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H Damasio

Publications and source records attributed to H Damasio.

At least 37 records · Page 2Linked to original sources
PubMed2000

Long-term sequelae of prefrontal cortex damage acquired in early childhood.

Frontal lobe dysfunction is often invoked as a contributing factor in developmental disorders characterized by chronic maladaptive behavior, but interpretation of relevant neuropsychological findings has been hampered by the limited information available regarding the consequences of focal prefrontal damage early in life. We describe here the long-term behavioral and cognitive sequelae of damage to prefrontal cortex in two young adult patients who had sustained their brain damage prior to 16 months of age. In the context of normal neurological examinations, both cases had remarkable histories of impaired decision making, behavioral dyscontrol, social defects, and abnormal emotion. Performances were primarily normal on a broad range of neuropsychological measures (intellect, memory, language, academic achievement, visual perception, and visuoconstruction), but selective impairments of executive function were evident. Early dysfunction in the prefrontal region may result in severe and chronic social maladjustment despite largely normal cognitive abilities. These findings can help inform neuropsychological evaluation of patients with possible prefrontal dysfunction in the setting of developmental disabilities or early brain trauma.

Adult↗
PubMed1999

Different contributions of the human amygdala and ventromedial prefrontal cortex to decision-making.

The somatic marker hypothesis proposes that decision-making is a process that depends on emotion. Studies have shown that damage of the ventromedial prefrontal (VMF) cortex precludes the ability to use somatic (emotional) signals that are necessary for guiding decisions in the advantageous direction. However, given the role of the amygdala in emotional processing, we asked whether amygdala damage also would interfere with decision-making. Furthermore, we asked whether there might be a difference between the roles that the amygdala and VMF cortex play in decision-making. To address these two questions, we studied a group of patients with bilateral amygdala, but not VMF, damage and a group of patients with bilateral VMF, but not amygdala, damage. We used the "gambling task" to measure decision-making performance and electrodermal activity (skin conductance responses, SCR) as an index of somatic state activation. All patients, those with amygdala damage as well as those with VMF damage, were (1) impaired on the gambling task and (2) unable to develop anticipatory SCRs while they pondered risky choices. However, VMF patients were able to generate SCRs when they received a reward or a punishment (play money), whereas amygdala patients failed to do so. In a Pavlovian conditioning experiment the VMF patients acquired a conditioned SCR to visual stimuli paired with an aversive loud sound, whereas amygdala patients failed to do so. The results suggest that amygdala damage is associated with impairment in decision-making and that the roles played by the amygdala and VMF in decision-making are different.

Acoustic Stimulation↗
PubMed1999

Impairment of social and moral behavior related to early damage in human prefrontal cortex.

The long-term consequences of early prefrontal cortex lesions occurring before 16 months were investigated in two adults. As is the case when such damage occurs in adulthood, the two early-onset patients had severely impaired social behavior despite normal basic cognitive abilities, and showed insensitivity to future consequences of decisions, defective autonomic responses to punishment contingencies and failure to respond to behavioral interventions. Unlike adult-onset patients, however, the two patients had defective social and moral reasoning, suggesting that the acquisition of complex social conventions and moral rules had been impaired. Thus early-onset prefrontal damage resulted in a syndrome resembling psychopathy.

Adult↗
PubMed1998

Dissociation Of working memory from decision making within the human prefrontal cortex.

We tested the hypothesis that cognitive functions related to working memory (assessed with delay tasks) are distinct from those related to decision making (assessed with a gambling task), and that working memory and decision making depend in part on separate anatomical substrates. Normal controls (n = 21), subjects with lesions in the ventromedial (VM) (n = 9) or dorsolateral/high mesial (DL/M) prefrontal cortices (n = 10), performed on (1) modified delay tasks that assess working memory and (2) a gambling task designed to measure decision making. VM subjects with more anterior lesions (n = 4) performed defectively on the gambling but not the delay task. VM subjects with more posterior lesions (n = 5) were impaired on both tasks. Right DL/M subjects were impaired on the delay task but not the gambling task. Left DL/M subjects were not impaired on either task. The findings reveal a cognitive and anatomic double dissociation between deficits in decision making (anterior VM) and working memory (right DL/M). This presents the first direct evidence of such effects in humans using the lesion method and underscores the special importance of the VM prefrontal region in decision making, independent of a direct role in working memory.

Adult↗
PubMed1998

Premotor and prefrontal correlates of category-related lexical retrieval.

It has been shown that the retrieval of words denoting visually presented concrete entities engages neural systems in the left temporal lobe and that the precise pattern of activation within the temporal lobe depends in part on the conceptual category to which the entity belongs. Here, we used [15O]water positron emission tomography to test the hypothesis that the pattern of activation associated with word retrieval in left frontal lobe would also be related to conceptual category. The design entailed the performance of three tasks requiring the retrieval of words denoting animals, tools, and unique persons. The visual stimuli were presented at different rates, to produce equal performance success across categories, a feature which also had the effect of equalizing the proportion of scan time spent in mental search. All three word retrieval tasks activated the left inferior frontal gyrus, but they differed in their recruitment of two other premotor and prefrontal areas. Activity in a portion of the middle frontal gyrus, corresponding to Brodmann area 46, bore a linear relation to response latency and may index the extent of mental search. This region was most active when subjects named persons. Activity in the anterior bank of the precentral gyrus, along the inferior and middle frontal gyri, was most marked for naming tools. This region overlaps the area activated when subjects generate words for actions. We suggest that it is engaged by the retrieval of words denoting actions or objects with characteristic actions. The data presented here provide additional support for the notion that "nonclassical" language areas in extrasylvian frontal and temporal regions mediate word retrieval and that the pattern of their engagement relates to conceptual category.

Adult↗
PubMed1997

Deciding advantageously before knowing the advantageous strategy.

Deciding advantageously in a complex situation is thought to require overt reasoning on declarative knowledge, namely, on facts pertaining to premises, options for action, and outcomes of actions that embody the pertinent previous experience. An alternative possibility was investigated: that overt reasoning is preceded by a nonconscious biasing step that uses neural systems other than those that support declarative knowledge. Normal participants and patients with prefrontal damage and decision-making defects performed a gambling task in which behavioral, psychophysiological, and self-account measures were obtained in parallel. Normals began to choose advantageously before they realized which strategy worked best, whereas prefrontal patients continued to choose disadvantageously even after they knew the correct strategy. Moreover, normals began to generate anticipatory skin conductance responses (SCRs) whenever they pondered a choice that turned out to be risky, before they knew explicitly that it was a risky choice, whereas patients never developed anticipatory SCRs, although some eventually realized which choices were risky. The results suggest that, in normal individuals, nonconscious biases guide behavior before conscious knowledge does. Without the help of such biases, overt knowledge may be insufficient to ensure advantageous behavior.

Aged↗
PubMed1997

The evolution of the frontal lobes: a volumetric analysis based on three-dimensional reconstructions of magnetic resonance scans of human and ape brains.

Scenarios regarding the evolution of cognitive function in hominids depend largely on our understanding of the organization of the frontal lobes in extant humans and apes. The frontal lobe is involved in functions such as creative thinking, planning of future actions, decision making, artistic expression, aspects of emotional behavior, as well as working memory, language and motor control. It is often claimed that the frontal lobe is disproportionately larger in humans than in other species, but conflicting reports exist on this issue. The brain of the apes in particular remains largely unknown. In this report we measure the volume of the frontal lobe as a whole and of its main sectors (including cortex and immediately underlying white matter) in living humans, and in post-mortem brains of the chimpanzee, gorilla, orang-utan, gibbon and the macaque using three-dimensional reconstructions of magnetic resonance (MR) scans of the brain. On the basis of these data we suggest that although the absolute volume of the brain and the frontal lobe is largest in humans, the relative size of the frontal lobe is similar across hominoids, and that humans do not have a larger frontal lobe than expected from a primate brain of the human size. We also report that the relative size of the sectors of the frontal lobe (dorsal, mesial, orbital) is similar across the primate species studied. Our conclusions are preliminary, because the size of our sample, although larger than in previous studies, still remains small. With this caveat we conclude that the overall volume of the frontal lobe in hominids enlarged in absolute size along with the rest of the brain, but did not become relatively larger after the split of the human line from the ancestral African hominoid stock. Aspects other than relative volume of the frontal lobe have to be responsible for the cognitive specializations of the hominids.

Animals↗
PubMed1997

Brainvox: an interactive, multimodal visualization and analysis system for neuroanatomical imaging.

A study of cognition emerging from a neurobiological perspective, as opposed to one emerging from a purely computational or psychological perspective, begins with observations of the human brain in normal and pathological states and is furthered by the investigation of hypotheses which are articulated using neuroanatomical nomenclature. Brainvox is an interactive three-dimensional brain imaging software package designed to permit such research through the support of the description and quantification of brain pathology in magnetic resonance images and of the experimental investigation of human cognition in lesion and functional imaging studies. Important general features of Brainvox, for these purposes, are: (1) adaptation of volume rendering for brain lesions and for corendered datasets; (2) shared memory architecture, which enables the user to identify and label anatomical structures, while inspecting the brain in multiple views simultaneously; (3) modular program design, including interlocking command-line utilities, which make Brainvox extensible and empower users without programming expertise to implement new analysis techniques through Unix shell scripting; and (4) full integration of three-dimensional tools for visualization with tools for analysis. Specific features include a new object templating technique (MAP-3) for studies of groups of brain-lesioned subjects, a complete and extensible suite of command-line processing utilities, a three-dimensional optimal graph-searching tool, and a method for planning PET slices and matching MR and PET slices (MP_FIT).

Artificial Intelligence↗
PubMed1997

A neural basis for the retrieval of conceptual knowledge.

Both clinical reports and systematic neuropsychological studies have shown that patients with damage to selected brain sites develop defects in the retrieval of conceptual knowledge for various concrete entities, leading to the hypothesis that the retrieval of knowledge for entities from different conceptual categories depends on partially segregated large-scale neural systems. To test this hypothesis, 116 subjects with focal, unilateral lesions to various sectors of the telencephalon, and 55 matched controls, were studied with a procedure which required the visual recognition of entities from three categories--unique persons, non-unique animals and non-unique tools. Defective recognition of persons was associated with maximal lesion overlap in right temporal polar region; defective recognition of animals was associated with maximal lesion overlap in right mesial occipital/ventral temporal region and also in left mesial occipital region; and defective recognition of tools was associated with maximal lesion overlap in the occipital-temporal-parietal junction of the left hemisphere. The findings support the hypothesis that the normal retrieval of knowledge for concrete entities from different conceptual domains depends on partially segregated neural systems. These sites may operate as catalysts for the retrieval of the multidimensional aspects of knowledge which are necessary and sufficient for the mental representation of a concept of a given entity.

Agnosia↗
PubMed1996

Cortical systems for the recognition of emotion in facial expressions.

This study is part of an effort to map neural systems involved in the processing of emotion, and it focuses on the possible cortical components of the process of recognizing facial expressions. We hypothesized that the cortical systems most responsible for the recognition of emotional facial expressions would draw on discrete regions of right higher-order sensory cortices and that the recognition of specific emotions would depend on partially distinct system subsets of such cortical regions. We tested these hypotheses using lesion analysis in 37 subjects with focal brain damage. Subjects were asked to recognize facial expressions of six basic emotions: happiness, surprise, fear, anger, disgust, and sadness. Data were analyzed with a novel technique, based on three-dimensional reconstruction of brain images, in which anatomical description of surface lesions and task performance scores were jointly mapped onto a standard brain-space. We found that all subjects recognized happy expressions normally but that some subjects were impaired in recognizing negative emotions, especially fear and sadness. The cortical surface regions that best correlated with impaired recognition of emotion were in the right inferior parietal cortex and in the right mesial anterior infracalcarine cortex. We did not find impairments in recognizing any emotion in subjects with lesions restricted to the left hemisphere. These data provide evidence for a neural system important to processing facial expressions of some emotions, involving discrete visual and somatosensory cortical sectors in right hemisphere.

Adult↗
PubMed1996

A chronic microelectrode investigation of the tonotopic organization of human auditory cortex.

We investigated the functional organization of human auditory cortex using a new chronic microelectrode technique. Tonotopic mapping data was obtained at the single unit level for the first time in humans. All sound-driven units were noted to have frequency-dependent response patterns. The majority of units (73%) demonstrated sharply tuned excitatory best-frequency responses. Twenty seven percent of units showed wide receptive fields, representing excitatory responses to almost the entire range of frequencies presented. A tonotopic pattern was observed with best frequencies systematically increasing as more medial-caudal recording sites were sampled.

Acoustic Stimulation↗
PubMed1996

A neural basis for lexical retrieval.

Two parallel studies using positron emission tomography, one conducted in neurological patients with brain lesions, the other in normal individuals, indicate that the normal process of retrieving words that denote concrete entities depends in part on multiple regions of the left cerebral hemisphere, located outside the classic language areas. Moreover, anatomically separable regions tends to process words for distinct kinds of items.

Adult↗
PubMed1995

Double dissociation of conditioning and declarative knowledge relative to the amygdala and hippocampus in humans.

A patient with selective bilateral damage to the amygdala did not acquire conditioned autonomic responses to visual or auditory stimuli but did acquire the declarative facts about which visual or auditory stimuli were paired with the unconditioned stimulus. By contrast, a patient with selective bilateral damage to the hippocampus failed to acquire the facts but did acquire the conditioning. Finally, a patient with bilateral damage to both amygdala and hippocampal formation acquired neither the conditioning nor the facts. These findings demonstrate a double dissociation of conditioning and declarative knowledge relative to the human amygdala and hippocampus.

Acoustic Stimulation↗
PubMed1995

Fear and the human amygdala.

We have previously reported that bilateral amygdala damage in humans compromises the recognition of fear in facial expressions while leaving intact recognition of face identity (Adolphs et al., 1994). The present study aims at examining questions motivated by this finding. We addressed the possibility that unilateral amygdala damage might be sufficient to impair recognition of emotional expressions. We also obtained further data on our subject with bilateral amygdala damage, in order to elucidate possible mechanisms that could account for the impaired recognition of expressions of fear. The results show that bilateral, but not unilateral, damage to the human amygdala impairs the processing of fearful facial expressions. This impairment appears to result from an insensitivity to the intensity of fear expressed by faces. We also confirmed a double dissociation between the recognition of facial expressions of fear, and the recognition of identity of a face: these two processes can be impaired independently, lending support to the idea that they are subserved in part by anatomically separate neural systems. Based on our data, and on what is known about the amygdala's connectivity, we propose that the amygdala is required to link visual representations of facial expressions, on the one hand, with representations that constitute the concept of fear, on the other. Preliminary data suggest the amygdala's role extends to both recognition and recall of fearful facial expressions.

Amygdala↗
PubMed1994

Impaired recognition of emotion in facial expressions following bilateral damage to the human amygdala.

Studies in animals have shown that the amygdala receives highly processed visual input, contains neurons that respond selectively to faces, and that it participates in emotion and social behaviour. Although studies in epileptic patients support its role in emotion, determination of the amygdala's function in humans has been hampered by the rarity of patients with selective amygdala lesions. Here, with the help of one such rare patient, we report findings that suggest the human amygdala may be indispensable to: (1) recognize fear in facial expressions; (2) recognize multiple emotions in a single facial expression; but (3) is not required to recognize personal identity from faces. These results suggest that damage restricted to the amygdala causes very specific recognition impairments, and thus constrains the broad notion that the amygdala is involved in emotion.

Adult↗
PubMed1994

The return of Phineas Gage: clues about the brain from the skull of a famous patient.

When the landmark patient Phineas Gage died in 1861, no autopsy was performed, but his skull was later recovered. The brain lesion that caused the profound personality changes for which his case became famous has been presumed to have involved the left frontal region, but questions have been raised about the involvement of other regions and about the exact placement of the lesion within the vast frontal territory. Measurements from Gage's skull and modern neuroimaging techniques were used to reconstitute the accident and determine the probable location of the lesion. The damage involved both left and right prefrontal cortices in a pattern that, as confirmed by Gage's modern counterparts, causes a defect in rational decision making and the processing of emotion.

Accidents, Occupational↗
PubMed1994

How reliable are occipital asymmetry measurements?

In vivo occipital asymmetry (OA) measurements have been used to infer functional asymmetries such as language dominance. We investigated the degree of correlation between OA measurements derived by the same rater from different scans of the same subject. We used magnetic resonance (MR) and computerized axial tomography (CT) to study correlations between MR:MR, CT:CT and CT:MR. The highest intrasubject correlation was for MR:MR (r = 0.79). The CT:CT value was similar (r = 0.78) and the CT:MR correlation was slightly lower (r = 0.72). The findings indicate that the reliability of occipital asymmetry measurements is modest at best, setting a low ceiling on the valid use of this variable to infer other indexes.

Adolescent↗