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Biomedical subjects

Antoine Bechara

Publications and source records attributed to Antoine Bechara.

33 records · Page 2Linked to original sources
PubMed2005

Using cognitive models to map relations between neuropsychological disorders and human decision-making deficits.

Findings from a complex decision-making task (the Iowa gambling task) show that individuals with neuropsychological disorders are characterized by decision-making deficits that lead to maladaptive risk-taking behavior. This article describes a cognitive model that distills performance in this task into three different underlying psychological components: the relative impact of rewards and punishments on evaluations of options, the rate that the contingent payoffs are learned, and the consistency between learning and responding. Findings from 10 studies are organized by distilling the observed decision deficits into the three basic components and locating the neuropsychological disorders in this component space. The results reveal a cluster of populations characterized by making risky choices despite high attention to losses, perhaps because of difficulties in creating emotive representations. These findings demonstrate the potential contribution of cognitive models in building bridges between neuroscience and behavior.

Cognition Disorders↗
PubMed2004

The role of emotion in decision-making: evidence from neurological patients with orbitofrontal damage.

Most theories of choice assume that decisions derive from an assessment of the future outcomes of various options and alternatives through some type of cost-benefit analyses. The influence of emotions on decision-making is largely ignored. The studies of decision-making in neurological patients who can no longer process emotional information normally suggest that people make judgments not only by evaluating the consequences and their probability of occurring, but also and even sometimes primarily at a gut or emotional level. Lesions of the ventromedial (which includes the orbitofrontal) sector of the prefrontal cortex interfere with the normal processing of "somatic" or emotional signals, while sparing most basic cognitive functions. Such damage leads to impairments in the decision-making process, which seriously compromise the quality of decisions in daily life. The aim of this paper is to review evidence in support of "The Somatic Marker Hypothesis," which provides a systems-level neuroanatomical and cognitive framework for decision-making and suggests that the process of decision-making depends in many important ways on neural substrates that regulate homeostasis, emotion, and feeling. The implications of this theoretical framework for the normal and abnormal development of the orbitofrontal cortex are also discussed.

Adolescent↗
PubMed2004

Cognitive impulsivity and HIV serostatus in substance dependent males.

HIV-seropositive (HIV+) drug users show impaired performance on measures of integrity of prefrontal-subcortical systems. The Iowa Gambling Task (GT) is mediated primarily through ventromedial-prefrontal systems, and poor performance on this measure ("cognitive impulsivity") is common among substance dependent individuals (SDIs) as well as patients with disease involving prefrontal-subcortical systems (e.g., Huntington disease). We hypothesized that HIV+ SDIs might be more vulnerable to cognitive impulsivity when compared with HIV-seronegative (HIV-) SDIs because recent studies report evidence of additive effects of HIV serostatus and drug dependence on cognition. Further, working memory is considered a key component of GT performance and is reliably impaired among HIV+ SDIs compared to controls. We administered the GT to 46 HIV+ and 47 well-matched HIV- males with a past or current history of substance dependence. In addition, we evaluated correlations between subjects' scores on the GT and on a delayed nonmatch to sample (DNMS) task in order to test if working memory deficits accounted for cognitive impulsivity among the HIV+ subjects. The HIV+ subjects performed significantly more poorly on the GT compared to the HIV- group but this effect could not be explained by working memory deficits. Implications of these findings for future basic and applied studies of HIV and substance dependence are discussed.

Adolescent↗
PubMed2004

Impaired decision making related to working memory deficits in individuals with substance addictions.

This study examined whether individuals with substance dependence (ISDs) show impairments in working memory and whether there is a relationship between their impairments in decision making as measured by the gambling task (GT) paradigm and working memory as measured by a delayed nonmatching to sample (DNMS) task. Using the GT, 11% of healthy control participants and 61% of ISDs opted for choices with high immediate gains in spite of higher future losses. For the ISDs and controls with equal GT impairments, the ISDs performed significantly lower than controls on the DNMS task. The nonimpaired ISDs on the GT also performed significantly worse than matched controls on the DNMS task. The DNMS task deficit in ISDs was across all delay times, suggesting the deficit may lie in the "executive" process of working memory, which supports earlier findings (E. M. Martin et al., 2003). The authors suggest that the prefrontal cortex hosts multiple distinct mechanisms of decision making and inhibitory control and that ISDs may be affected in any one or combination of them.

Adult↗
PubMed2003

Exploring the neurological substrate of emotional and social intelligence.

The somatic marker hypothesis posits that deficits in emotional signalling (somatic states) lead to poor judgment in decision-making, especially in the personal and social realms. Similar to this hypothesis is the concept of emotional intelligence, which has been defined as an array of emotional and social abilities, competencies and skills that enable individuals to cope with daily demands and be more effective in their personal and social life. Patients with lesions to the ventromedial (VM) prefrontal cortex have defective somatic markers and tend to exercise poor judgment in decision-making, which is especially manifested in the disadvantageous choices they typically make in their personal lives and in the ways in which they relate with others. Furthermore, lesions to the amygdala or insular cortices, especially on the right side, also compromise somatic state activation and decision-making. This suggests that the VM, amygdala and insular regions are part of a neural system involved in somatic state activation and decision-making. We hypothesized that the severe impairment of these patients in real-life decision-making and an inability to cope effectively with environmental and social demands would be reflected in an abnormal level of emotional and social intelligence. Twelve patients with focal, stable bilateral lesions of the VM cortex or with right unilateral lesions of the amygdala or the right insular cortices, were tested on the Emotional Quotient Inventory (EQ-i), a standardized psychometric measure of various aspects of emotional and social intelligence. We also examined these patients with various other procedures designed to measure decision-making (the Gambling Task), social functioning, as well as personality changes and psychopathology; standardized neuropsychological tests were applied to assess their cognitive intelligence, executive functioning, perception and memory as well. Their results were compared with those of 11 patients with focal, stable lesions in structures outside the neural circuitry thought to mediate somatic state activation and decision-making. Only patients with lesions in the somatic marker circuitry revealed significantly low emotional intelligence and poor judgment in decision-making as well as disturbances in social functioning, in spite of normal levels of cognitive intelligence (IQ) and the absence of psychopathology based on DSM-IV criteria. The findings provide preliminary evidence suggesting that emotional and social intelligence is different from cognitive intelligence. We suggest, moreover, that the neural systems supporting somatic state activation and personal judgment in decision-making may overlap with critical components of a neural circuitry subserving emotional and social intelligence, independent of the neural system supporting cognitive intelligence.

Adult↗
PubMed2003

Risky business: emotion, decision-making, and addiction.

Although metabolic abnormalities in the orbitofrontal cortex have been observed in substance dependent individuals (SDI) for several years, very little attention was paid to the role of this brain region in addiction. However, patients with damage to the ventromedial (VM) sector of the prefrontal cortex and SDI show similar behaviors. (1) They often deny, or they are not aware, that they have a problem. (2) When faced with a choice to pursue a course of action that brings an immediate reward at the risk of incurring future negative consequences, they choose the immediate reward and ignore the future consequences. Studies of patients with bilateral lesions of the VM prefrontal cortex support the view that the process of decision-making depends in many important ways on neural substrates that regulate homeostasis, emotion, and feeling. Parallel lines of study have revealed that VM cortex dysfunction is also evident in subgroups of individuals who are addicted to substances. Thus, understanding the neural mechanisms of decision-making has direct implications for understanding disorders of addiction and pathological gambling, and the switch from a controlled to uncontrolled and compulsive behavior. On the clinical front, the approach to treat addictive disorders has been dominated by a diagnostic system that focuses on behaviors, physical symptoms, or choice of drugs. The article emphasizes the concept of using neurocognitive criteria for subtyping addictive disorders. This is a significant paradigm shift with significant implications for guiding diagnosis and treatment. Using neurocognitive criteria could lead to more accurate subtyping of addictive disorders, and perhaps serve as a guide for more specific, and potentially more successful, behavioral and pharmacological interventions.

Behavior, Addictive↗
PubMed2003

Delayed nonmatch-to-sample performance in HIV-seropositive and HIV-seronegative polydrug abusers.

Working memory (WM) deficits are common in HIV-seropositive (HIV+) individuals and can be amplified by manipulating a variety of task parameters, such as increasing memory load or information complexity. The authors investigated the role of timing in HIV-associated WM defects by varying the amount of time required to maintain information online while holding memory load and information complexity constant. The authors studied 50 HIV+ and 35 HIV-seronegative (HIV-) polydrug abusers abstinent at testing and well-matched on demographic variables. The HIV- group outperformed the HIV+ group across all stimulus-response time delays. HIV-associated WM defects are not critically dependent on the amount of time stimulus representations must be maintained and might be attributed to impaired encoding or retrieval of stimulus representations.

Adult↗
PubMed2003

Role of the amygdala in decision-making.

The somatic marker hypothesis proposes that both the amygdala and the orbitofrontal cortex are parts of a neural circuit critical for judgment and decision-making. Although both structures couple exteroceptive sensory information with interoceptive information concerning somatic/emotional states, they do so at different levels, thus making different contributions to the process. We define "primary inducers" as stimuli that unconditionally, or through learning (e.g., conditioning and semantic knowledge), can (perceptually or subliminally) produce states that are pleasurable or aversive. Encountering a fear object (e.g., a snake), a stimulus predictive of a snake, or semantic information such as winning or losing a large sum of money are all examples of primary inducers. "Secondary inducers" are entities generated by the recall of a personal or hypothetical emotional event or perceiving a primary inducer that generates "thoughts" and "memories" about the inducer, all of which, when they are brought to memory, elicit a somatic state. The episodic memory of encountering a snake, losing a large sum of money, imagining the gain of a large sum of money, or hearing or looking at primary inducers that bring to memory "thoughts" pertaining to an emotional event are all examples of secondary inducers. We present evidence in support of the hypothesis that the amygdala is a critical substrate in the neural system necessary for triggering somatic states from primary inducers. The ventromedial cortex is a critical substrate in the neural system necessary for the triggering of somatic states from secondary inducers. The amygdala system is a priori a necessary step for the normal development of the orbitofrontal system for triggering somatic states from secondary inducers. However, once this orbitofrontal system is developed, the induction of somatic states by secondary inducers via the orbitofrontal system is less dependent on the amygdala system. Perhaps the amygdala is equivalent to the hippocampus with regard to emotions, that is, necessary for acquiring new emotional attributes (anterograde emotions), but not for retrieving old emotional attributes (retrograde emotions). Given the numerous lesion and functional neuroimaging studies illustrating the involvement of the amygdala in complex cognitive and behavioral functions, including "social cognition," we suggest that this involvement is a manifestation of a more fundamental function mediated by the amygdala, which is to couple stimuli/entities with their emotional attributes, that is, the processing of somatic states from primary inducers.

Amygdala↗
PubMed2002

Asymmetric functional roles of right and left ventromedial prefrontal cortices in social conduct, decision-making, and emotional processing.

The aim of this study was to begin to parse the relative contributions of the right and left ventromedial prefrontal cortices (VMPC) in regard to social conduct, decision-making, and emotional processing. We hypothesized that the right VMPC is a critical component of the neural systems that subserve such functions, whereas the left VMPC is not. Seven participants with focal, stable unilateral lesions to the right (n = 4) or left (n = 3) VMPC were studied with procedures designed to measure social conduct, decision-making, and emotional processing and personality. The right-sided participants had profound disturbances of social and interpersonal behavior and of the ability to maintain gainful employment; they had defective performance and impaired anticipatory skin conductance responses during the Gambling Task; most had profound abnormalities of emotional processing and personality, and met criteria for "acquired sociopathy." By contrast, the left-sided participants had normal social and interpersonal behavior; they had stable employment; they performed normally and had normal skin conductance responses on the Gambling Task; they had normal emotional processing; and their personalities were unchanged from premorbid status. The marked deficits in social conduct, decision-making, and emotional processing in participants with unilateral right VMPC lesions are reminiscent in kind of those that have been reported in connection with bilateral VMPC lesions, albeit perhaps of lesser severity. The findings provide preliminary evidence that insofar as social, decision-making, and emotional functions are concerned, the right-sided component of the VMPC system may be critical, whereas the left-sided component may be less important.

Adult↗
PubMed2002

Decision-making and addiction (part I): impaired activation of somatic states in substance dependent individuals when pondering decisions with negative future consequences.

Some substance dependent individuals (SDI) suffer from a decision-making impairment akin to that seen in neurological patients with lesions of the ventromedial (VM) prefrontal cortex. The somatic-marker hypothesis posits that decision-making is a process that depends on emotion and that deficits in emotional signaling will lead to poor decision-making. In this study, we tested the hypothesis that SDI who perform disadvantageously on a decision-making instrument, the gambling task (GT), have a deficit in the somatic signals that help guide their decision in the advantageous direction. Since deficits in decision-making/somatic markers can also result from dysfunctional amygdala, we asked indirectly (i.e. via tests sensitive to VM or amygdala dysfunction) whether such a deficit in SDI is restricted to VM dysfunction or includes the amygdala. Using the GT, and skin conductance response (SCR) as an index of somatic state activation, we studied groups of SDI (n=46), normal controls (n=49), and VM patients (n=10). A subgroup of SDI showed defective performance on the GT coupled with impaired anticipatory SCR, but normal SCR to punishment, and normal acquisition of conditioned SCR to an aversive loud sound. This supports the hypothesis that the poor decision-making in some SDI is associated with defective somatic state activation that is linked to a dysfunctional VM cortex. Thus, the dysfunctional VM cortex underlying the "myopia" for the future in some SDI may be one of the principle mechanisms underlying the transition from casual substance taking to compulsive and uncontrollable behavior.

Adult↗
PubMed2002

Decision-making and addiction (part II): myopia for the future or hypersensitivity to reward?

On a decision-making instrument known as the "gambling task" (GT), a subgroup of substance dependent individuals (SDI) opted for choices that yield high immediate gains in spite of higher future losses. This resembles the behavior of patients with ventromedial (VM) prefrontal cortex lesions. In this study, we addressed the possibility that hypersensitivity to reward may account for the "myopia" for the future in this subgroup of SDI. We used a variant version of the GT, in which the good decks yielded high immediate punishment but higher delayed reward. The bad decks yielded low immediate punishment and lower delayed reward. We measured the skin conductance response (SCR) of subjects after receiving reward (reward SCR) and during their pondering from which deck to choose (anticipatory SCR). A subgroup of SDI who was not impaired on the original GT performed normally on the variant GT. The subgroup of SDI who was impaired on the original GT showed two levels of performance on the variant GT. One subgroup (36% of the sample) performed poorly on the variant GT, and showed similar behavioral and physiological impairments to VM patients. The other subgroup of SDI (64% of the sample) performed normally on the variant task, but had abnormally large physiological responses to reward, i.e. large SCR after receiving reward (reward SCR) and large SCR in anticipation of outcomes that yield large reward. Thus, the combined cognitive and physiological approach of assessing decision-making characterizes three sub-populations of SDI. One sub-population is without impairments that can be detected by any measure of the GT paradigm. Another sub-population is similar to VM patients in that they are insensitive to the future, both positive and negative. A third sub-population is hypersensitive to reward, so that the presence or the prospect of receiving, reward dominates their behavior.

Adult↗
PubMedDate not supplied

The effects of vagus nerve stimulation on decision-making.

Subcortical and brainstem structures are increasingly becoming recognized as important contributors to higher cognitive functioning. Decision-making is one such function, particularly as viewed within the framework of the somatic marker hypothesis (SMH). The SMH views the participation in decision-making by the body proper as integral to emotional biasing and hence key to choosing in an advantageous manner. This study focuses on the vagus nerves as a possible conduit for somatic afferent signals pertinent to decision-making. We tested eight epileptic patients with implanted left vagus nerve stimulators. To assess decision-making we used the gambling task, which is sensitive to real-life decision-making deficits. Using a counterbalanced design, each participant performed the gambling task under a condition in which low-level vagus nerve stimulation (VNS) was covertly delivered, and another condition in which no VNS was delivered. Participants showed improved performance, that is, made more advantageous choices, in the stimulated relative to the unstimulated condition. Although these results should be viewed as preliminary, they suggest that the vagus nerve is a conduit for afferent somatic signals that can influence decision-making.

Adult↗