Brain Diseases and Disorders

3

1.2

Brain: The Command Center of the Body

The brain performs a multitude of vital tasks. It is the reason we are capable

of evaluating and interpreting the events that are transpiring around us. All

five of our senses—sight, smell, hearing, touch, and taste—can all be used to

simultaneously transmit instructions to the brain. The brain is responsible for

many bodily functions, including thinking, memory, speech, and movement

of the limbs. The brain’s body control determines how a person responds to

stress (such as exam excitement, losing a job, illness) by changing respiration

and heart rates.

The brain is organized, and each part is divided into certain functions

[2]. Considering the anatomy of the brain, it is clear that the cerebrum also

known as the telencephalon is the largest and main part of the brain, and,

together with the diencephalon, they assemble into the forebrain. The cere-

brum consists of right and left hemispheres connected to each other by the

corpus callosum and fornix which provides signal transmission of nerve cells

and consists of axon fibers. Each hemisphere of the brain is divided into 4

different lobes: Frontal lobe, occipital lobe, temporal lobe, and parietal lobe

forming the front, posterior, lower, and upper parts of the brain, respectively

(Figure 1.1B) [3]. The frontal lobe directs purposeful actions such as creativ-

ity, problem solving, decision making, and planning [4]. The occipital lobe in

the upper posterior region carries out processes involving vision. The tempo-

ral lobe (right and left) is located around and above the ears. This region is

mainly responsible for hearing, memory, emotion, smell, and comprehension of

language. In contrast, the parietal lobe is crucial for perception and visual pro-

cessing [5]. The diencephalon region consists of the hippocampus, thalamus,

hypothalamus, and amygdala. Also known as the limbic system, this section

of the brain is required for the production of emotions, sleep, attention, body

functioning, hormones, sex, smell, and many of the brain chemicals [6].

The outermost part of the cerebrum (cerebral cortex, gray matter) con-

tains neurons which are unmyelinated and have slower conduction. This cortex

is the region where the most important perceptual functions such as memory,

attention, perceptual awareness, thought, language, and consciousness are cre-

ated. Therefore, this region is significant for the body and is of interest for

routine functions. The walnut-shaped brain shell contains folds called gyrus,

while the slits between the folds are called sulcus [7]. One of the most inter-

esting facts about the cerebrum is that it contains tens of billions of neurons,

forming nerve fibers, and these nerve fibers produce behaviors that “we think

we are doing consciously” by constantly evaluating the data coming from the

environment [8].

The

diencephalon

is

the

region

between

the

cerebrum

and

the

brain stem. This structure consists of the thalamus, hypothalamus, and

epithalamus. Another nucleus known as the subthalamic nucleus often has