INTRODUCTION

To fully understand the condition, we need to first understand the inner workings of the brain.
The human brain is the hub, the central processing unit if you will, around which our entire
bodies revolve. But how exactly do our brains connect and relate with our bodies? Do they work
together or independently? Do our brains define who we are? Now, I realize that neuroscience
and/or biology is not everybody’s cup of tea so I will honestly and hastily try to make this as
painless as I possibly can. But first, a short story. An ancient legend from India (Rosenzweig &
Leiman, 1989; as cited in Sternberg & Sternberg, 2016) tells the story of Sita, who marries one
man despite also having feelings for another. In their frustration, the two males decapitate
themselves. Grieving, Sita beseeches the goddess Kali to restore them to life. Having her wish
granted, she is permitted to reattach their heads to their respective bodies. In her haste, Sita
incorrectly switches their heads and attaches them to the incorrect bodies. Who is she married
to now? Who is whom in this little tale of two heads? Where, if anywhere, is the mind placed in
the body? How do we think? Talk? Speak? Plan? Reason? Remember? What are the physical
foundations of our cognitive abilities? How can the brain create our mental world. Philosophers
and scientists have long been fascinated by the mind-body problem. The mind-body problem is
the "problem of how a physical substance (the brain) can give rise to our sensations, thoughts
and emotions (our mind)” (Ward, 2015). While these inquiries appear to examine the link
between cognitive psychology and neurobiology, cognitive psychologists are more interested in
the anatomy and physiology of the nerve systems and how they influence and are influenced by
human cognition. The exciting new field of cognitive neuroscience is responsible for much of the
buzz in the field of cognitive psychology. Cognitive neuroscience is the field of study linking the
brain with other aspects of the nervous system to cognitive processing and behavior. It
integrates cognitive psychology and neuroscience (Solso et al., 2014; Sternberg & Sternberg,
2016). The brain, for those of you who aren’t so familiar with that thing between your ears, is
one of the most complex objects in the known universe. It has “100 billion neurons, and each
neuron is on average connected to 7000 other neurons - that makes a stunning 700 trillion
connections” (Gobet et al., 2011) and is "most directly in control of our thoughts, emotions, and
motivations” (Sternberg & Sternberg, 2016). Pretty staggering numbers! This chapter on
cognitive neuroscience looks at the structures and functions of the brain and neural
communication as well as the methods of examining the brain and brain disorders and how they
link to cognitive psychology.

COGNITION IN THE BRAIN

Let’s start our little trip to the brain with a pitstop at the nervous system. The nervous system is
the basis for our ability to perceive, adapt to, and interact with the world around us (Gazzaniga,
1995b, 2000; Gazzaniga, Ivry, & Mangun, 2014; as cited in Sternberg & Sternberg, 2016). It is
through this system that we receive, process, and then respond to information from the
environment. The nervous system is divided into two: the central nervous system and the
peripheral nervous system. The central nervous system or the CNS is composed of the brain
and spinal cord, while the peripheral nervous system (PNS) comprises all neural tissue, such as
neurons, that branch out from the brain and spinal cord and serves as a connection to and from
the brain and the rest of the body (Banich & Compton, 2018). Let’s bypass the PNS and spinal
cord and slowly make our way to that wonder structure that is the brain. How is it possible that
this 3.5 wrinkled looking structure called the brain is the seat of the mind and controls of the
body’s day-to-day functioning? What can the brain do? The more appropriate question would
be, what can’t the brain do? It receives information within a fraction of a second, it utilizes
language, possess emotions, it thinks, it controls autonomic functions like respiration, heart rate,
homeostasis, and it controls your immune system! (Smith & Kosslyn, 2013) Boggles the mind,
doesn’t it? …Get it? Mind? Sorry, just a little bit of smooth comedy to relieve your stress. Moving
on!

GROSS ANATOMY OF THE BRAIN

The cerebral cortex is the brain's outer covering and is where the majority of our higher-level
thoughts are processed. The forebrain, midbrain, and hindbrain are the three primary divisions
of the brain; however, these labels don't quite match up with where the various regions are
located in an adult or even a child's brain. These names come from the way these parts of the
developing embryo are set up from front to back. At first, the forebrain is usually the most
forward part of the brain, closest to what will become the face. The midbrain comes next. And
the hindbrain is usually farthest from the front brain, near the back of the neck.During embryonic
and fetal development, the brain becomes more specialized, and the hindbrain, midbrain, and
forebrain move around and change places from conception to birth (Sternberg & Sternberg,
2016; Taylor & Workman, 2022).

FOREBRAIN
For cognitive psychologists, the most interesting part of the brain is the forebrain, which also
happens to be the largest part of the brain (for humans, at least). The forebrain (also called the
prosencephalon) is the area of the brain that is near the top and front of the head; it includes the
cerebral cortex, the basal ganglia, the limbic system, the thalamus, and the hypothalamus,
Drawings of the brain don't show much else besides the forebrain. This is because the forebrain
wraps around the midbrain and most of the hindbrain, hiding these parts from view. Of course,
these pictures only show the cerebral cortex, which is the outside layer of the forebrain; and is
essential in our thinking and mental processes. A special section on the cortex will follow after
the present discussion on the forebrain (Reisberg, 2018; Sternberg & Sternberg, 2016). The
basal ganglia (singular: ganglion) are collections of neurons involved both in basic motor control
and in the control of complex cognition. Disorders such as Parkinson’s disease and Huntington’s
disease result from damage to the basal ganglia. Symptoms include tremors, involuntary
movements, changes in posture and muscle tone, slowness of movement, and difficulties with
cognitive tasks (Anderson, 2014; Sternberg & Sternberg, 2016). Emotion, motivation, memory,
and learning all rely on the limbic system. Our limbic system enables us to inhibit instinctual
responses. Hmmm, so apparently it's my limbic system that stops me from choking someone
who decides to scare the living s**t out of me - good to know. Curiously enough, the sense of
smell goes straight to the limbic system, so it shouldn't be a surprise that smell can make us feel
things that other senses can’t. The limbic system comprises three central interconnected
cerebral structures: the septum, the amygdala, and the hippocampus. (Galotti, 2007; Sternberg
& Sternberg, 2016). The septum (or septal area) is a subcortical region (meaning below the
cortex) that has strong projections to emotiongenerating areas and has a key role in anger and
fear. The amygdala also plays an important part in emotion, specifically in anger and
aggression; as well as tying emotional meanings to our memories. When stimulated it can
manifest in different ways, such as heart palpitations, terrifying hallucinations, or alarming
flashbacks. The hippocampus is an essential structure for learning and long-term memory
formation (Smith & Kosslyn, 2013; Sternberg & Sternberg, 2016; Sturm et al., 2016). The
thalamus is roughly in the center of the brain, approximately at eye level. It acts as a relay
station or switching station for nearly all the sensory information going to the cortex. With the
exception of smell, all of our senses pass via the thalamus before being directed to other parts
of the brain for processing (Galotti, 2007; Reisberg, 2018; Smith & Kosslyn, 2013). The
thalamus is also involved in the regulation of sleep and awakening. When the thalamus
malfunctions, it can cause discomfort, tremor, amnesia, language difficulties, and disturbances
in waking and sleeping (Cipolotti et al., 2008; Rockland, 2000; Steriade, Jones, & McCormick,
1997; as cited in Sternberg & Sternberg, 2016). The hypothalamus (hypo means “under” - and
guess where the thalamus is…you guessed it! UNDER the thalamus!) is a structure that plays a
crucial role in controlling behaviors that serve specific biological needs and functions (i.e.
species survival) - including keeping the body's temperature and blood pressure stable, eating
and drinking, keeping the heart rate within normal limits, and controlling sexual behavior
(Reisberg, 2018; Smith & Kosslyn, 2013; (Sternberg & Sternberg, 2016).

MIDBRAIN

The midbrain (also called the mesencephalon) is, predictably, positioned in the center of the
brain; but if you want to get technical, it is actually part of the brainstem. Many of the structures
in the midbrain, like the inferior (involved in hearing) and superior (involved in vision) colliculi,
send information to other parts of the brain, like the cerebellum and forebrain. (Galotti, 2007).
Among the other functions of the midbrain is the part it plays in coordinating movements
(especially in the precise movements of the eye as they explore the visual world. Suffice it to
say, the midbrain helps to control eye movement and coordination (Reisberg, 2018; Sternberg &
Sternberg, 2016). The reticular activating system (RAS) - also called the reticular formation - is
by far the most important of the structures found in the midbrain. They are a group of small
structures that are involved in regulating consciousness. What do we mean when we say
“consciousness?” The RAS is crucial in controlling sleep, wakefulness, arousal, attention, and
even to some key functions like heartbeat and breathing (Sarter, Bruno, & Berntson, 2003; as
cited in Sternberg & Sternberg, 2016). The RAS expands into the hindbrain as well and our
ability to be conscious of or have control over our existence depends on both the RAS and the
thalamus. The brainstem, which connects the forebrain to the spinal cord, is made up of the
hindbrain, thalamus, midbrain, and hypothalamus. The brainstem is positioned near the base of
the brain and contains numerous structures that receive and transmit information to and from
the spinal cord brain death is based on the functionality of the brainstem. Extensive damage to
the brainstem, the lack of electrical activity or blood flow to the brain, and the loss of reflexes
(such as the pupillary response) for more than 12 hours are the criteria used by doctors to
determine brain death (Smith & Kosslyn, 2013; Berkow, 1992; Shappell et al., 2013, as cited in
Sternberg & Sternberg, 2016).

HINDBRAIN

The hindbrain (also called the rhombencephalon), which includes the medulla oblongata, the
pons, and the cerebellum, is responsible some of the oldest and most primitive body functions
and is located at the very top of the spinal cord (or the lowest part of the brainstem). The
structures of the hindbrain are critical in controlling and regulating important life functions such
as heartbeat and breathing rhythm, maintaining body posture and balance, and modulating the
brain's state of attention (Reisberg, 2018). The medulla oblongata (sometimes simply called the
medulla) sits at the transition zone between the brain and the spinal cord - it is the continuation
of the spinal cord within the skull, forming the lowest part of the brainstem. It is the first region
that formally belongs to the brain (rather than the spinal cord). The medulla is also where nerves
from the right side of the body connect to the left side of the brain and nerves from the left side
of the body connect to the right side of the brain (Sternberg & Sternberg, 2016). Aside from
transmitting information from the spinal cord to the brain, the medulla regulates life support
tasks such as respiratory, cardiovascular, and digestive functions; such as breathing, blood
pressure, coughing, sneezing, vomiting, and heart rate (Pritchard & Alloway, 1999; as cited in
Galotti, 2007; Reisberg, 2018). So basically the medulla aids in our survival. This is one reason
why helmets are IMPORTANT. The helmet literally protects your head, and by extension, your
brain. Damage to your medulla could literally mean death. Pons (Latin for “bridge”) connects the
medulla oblongata with the midbrain region, and also relays signals from the forebrain to the
cerebellum. The pons houses a portion of the RAS as well as nerves that serve the head and
face (Sternberg & Sternberg, 2016); and helps with balance and visual and auditory processing
(Galotti, 2007). The cerebellum takes its name from the Latin for “little brain”. It is a separate
region of the brain located behind the medulla oblongata and pons and is the largest part of the
hindbrain.The main function of the cerebellum is muscle coordination. However, it is also
responsible for balance and posture, and it is also involved in some aspects of memory
involving procedurerelated movements such as when we are learning a new motor skill, such as
playing a sport or musical instrument. Brain lesions in the cerebellum can make people move in
strange, jerky ways, have tremors, and have trouble keeping their balance and walking (Galotti,
2007; Sternberg & Sternberg, 2016). I remember a news story back in 2014 where a 24 yearold
woman from China’s Shandong province showed up in a hospital because she was complaining
of nausea and dizziness. Since these are not uncommon issues, doctors proceeded as normal,
conducting a CAT scan to see if there was anything abnormal. The CAT scan results
immediately identified the source of the problem – her entire cerebellum was missing! The
woman was missing her cerebellum her whole life. Where the cerebellum would be found was
filled with cerebrospinal fluid - which cushions both the brain and spinal cord. The woman
commented that she had problems with balance and walking straight and steady for most of her
life. The case highlights just how adaptable the brain really is. She has since lived a normal life -
she holds a job and has had several kids. No neurological disorders so to speak. The amazing
brain, ladies and gentlemen!
CEREBRAL CORTEX AND LOCALIZATION OF FUNCTION

The cerebral cortex is the region that most often comes to mind when we think of the brain. It
wraps the surface of the brain in a thin 1 to 3 millimeter layer, much like the bark of a tree wraps
around the trunk. The cerebral cortex comprises 80% of the human brain and is extremely
important in human cognition. Because of cerebral cortex, we are able to think; we are able to
plan, to organize our thoughts and activities, to recognize patterns in both sight and sound, and
to communicate verbally. The numerous convolutions, or wrinkles, of the cerebral cortex in
humans have three parts. Sulci are tiny grooves (plural: sulcus). Fissures are deep striations.
And gyri (plural: gyrus) are bulges that form between adjacent sulci or fissures. These folds
significantly enhance the cortex's surface area. If the wrinkled human cortex was straightened
out, it would take up around 2 square feet. (Kolb & Whishaw, 1990; as cited in Sternberg &
Sternberg, 2016). Imaging crumpling up one entire newspaper page into a small, wrinkled ball
and then spread it out - that’s how much surface area the cortex would take up. The grayish
surface of the cerebral cortex It is sometimes called "gray matter" because most of it is made up
of the grayish bodies of the nerve cells that process the information the brain receives and
sends. In contrast, most of the myelinated axons in the white matter of the brain's interior are
white (Galotti, 2007; Sternberg & Sternberg, 2016). The cerebral cortex is the outer layer of the
brain's two halves, the left and right cerebral hemispheres. Although the two hemispheres
appear to be very similar to one another, they each serve a distinct purpose. For example,
receptors in the skin on the right side of the body generally send information through the
medulla to areas in the left hemisphere of the brain. Most of the time, the left side's receptors
send information to the right side of the brain. In a similar way, the left side of the brain controls
how the right side of the body moves. The left side of the body is controlled by the right side of
the brain. This is known as contralateral transmission, which means transmission from one side
to the other (contra-, "opposite"; lateral, "side"). There is also some ipsilateral transmission (on
the same side) that happens. Right Nasal odors move to the right side of the brain. About half of
right-eye information gets to the right side of the brain. In addition to contralateral specialization,
hemispheres communicate directly. (Sternberg & Sternberg, 2016).

HEMISPHERIC SPECIALIZATION

According to research with other individuals who have had certain brain regions damaged, there
are areas in the left cortex known as Broca's area (located in the frontal lobe) and Wernicke's
area (located in the temporal lobe) that appear to be crucial for speaking, because injury to
them results in aphasia, or severe impairment of speech. These are not the only brain areas
involved in speech, but they are essential. Damage to Broca's area or Wernicke's area can
cause different problems with language. People who have Broca's aphasia (which is caused by
damage to Broca's region) have trouble forming complete phrases and speak in fragments.
Patients diagnosed with Wernicke's aphasia, on the other hand, are able to form sentences that
are largely grammatical but virtually entirely devoid of meaning. Patients struggle with their
vocabulary and produce speech that is perceived as being “empty” (Anderson, 2014). In
addition to contralateral specialization, hemispheres also communicate directly. The corpus
callosum is a large band of fibers that connects the left and right hemispheres of the brain. It
communicates information back and forth. When information reaches one hemisphere, it is
transferred to the other by the corpus callosum. If the corpus callosum is severed, the two
cerebral hemispheres cannot interact with each other. In certain patients, the corpus callosum
has been surgically cut to prevent epileptic seizures. Such patients are referred to as split brain
patients. The operation is typically successful, and patients seem to function fairly well
(Anderson, 2014; Sternberg & Sternberg, 2016). Studies of split-brain patients have revealed
the right and left hemispheres' independent functions. Research has shown that the left side of
the brain is better at language. For example, commands could be given to these people in their
right ear, which would go to their left hemisphere, or in their left ear (and hence to the right
hemisphere). The right hemisphere understands only the most basic linguistic commands, but
the left hemisphere understands everything. A different result is obtained when the ability of the
right hand (hence the left hemisphere) to perform manual tasks is compared with that of the left
hand (hence the right hemisphere). In this situation, the right hemisphere clearly outperforms
the left hemisphere (Anderson, 2014; Reisberg, 2018; Sternberg & Sternberg, 2016). The left
hemisphere is vital in both language and movement. Damage to the left hemisphere is common
in people with apraxia (disorders of skilled movements and gestures). The right hemisphere is
mainly "silent." It lacks grammatical and phonetic knowledge. However, it has strong semantic
knowledge (general knowledge) and is also involved with practical language use (Sternberg &
Sternberg, 2016).

LOBES OF THE CEREBRAL HEMISPHERES

There are four lobes in each brain hemisphere: frontal (underneath the forehead), parietal
(underneath the top rear part of the skull), occipital (at the back of the head), and temporal (on
the side of the head); and are involved in numerous functions (Pritchard & Alloway, 1999; as
cited in Galotti, 2007). The frontal lobe is connected with motor processing and higher thinking
processes (or executive functions) such as abstract reasoning, problem solving, planning, and
judgment; and is also critical in producing speech. The front portion, called the prefrontal cortex,
is thought to involve complex motor control (i.e. activities requiring hand-eye coordination,
balance coordination, etc.). The primary motor cortex is also part of the frontal lobe. Its job is to
plan, control, and carry out movement, especially movement that requires a delayed response.
(Gazzaniga, Ivry, & Mangun, 2013; Stuss & Floden, 2003; as cited in Sternberg & Sternberg,
2016). The parietal lobe is linked to the processing of somatosensory information. It combines
various types of sensory information and is especially important in spatial processing and
navigation. The primary somatosensory cortex and a part of the visual system are both found in
the parietal lobe. The somatosensory cortex is like a "map" of the body. It uses information from
different parts of the body to process sensory information. Several parts of the parietal lobe are
important for language and visuospatial processing. The left parietal lobe is involved in symbolic
functions in language and math, while the right parietal lobe is specialized to process images
and interpret maps (i.e., spatial relationships) (Anderson, 2014; Solso et al., 2014). The
temporal lobe is associated with the retention of short- and long-term memories. It houses the
primary auditory cortex and is involved in auditory processing - it plays a critical role in our ability
to perceive sound. It processes sensory input including auditory information and language
comprehension (Sternberg & Sternberg, 2016). The occipital lobe contains most of the visual
cortex and is the visual processing center of the brain. Located at the back of the brain (it is the
rearmost lobe), damage to the occipital lobes may impair visual perception (Groome, 2014). The
brain normally accounts for “one-fortieth of an adult human body's weight” but it consumes
around "one-fifth of the circulating blood, one-fifth of the available glucose, and one-fifth of the
available oxygen”. Suffice it to say that the brain is the “supreme organ of cognition” (Sternberg
& Sternberg, 2016).

NEURONAL STRUCTURE AND FUNCTION

In the introduction, we talk about how the brain has “100 billion neurons, and each neuron is on
average connected to 7000 other neurons - that makes a stunning 700 trillion connections”
(Gobet et al., 2011). To understand how the nervous system as a whole processes information,
we must look at the structure and function of the cells that make up the nervous system. This
section looks into the core component of the nervous systems. Nervous tissue, present in both
the CNS and PNS, contains two basic types of cells: neurons and glial cells. Neurons are the
cells in the nervous system that carry information from one place to another by means of a
combination of electrical and chemical signals, and though they may vary in structure, neurons
have four basic parts: soma (cell body), dendrites, an axon, and terminal buttons. (Banich &
Compton, 2018; Sternberg & Sternberg, 2016). Glial cells (glia, from the Greek word meaning
“glue”) make up 90% of the cells in the brain and help separate, support, and insulate the
neurons from each other. Glial cells, which include astrocytes, oligodendrocytes and Schwann
cells, have a number of functions: astrocytes form the bloodbrain barrier and regulate chemicals
around the neurons and blood flow to the brain, oligodendrocytes produce myelin for the
neurons found in the CNS, while the Schwann cells produce myelin for the neurons in the PNS
(Gobet et al., 2011). Neurons are cells and therefore have a soma, or cell body, which contains
the nucleus - the central section of the cell that performs metabolic and reproductive processes.
The nucleus powers the soma and is responsible for the life of the neuron; it also connects the
dendrites to the axon. Dendrites are the branching structures that emanate from the soma; they
receive information from other neurons. The axon is a long, thin tube that extends (or splits)
from the soma and transmits information to neighboring neurons. There are 2 types of axons.
Myelinated axons are a type of axon that is covered by a fatty, white substance called myelin.
There are gaps in the sheath of myelin at locations known as the nodes of Ranvier. Myelin
protects the axon from its surroundings, making electric transmission more efficient and faster.
Myelinated axons are required for correct electrical transmission and its loss causes
catastrophic neurological illnesses such as multiple sclerosis. The second type of axon is not
wrapped by myelin, hence their electric transmission is slower. The axon ends with terminal
buttons. These are small knobs at the end of the end-braces of the axon and contain chemicals
used for inter-neuron transmission. Keep in mind that terminal buttons do not have direct
contact with the dendrites of the adjacent neuron. Instead, there is a slight gap, known as the
synapse which connects the terminal buttons of one or more neurons to the dendrites (or, in
certain cases, the soma) of one or more other neurons. Located within these knobs are
neurotransmitters - chemical messengers that transmit across the synaptic gap and ultimately
have either an excitatory (the probability that the receiving neuron will fire increases) or
inhibitory effect (the probability that the receiving neuron will fire decreases) on neurons.
Examples of neurotransmitters include: Acetylcholine, which is involved in muscle action,
cognitive functioning, memory, and emotion; Dopamine, involved in voluntary movement,
learning, memory, and emotion, GABA (Gamma-aminobutyric acid), which is a major inhibitory
neurotransmitter in the brain, Norepinephrine, which leads to increased heart rate and the
slowing of intestinal activity during stress, learning, memory, dreaming, waking from sleep, and
emotion; and Serotonin which is involved in sleep, appetite, sensory perception, temperature
regulation, pain suppression, and mood (Gobet et al., 2011; Groome, 2014; Sternberg &
Sternberg, 2016).

VIEWING STRUCTURES AND FUNCTIONS OF THE BRAIN

How can we learn about the many brain structures? Cognitive neuroscience studies the brain
and nervous system using a variety of evidence. Let's have a look at some of the options.

POST-MORTEM STUDIES Brain dissections and postmortem research date back centuries.
Even in the 21st century, scientists dissect brains to study behavior. Ideally, studies start when a
person is still living. Researchers observe how people with brain injury act while alive (Wilson,
2003; as cited in Sternberg & Sternberg, 2016). After patients die, researchers check for
lesions, or damaged tissue, in their brains. Then, the researchers infer that the places where the
lesions were may be related to the changed behavior. (sounds pretty morbid if you ask me…).

STUDYING LIVE NON-HUMAN ANIMALS

Researchers are also interested in the physiological processes and activities of the living brain.
To investigate how the living brain's activity changes, researchers must do in vivo (Latin for
“within the living”) experiments. Early in vivo operations were frequently only carried out on
animals. Methods include: single-cell recordings, lesioning, and gene knockout (KO).

Single-cell recording is a brain activity recording technique that records activity from a single
neuron or small group of neurons in the brain. A tiny recording needle is stuck into a neuron in a
part of the brain that is of interest to the researcher. This method requires surgery to insert the
needle in and bonding to the head to keep the needle in place. As such, this method is usually
only used in research with lab animals. In the process of lesioning, a portion of the brain is
either physically removed or damaged in order to study the subsequent functional deficits. A
gene or genetic knockout refers to the use of genetic engineering and manipulation to inactivate
or remove one or more specific genes from an organism (McBride & Cutting, 2018; Sternberg &
Sternberg, 2016).

STUDYING LIVE HUMANS

Many of the techniques used to study living animals can't be used on people; so, it's hard to
make broad statements about people based on these studies. But many imaging methods for
people that are less invasive have been developed. Some of the techniques are discusses in
this section.
Electroencephalography, or EEG, a brain recording technique that records the activity of large
sections of neurons from different areas of the scalp. During an electroencephalogram, a set of
electrodes are placed on the head to record electrical signals from different parts of the brain.
Since the electrodes are outside the skull, they can record the activity of the neurons closest to
the skull, which are mostly in the outer cortex. The activity is tracked over time to detect
changes in the electrical signals (positive or negative). EEG recordings can be used by
researchers to investigate an event-related potential (ERP), which is a shift in activity caused by
a specific event, such as the presentation of a stimulus. They can then evaluate whether the
stimulus presentation has an effect on neuron activity and where in the brain the effect occurs
(McBride & Cutting, 2018; Sternberg & Sternberg, 2016).

Positron emission tomography (PET) is a technique that images neuron activity in the brain
through radioactive markers in the bloodstream. A radioactive tracer is put into the bloodstream
during PET (the radiation exposure in a typical PET study is equivalent to two chest X rays and
is not considered dangerous). The person is put in a PET scanner, which can measure how
much of the radioactive element is in their bodies. With the methods we have now, we can get a
spatial resolution of 5–10 mm (Anderson, 2014; Sternberg & Sternberg, 2016).

Large abnormalities of the brain, such as damage caused by strokes or tumors, can be
observed using X-ray techniques. They are, however, restricted in resolution and cannot provide
much information regarding tiny lesions and aberrations. Traditional X-rays only show
a two-dimensional image of an object.

A computed tomography CT or CAT scan, on the other hand, uses many different X-ray images
of the brain taken from different angles to make a three-dimensional image (Sternberg &
Sternberg, 2016).

Magnetic resonance imaging (MRI) is a technique to image the internal portions of the body
using the magnetic fields present in the cells. MRIs are often used medically to gain clear
images of interior structures of the body. An MRI scan uses a magnetic field to create an image
by recording the signal from the positive hydrogen atoms within the body's cells. An MRI of the
brain can produce a clear image of the various brain regions, allowing for comparison between
individuals and the detection of damage or the presence of tumors (McBride & Cutting, 2018;
Sternberg & Sternberg, 2016)

BRAIN DISORDERS When your brain is injured, it can have a wide range of consequences,
including changes in your memory, sensation, perception, and even personality. Any ailment or
disability that affects your brain is considered a brain disorder. This category comprises
conditions caused by sickness, heredity, or traumatic injury.

STROKE
A vascular disorder is caused by a stroke which in turn occurs when the blood supply to the
brain is suddenly disrupted. Stroke victims typically experience significant loss of cognitive
functioning (the type of cognitive deficits depends on which part of the brain is affected), as well
as paralysis, pain, numbness, a loss of speech or language comprehension, impairments in
thought processes, and a loss of movement in parts of the body. There are two types of strokes:
ischemic (fatty buildup or calcification in the blood vessel breaks off and gets lodged in arteries
of the brain), or hemorrhagic (sudden rupture of a blood vessel in the brain leaks into
surrounding tissue, cutting off oxygen). Symptoms of an impending stroke include numbness or
weakness in the face, arms, or legs (especially on one side of the body), confusion and difficulty
speaking or understanding speech, vision disturbances in one or both eyes, dizziness, trouble
walking, or loss of balance or coordination, or a severe headache with no known cause
(Sternberg & Sternberg, 2016). My mom had a mini-stroke about 15 years ago. She didn’t
realize she was having a stroke when she went grocery shopping - she just complained that she
couldn’t focus on objects. She went to her eye doctor who suggested she take her blood
pressure as there was nothing wrong with her eyes. Her BP was extremely high and she was
rushed to the ER. Good thing was she did not suffer any physical or neurological damages from
her stroke.

TUMORS
A tumor is a swelling of a part of the body, generally without inflammation, caused by an
abnormal growth of tissue, whether benign (non-cancerous and removable - but can cause
cognitive impairment if pressing on sensitive parts of the brain) or malignant (cancerous, grows
quickly and may metastasize - spread - and infect healthy cells, may be removed through
surgery and treated with radiation and/or chemotherapy). Brain tumors or neoplasms can
seriously impair cognitive functioning. There are two forms of brain tumors. Primary brain tumors
develop within the brain. This is the most common kind of childhood brain tumor. Secondary
brain tumors develop from malignancies elsewhere in the body, such as the lungs (Sternberg &
Sternberg, 2016).

HEAD INJURIES
Head injuries can be caused by a variety of factors, including vehicular accidents, contact with
hard surfaces, or bullet wounds. Closedhead injuries happen when the skull remains intact but
the brain is damaged. This is usually caused by the force of a blow to the head. Open-Head
injuries are when skull does not remain intact but rather is penetrated (Sternberg & Sternberg,
2016). Remember Phineas Gage? He was the victim of an accident while working on a railroad
in 1848. Gage had a large iron rod impaled through the 3 of his frontal lobe. After the accident,
his personality appeared to change, but he eventually learned to cope with the trauma and lived
as a coach driver even after such a traumatic event.