The Brain Is the Most Complex Organ of the Human Body. with Over an Estimated 50 - 100

The brain is the most complex organ of the human body. With over an estimated 50 - 100 billion neurons in it, the brain ticks and works in ways that is still a mystery to many neurologists. The scientific study of the brain and the nervous system is called neurobiology or neuroscience. The brain is a part of the central nervous system along with the spinal cord and the peripheral nervous system (PNS) which is made of nerves. Nervous system plays the role of controlling every aspect of our life; from simple memorization to critical thinking, from lifting a pin, to voluntary smooth functioning of all the other organs in the body. Of all the parts of the brain, the cerebrum or cortex is the largest part, which is further sub-divided into four lobes; frontal lobe, parietal lobe, occipital lobe, and temporal lobe. Given below is an overview on the lobes of the brain and their functions.

Diagram: Lobes of the Brain

Brain Lobes and Their Functions

⇨ Frontal Lobe

The frontal lobe is home to our cognitive thinking, and it is this process that determines and shapes an individual's personality. In human beings, the frontal lobe attains maturity when the individual is around the age of 25. This means that by the time we are 25 years of age, we have achieved a level of cognitive maturity. The frontal lobe is made up of the anterior portion (prefrontal cortex) and the posterior portion, and is divided from the parietal lobe by the central sulcus. The anterior portion is responsible for higher cognitive functions, and the posterior portion consists of the premotor and motor areas, thus, governing voluntary movements. Functions of the frontal lobe include reasoning, planning, organizing thoughts, behavior, sexual urges, emotions, problem-solving, judging, organizing parts of speech, and motor skills (movement). The frontal lobe is extremely vulnerable to injury due to its location, as it is in front of the central cranium. Any damage to this lobe of the brain can lead to one or more of the following problems.

 Increased or decreased problem solving ability and creativity  Alteration in talking habits  Reduced sexual interest or peculiar sexual habits  Impaired risk-taking ability  Reduced or no sense of taste and/or smell  Impaired spontaneity and mental flexibility  Increased susceptibility to distractions

⇨ Parietal Lobe

The parietal lobe is located behind the central sulcus, and above the occipital lobe. It has four anatomical boundaries; the central sulcus, which separates the parietal lobe from the frontal lobe, the parieto-occipital sulcus which separates the parietal and occipital lobes, the lateral sulcus which separates the parietal from the temporal lobe, and the medial longitudinal fissure which divides the two hemispheres (right and left). The parietal lobe is responsible for integrating sensory information from various parts of the body. The optic nerves passes through the parietal lobe to the occipital lobe. Functions of the parietal lobe include information processing, movement, spatial orientation, speech, visual perception, recognition, perception of stimuli, pain and touch sensation and cognition.

Any damage to the parietal lobes result in abnormalities in spatial processing and body image. Mentioned below are the problems that occur after damage to a particular site of the parietal lobe.

 Left Parietal Lobe Damage: Any damage to left side of this lobe can cause Gerstmann's syndrome, aphasia (language disorder), and agnosia (abnormal perception of objects).  Right Parietal Lobe Damage: Right side damage results in difficulty in making something, impaired personal care skills and impaired drawing ability.  Bi-lateral Parietal Lobe Damage: It causes Balint's syndrome which is characterized by impaired visual attention and motor activities.

⇨ Occipital Lobe

Smallest of all the four lobes, the occipital lobes are located in the rearmost portion of the skull. These are located on the tentorium cerebelli, that separates the cerebrum from the cerebellum. This lobe is responsible for visual perception system, as it contains the primary visual cortex. Functions of the occipital lobe include visual reception, visual-spatial processing, movement and color recognition. Disorders of the occipital lobe can cause visual illusions.

Because of the location, these lobes are not particularly susceptible to injury, although significant trauma can result in a few problems.

 Disruption of the visual-perceptual system  Homonomous vision loss

⇨ Temporal Lobe

There are two temporal lobes, each of which are located on each side of the brain; left and right, at about the level of the ears. The temporal lobes contain the primary auditory cortex, and hence, are responsible for all auditory processing. These lobes also contain the hippocampus, responsible for formation of long-term memory and sorting new information. Functions of both (left and right) temporal lobes include distinguishing and discrimination of smell and sound from other smells and sounds respectively. Between them, they control visual memory (right lobe) and verbal memory (left lobe), and thus, hearing, speech and memory. Effects of temporal lobe damage can again be classified depending on which side of the lobe is affected.

 Left Temporal Lobe Damage: It leads to decreased ability to recall audio and visual content, difficulty in recognizing words and remembering verbal material.  Right Temporal Lobe damage: Damage to right side of this lobe results in difficulty in recognizing visual content and tonal sequences, recall of previously encountered music or drawings, and reduced inhibition of talking.

The brain plays an important role in the human body. Its four lobes determine who we are and the reasons behind our perceptions. Hope this write-up has helped you in understanding the lobes of the brain and their functions. By Loveleena Rajeev Last Updated: 3/20/2012