4

Bioinformatics of the Brain

been under debate whether it should be a part of the ventral thalamus or

the hypothalamus [9]. As the largest part of the diencephalon, thalamus is

reported to relay information for motor, sensory, limbic, cognitive, and high-

order functions [10–12]. The hypothalamus is the hormonal output regulatory

center, located at the base of the brain. It is the main mediator for the activity

of the pituitary gland on the target organs. In this axis, the pituitary gland

secretes adrenocorticotropic hormone, thyroid-stimulating hormone, growth

hormone, prolactin, and the gonadotrophs to manipulate the cellular activity

throughout the body [13]. Located dorsal to the thalamus, epithalamus-based

outputs are essential for motor control, biological clock, and stress responses

[14]. The brain stem forms the connection between cerebrum to spinal cord

and cerebellum and, consists of the medulla, the pons, and the midbrain [15].

The path of all nerve fibers that transmit signals between the cortex and

spinal cord passes through the brain stem. Therefore, it receives information

from all areas of the CNS and processes this information by integrating it.

Its main functions are control of circulation and respiration, control of sleep

and attention, gastrointestinal activity, and other neurological activities [16].

Additionally, the medulla plays a crucial role in breathing, blood pressure,

blood rhythm, coughing, sneezing, and swallowing reflexes [17]. As a result,

the prominent role of the brain stem and its part is significant to sustain life.

Another subunit, pons, (meaning “bridge” in Latin) acts as a bridge to the

brain. It receives and distributes signals from and to the brain [18]. It also has

many important tasks such as biological clock, control of swallowing, hearing,

tasting, and posture. Finally, the midbrain, rostral to the pons and caudal to

the thalamus and the basal ganglia carry out the tasks of motor movements,

visual and auditory senses, balance, sleep/wake cycles, alertness, arousal and

control and regulation of eye movements [19]. The cerebellum as the largest

section of the brain is assembled with two hemispheres and midline vermis.

It is suggested that this brain section is involved in cognitive function and

movements [20]. Although the cerebellum occupies around 10% of the entire

brain mass, it accounts for nearly 80% of cerebral neurons [21].

1.3

Body Under Control of Brain

The brain is a perfect composition of fine structural and functional units com-

posed of groups of neurons arranged together as a clear anatomical model.

These neurons pass signals to each other and to other types of cells such as

glia to communicate. Neurons consist of three parts: Cell body, axon, and

dendrites (Figure 1.1C). The greater the number of network patterns formed

by neurons, the stronger the information processing process occurs. Each neu-

ron has many short extensions called dendrites and one long extension called

axon surrounded by a myelin sheath. Neurons communicate with each other