Introduction
The functioning of human brain is one of the most complex systems studied by the scientists. Even after so many years of research, there still remain parts if the brain the functions of which are not yet known. Everything that we do is controlled by our brain even the slightest injury can have adverse effects on normal human functioning.
Thomas Willis, also known as the father of neurology, was the first to suggest that different parts of the brain were responsible for different cognitive functions (Molnar, 2004). Cognitive functions may be defined as “any mental process that involves symbolic operations e.g. perception, memory, creation of imagery, and thinking; Cognitive functions encompasses awareness and capacity for judgement” (Medical Dictionary, 2010).
It is now an established fact the different parts of human brain control different activities. To develop a better understanding, the human brain is said to be composed of three concentric layers: Central core, the limbic system, and the cerebral hemisphere (Joseph, 1992).
Central Core
Most of the brain stem is a part of the central core. It controls a number of reflexes including breathing and also helps in standing upright (Atkinson, Hilgard, & Atkinson, 1983). The central core is composed of cerebellum, thalamus and hypothalamus, Pons, medulla, and the reticular system (Patestas & Gartner, 2006).
All these part have a special function to perform, for instance the hypothalamus controls the visceral and somatic function like temperature and metabolism while the medulla takes care of reflexes such as heart beat, respiration, and blood pressure (Atkinson, Hilgard, & Atkinson, 1983).
The Limbic System
The limbic system is made of Amygdala and the Hippocampus. The Amygdala performs the cognitive function of emotions and the behavioural, autonomic, as well and endocrine response to the stimulus present in the environment (Cristinzio & Vuilleumier, 2007). When the amygdala is damaged, it may result in impaired emotional functioning of an individual and the lack of “social significance of sensory events…[such as] attention, memory [etc]” (Cristinzio & Vuilleumier, 2007, pp.87).
The hippocampus on the other hand is responsible for memories, their storage and retreival which is an importan cognitive function (Swenson, 2010).
Cerebral Cortex
The cerbral cortex is the thick layer which covers the cerebrum which is filled with myelinated axons and control some of our most complex cognitive activities (Atkinson, Hilgard, & Atkinson, 1983). The cerebral cortex is divided into different parts: the occipital lobe which controls vision and processes the visual information; the Temporal lobe is responsible for smell, hearing, language, motivation, etc; the Parietal lobe which controls spatial abilities and sensory projection; and the Frontal lobe is responsible for the thought process which are required to solve problems, coordination of messages received from other parts of the brain, controls many parts of personality, concentration, etc (Atkinson, Hilgard, & Atkinson, 1983). Many functions of the frontal lobe were discovered after the severe injuries suffered by Phineas Gage.
Phineas Gage
Phineas Gage (1823-1860) was a railroad construction foreman who suffered some extreme injuries in the head at the age of 25, when an iron rod, 1.1 mm long and 6 mm in diameter weighing 6 kg, drove through his head coming out from in left cheek (Leach & O’Driscoll, 1998).
After bleeding continuously for two day and five weeks of treatment by Dr. Harlow, Gage regained his consciousness and was able to go back to his normal routine (Leach & O’Driscoll, 1998). The case did not end there as Dr. Harlow continued to observe Gage after the treatment to see the effects of the injury.
After the accident some significant changes were noticed in the personality of Gage by his wife and other people around him. Before the injuries, Gage was considered to be one of the most efficient workers by his employers but the change in his personality was so severe that they forced to change their opinion about him and his friends even said that after the accident he was no lone the Gage they knew earlier (Cuizon, 2009).
In the accident mainly the frontal lobe of Gage was damaged and Dr. Harlow concluded that due to the damage done to frontal lobe, Gage had completely lost his social inhibition which resulted in unacceptable behaviour (Cuizon, 2009).
The case of Phineas Gage, though gruesome, contributed a lot to the neurobiology in the nineteenth century. It was because of the injuries of Phineas Gage that proved functions of the frontal lobe and that different parts of the brain are responsible for different cognitive functions.
Gage was able to fully recover and was physically fit. The only changes noticed were in his completely changed personality which was so extreme that his family and friends found it hard to believe that Gage was the same person they knew before the accident. It is one of the most amazing cases in the medical world and has revealed many facts about the brain and cognitive functions.
References
Atkinson, R. L., Hilgard, E. R., & Atkinson, R. C. (1983). Introduction to Psychology. New York: harcourt Brace Jovanovich.
Cristinzio, C., & Vuilleumier, P. (2007). The Role of Amygdala in Emotional and Social Functions. Epileptologie , 78-89.
Cuizon, G. (2009). The Amazing Case of Phineas Gage. Web.
Joseph, R. (1992). The four ego personalities and the unconscious child and parent within. New York: Plenum Press.
Leach, J. P., & O’Driscoll, K. (1998). “No longer Gage”: an iron bar through the head . BMJ , 1673–1674.
Medical Dictionary. (2010). Cognitive function. Web.
Molnar, Z. (2004). Thomas Willis (1621-1675), the founder of clinical neuroscience. Nature Reviews Neuroscience , 329-335.
Patestas, M. A., & Gartner, L. P. (2006). Neuroanatomy. New Jersey: Blackwell Publishing.