Copyright © 2007-2017 Russ Dewey
Ever since the time of the ancient Egyptians, brain injuries provided the richest source of data about the relationship of brain to behavior. The discipline of neuropsychology is the study of brain/behavior relationships.
What is neuropsychology?
Neuropsychologists are interested in helping people with brain injuries, diagnosing their problems and devising therapies for rehabilitation. They are also interested in brain/behavior relations in their own right, as scientific topics for research.
The brain can be damaged by accidents, tumors, or strokes. It can also be damaged by near-fatal drowning, heart attacks, choking, or anything else that cuts off the brain's oxygen supply.
Penetrating wounds are one obvious source of brain injuries. They occur when a bullet or other projectile penetrates the skull and injures the brain.
The ancient Egyptians knew the brain was the physical organ of the mind. They inferred this after observing effects of penetrating injuries.
Penetrating wounds are only one of the types of brain injury that provide information to neuropsychologists. Strokes, known to doctors as cerebrovascular accidents or CVAs, are also a common cause of brain injury.
Strokes can have several causes. These include fatty deposits in the brain's arteries (atherosclerosis), thickening and hardening of the artery walls (arteriosclerosis), and clots forming in a narrowed artery (thrombosis).
A clot formed somewhere else in the body can be carried to the brain in the bloodstream (embolism). Sometimes blood is cut off from portions of the brain when an artery wall balloons out (aneurysm) or bursts (hemorrhage).
What are different ways the brain can be damaged?
Four out of five stroke victims suffer temporary strokes first. These are called transient ischemic attacks (TIAs) and are caused by brief interruptions in the blood supply. Symptoms include weakness or numbness of an arm, hand, leg, or facial muscle, difficulty speaking, blurry vision in one eye, deafness, loss of balance, sudden unexplained headache or abrupt personality change.
A TIA usually lasts only a few minutes (almost always less than an hour) and the effects wear off quickly, so people tend to ignore them. However, it is important not to brush off the symptoms because about a third of TIA victims have a stroke within five years unless treated.
What are TIAs?
A full-blown stroke is indicated by symptoms that last more than a few minutes. If this happens, it is very important to get them to a hospital quickly.
Why is it important to get a stroke victim to the hospital quickly?
Doctors can inject tissue plasminogen activator (abbreviated tPA or PLAT) and dissolve the clot, but this must be done right after a stroke. If the patient comes to the hospital within a few hours of having a stroke, damage can be reversed. Otherwise the damage is permanent.
Perhaps the most famous brain injury in history was a penetrating wound suffered by a railroad worker named Phineas Gage. Gage was setting up a black powder charge when the explosion went off prematurely, sending an iron bar shooting through Gage's skull. The iron bar left a clean exit wound and landed on the ground several meters away.
Gage was stunned but quickly regained full consciousness and was able to walk and talk. Although the iron bar penetrated his brain, Gage survived the accident. However, his personality was changed. "Gage was no longer Gage" as one observer put it.
Previously, Gage was an easy-going, friendly type of person. After the injury he grew irritable and suspicious and moved from job to job. He died twelve years later, and his skull remains on display at the Warren Museum of Harvard Medical School.
What area of Gage's brain was affected by the wound?
The research team of Damasio, Grabowski, Frank, Galaburda, and Damasio (1994) used imaging techniques to reconstruct the exact path of the iron bar. They were able to create a three-dimensional model of Gage's skull showing that the iron bar went through prefrontal areas of the brain.
The Damasio research team reported, "Gage fits a neuroanatomical pattern that we have identified to date in 12 patients," all of whom suffered similar psychological effects. "Their ability to make rational decisions in personal and social matters is invariably compromised and so is their processing of emotion" (Damasio, Grabowski, Frank, Galaburda, and Damasio, 1994).
The Gage case shows the brain can be an incredibly resilient organ that keeps functioning after massive injury. Gage was lucky; the iron bar missed the major arteries supplying blood to the brain. With the blood supply preserved, his brain was able to continue operating.
The case of Phineas Gage has become so well known that a web site is devoted to it. Malcolm Macmillan of Akron University maintains a Phineas Gage Information Page" with interesting illustrations and links to articles and books about Gage.
Brain injuries in particular areas produce recognizable syndromes. The word syndrome refers to an identifiable pattern of symptoms. Not every symptom is present in every case, but the symptoms form a recognizable cluster.
The first brain damage syndromes to be documented by scientists were aphasias. Aphasias are disorders of speech due to brain injury. The most famous types are Broca's aphasia and Wernicke's aphasia. Most people process language in the left hemisphere, so aphasias usually occur after injuries on the left side of the brain.
Paul Broca, a French physician, first publicized the language specialization of the left hemisphere (although other researchers had noted the correlation). Broca had a patient who was unable to speak after a brain injury but seemed normal in other ways.
After the patient died, Broca discovered a damaged area above the left temporal lobe. In 1865, after collecting data on many such patients, Broca declared, "We speak with the left hemisphere."
What did Broca declare in 1865?
Broca's aphasia comes in all degrees of severity. People with mild cases speak well except for lapses when a word is mysteriously unavailable.
People with severe Broca's aphasia are more disabled. Sometimes they are unable to speak at all. Sometimes they say a few syllables over and over. A student reported such a case:
The family across the street from us is good friends with my family. I can remember back when Dr. Monroe and his mother, who had a stroke, came over to our house. His mother has died since, but after she had the stroke, the only words she could say were "Find a way."
She would say this over and over again: "Find a way find a way find a way find a way..." She would say it with a different kind of emotion and putting emphasis on different words that made sense for the occasion.
She probably had the meanings in her mind but couldn't express them. Her retrieval abilities had been damaged and she may have been suffering from Broca's aphasia. [Author's files]
Two types of speech are often spared in people with Broca's aphasia: cursing and song lyrics. Aphasic patients can often sing the words to a song if assisted by somebody who sings along with them. If the assistant stops singing, the aphasic person may continue to sing a few more bars before trailing off into silence.
Probably the reason cursing and singing are spared is that neither requires a conscious act of retrieval. Curse words just "pop out." Song lyrics are encoded into memory as sounds (demonstrated by singers who memorize lyrics in a language they do not understand).
What types of speech often remain possible for a patient with severe Broca's aphasia?
Broca's aphasia eliminates the ability to communicate meanings in language, but it does not eliminate the ability to pronounce words. Broca's aphasia in a deaf person who uses sign language impairs the ability to communicate with signs. Broca's aphasia is often called expressive aphasia.
Areas of the brain affected in two types of aphasia
Broca's and Wernicke's Areas
Can Broca's aphasics understand language?
Broca's aphasics typically understand language, although they cannot express it. Sometimes a sentence or two can be spoken, to the surprise of relatives and doctors.
I knew of a man who suffered Broca's aphasia after an auto accident. He had serious brain damage and was confined to a hospital bed until he died about 10 years later, but he could still understand language and he appreciated visitors.
One visitor commented about the man's son, saying the son had "nice dark hair." The man suddenly said, "He's blond." His wife said those were the only words he spoke after the accident, and he never spoke again before he died.
My interpretation of this event is that it was a pop-out phenomenon similar to cursing (above). The response to the visitor's comment was immediate and automatic.
When words pop out, they bypass the retrieval impairment of Broca's aphasia. A Broca's aphasic has trouble formulating and expessing meaning, but a meaningful phrase can emerge if it requires no planning process.
An type of aphasia entirely different from Broca's or expressive aphasia is Wernicke's aphasia, named after the German neurologist Carl Wernicke (VARE-neek) who described it. Wernicke's aphasia is also known as jargon aphasia.
A patient with damage to Wernicke's area produces lots of language but makes no sense. Patients with Wernicke's aphasia also have trouble comprehending speech, unlike Broca's aphasics.
What are symptoms of Wernicke's aphasia?
Kinsbourne and Warrington (1963) described a patient with Wernicke's aphasia:
E.F. (the patient) was a willing subject for testing. When greeted with the question, "How are you today?" he responded as follows:
Gossiping OK and Lords and cricket and England and Scotland battles. I don't know. Hypertension and two won cricket, bowling, batting, and catch, poor old things, cancellations maybe gossiping, cancellations, arm and argument, finishing bowling.
A few elements in the patient's response make sense. "OK" and "I don't know" and "Hypertension" are all partial answers to the question, "How are you today?"
The rest seems to be an involuntary intrusion of thoughts from somewhere else. Kinsbourne and Warrington noted the partial meaningfulness of the patient's speech:
His responses were recognized to be less incoherent than was at first believed when it was realized that he was regularly following private verbal associations. For example, when asked what "Strike while the iron is hot" means, he said:
"Ambition is very very and determined. Better to be good and to Post Office and Pillar Box and to distribution and to mail and survey and headmaster. Southern Railway very good and London and Scotland."
Without defining the proverb exactly he illustrated it by the example of posting a letter immediately, and this train of thought took him far afield by British Railways. (p.29)
The patient also had trouble reading words, although he often came up with associations. Shown the word "ball" and asked to read the single word out loud, he responded, "Pencil, rubber, bouncing, elliptical, expansion." Shown the word "airplane" he came back with, "Zooming, recognition, plane or zoom."
The Broca's aphasic is aware of the language difficulties and often expresses frustration; a Wernicke's aphasic may be unaware of the language problem and act surprised when people do not understand his or her speech.
An arc-shaped bundle of nerve fibers connects Wernicke's and Broca's areas. Normal speech requires cooperative efforts between the two areas. This bundle of fibers (the arcuate fasciculus) has been found to show disordered activity in some people with dyslexia, the reading disorder (Kershner, 2015).
Damasio, H., Grabowski, T., Frank, R., Galaburda, A.M., & Damasio, A.R. (1994) The return of Phineas Gage: Clues about the brain from the skull of a famous patient. Science, 264, 1102-1105.
Kershner, J. R. (2015) A mini-review: Toward a comprehensive theory of dyslexia. Journal of Neurology and Neuroscience Retrieved from: http://www.jneuro.com/
Kinsbourne, M. & Warrington, E. K. (1963). Jargon aphasia. Neuropsychologia, 1, 27-37.
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Copyright © 2007-2017 Russ Dewey