Rebecca Martin
Psychology 472
3/13/97
The Cerebral Cortex:
A Review of Emotional Results of Frontal Lesions
Emotions play a big role in our individual
personalities and our behavior. Our individual
emotional states and methods of expressing our emotions
are important to our self-perception, interpersonal
relationships and the way we run our lives in general.
Due to their prevalence in day to day situations,
emotions (or emotional responses) are always observable,
though not often tangible. It is partially due to this
lack of emotional tangibility and the interaction and
interconnection of different areas of the brain, that
have made it very difficult to pinpoint an area of the
brain and explicitly relate it to a specific emotional
response.
Researchers who have studied in the area of
determining the sites of emotional responses have made
major implications in the role of the cerebral cortex in
the functioning of emotion. The cerebral cortex is
responsible for making judgments and decisions about the
outside world from information it receives. First,
sensory information enters the brain. When it reaches
the cortex, this information is analyzed and compared
with stored information of previous experience and
knowledge. A decision is then made by the cortex and
this information is sent back to the body for execution.
The functions of the cerebral cortex involve
thinking, planning, and some aspects of learning. There
have been many notable findings made in the post-traumatic
study of patients suffering from various types
of brain damage involving the frontal cerebral cortex.
Patients with lesions in this area of the brain often
exhibit permanent, post injury personality changes.
These changes are classified as complete shifts in
emotions and emotional responses, as compared with states
prior to injury.
Understanding the interaction of brain functions
involved in emotional processing is important to
understanding the study of the effects of any type of
brain damage on emotion. Emotional sensory information
(visual, olfactory, and bodily sensation) is relayed to
the brain via specific functions, then transferred to
another area of the brain for processing and response.
Information resulting from bodily sensation enters the
brain through the spinal column and brain stem, then is
transferred to either the hypothalamus or basal ganglia
(in the limbic system), or it goes directly to the
cerebral cortex. Visual and olfactory information is
processed in the hippocampus, amygdala (also in the
limbic system), and then goes on to the cerebral cortex.
The cerebral cortex is responsible for mastery of
the emotions. The cortex of the frontal lobes has been
identified as the most important, in this respect. The
limbic system is closely connected to the functions of
the cortex, and emotional processing as well, so any
damage to these parts of the brain will cause drastic
emotional effects. In the past, lobotomies used to treat
depression involved destroying the neurons connecting
the limbic system to the cerebral cortex. The result was
the permanent relief from chronic anxiety and depression,
and replaced these symptoms with "slaphappy" behavior.
Due to the difficulty involved in observing brain
functions and emotional processing, there are many
problems associated with the study of the effect of
cortical lesions on emotion. In the early stages of
technology, the only way to study the effects of brain
damage were to observe the behaviors of a patient with
brain damage and wait to perform an autopsy to find the
exact location of damage. The method of combining the
clinical observations of patients with the site of their
lesions has continued, but scientific developments have
allowed us to view brain lesions while a patient is still
alive. Beginning with the CT scan, advancements have
brought us to more accurate visualization of brain images
and functions, like the EEG, MRI and PET scan.
There are always confounding variables present with
the study of post-traumatic behavior as a result of
brain damage. In studies involving stroke patients,
simply knowing they had a stroke may influence a
patient's emotions. Other aspects of recovery, such as
speech or movement rehabilitation, also affect emotion.
There are often significant relationships between
severity of physical impairment, and severity of reported
depression resulting from brain lesions. The further
injurious aspects of lesions, such as possible swelling,
clotting, pressure, etc., may have effects on emotions as
well and contribute to the confounding. Despite the
difficulties involved, researchers in the area of the
localization of emotional processes in the brain have
made some significant findings involving the effect of
lesions on certain areas of the cerebral cortex,
especially the frontal region.
Some studies have been conducted to determine
emotional differences between the two hemispheres of the
cerebral cortex. The anterior regions appear to be
differentially involved in positive and negative
emotions. The right hemisphere is associated with
expression and mediation of almost all aspects of
emotion. In some cases of frontal brain damage, the
effects involve the patient being exactly the opposite
emotionally, after recovery. In one such study, (Joseph;
1988) found that the right hemisphere of the cerebral
cortex demonstrates more emotional dominance than the
left, and damage to the left cortical hemisphere leads to
a disturbance in the reproduction of emotion.
Another study, (Kola, and Taylor; 1981) showed that
damage to the right hemisphere of the cerebral cortex can
result in indifference, lability, hysteria, florid manic
excitement, pressured speech, ideas of reference, bizarre
confabulatory responding, childishness, irritability,
euphoria, impulsivity, promiscuity, and abnormal sexual
behavior. Cortical right brain damage, in this study,
was also implicated in the inability to interpret
emotion. Subjects with damage to either side of the
brain were tested on their ability to interpret emotional
language. Language is a combination of description and
emotion. The interpreter of spoken language used the
current context of a situation, and the speaker's emotion
to help understand what is being said. Patients with
damage on the left hemisphere, but the right still
intact, were unable to understand and interpret the
emotion behind what the speaker was trying to
communicate. Patients with right hemisphere damage, and
the left side intact were able to interpret only the
words used. These patients were unable to identify and
interpret expressed emotion in language, and as a result
became very literal. When presented with the statement
"she had a heavy heart", these "literal" patients were
more likely to identify the response portraying a person
standing under an enormous heart and struggling under its
weight than a picture of someone crying.
In another study involving cerebral symmetry, (Lee,
et. al., 1993) researched the effects of premorbid
personality and the hemispherical location of lesions on
emotional expression. Rather than involving traumatic
brain injury, this study was conducted on epileptic
patients experiencing unilateral hemispheric
inactivation, and those with right hemisphere
inactivation were compared with those with left
hemisphere inactivation. Inactivation occurred as the
result of amobarbital injections in one hemisphere or the
other. The results showed that while premorbid
personality does play a large role in post "injury"
emotional changes, the location of the lesion had a more
measurable effect.
Studies have also identified the roles of areas of
the cerebral cortex in emotional functions that are more
specific than cerebral symmetry. In one such study,
(Irle, et. al.; 1994) studied the effects of tumors
removed from seven specified areas of the cerebral
cortex; lesions in five of these areas involved the
frontal cortex and resulted in changes in emotional
behavior. The lesioned cortical areas involving the
frontal region were specified as the ventral frontal area
(covering the ventral and medial frontal cortex, and may
also include the ventral parts of the lateral frontal
cortex); the lateral frontal area (covering either the
premotor/motor cortex or the frontal pole alone, or the
lateral frontal and premotor/motor cortexes together),
the frontal area (covering ventral and medial, lateral,
and premotor/motor aspects of the frontal cortex); the
frontal and parietal area (covering the parietal region
with some combination with frontal lesions, or lesions of
the premotor/ motor cortex); and the frontal, temporal
and parietal area (covering the frontal temporal and
parietal cortexes).
The results of the study are based on the patients'
self reported changes in emotion, rated as increasing or
decreasing vigor, extroversion, fatigue,
irritability/anger, and depression/anxiety. The subjects
involved were 141 patients who underwent microsurgery to
remove tumors on different areas of the cerebral cortex.
The perceived changes in emotions and behavior were
attributed to the lesions occurring as a result of the
tumor removal and the effects of the tumors; no attempts
were made at establishing relationships between extent of
change and tumor severity or damage extensivity.
Patients with lesions in the frontal, frontal and
parietal, and temporal, frontal and parietal cortical
regions all exhibited similar symptoms, while the ventral
frontal and lateral frontal groups exhibited different
changes after surgery. The frontal, frontal and
parietal, and temporal, frontal and parietal groups all
reported increased vigor and extroversion; and decreased
fatigue, irritability/ anger, and depression/ anxiety.
The ventral frontal group reported decreased extroversion
and vigor, and increased fatigue, irritability/ anger,
and depression/ anxiety; and the lateral frontal group
reported stronger changes in mood than the other groups.
To help illustrate some of the emotional changes
that can take place as a result of cortical lesions, one
researcher, (Bigler, 1989), published the report of a
young woman's observations of the changes in her husband
after he had sustained traumatic brain injury. This
report describes the changes in several aspects of the
personality of "Sam" (not his real name). Prior to his
injury, Sam was a musician in his own band and a very
outgoing individual. After the injury, however, Sam's
personality changed so much that his wife found
continuing their marriage to be difficult. It was for
this reason that she sought professional help in her
situation, and as part of her therapy, she was to write
down the changes she observed.
Sam's confidence in himself and his work completely
disappeared. He exhibited loss of drive and energy,
going from a workaholic to someone who doesn't even have
the motivation to pick up after himself. His self esteem
and self image plummeted, leaving him uncomfortable doing
anything by himself, and very dependent on his wife.
Sam's wife also reported a decrease in laughter and
happiness and increases in depression, and fear. She
stated that prior to injury, Sam was secure in his plans
for their future, especially their son's future, and
after the injury, he had no clue as to what the future
held for him. Sam also exhibited less personal control,
easily losing his temper after the injury when he had
been a very patient person.
Some similar behavior changes were reported in
another case, this one involved extensive damage to the
frontal cortex and much of the frontal portion of the
brain. In 1848, Phonies Gage was a foreman for a
railroad construction company in New England. He was 25
years old, and had been described as: responsible,
intelligent, socially well adapted and "a favorite with
peers and elders". While performing occupational duties
on one occasion, Gage became distracted and made a
mistake in one of his tasks, and became the victim of a
devastating accident. As the result of a premature
explosion, a fine pointed, 109 cm long, 3 cm thick, iron
tamping rod was hurled, "rocket like" through his face,
skull, and brain.
Gage miraculously survived the injury and his
recovery. He lived for another twelve years, but he was
different. He remained as able bodied as before, with no
speech or motor impairment; and his intellect, memory,
and comprehension in the conventional sense remained
intact. However, Phineas Gage had become "irreverent and
capricious", He no longer respected the social
conventions by which he had once abided, and he had taken
leave of his sense of responsibility. One physician
described the change as "the equilibrium, or balance,
between his intellectual faculty and his animal
propensities" had been destroyed.
(Damasio, et al.; 1994), published findings in the
results of studying Gage's skull, many years after his
death, to verify speculations made as to the exact area
of the brain affected by the tamping iron. Photographs
and measurements of all possible views of Gage's skull
were made to manipulate a skull model to be an exact
replica. This skull model, and descriptions of the
incident, were used to identify a suitable trajectory of
the tamping iron to determine the exact area of brain
damage; this area was found to involve much of the white
matter of the frontal lobes, and a great deal of the
cerebral cortex was extensively damaged as well. Gage's
symptoms of emotional changes and the discovered location
of cortical damage are consistent with other studies
involving frontal cortex damage and changes in emotion.
Further research in this area has been considered
critical, due to emotional recovery from brain injury
being the slowest recovery process.
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