Preserved complex emotion-based learning in amnesia

Separated at birth: Rediscovering the lost emotions in Luria's Working Brain

Aleksandr Luria repeatedly emphasised the importance of emotions and the right hemisphere in his neuropsychological writings. It is surprising, therefore, that Luria's most influential book, The Working Brain, appears to lack an explicit section on these topics. This is especially notable because of a comment in the book's English-language Introduction, by Karl Pribram, referencing Luria's thoughts about precisely this material. Remarkably, it seems that Luria did write such an explicit chapter, in the original Russian edition. However, in the English-language version, the relevant sections were separated, embedded elsewhere without chapter headings, and altered, presumably following an explicit translation decision. The present paper tracks the nature of these changes and, 50 years later, presents the material for the first time translated and reunited in English, as Luria intended. After the translation, we offer a brief commentary, on the ways in which Luria's ideas were in some respects prescient, and in other respects less well-informed about the brain basis of emotions and the right hemisphere. This reunification offers an interesting time capsule on the opinions of one of neuropsychology's greatest minds, on a topic which Luria admits had, at the time, only a modest empirical foundation.

Detecting valence from unidentified images: A link between familiarity and positivity in recognition without identification

Research using the Recognition Without Identification paradigm (Cleary & Greene, 2000, Journal of Experimental Psychology: Learning, Memory, and Cognition, 26[4], 1063-1069; Peynircioǧlu, 1990, Journal of Memory and Language, 29, 493-500) has found that participants can discriminate between old and new stimuli even when the stimuli are obscured to a degree that they are unidentifiable. This methodology has been adapted in the past by using heavily obscured threatening and nonthreatening images and asking participants to try to identify each image followed by a familiarity rating of the image. Past results showed that threatening images that were not able to be identified were rated as more familiar than nonthreatening images that were not able to be identified (Cleary et al., 2013, Memory & Cognition, 41, 989-999). The current study used a similar methodology to explore the possibility that a sense of familiarity can serve to guide our attention toward potential threats in the environment. However, contrary to earlier results, we found that positive images were rated as more familiar than negative images. This pattern was found with both identified and unidentified images and was replicated across five experiments. The current findings are consistent with the view that feelings of positivity and familiarity are closely linked (e.g., de Vries et al., 2010, Psychological Science, 21[3], 321-328; Garcia-Marques et al., 2004, Personality and Social Psychology Bulletin, 30, 585-593; Monin, 2003, Journal of Personality and Social Psychology, 85[6], 1035-1048).

Like a rolling stone: Psychotherapy without (episodic) memory

People with profound amnesia still retain the capacity to learn about the emotional value of experiences, which is crucial in developing and sustaining interpersonal relationships. In a 2017 paper, we demonstrated for the first time (with patient JL) that transferential feelings develop across the therapeutic process, despite profound episodic memory impairment after medial temporal lesions. This paper reports a second case (GA) of a profoundly amnesic patient in psychotherapy, this time after lesions to the anterior fornix. The work with GA opens issues such as the differences and similarities to the previous case, counter-transference phenomena, and the effects of hyperphagia. The findings make it clear that many phenomena are common to both GA and JL, such as forgetfulness, various types of repetition, the importance of the therapeutic alliance, and the ability to make therapeutic gain. However, there were differences between the cases, for example as regards confabulation, which may relate to either pre-morbid personality or lesion site. The paper also discusses the way in which patients of this type bear the very status of psychotherapeutic work with profoundly amnesic patients. Where others have seen barriers and in principle problems in working with such patients, we see many opportunities.

Decision-Making Under Ambiguity or Risk in Individuals With Alzheimer's Disease and Mild Cognitive Impairment

BACKGROUND

Making advantageous decisions is essential in everyday life. Our objective was to assess how patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) make decisions under conditions of ambiguity or risk. In addition, the study also aimed to examine the relationship between decision-making competence and memory and executive function.

METHODS

Patients with MCI (n = 36) and AD (n = 29) and healthy elderly controls (HC, n = 34) were recruited from the memory clinic. All subjects were administered a comprehensive neuropsychological battery test. We used the Iowa Gambling Task (IGT) to measure decision-making under ambiguity and the Game of Dice Task (GDT) to measure decision-making under risk. Pearson's correlation was used to examine the relationship between the performance of IGT and GDT with delayed recall and the Stroop test.

RESULTS

In the GDT, MCI and AD patients presented similar performance but showed different patterns when compared with the HC group. The proportion of those making advantageous choices was lower in the AD group than in the HC group (p = 0.01), while the MCI and HC groups did not differ (p = 0.14). Meanwhile, concerning the ratio of accepting negative feedback, the AD (p < 0.01) group was significantly different from the HC patients, but the MCI (p = 0.06) and HC groups did not differ. In the IGT, MCI and AD patients selected randomly from advantageous and disadvantageous decks (p = 0.94 and p = 0.54), showing no significant change in performance over time. In contrast, the HC group made increasingly frequent advantageous selections over time (p = 0.04). Furthermore, the proportion of advantageous decision-makers for the GDT had a linear relationship with delayed recall of the Hopkins Verbal Learning Test and Stroop color words (p < 0.01 and p < 0.01, respectively).

CONCLUSION

Our findings suggest that decision-making ability under ambiguity is compromised in MCI and AD, and the decision-making under risk is only impaired in AD. Reduced decision-making performance under risk is closely correlated with lower executive functions and memory.

Preserved re-experience of discrete emotions: Amnesia and executive function

Amnesic patients can re-experience emotions elicited by forgotten events, suggesting that brain systems for episodic and emotional memory are independent. However, the range of such emotional memories remains under-investigated (most studies employing just positive-negative emotion dyads), and executive function may also play a role in the re-experience of emotions. This is the first investigation of the intensity of the emotional re-experience of a range of discrete emotions (anger, fear, sadness, and happiness) for a group of amnesic patients. Twenty Korsakoff syndrome (KS) patients and 20 neurologically normal controls listened to four novel emotional vignettes selectively eliciting the four basic emotions. Emotional experience was measured using pen-and-paper Visual Analogue Mood Scales and episodic memory using verbal recollections. After 30 min, the recollection of stories was severely impaired for the patient group, but the emotional re-experience was no different from that of controls. Notably, there was no relationship between episodic recall and the intensity of the four emotions, such that even profoundly amnesic patients reported moderate levels of the target emotion. Exploratory analyses revealed negative correlations between the intensity of basic emotions and executive functions (e.g., cognitive flexibility and response inhibition) for controls but not patients. The results suggest that discrete emotions can be re-experienced independently of episodic memory, and that the re-experience of certain discrete emotions appears to be dampened by executive control. KS patients with absent or mild cognitive symptoms should benefit from emotion-regulation interventions aimed at reducing the recognized affective burden associated with their episodic memory deficit.

Observations on Working Psychoanalytically with a Profoundly Amnesic Patient

Individuals with profound amnesia are markedly impaired in explicitly recalling new episodic events, but appear to preserve the capacity to use information from other sources. Amongst these preserved capacities is the ability to form new memories of an emotional nature - a skill at the heart of developing and sustaining interpersonal relationships. The psychoanalytic study of individuals with profound amnesia might contribute to the understanding the importance of each memory system, including effects on key analytic processes such as transference and countertransference. However, psychoanalytic work in the presence of profound amnesia might also require important technical modifications. In the first report of its kind, we describe observations from a long term psychoanalytic process (72 sessions) with an individual (JL) who has profound amnesia after an anoxic episode. The nature of therapy was shaped by JL's impairment in connecting elements that belong to distant (and even relatively close) moments in the therapeutic process. However, we were also able to document areas of preservation, in what appears to be a functioning therapeutic alliance. As regards transference, the relationship between JL and his analyst can be viewed as the evolution of a narcissistic transference, and case material is provided that maps this into three phases: (i) rejecting; (ii) starting to take in; and (iii) full use of the analytic space - where each phase exhibits differing degrees of permeability between JL and the analyst. This investigation appears to have important theoretical implications for psychoanalytic practice, and for psychotherapy in general - and not only with regard to brain injured populations. We especially note that it raises questions concerning the mechanism of therapeutic action in psychoanalysis and psychotherapy, and the apparent unimportance of episodic memory for many elements of therapeutic change.

Frontal-subcortical circuitry in social attachment and relationships: A cross-sectional fMRI ALE meta-analysis

Researchers have explored the concept of attachment in multiple ways, from animal studies examining imprinting to abnormal attachment in psychopathology. However, until recently, few have considered how neural circuitry develops the effective social bonds that are subsequently replicated in relationships across the lifespan. This current cross-sectional study undertook a fMRI Activation Likelihood Estimation (ALE) meta-analyses to examine the neurocircuitry that governs emotional and behavioural functions critical for building effective social relationships in children and adults. Results suggest that dissociable dorsal cognitive ("cool") and ventral - affective ("hot") frontal-subcortical circuits (FSC) work together to govern social relationships, with repeated social consequences leading to potentially adaptive - or maladaptive - relationships that can become routinized in the cerebellum. Implications for forming stable, functional, social bonds are considered, followed by recommendations for those who struggle with cool and hot FSC functioning that can hinder the development of adaptive prosocial relationships.

No evidence of risk-taking or impulsive behaviour in a person with episodic amnesia: Implications for the role of the hippocampus in future-regarding decision-making

Does advantageous decision-making require one to explicitly remember the outcome of a series of past decisions or to imagine future personal consequences of one's choices? Findings that amnesic people with hippocampal damage cannot form a clear preference for advantageous decks over many learning trials on the Iowa Gambling Task (IGT) have been taken to suggest that complex decision-making on the IGT depends on declarative (episodic) memory and hippocampal integrity. Alternatively, impaired IGT performance in amnesic individuals could be secondary to risk-taking and/or impulsive behaviour resulting from impaired episodic future thinking (i.e. prospection) known to accompany amnesia. We tested this possibility in the amnesic individual K.C. using the IGT and the Toronto Gambling Task (TGT), a novel task that dissociates impulsivity from risk-taking without placing demands on declarative memory. K.C. did not develop a preference for advantageous over disadvantageous decks on the IGT and, instead, showed a slight preference for short-term gains and an inability to acquire a more adaptive appreciation of longer-term losses. He also did not display impulsive or risk-taking behaviour on the TGT, despite a profound inability to imagine personal future experiences. These findings suggest that impaired decision-making on the IGT in amnesia is unlikely to reflect a predilection to act in the moment or failure to take future consequences into account. Instead, some forms of future-regarding decision-making may be dissociable, with performance on tasks relying on declarative learning or on episodic-constructive processes more likely to be impaired.

Profound anterograde amnesia following routine anesthetic and dental procedure: a new classification of amnesia characterized by intermediate-to-late-stage consolidation failure?

Anterograde amnesia caused by bilateral hippocampal or diencephalon damage manifests in characteristic symptoms of preserved intellect and implicit learning, and short span of awareness with complete and rapid forgetting of episodic material. A new case, WO, 38-year-old male with anterograde amnesia, in the absence of structural brain changes or psychological explanation is presented, along with four comparison cases from the extant literature that share commonalities between them including preserved intellect, span of awareness greater than working memory, and complete forgetting within hours or days following successful learning, including notably for both explicit and implicit material. WO's amnesia onset coincided with anesthetic injection and root canal procedure, with extended vasovagal-like incident. The commonalities between the five cases presented may suggest a shared biological mechanism involving the breakdown of intermediate-to-late-stage consolidation that does not depend on the structural integrity of the hippocampi. Speculation on the mechanism of consolidation breakdown and diagnostic implications are discussed.

Emotion-based learning: insights from the Iowa Gambling Task

Interest in the cognitive and/or emotional basis of complex decision-making, and the related phenomenon of emotion-based learning, has been heavily influenced by the Iowa Gambling Task. A number of psychological variables have been investigated as potentially important in understanding emotion-based learning. This paper reviews the extent to which humans are explicitly aware of how we make such decisions; the biasing influence of pre-existing emotional labels; and the extent to which emotion-based systems are anatomically and functionally independent of episodic memory. Review of literature suggests that (i) an aspect of conscious awareness does appear to be readily achieved during the IGT, but as a relatively unfocused emotion-based "gut-feeling," akin to intuition; (ii) Several studies have manipulated the affective pre-loading of IGT tasks, and make it clear that such labeling has a substantial influence on performance, an experimental manipulation similar to the phenomenon of prejudice. (iii) Finally, it appears that complex emotion-based learning can remain intact despite profound amnesia, at least in some neurological patients, a finding with a range of potentially important clinical implications: in the management of dementia; in explaining infantile amnesia; and in understanding of the possible mechanisms of psychotherapy.

Learning on the IGT follows emergence of knowledge but not differential somatic activity

The importance of unconscious autonomic activity vs. knowledge in influencing behavior on the Iowa Gambling Task (IGT) has been the subject of debate. The task's developers, Bechara and colleagues, have claimed that behavior on the IGT is influenced by somatic activity and that this activity precedes the emergence of knowledge about the task contingencies sufficient to guide behavior. Since then others have claimed that this knowledge emerges much earlier on the task. However, it has yet to be established whether somatic activity which differentiates between advantageous and disadvantageous choices on the IGT is found before this point. This study describes an experiment to determine whether knowledge sufficient to guide behavior precedes differential autonomic activity or vice versa. This experiment used a computerized version of the IGT, knowledge probes after every 10 trials and skin conductance recording to measure somatic activity. Whereas in previous reports the majority of participants end the task with full conceptual knowledge of the IGT contingencies we found little evidence in support of this conclusion. However, full conceptual knowledge was not critical for advantageous deck selection to occur and most participants had knowledge sufficient to guide behavior after approximately 40 trials. We did not find anticipatory physiological activity sufficient to differentiate between deck types in the period prior to acquiring this knowledge. However, post-punishment physiological activity was found to be larger for the disadvantageous decks in the pre-knowledge period, but only for participants who displayed knowledge. Post-reward physiological activity distinguished between the advantageous and disadvantageous decks across the whole experiment but, again, only in participants who displayed knowledge and then only in later trials following their display of knowledge.

Learning on the IGT follows emergence of knowledge but not differential somatic activity

The importance of unconscious autonomic activity vs. knowledge in influencing behavior on the Iowa Gambling Task (IGT) has been the subject of debate. The task's developers, Bechara and colleagues, have claimed that behavior on the IGT is influenced by somatic activity and that this activity precedes the emergence of knowledge about the task contingencies sufficient to guide behavior. Since then others have claimed that this knowledge emerges much earlier on the task. However, it has yet to be established whether somatic activity which differentiates between advantageous and disadvantageous choices on the IGT is found before this point. This study describes an experiment to determine whether knowledge sufficient to guide behavior precedes differential autonomic activity or vice versa. This experiment used a computerized version of the IGT, knowledge probes after every 10 trials and skin conductance recording to measure somatic activity. Whereas in previous reports the majority of participants end the task with full conceptual knowledge of the IGT contingencies we found little evidence in support of this conclusion. However, full conceptual knowledge was not critical for advantageous deck selection to occur and most participants had knowledge sufficient to guide behavior after approximately 40 trials. We did not find anticipatory physiological activity sufficient to differentiate between deck types in the period prior to acquiring this knowledge. However, post-punishment physiological activity was found to be larger for the disadvantageous decks in the pre-knowledge period, but only for participants who displayed knowledge. Post-reward physiological activity distinguished between the advantageous and disadvantageous decks across the whole experiment but, again, only in participants who displayed knowledge and then only in later trials following their display of knowledge.

Dual conception of risk in the Iowa Gambling Task: effects of sleep deprivation and test-retest gap

Risk in the Iowa Gambling Task (IGT) is often understood in terms of intertemporal choices, i.e., preference for immediate outcomes in favor of delayed outcomes is considered risky decision making. According to behavioral economics, healthy decision makers are expected to refrain from choosing the short-sighted immediate gain because, over time (10 trials of the IGT), the immediate gains result in a long term loss (net loss). Instead decision makers are expected to maximize their gains by choosing options that, over time (10 trials), result in delayed or long term gains (net gain). However, task choices are sometimes made on the basis of the frequency of reward and punishment such that frequent rewards/infrequent punishments are favored over infrequent rewards/frequent punishments. The presence of these two attributes (intertemporality and frequency of reward) in IGT decision making may correspond to the emotion-cognition dichotomy and reflect a dual conception of risk. Decision making on the basis of the two attributes was tested under two conditions: delay in retest and sleep deprivation. An interaction between sleep deprivation and time delay was expected to attenuate the difference between the two attributes. Participants were 40 male university students. Analysis of the effects of IGT attribute type (intertemporal vs. frequency of reinforcement), sleep deprivation (sleep deprivation vs. no sleep deprivation), and test-retest gap (short vs. long delay) showed a significant within-subjects effect of IGT attribute type thus confirming the difference between the two attributes. Sleep deprivation had no effect on the attributes, but test-retest gap and the three-way interaction between attribute type, test-retest gap, and sleep deprivation were significantly different. Post-hoc tests revealed that sleep deprivation and short test-retest gap attenuated the difference between the two attributes. Furthermore, the results showed an expected trend of increase in intertemporal decision making at retest suggesting that intertemporal decision making benefited from repeated task exposure. The present findings add to understanding of the emotion-cognition dichotomy. Further, they show an important time-dependent effect of a universally experienced constraint (sleep deprivation) on decision making. It is concluded that risky decision making in the IGT is contingent on the attribute under consideration and is affected by factors such as time elapsed and constraint experienced before the retest.

Memory as social glue: close interpersonal relationships in amnesic patients

Memory may be crucial for establishing and/or maintaining social bonds. Using the National Social life, Health, and Aging Project questionnaire, we examined close interpersonal relationships in three amnesic people: K.C. and D.A. (who are adult-onset cases) and H.C. (who has developmental amnesia). All three patients were less involved than demographically matched controls with neighbors and religious and community groups. A higher-than-normal percentage of the adult-onset (K.C. and D.A.) cases’ close relationships were with family members, and they had made few new close friends in the decades since the onset of their amnesia. On the other hand, the patient with developmental amnesia (H.C.) had forged a couple of close relationships, including one with her fiancé. Social networks appear to be winnowed, but not obliterated, by amnesia. The obvious explanation for the patients’ reduced social functioning stems from their memory impairment, but we discuss other potentially important factors for future study.

Mirrored prominent deck B phenomenon: frequent small losses override infrequent large gains in the inverted Iowa Gambling Task

Since Bechara et al. pioneered its development, the Iowa Gambling Task (IGT) has been widely applied to elucidate decision behavior and medial prefrontal function. Although most decision makers can hunch the final benefits of IGT, ventromedial prefrontal lesions generate a myopic choice pattern. Additionally, the Iowa group developed a revised IGT (inverted IGT, iIGT) to confirm the IGT validity. Each iIGT trial was generated from the trial of IGT by multiplying by a "-" to create an inverted monetary value. Thus, bad decks A and B in the IGT become good decks iA and iB in the iIGT; additionally, good decks C and D in the IGT become bad decks iC and iD in the iIGT. Furthermore, IGT possessed mostly the gain trials, and iIGT possessed mainly the loss trials. Therefore, IGT is a frequent-gain-based task, and iIGT is a frequent-loss-based task. However, a growing number of IGT-related studies have identified confounding factors in IGT (i.e., gain-loss frequency), which are demonstrated by the prominent deck B phenomenon (PDB phenomenon). Nevertheless, the mirrored PDB phenomenon and guiding power of gain-loss frequency in iIGT have seldom been reexamined. This experimental finding supports the prediction based on gain-loss frequency. This study identifies the mirrored PDB phenomenon. Frequent small losses override occasional large gains in deck iB of the iIGT. Learning curve analysis generally supports the phenomenon based on gain-loss frequency rather than final outcome. In terms of iIGT and simple versions of iIGT, results of this study demonstrate that high-frequency loss, rather than a satisfactory final outcome, dominates the preference of normal decision makers under uncertainty. Furthermore, normal subjects prefer "no immediate punishment" rather than "final reward" under uncertainty.

Decision making under stress: a selective review

Many decisions must be made under stress, and many decision situations elicit stress responses themselves. Thus, stress and decision making are intricately connected, not only on the behavioral level, but also on the neural level, i.e., the brain regions that underlie intact decision making are regions that are sensitive to stress-induced changes. The purpose of this review is to summarize the findings from studies that investigated the impact of stress on decision making. The review includes those studies that examined decision making under stress in humans and were published between 1985 and October 2011. The reviewed studies were found using PubMed and PsycInfo searches. The review focuses on studies that have examined the influence of acutely induced laboratory stress on decision making and that measured both decision-making performance and stress responses. Additionally, some studies that investigated decision making under naturally occurring stress levels and decision-making abilities in patients who suffer from stress-related disorders are described. The results from the studies that were included in the review support the assumption that stress affects decision making. If stress confers an advantage or disadvantage in terms of outcome depends on the specific task or situation. The results also emphasize the role of mediating and moderating variables. The results are discussed with respect to underlying psychological and neural mechanisms, implications for everyday decision making and future research directions.

Remembering relationships: preserved emotion-based learning in Alzheimer's disease

Research into Alzheimer's disease has long focused on cognitive impairments. Advocates of the person-centered approach argue that emotions and interpersonal responses may remain intact. The answer to this paradox may derive from the neuropsychology of emotion, demonstrating preserved ability on simple emotion learning tasks, though this may not capture the complex interpersonal interactions that some patients appear able to manage in everyday life. This study demonstrates, for the first time, preserved complex emotion-based learning capacity, despite profound episodic memory impairment in Alzheimer's disease. These findings offer a starting point for the development of a solid neuropsychological and neuroanatomical account for the person-centered approach.

Decision making under ambiguity in temporal lobe epilepsy: does the location of the underlying structural abnormality matter?

Previous studies have reported decision-making deficits in patients affected by mesial temporal lobe epilepsy (TLE). The aim of the study described here was to assess the specificity of these deficits by comparing performance of patients with neocortical TLE, patients with mesial TLE, and healthy controls. The mesial TLE group performed lower than healthy controls and the neocortical TLE group in decision making under initial ambiguity. Although patients with neocortical TLE and controls showed a significant learning effect over the blocks of the Iowa gambling task, performance of patients with mesial TLE did not improve from the first to the last block of trials. Results suggest that TLE associated with neocortical brain abnormalities does not have deleterious effects on decision making as is found for epilepsy caused by mesial temporal lobe pathologies. The present findings highlight the specificity of the mesial temporal lobes in reward-based, adaptive learning and decision making.

Sustained experience of emotion after loss of memory in patients with amnesia

Can the experience of an emotion persist once the memory for what induced the emotion has been forgotten? We capitalized on a rare opportunity to study this question directly using a select group of patients with severe amnesia following circumscribed bilateral damage to the hippocampus. The amnesic patients underwent a sadness induction procedure (using affectively-laden film clips) to ascertain whether their experience of sadness would persist beyond their memory for the sadness-inducing films. The experiment showed that the patients continued to experience elevated levels of sadness well beyond the point in time at which they had lost factual memory for the film clips. A second experiment using a happiness induction procedure yielded similar results, suggesting that both positive and negative emotional experiences can persist independent of explicit memory for the inducing event. These findings provide direct evidence that a feeling of emotion can endure beyond the conscious recollection for the events that initially triggered the emotion.

The contingency-shifting variant Iowa Gambling Task: an investigation with young adults

The contingency-shifting variant Iowa Gambling Task (IGT), in which the reward and punishment contingencies of different decks of cards are systematically altered, was investigated with a large group of healthy young adults (n = 208). Our findings demonstrate that the onset of unsignaled, contingency-shift phases initially disrupted learning but that performance subsequently improved during each shift. Subjective experience ratings were positively correlated with performance across all phases. A regression model showed that performance early in the task, in Blocks 3 and 4, significantly predicted later ability to shift to the changing contingencies. Subdividing participants into high performer and low performer groups revealed an increased number of selections of previously good-now-bad decks in the latter group. Overall, the contingency-shifting variant IGT may have potential as a novel measure of reversal learning in experimental and clinical settings.

The Effect of Education and Gender on Emotion-Based Decision-Making

In the last decade, the Iowa Gambling Task (IGT) has become a widely employed instrument for the investigation of emotion-based decision-making. Previous research has suggested that education may de-emphasise the role of emotion-based learning in decision-making, which suggests the paradox that better-educated participants should show poorer performance on the IGT. Previous research has also demonstrated gender differences on the task. We investigated the effects of education level and gender on performance on the IGT in the South African context. In order to investigate the effects of these two variables, two contrast groups were utilised: 32 volunteer university students and 20 less educated volunteers with, at most, a Grade 10 level of schooling. Both groups were divided equally by gender. It was found that the university-educated group outperformed the less educated group only in the last stage of the task. The learning profiles for the two genders appeared to be similar; no significant gender differences were found. A range of possible explanations are explored for these findings including: lack of motivation, differences in tracking punishments, differences in risk taking behaviours and difficulty with reversal learning. The implication of these findings is that, in real world situations, an excessive reliance on emotion-based resources may not be an advantage, and it may be that the university educated group was advantaged by a combination of emotional and cognitive sources of evidence. These results are discussed with reference to international findings.

Declarative memory is critical for sustained advantageous complex decision-making

Previous studies have reported conflicting evidence concerning the contribution of declarative memory to advantageous decision-making on the Iowa Gambling Task (IGT). One study, in which the measurement of psychophysiology during the task necessitated a 10-s delay between card selections, found that six participants with amnesia due to hippocampal damage failed to develop a preference for advantageous decks over disadvantageous decks [Gutbrod, K., Krouzel, C., Hofer, H., Muri, R., Perrig, W., & Ptak, R. (2006). Decision-making in amnesia: Do advantageous decisions require conscious knowledge of previous behavioural choices? Neuropsychologia, 44(8), 1315-1324]. However, a single-case study (where psychophysiology was not measured and no delay between card selections occurred) showed that an amnesic patient developed normal preference for advantageous decks [Turnbull, O. H., & Evans, C. E. (2006). Preserved complex emotion-based learning in amnesia. Neuropsychologia, 44(2), 300-306]. We sought to resolve these discrepant findings by examining IGT performances in five patients with profound amnesia (WMS-III General Memory Index M=63) and bilateral hippocampal damage caused by anoxia (n=4) or herpes simplex encephalitis (n=1). In one administration of the IGT, psychophysiology measurements were utilized and a 6-s delay was interposed between card selections. In a second administration, no delay between card selections was interposed. While age-, sex-, and education-matched healthy comparison participants showed significant learning with a gradual preference for advantageous decks in both conditions, amnesic patients, irrespective of IGT administration condition and extent of medial temporal lobe damage, failed to develop this preference. These findings strongly discount the possibility that the delay between card selections explains why amnesic participants fail to learn in the IGT, and suggest instead a significant role for medial temporal lobe declarative memory systems in the type of complex decision-making tapped by the IGT.

Impact of ambiguity and risk on decision making in mild Alzheimer's disease

Decisions under ambiguity and decisions under risk are crucial types of decision making in daily living at any age. This is the first study assessing these two types of decisions in patients with mild dementia of Alzheimer's type (DAT) by means of the Iowa Gambling Task (IGT) and a newly developed, Probability-Associated Gambling (PAG) task. While rules for gains and losses are implicit in the IGT, in the PAG task rules are explicit and winning probabilities, which change from trial to trial, can be estimated. Results of the IGT indicated that DAT patients made more disadvantageous decisions than healthy controls. Patients also shifted more frequently among decks, i.e. under ambiguity decisions were taken randomly and no advantageous strategy was established over time by DAT patients. Thus, not only actual choices but also development of advantageous strategies may be revealing about decision making in the IGT. Compared to controls, patients demonstrated less advantageous choices in the PAG task as well. They gambled more often in the low winning probabilities and less frequently in the high probabilities than healthy participants. Patients' performance on both tasks correlated with measures of executive functions. Findings of the present investigation are consistent with the early pathological cerebral changes and related (cognitive, emotional) deficits reported for DAT. As suggested by our study, decisions under ambiguity as well as decisions under risk are impaired in mild DAT. It may thus be expected that patients with mild DAT have difficulties in taking decisions in every-day life situations, both in cases of ambiguity (information on probability is missing or conflicting, and the expected utility of the different options is incalculable) and in cases of risk (outcomes can be predicted by well-defined or estimable probabilities).

Decision-making with explicit and stable rules in mild Alzheimer's disease

Decision-making in mild dementia of Alzheimer's type (DAT) was assessed in a gambling task with stable and explicit rules [Game of Dice Task; Brand, M., Labudda, K., Kalbe, E., Hilker, R., Emmans, D., Fuchs, G., et al. (2004). Decision-making impairments in patients with Parkinson's disease. Behavioural Neurology, 15, 77-85]. DAT patients in an early stage of the disease chose safe alternatives as frequently as healthy elderly persons and did not show risky behaviour as has been reported for other neurological patient groups. However, a more detailed analysis disclosed important differences between DAT and healthy elderly. Compared to healthy controls, DAT patients shifted more frequently between safe and risky alternatives and showed less consistent response patterns. Frequent changes between strategies indicate that decisions were taken randomly, that no advantageous strategy was established and that no consistent response pattern was developed over time. As regards performance changes over the task, healthy participants had a stronger tendency towards safe and advantageous responses than DAT patients. While healthy controls showed learning as the task proceeded, DAT patients did not adapt their strategies. The proportion of "consistently safe responders" was significantly higher in the control group than in the DAT group. Analysis of reaction times indicated that differences in response behaviour were not due to fast and impulsive decision taking in the DAT group. DAT patients' response pattern may be attributed to deficits in learning and in executive functions. The frequency of changes between safe and risky choices proved to be a fair predictor for the distinction between mild DAT and healthy aging.

The somatic marker hypothesis: A critical evaluation

The somatic marker hypothesis (SMH; [Damasio, A. R., Tranel, D., Damasio, H., 1991. Somatic markers and the guidance of behaviour: theory and preliminary testing. In Levin, H.S., Eisenberg, H.M., Benton, A.L. (Eds.), Frontal Lobe Function and Dysfunction. Oxford University Press, New York, pp. 217-229]) proposes that emotion-based biasing signals arising from the body are integrated in higher brain regions, in particular the ventromedial prefrontal cortex (VMPFC), to regulate decision-making in situations of complexity. Evidence for the SMH is largely based on performance on the Iowa Gambling Task (IGT; [Bechara, A., Tranel, D., Damasio, H., Damasio, A.R., 1996. Failure to respond autonomically to anticipated future outcomes following damage to prefrontal cortex. Cerebral Cortex 6 (2), 215-225]), linking anticipatory skin conductance responses (SCRs) to successful performance on a decision-making paradigm in healthy participants. These 'marker' signals were absent in patients with VMPFC lesions and were associated with poorer IGT performance. The current article reviews the IGT findings, arguing that their interpretation is undermined by the cognitive penetrability of the reward/punishment schedule, ambiguity surrounding interpretation of the psychophysiological data, and a shortage of causal evidence linking peripheral feedback to IGT performance. Further, there are other well-specified and parsimonious explanations that can equally well account for the IGT data. Next, lesion, neuroimaging, and psychopharmacology data evaluating the proposed neural substrate underpinning the SMH are reviewed. Finally, conceptual reservations about the novelty, parsimony and specification of the SMH are raised. It is concluded that while presenting an elegant theory of how emotion influences decision-making, the SMH requires additional empirical support to remain tenable.