Cases reported "Brain Damage, Chronic"

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1/19. Impaired declarative memory for emotional material following bilateral amygdala damage in humans.

    Everyday experience suggests that highly emotional events are often the most memorable, an observation supported by psychological and pharmacological studies in humans. Although studies in animals have shown that nondeclarative emotional memory (behaviors associated with emotional situations) may be impaired by lesions of the amygdala, little is known about the neural underpinnings of emotional memory in humans, especially in regard to declarative memory (memory for facts that can be assessed verbally). We investigated the declarative memory of two rare patients with selective bilateral amygdala damage. Both subjects showed impairments in long-term declarative memory for emotionally arousing material. The data support the hypothesis that the human amygdala normally enhances acquisition of declarative knowledge regarding emotionally arousing stimuli.
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2/19. Are some memory deficits unique to lesions of the mammillary bodies?

    The role of the mammillary bodies in human memory is still in debate. A recent model of human amnesia proposes similar functions for the mammillary bodies and the hippocampus. But the main evidence for this model comes from animal studies using the delayed non-matching to sample paradigm. We describe a patient who developed a severe memory impairment after surgical removal of a germinoma. Postsurgical high resolution MRI revealed bilaterally shrunken mammillary bodies and an infarct of the left mammillary body. There were no other relevant lesions. Neuropsychological testing showed mildly impaired frontal lobe functions (executive functions, working memory and word fluency), almost intact learning and recognition, but severely impaired free and delayed recall. Experimental investigations revealed a reduced but preserved release of proactive interference and a pronounced impairment of recency and source judgments. We conclude that the mammillary bodies do play a prominent role in human memory, although the role differs slightly from that of the hippocampus.
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3/19. Naming impairments following recovery from herpes simplex encephalitis: category-specific?

    An apparently clear case of category-specific naming impairment selectively affecting animals was detected in a patient who had recovered from herpes simplex encephalitis. However, subsequent investigation demonstrated that these category-specific effects could be eliminated by controlling simultaneously for three factors in picture naming: word frequency, concept familiarity, and visual complexity. The results emphasize the importance of controlling for all factors pertinent to picture naming when attempting to demonstrate category specificity in picture naming. Further testing indicated that deficits were also apparent when naming to definition was required, and some impairment in the ability to answer questions about objects and living things was also noted. Theoretical implications of these data are considered.
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4/19. A deficit in discriminating gaze direction in a case with right superior temporal gyrus lesion.

    The superior temporal sulcus (STS) region is well recognized as being heavily involved in detecting and discriminating gaze. Lesions confined to this area are quite rare in humans, and so the research has mainly depended on animal studies and functional neuroimaging in normal human subjects. We report one such rare case, a 54-year-old Japanese female with a possible congenital s anomaly who, after a cerebral hemorrhage, demonstrated a lesion almost completely confined to the entire right superior temporal gyrus (STG). In the subacute phase, the patient showed evidence of left hemispatial neglect, from which she gradually recovered. In the chronic phase, she showed a puzzling difficulty in obtaining eye-contact. We have conducted, in conjunction with conventional neuropsychological evaluations, experimental assessment of her ability in gaze cognition. Her performance on neuropsychological testing demonstrated no compromise in intellect, memory, or language skills, and a close-to-full recovery from neglect. On gaze cognition experiments, she was repeatedly shown to perceive left gaze as straight, and to a lesser degree, straight gaze as right. We suggest that the function of the STG in detecting gaze, together with the directional information it receives from earlier visual areas, may be associated, when damaged, with this deficit in detecting contra-directional gaze. We have demonstrated for the first time that a single circumscribed lesion to the STG results in both gaze processing deficit and concurrent aberrant gaze behavior of the victim herself, implicating a mechanism within the STG as an interface between gaze of others and gaze of self.
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5/19. Status dissociatus--a perspective on states of being.

    During the course of routine clinical study, it has become apparent that the all-or-none concept of state determination (wakefulness, nonrapid eye movement sleep, rapid eye movement sleep) does not always exist, and that ambiguous, multiple, or rapid oscillation of state-determining variables appear in a wide variety of experimental and clinical situations. Six cases of extreme state dissociation are presented, with a review of the human and animal clinical and experimental literature. This multiple component concept of state determination must be kept in mind when pharmacologic or lesion studies are employed to suppress one or another state. Such manipulation may suppress some of the commonly used markers for that state (i.e., polygraphic) without affecting other variables of that state. The existence of mixed states will be a challenge to the development of automated computerized polysomnogram scoring.
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6/19. Sensitivity to eye gaze in prosopagnosic patients and monkeys with superior temporal sulcus ablation.

    Accuracy at perceiving frontal eye gaze was studied in monkeys and human subjects using a forced-choice detection task on paired photographs of a single human face. Monkeys learned the task readily, but after bilateral removal of the banks and floor of the superior temporal sulcus (STS) they failed to perform the task efficiently. This result is consistent with the conclusion, based on recordings from single cells in awake, behaving monkeys [Perret et al., Physiological Aspects of Clinical Neuro-ophthalmology, Chapman & Hall, london, 1988] that this region of the temporal lobe is important for coding information about eye-gaze of a confronting animal. Human subjects were given identical stimuli in a task where they were asked to detect "the face that is looking straight at you". Human performance is sensitive to the degree of angular deviation from the frontal gaze position, being poorest at small angular deviations from 0 degrees. This was also true of monkeys viewing these stimuli, pre- and post-operatively. Compared with normal controls, two humans prosopagnosics were impaired at this task. However the extent of impairment was different in the two patients. These findings are related to earlier reports (including those for patients with right-hemisphere damage without prosopagnosia), to normal performance with upright and inverted face photographs, and to notions of independent subsystems in face processing.
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7/19. Progressive language impairment without dementia: a case with isolated category specific semantic defect.

    A patient is described with a 5 year progressive defect of naming and auditory verbal comprehension, the pathological nature of which was presumably degenerative. The auditory comprehension defect unevenly affected different semantic categories, and was particularly severe for the names of animals, fruits and vegetables. The patients showed loss of the verbal knowledge of the physical attributes of the concepts corresponding to the words he was unable to understand, and sparing of the verbal knowledge of the functional attributes. His performance was defective also on the colour-figure and sound-picture matching test.
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8/19. Rejection behaviour: a human homologue of the abnormal behaviour of Denny-Brown and Chambers' monkey with bilateral parietal ablation.

    A unique behavioural syndrome in humans followed two separate strokes involving both parietotemporal regions. The behavioural alterations resemble those of Denny-Brown and Chambers' monkey with bilateral ablation of the parietal lobe which were characterised by strong withdrawal or refusal to be touched on the limbs and head. In both humans and animals, touch on the limbs or head elicited exaggerated withdrawal movements and refusal to be touched on the lips and tongue resulted in difficulty in feeding. These behavioural alterations can be interpreted as loss of exploratory activities towards extrapersonal space, or more positively, as rejection of contact with the environment. This rejection behaviour in which tactile, visual, and/or gustatory exploration tendencies are altered, is a counterpart of human frontal lobe syndrome and human kluver-bucy syndrome.
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9/19. Successful resuscitation of an elderly patient following cardiac arrest: possible role of reduction of reactive oxygen.

    The presence of hyperoxia during reperfusion following brain ischemia has been shown in experimental animals to result in increased mortality and increased lipid peroxidation. Although no human studies have been reported, prolonged hyperoxia after resuscitation from cardiac arrest probably would result in increased cerebral injury. We report the case of an 88-year-old man who had a 5- to 6-minute cardiac arrest and then had decerebrate posturing during the post-resuscitation period, indicating that he had suffered a significant ischemic/anoxic insult. Early attention was paid to normalizing the arterial Po2 following resuscitation, which, according to experimental evidence, contributed to his eventual complete recovery of neurologic function, including mental state.
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10/19. Auditory deprivation--an intrinsic or extrinsic problem? Some comments on Kyle (1978).

    The relevance of animal work to early auditory deprivation, as discussed by Kyle (1978), is questioned. It is argued that auditory experience from birth, or even much later, is not necessarily required for subsequent hearing for spoken language. It is also questioned whether concern for intrinsic difficulties, such as possible cortical damage resulting from auditory deprivation, is appropriate. A more productive approach may be to pay more attention to the extrinsic aspect--the linguistically principled rehabilitation of the hearing-impaired child.
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