The central nervous system (CNS) is composed of the brain and the spinal cord. The spinal cord controls movement and feeling of body regions located below the brain. The brain also plays a role in movement and feeling. However, the brain's role is more complex than that of the spinal cord, and the brain controls complex psychological processes as well (e.g., attention, perception, motivation, emotion, language, cognition, and purposeful behaviors). When certain parts of the brain are damaged, specific functions may be lost. The type and extent of functional loss depend upon the age of the individual, the location of the brain damage, its etiology, and the amount of brain tissue that is compromised. For example, damage to a strip of cortex in the posterior part of the frontal lobes controlling movement of parts of the body will result in paralysis of those body parts. Lesions within relay stations along the visual sensory system—from the optic nerves to the occipital lobes—will result in visual field defects such as scotomas (blind spots).
Lesions deep in the hypothalamus may produce hunger, uncontrolled eating, and obesity. Destruction of areas involved in arousal may result in a permanent comatose state. Finally, damage early in life can be less devastating than analogous damage in late adulthood.
Disorders of the CNS usually are classified according to lesion location (e.g., abnormalities occurring after frontal lobe damage) or according to etiology, symptomatology, and functional loss (e.g., amnesia). The following discussion focuses on two exemplars of CNS disorders. The first, frontal system disorders, exemplifies possible consequences of damage to the anterior regions of the frontal lobes (Stuss & Knight, 2002). The second, amnesia after long-term alcoholism (Oscar-Berman, 2000), exemplifies a disorder recognized by abnormalities of memory, especially memory for recent events (anterograde amnesia). Keep in mind that the distinction between structure and function is not a mutually exclusive one. The brain has many highly interconnected parts, and when one part is damaged, other parts will be affected as well. Similarly, behavioral abnormalities are complex; they involve a broad spectrum of perceptual and cognitive deficits that may be integral to the presenting symptoms of many disorders of the CNS (Armengol & Jamieson, 2001; Lezak, 1995; Mesulam, 2000; Spreen & Strauss, 1998).
Was this article helpful?
It seems like you hear it all the time from nearly every one you know I'm SO stressed out!? Pressures abound in this world today. Those pressures cause stress and anxiety, and often we are ill-equipped to deal with those stressors that trigger anxiety and other feelings that can make us sick. Literally, sick.