these odours. Combinations
of these seven basic odours can simulate most other odour responses.
1.3.3 Your Sense of Touch
The skin is your body’s largest organ. The layers of your skin provide a flexible shield
against physical injury, infection, and ultraviolet radiation. The skin acts as a
container to prevent the loss of vital fluids. It also has insulating properties that help
to regulate your body temperature. Your skin is covered with a network of nerve
endings that are sensitive to touch, pressure, temperature, and pain.
Your sense of touch is most sensitive on your hands, feet, and face; and less sensitive
on your legs, arms, and trunk. Pressure is felt when it causes the skin to deform, but
there is no sensation when pressure is applied evenly and there is no deformation.
Scuba divers seldom experience a sense of pressure in depths less than 30 metres
because the water pushes evenly on all skin surfaces. Continued touch or pressure
tends to be ignored after a few minutes. When our clothes are comfortable, we tend
not to notice them wrapped around our bodies shortly after dressing. To detect light
touches, hairs on the skin act as tiny levers so that an object weighing just a fraction
of a gram can twist a hair in its follicle, cause a local deformation of the skin, and
signal a touch sensation.
The skin has a typical temperature of 33 degrees Celsius and is able to detect changes
as small as a hundredth of a degree. The skin’s sensitivity to hot or cold varies over
the surface of the body and also depends on the body’s recent heat history. On a very
hot day, a cloth dipped in warm water can feel delightfully cool. The skin adapts to a
reasonable range of temperatures within a few minutes. If you dive into a cold lake,
or climb into a hot bath, the thermal sensation soon decreases.
A sensation of pain is generated if the pressure or temperature sensors on the skin are
over stimulated. Pain is a warning to the brain that action needs to be taken to avoid

harm or damage. In the disease of leprosy, the nerve endings of the extremities are
damaged so that pain receptors no longer work. Without pain receptors, those
suffering from leprosy receive no warning pain when fingers and toes are damaged.
The result is that the extremities are gradually destroyed, not directly by the disease
but by excessive wear that is not moderated by pain. Some types of skin pain, such as
burns, tend to persist over time with no adaptation. Other types of skin pain, such as
that inflicted by the stab of a needle, tend to decrease rapidly with time.
1.3.4 Your Auditory System
Your ears convert vibrations in the air into nerve impulses in three stages. Your outer
ear funnels sound waves to your eardrum and the waves cause that delicate layer of
skin to vibrate. Then tiny bone structures in your middle ear amplify the mechanical
vibrations of the eardrum and pass the amplified motion to your inner ear. The
cochlea is the main structure in the inner ear. It is a coil about 3 cm long, filled with
fluid and lined with nerve endings. Vibrations from the bones in your middle ear cause
the fluid in the cochlea to vibrate and that motion generates auditory nerve impulses.
About forty percent of the nerve impulses from an ear on one side of your head go the
same side of the brain, and sixty percent are transferred to the opposite side of the
brain.
With both ears operating you are able to determine the approximate direction of a
source of sound. And, if you are familiar with a source of sound, you can also make a
reasonable estimate of the distance to the source.
Human ears are sensitive to a wide range of vibrations, from a low hum at 20 Hertz
(cycles per second) to a high squeak at 20 000 Hertz. Your ears can also detect a wide
range of intensities, from a pin dropping on the floor, to a jet engine. Your ears can
also detect more than one frequency at a time; when two notes are played on a piano
you can detect both notes. This ability lets you interpret speech and enjoy music.
Your ability to interpret speech also depends on the social context of a conversation,
since you do not always hear every word that is spoken. In an experiment to test the
ability of subjects to perceive spoken language, portions of the words in a
conversation were blanked out at random. As long as a conversation had a known

context, subjects were still able to understand about 85% of the words spoken, even
when 50% of the sounds were deleted.
For a right-handed person, the right ear (feeding most of its impulses to the left
hemisphere) dominates in perceiving speech and language. The left ear (feeding most
of its impulses to the right hemisphere) dominates in perceiving non-verbal sounds.
Your ability to detect high frequencies declines with age, at the rate of about 150
Hertz per year after age 40.
1.3.5 Your Visual System
Your visual system is the most sophisticated and complicated of your senses. Vision
supplies information about the status of your environment, what it contains, and what
is moving within it. Vision supplies you with information about shape, size, distance,
brightness, and colour.
The seemingly simple task of interpreting shape requires information about vertical
lines, horizontal lines, diagonal lines, edges, and shading. Your sense of colour is
restricted to light with wavelengths between red (700 nm ) and violet (400 nm). Your
eyes are positioned in the front of the skull and slightly separated to provide
stereoscopic vision. Each eye provides a slightly different view of an object. These
different views provide information about the distance and shape of an object. Both
eyes survey the field of view directly ahead of you, while objects to each side can be
detected peripherally by just one eye. It takes about 0.1 seconds for your brain to
process a field of view and then get ready to for the next field of view. A series of
still pictures flashed on a screen at twice that rate is interpreted by your brain as
continuous action.
Your eyes convert incoming photons (fundamental bits of light energy) into nerve
impulses. Each eye has a number of substructures that contribute to your ability to
see:
1. The upper and lower eyelids regularly sweep the surface of your eye and can
close rapidly to protect its surface.
2. The cornea is a clear protective layer and acts as a preliminary lens.
3. The aqueous humour is the fluid-filled cavity between the cornea and the lens.

4. The iris is a coloured disk in front of the lens. It has an opening that can vary in
diameter from 0.5 to 9.0 mm to control the intensity of light that reaches the
retina.
5. The lens is a flexible structure that is normally thick and curved for viewing
objects up close. It can be stretched by ocular muscles to a thinner and less
curved shape for viewing objects in the distance. With age the lens loses some
of its elasticity and can no longer return to its highly curved status. That is
when you have to start using reading glasses.
6. The vitreous humour is the liquid-filled region in the centre of the eye. The
vitreous humour has to exert enough pressure to maintain the shape of the
eye, but too much pressure (glaucoma) can damage the retina.
7. The retina is the lining at the back of your eye that is coated with light-
detecting sensors, called rods and cones. There are about 120 million rods
spread over most of the retina to provide a basic black and white view of the
universe. In addition there are about 7 million cones concentrated in the
region directly behind the lens to provide a high-resolution image, in living
colour, of the region directly in front of each eye. The rods are more sensitive
to faint light than the cones, so faint scenes are typically perceived in black
and white.
The muscles that move your eyes also play a key role in your vision system. Every
twentieth of a second your eyes make rapid and abrupt jumps through about 15
degrees, as if they are in a constant search mode. This jumping motion, called a
saccade, occurs when the background remains stationary and you are concentrating
on an object in the foreground, as when you are reading. The eye muscles can also
execute smooth pursuit movements to follow an object as it moves across your field
of view. These two types of movements help to keep an object of interest focused on
the more sensitive cones at the centre of the retina.
The neural connections associated with the visual system are the most complicated of
any of our senses. Behind the eyes, there is a partial switch-over in the optic nerves
(called the chiasm) so that all the information from the left half of the field of view,

from both eyes, is directed to the right occipital lobe at the back of your brain.
Similarly, information from the right field of view, from both eyes, is channelled to
the left occipital lobe. The analysis of visual information is quite complicated. So far
neurologists have been able to trace twenty-eight different sub-channels in the brain
for analyzing visual information.
1.3.6 Your Sense of Orientation
There are two components to our sense of orientation: kinaesthetic sensors and
vestibular organs.
Kinaesthetic sensors provide information about your body’s spatial position, and the
movement of your joints and muscles. Special sensors in the mobile joints of the
skeleton provide information on the motion of single joints, and the relative motion
of sets of related joints. The shoulder is most sensitive to detecting small motions.
The wrist is next most sensitive, then the knuckle of the index finger. The ankle is the
joint least sensitive to detecting small motions. The brain receives information from
these sensors and uses it to determine the direction and the movement of your limbs
in space.
For controlled motion, you also need information on the position and orientation of
your whole body in space. In all mammals, vestibular organs located in the inner ears
provide information on position and orientation. A vestibular organ is a tiny sac filled
with fluid. It is lined with cilia (fine sensory hairs), and contains small crystals of
calcium carbonate. Both gravity and acceleration in a straight line can force the
crystals into the cilia, causing them to bend and send neural impulses to the
cerebellum and the medulla. The vestibular organ also includes two fluid-filled loops
at approximate right angles to each other. If your head moves in a circular motion,
fluid in these loops flows and the cilia are bent, sending more neural impulses to the
brain that correspond to the rotation of your head.
Visual input provides a backup check on the orientation and motion of your body.
The vestibular system can provide signals to help you interpret how your body is
moving during most everyday activities. Even the repeated action of jogging presents
no difficulty. However, large repeated motions, or motions in which the visual and

vestibular systems provide conflicting information, can lead to motion sickness. Over
time, most individuals eventually become habituated to an over stimulated vestibular
system. If you spend enough time at sea, your seasickness will gradually disappear.
Our sense organs are highly specialized organs for collecting information about our
environment. However, they are not mechanical machines that make absolute
measurements, and they tire under constant stimulation. Organic sensors are best at
monitoring changing conditions within their normal range of operation.
Raw input from your senses is filtered so that irrelevant data is disregarded. The
remaining input is interpreted and constantly analyzed for danger factors, for
emotional factors, and for practical information related to your current situation.
This filtering and interpretative activity occurs in your sub-conscious mind before the
results are passed on to your conscious mind for consideration.
Your senses provide you with a continuous update on the state of your immediate
physical environment.
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Chapter 2: Framing Your Thoughts
2.1 Human Thinking
2.2 The Nature of the Physical Universe
2.3 Approaches to Clear Thinking
The model of the universe that you create in your brain is based on a summary of your
sensory inputs and physical experiences. Your past experiences, your social setting,
and your knowledge of the world around you all have a profound impact on what you
think and the conclusions that you reach.
2.1 Human Thinking
When you think, you are activating neural networks in your brain and searching
through all the information that you have been able to gather since you were born.
You tend to consider yourself as a freethinking being, but your brain works with
evolutionary structures, cultural frameworks, and personal traits that set limits on
your thought processes.
You inherited a brain that is anatomically similar to other human brains. Some of your

particular behaviour patterns were also inherited from your parents along with the
colour of your hair and the size of your feet. Some of your learned behaviour patterns
have been shaped by the community in which you live.
Still, much of your mental universe is unique to yourself. Your life’s experiences are
your own. The neural networks that develop during your childhood are your own. Your
individual memories were shaped in your mind by events in your life.
Your mind creates a mental model of reality based on the information your mind is
currently receiving from your senses and the past information you have gathered from
your life’s experiences. When you reach out to pick up a coffee mug you are
integrating information about colour, shape, texture, and function for the mug, as
well as past experience in handling hollow objects filled with hot liquids. You have
also made a prediction regarding the satisfaction of drinking the coffee in the mug.
2.1.1 Basic Sources of Thought
Our thoughts are stimulated either by external or internal sources. Sometimes we
have total control over the source of our thoughts; sometimes thoughts are forced
upon us.
Sensory input
While your senses detect a continuous flow of stimuli from your environment only a
filtered version of that information actually reaches your conscious brain.
A significant part of our ability to interpret sensory input is learned. With much effort