Lecture: The Nervous System
Reading Assignment 7:
Subcortical Forebrain/Cerebral Cortex (pp.78-88)
Click for Objectives for Reading Assignment 7


Summary:
The seventh reading assignment follows up on the introduction to the Central Nervous System by taking a deeper exploration into the Brain structures.

The Three Major Subdivisions
The Brain can be broken into three major subdivisions (See reading assignment 6 for a deeper discussion about the three major subdivisions of the Brain); however, to fully appreciate the Brain, each of the subdivisions require a more comprehensive discussion.
The Hindbrain
The Hindbrain is a theoretically defined. It contains components responsible for very basic skills. These skills are essential or necessary for survival. For purposes of this class, the components of the Hindbrain includes the following three structures: the Medulla Oblongata, Cerebellum, and Reticular Formation. It is with a deep sadness, that I state that you may have to forget what you think you know about the Medulla Oblongata to succeed in this class. The Adam Sandler movie Waterboy popularized the term Medulla Oblongata in a very memorable classroom scene in which the main character got into a debate with the instructor. The information relayed in the movie scene, however, was incorrect. That scene essentially stated that alligators are so angry as a result of their Medulla Oblongata. Unfortunately, the Medulla Oblongata is not responsible for aggression, but for some of the vital functions needed for survival. The Cerebellum, which means little cerebrum in Latin, is a protruding structure located near the top of the Hindbrain. It is in close proximity to the visual cortex (named and defined later). It is also responsible for a set of skills that benefit from visual information pertaining to the environment. Finally, the Reticular Formation aids the functioning of other neighboring brain structures. It is also involved in actions such as the sleep cycle and filtering incoming stimuli (Wikipedia/wiki/Reticular_formation).
The Midbrain
The Midbrain is another theoretically defined subdivision of the Brain. Please note that for the second time I stated that the subdivisions are theoretical. It should be noted that the Reticular Formation is debated as to whether it is a structure of the hind- or midbrain. This debate likely comes from the question of whether the sleep cycle is a primitive process (worthy of being a part of the Hindbrain) or a higher level process (worthy of being part of the Midbrain).

The Midbrain is located directly above the Hindbrain and below the ForeBrain (discussed later). The midbrain is almost completely surrounded by the forebrain. It contains components responsible for vision, hearing, motor control, temperature regulation, alertness, and the sleep cycle (Wiki/wiki/Midbrian). For purposes of this class, the components of the Midbrain includes the following two structures: the Tectum and Tegmentum.

The Forebrain
The Forebrain is the front most portion of the Brain. Its major components include the Cerebral Cortex, Basal Ganglia, Hypothalamus, Thalamus, and the Limbic System which contains the Amygdala, Limbic Cortex, and Hippocampus. The Limbic System is a collection of subcortical structures that collectively serves as the motivation, emotion, learning, and memory center, which should not be confused with the cortex with the same prefix name (I.e., the Limbic Cortex). As stated in the previous chapter, the Amygdala is the component of the brain that should have been referenced in the movie Waterboy as being responsible for emotions such as aggression. Also a part of the Limbic System is the Hippocampus which is involved in the acquisition and consolidation of new information in memory (Kowalski & Westen, 2009). The Basal Ganglia is not a part of the Limbic System, however, it is a set of structures that is responsible for the coordination of smooth movements and judgments requiring minimal thought. The Basal Ganglia is also believed to be linked with Parkinson’s Disease, which is characterized by an inability to regulate muscle movements.

The last major component of the Forebrain discussed here is the Cerebral Cortex, which consists of four lobes that surround the hind and mid portions of the brain. The lobes are responsible for many of the functions that are uniquely human and that contribute to the quality of life that we often take for granted. Starting from the forehead and going over and under the rest of one’s head the following lobes will be encountered: the Frontal Lobes, the Parietal Lobes, the Occipital Lobes, and Temporal Lobes

The Great Divide
Humans have two independent hemispheres of the Brain that often engage in parallel processing. As a matter of fact, humans actually have a pair of the four lobes, which were discussed above, for a total of eight lobes. In the event that the Corpus Callosum is severed, an individual would have two independently operating hemispheres of the Brain. With only a few exceptions, the majority of the functions of the Cerebral Cortex are redundantly processed in the two halves the Brain. Two of those exceptions are the Broca’s Area and Wernicke’s Area. Both areas are named after the physicians who identified them, with both of them having unique functions that occur on the left hemisphere only. Damage to these areas has been referred to as different types of Aphasia: Broca's Aphasia and Wernicke’s Aphasia, respectively. Another exception is the fact that researchers have identified sex differences in Lateralization, in that is, which reliable differences have been found in how the sexes process information in the Brain.


References:

Textbooks

A. Wilson, J. F. (2003). Biological Foundations of Human Behavior (Instructors Ed.). Thomson, Inc.
B. Klein, S. B. (2000). Biological Psychology. Prentice Hall, Inc.
C. Lefton, L. A. & Brannon, L. (2003). Psychology (Eighth Ed.). Allyn & Bacon: Pearson Educ., Inc.

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