PubMed Health⌕ Search

Biomedical subjects

H Damasio

Publications and source records attributed to H Damasio.

At least 19 recordsLinked to original sources
PubMed1992

Three-dimensional in vivo mapping of brain lesions in humans.

We describe a multistep technique for three-dimensional reconstruction and analysis of brain lesions in vivo, based on the manipulation of magnetic resonance raw data obtained with a special protocol. The technique permits the direct visual identification of neuroanatomical landmarks in each brain specimen and eliminates the need to rely on averaged templates of human brain sections, which can be a source of lesion localization error. The technique also allows for the bidirectional cross-reference between data points in two-dimensional slices and in volume reconstruction and for the projection of subcortical structures onto the three-dimensional cortical surface. The three-dimensional lesion mapping technique can be applied to research with the lesion method in both human and nonhuman primates, to the planning of neurosurgical lesion approach, and to the teaching of neuroanatomy.

Brain Diseases↗
PubMed1992

Developmental consequences of childhood frontal lobe damage.

A 33-year-old woman underwent neurologic and neuropsychological studies 26 years after she sustained damage to the frontal lobe. The findings of the neurologic examination were normal, and magnetic resonance imaging revealed a lesion in left prefrontal cortex and deep white matter. Cerebral blood flow studies showed an abnormal pattern in both left and right frontal regions. The patient exhibited striking neuropsychological defects in higher cognition, most notably in self-regulation of emotion and affect and in social behavior. Analysis of her behavioral development failed to yield a pattern of abrupt onset of defect immediately after the lesion occurred. On the contrary, there was a delayed onset of defects, followed by a period of seeming progression, and finally an arrest of development in adolescence. We suggest that this peculiar pattern is the natural consequence of the varied changes that occurred in brain development and social cognition during the patient's formative years. While certain long-term neuropsychological deficits in our case are similar to those following frontal damage in adults, the delayed onset and progression of deficits are different.

Adult↗
PubMed1992

Acquisition of signs from American sign language in hearing individuals following left hemisphere damage and aphasia.

Three severely aphasic hearing patients with no prior knowledge of sign language were able to acquire competency in aspects of American Sign Language (ASL) lexicon and finger spelling, in contrast to a near complete inability to speak the English counterparts of these visuo-gestural signs. Two patients with damage in left postero-lateral temporal and inferior parietal cortices mastered production and comprehension of single signs and short meaningful sign sequences, but the one patient with damage to virtually all left temporal cortices was less accurate in single sign processing and was unable to produce sequences of signs at all. These findings suggest that conceptual knowledge is represented independently of the auditory-vocal records for the corresponding lexical entries, and that left anterior temporal cortices outside of traditional "language areas" are part of the neural network which supports the linkage between conceptual knowledge and linguistic signs, especially as they are used in the sequenced activations required for production or comprehension of meaningful sentences.

Adult↗
PubMed1991

Wisconsin Card Sorting Test performance as a measure of frontal lobe damage.

We examined the sensitivity and specificity of the Wisconsin Card Sorting Test (WCST) as a measure of frontal lobe damage in 91 subjects with stable focal brain lesions. Anatomical information about the location and extent of brain damage was obtained from MR and CT transparencies. No significant differences in WCST performance were found between subjects with frontal vs. nonfrontal damage. Some subjects with extensive frontal lobe damage performed well on the WCST, and some subjects with damage outside of the frontal lobes failed. The optimal cutoff scores for discriminating frontal from nonfrontal subjects correctly classified only 62% of the subjects. Further analysis of WCST performances associated with damage to various subregions of the frontal lobes also failed to reveal any reliable relationships. These findings indicate that performance on the WCST cannot be interpreted in isolation as an index of frontal lobe damage.

Aging↗
PubMed1990

Individuals with sociopathic behavior caused by frontal damage fail to respond autonomically to social stimuli.

Following damage to ventromedial frontal cortices, adults with previously normal personalities develop defects in decision-making and planning that are especially revealed in an abnormal social conduct. The defect repeatedly leads to negative personal consequences. The physiopathology of this disorder is an enigma. We propose that the defect is due to an inability to activate somatic states linked to punishment and reward, that were previously experienced in association with specific social situations, and that must be reactivated in connection with anticipated outcomes of response options. During the processing that follows the perception of a social event, the experience of certain anticipated outcomes of response options would be marked by the reactivation of an appropriate somatic state. Failure to reactivate pertinent somatic markers would deprive the individual of an automatic device to signal ultimately deleterious consequences relative to responses that might nevertheless bring immediate reward (or, alternatively, signal ultimately advantageous outcomes relative to responses that might bring immediate pain). As an example, activation of somatic markers would (1) force attention to future negative consequences, permitting conscious suppression of the responses leading to them and deliberate selection of biologically advantageous responses, and (2) trigger non-conscious inhibition of response states by engagement of subcortical neurotransmitter systems linked to appetitive behaviors. An investigation of this theory in patients with frontal damage reveals that their autonomic responses to socially meaningful stimuli are indeed abnormal, suggesting that such stimuli fail to activate somatic states at the most basic level. On the contrary, elementary unconditioned stimuli (e.g. a loud noise) produce normal autonomic responses.

Adult↗
PubMed1990

Neuropsychological impairments associated with lesions caused by tumor or stroke.

Populations of patients with strokes or tumors constitute the most frequently used subjects in neuropsychological research, and these populations are often combined when the investigation aims at establishing brain-behavior relationships. We compared these two populations with respect to their neuropsychological profiles. Seventeen subjects with tumors were individually matched to subjects with unilateral strokes on the basis of lesion location. Despite close matching of lesions, there were major differences in the neuropsychological impairments of the two groups, eg, all subjects with stroke in the left hemisphere had more severe language defects than did their counterparts with tumors, and some tumor subjects performed normally on all neuropsychological tests. These findings demonstrate that the cognitive and/or behavioral consequences of tumors or strokes in similar locations can be radically different. The two patient types should be treated separately for the purpose of neuropsychological research.

Adult↗
PubMed1990

Auditory perception of temporal and spectral events in patients with focal left and right cerebral lesions.

The auditory perception of temporal and spectral information was studied in subjects with lesions in the temporoparietal region of the left (LH group), or right (RH group) hemisphere (n = 5 in each group) and in five normal controls. The temporal tasks included gap detection and two complex pattern perception tasks in which subjects had to identify the placement of the two closest tones (separated by the shortest interval) within a sequence of six tones. The spectral tasks involved pitch matching and frequency discrimination. The results showed a "double dissociation": (1) the LH group was impaired in their ability to perceive temporal information, but the perception of spectral information was normal, and (2) the RH group was impaired in their ability to perceive spectral information, but the perception of temporal information was normal. The findings are consistent with the notion that temporal processing is a function of left-hemisphere structures and that spectral processing is a function of right-hemisphere structures.

Adult↗
PubMed1990

Troubled letters but not numbers. Domain specific cognitive impairments following focal damage in frontal cortex.

A well educated right-handed woman developed severe and stable alexia and agraphia following a circumscribed surgical lesion in the left premotor cortex. The lesion was located in Brodmann's field 6, above Broca's area, in the region traditionally referred to as Exner's area. The alexia and agraphia occurred in a pure form, that is, in the setting of otherwise normal cognitive and neurological function. She was not aphasic or hemiparetic and her visual perception, intellect, memory, oral spelling and drawing were normal. The patterns of impairment of reading and writing closely paralleled one another. Reading of single words and letters was severely impaired, and she was entirely unable to read sentences. She was virtually unable to write recognizable letters, could write no words, and her writing attempts were severely distorted spatially. By contrast, she could easily read all numbers and nonverbal symbols, and she was equally able to write numbers and perform written calculations without difficulty. These striking dissociations provide further evidence of the domain specificity of cognitive/neural representations. They also point to the possible role of premotor cortices in the coactivation of precise sequences of motor and sensory activity patterns involved in reading and writing.

Agraphia↗
PubMed1990

Progressive aphasia in a patient with Pick's disease: a neuropsychological, radiologic, and anatomic study.

Although Pick's disease is generally considered as a dementia characterized by signs of frontal lobe dysfunction, it can present with selective language defects rather than with cognitive decline. In this study, we report prospective and serial clinical, neuropsychological, and neuroradiologic observations in a 59-year-old man whose prominent disturbance was in the retrieval and learning of names denoting concrete entities and actions. Postmortem study confirmed the diagnosis of Pick's disease and revealed that neuronal loss and gliosis were most prominent in left anterior temporal cortices. The findings are in keeping with evidence that the left anterior temporal cortices and interconnected hippocampal system are critically involved in the learning and retrieval of verbal lexical items. The evidence from this patient, along with similar evidence from the literature we reviewed, suggests that when patients present with a progressive aphasia characterized by anomia, Pick's disease should be considered as the probable diagnosis.

Aphasia↗
PubMed1989

Intact electrodermal skin conductance responses after bilateral amygdala damage.

Several lines of evidence have suggested that the amygdala is a crucial component of the anatomical network that mediates the skin conductance orienting response (SCOR). In this study, the electrodermal activity of a patient whose entire amygdaloid complex had been destroyed bilaterally, and of 7 age- and gender-matched controls, was recorded under the same experimental conditions. The results indicate unequivocally that the subject could generate normal skin conductance and SCORs, in response to stimuli of different sensory modalities and configurations. This suggests that the amygdala is not a necessary component of the neural network underlying SCORs and that there are alternate neural units and pathways that link sensory cortices to autonomic effectors.

Aged↗
PubMed1989

The role of individual difference in determining the nature of comprehension defects in aphasia.

This study was concerned with the relationship between locus of lesion and subtypes of language comprehension defect in aphasia. Previous studies had indicated that performance in sound recognition identified two subtypes of aural comprehension deficit and that performance in pantomime recognition identified two subtypes of reading comprehension defect. Defects in sound recognition and pantomime recognition were found in association with a variety of lesion loci. However, comprehension defective aphasics with normal sound recognition or pantomime recognition had lesions closely similar in location and size to those of aphasics who performed poorly on these tests. Findings suggest that whether an aphasic with a language comprehension defect is impaired in sound recognition or pantomime recognition depends, at least in part, on individually variable predisposing factors. It would appear possible that this phenomenon reflects a separate dimension of hemispheric cerebral dominance.

Adult↗
PubMed1988

Intact recognition of facial expression, gender, and age in patients with impaired recognition of face identity.

We conducted a series of experiments to assess the ability to recognize the meaning of facial expressions, gender, and age in four patients with severe impairments of the recognition of facial identity. In three patients the recognition of face identity could be dissociated from that of facial expression, age, and gender. In one, all forms of face recognition were impaired. Thus, a given lesion may preclude one type of recognition but not another. We conclude that (1) the cognitive demands posed by different forms of recognition are met at different processing levels, and (2) different levels depend on different neural substrates.

Adult↗
PubMed1987

Global aphasia without hemiparesis.

Three patients acutely developed global aphasia, but did not manifest the typical accompanying right hemiparesis. Computed tomography and magnetic resonance imaging studies demonstrated that the patients had two discrete left hemisphere lesions, one in the anterior language cortices or language-related subcortical areas, and one in the posterior language cortices. Cerebral angiography showed that two patients had complete occlusion of the left internal carotid artery, and the third had an intraluminal "clot" in the supraclinoid portion of the left internal carotid, findings suggestive of an embolic etiology. Our cases indicate that global aphasia without hemiparesis predicts two discrete lesions and a particularly good recovery of speech and language.

Adult↗
PubMed1987

Dissociable visual and spatial impairments following right posterior cerebral lesions: clinical, neuropsychological and anatomical evidence.

A double dissociation of visual and spatial performance is reported in two men with chronic focal missile injuries of the right cerebral hemisphere. The clinical, neuropsychological and post-mortem anatomical data are considered in relation to evidence from physiological research of two major cortico-cortical pathways for object-recognition and spatial perception.

Brain Mapping↗