The human brain is not only one of the
most important organs in the human body; it is also the most complex. In
the following tour, you will learn about the basic structures that make
up the brain as well as how the brain works. This is not an in-depth
look at all of the research on the brain (such a resource would fill
stacks of books). Instead, the goal of this brain tour is to familiarize
you with major brain structures and their functions.
The cerebral cortex is the part of the brain that functions to
make human beings unique. Distinctly human traits including higher
thought, language and human consciousness as well as the ability to
think, reason and imagine all originate in the cerebral cortex .
The Four Lobes
The brain can be divided into four sections, known as lobes.
The cerebral cortex can be divided into
four sections, which are known as lobes (see image above). The frontal
lobe, parietal lobe, occipital lobe, and temporal lobe have been
associated with different functions ranging from reasoning to auditory
perception.
The frontal lobe is located at the front
of the brain and is associated with reasoning, motor skills, higher
level cognition, and expressive language. At the back of the frontal
lobe, near the central sulcus, lies the motor cortex. This area of the
brain receives information from various lobes of the brain and utilizes
this information to carry out body movements. Damage to the frontal lobe
can lead to changes in sexual habits, socialization, and attention as
well as increased risk-taking.
The parietal lobe is located in the middle
section of the brain and is associated with processing tactile sensory
information such as pressure, touch, and pain. A portion of the brain
known as the somatosensory cortex is located in this lobe and is
essential to the processing of the body's senses. Damage to the parietal
lobe can result in problems with verbal memory, an impaired ability to
control eye gaze and problems with language.
The temporary lobe is located on the bottom section of the brain. This lobe is also the
location of the primary auditory cortex, which is important for
interpreting sounds and the language we hear. The hipocampus is also located in the temporal lobe, which is why this portion of the brain is also heavily associated with the formation of memorie. Damage to the temporal lobe can lead to problems with memory, speech perception, and language skills.
The occipital lobe is located at the back
portion of the brain and is associated with interpreting visual stimuli
and information. The primary visual cortex, which receives and
interprets information from the retinas of the eyes, is located in the
occipital lobe. Damage to this lobe can cause visual problems such as
difficulty recognizing objects, an inability to identify colors, and
trouble recognizing words.
The Brain Stem
The brain stem is comprised of the
hindbrain and midbrain. The hindbrain contains structures including
medulla, the pons and the reticular formation.
The Hindbrain
The hindbrain is the structure that connects the spinal cord to the brain.
The medulla is located directly above the spinal cord and
controls many vital autonomic functions such as heart rate, breathing
and blood pressure.
The pons connects the medulla to the cerebellum and helps coordinate movement on each side of the body.
The reticular formation is a neural network located in the medulla that helps control functions such as sleep and attention.
The Midbrain
The midbrain is the smallest region of the brain that acts as a sort of relay station for auditory and visual information.
The midbrain controls many important functions such as the
visual and auditory systems as well as eye movement. Portions of the
midbrain called the red nucleus and the substantia nigra
are involved in the control of body movement. The darkly pigmented
substantia nigra contains a large number of dopamine-producing neurons
are located. The degeneration of neurons in the substantia nigra is
associated with Parkinson’s disease.
The Cerebellum
Sometimes referred to as the "little brain,"
the cerebellum lies on top of the pons behind the brain stem. The
cerebellum is comprised of small lobes and receives information from the
balance system of the inner ear, sensory nerves, and the auditory and
visual systems. It is involved in the coordination of motor movements as
well as basic facets of memory and learning.
The cerebellum makes up approximately 10 percent of the brain total size, but it accounts for more than 50 percent of the total number of neurons
located in the entire brain. This structure is associated with motor
movement and control, but this is not because the motor commands
originate here. Instead, the cerebellum serves to modify these signals
and make motor movements accurate and useful.
For example, the cerebellum helps control posture, balance, and the
coordination of voluntary movements. This allows different muscle groups
in the body to act together and produce coordinated, fluid movement.
In addition to playing an essential role in motor control, the
cerebellum is also important in certain cognitive functions including
language.
The Thalamus
The thalamus is located above the brain stem.
Located above the brainstem, the thalamus processes and transmits movement and sensory information.
It is essentially a relay station, taking in sensory information and
then passing it on to the cerebral cortex. The cerebral cortex also
sends information to the thalamus, which then sends this information to
other systems.
The Hypothalamus
The hypothalamus is a grouping of nuclei
that lie along the base of the brain near the pituitary gland. The
hypothalamus connects with many other regions of the brain and is
responsible for controlling hunger, thirst, emotions, body temperature regulation, and circadian rhythms. The hypothalamus also controls the pituitary gland by secreting hormones,which gives the hypothalamus a great deal of control over many body functions.
The Limbic System
The amygdala is one of the major structures found in the limbic system.
The limbic system is comprised of four main structures: the amygdala, the hippocampus, regions of the limbic cortex and the septal area.
These structures form connections between the limbic system and the
hypothalamus, thalamus and cerebral cortex. The hippocampus is important
in memory and learning, while the limbic system itself is central in
the control of emotional responses.
The Basal Ganglia
The basal ganglia are a group of large
nuclei that partially surround the thalamus. These nuclei are important
in the control of movement. The red nucleus and substantia nigra of the
midbrain have connections with the basal ganglia.
REREFENCES
Thompson, R.F. (2000). The Brain: A Neuroscience Primer. New York: Worth Publishers.
The cerebral cortex. 
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