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.

Decision making in ambiguous and risky situations after unilateral temporal lobe epilepsy surgery.

Decision making is essential in everyday life. Though the importance of the mesial temporal structures in emotional processing and feedback learning is well established, decision making in patients after mesial temporal lobe surgery has rarely been studied. We studied 23 patients with mesial temporal lobe epilepsy after unilateral temporal lobe surgery and 26 healthy controls using two different gambling tasks, the Iowa Gambling Task (IGT) and the Probability-Associated Gambling (PAG) task. In the IGT, rules for gains and losses are implicit; in the PAG task, winning probabilities are well defined. Compared with healthy controls, patients performed poorly on the IGT (decisions under ambiguity). No group difference was found in the PAG task (decisions under risk). Results of the present investigation indicate that after mesial temporal lobe surgery, patients have difficulties in making decisions under ambiguity, whereas they decide advantageously when information about the decision situation is explicitly given.

Normal aging affects decisions under ambiguity, but not decisions under risk.

Old adults have to face many situations that require important decisions. In the present investigation, the authors examined the effects of aging on both decisions under ambiguity and decisions under risk. To this purpose, healthy young and old adults completed the Iowa Gambling Task (IGT) and the Probability-Associated Gambling task (PAG task). Old adults performed the PAG task as well as young adults, demonstrating ability to make decisions when full information about the problem situation, the options' probabilities and the associated gains and losses was given. Differently, old adults showed poor performance on the IGT relative to young adults, indicating difficulty in making advantageous decisions under ambiguous conditions. Indeed, in the IGT, participants are not aware of the rules for gains and losses and have to learn about the utility of their selections through experience. Results of our analyses point to the contribution of executive functions to all types of decisions. Our findings have also practical implications, suggesting that old people can make advantageous decisions when complete information about the decision situation is available.

Making decisions and advising decisions in traumatic brain injury.

OBJECTIVE AND BACKGROUND: Decision under ambiguity and decision under risk are fundamental in every-day life. METHODS: We investigated these 2 types of decision in traumatic brain injury (TBI) patients through the Iowa Gambling Task (IGT), the Probability-Associated Gambling (PAG) task, and a counsel version of the PAG task. Although in the IGT rules for gain and losses are implicit and probability information is missing, in the PAG task and the counsel task rules are explicit and probabilities are well-defined. RESULTS: In the IGT, TBI patients selected more disadvantageously than healthy controls and failed to develop an advantageous strategy over time. Patients also made less advantageous choices than controls in the PAG task and the counsel task. Compared with controls, TBI patients gambled more frequently with low probabilities and less frequently with high probabilities. Overall, participants decided more advantageously in the counsel task, which does not provide feedback, than in the PAG task. Importantly, our results indicate that TBI patients' performance on all decision tasks correlated with executive functions. CONCLUSIONS: Our study shows that TBI patients have difficulties in decision under risk and decision under ambiguity. Difficulties may be attributed to deficient learning from feedback and to reduced risk estimation, but not to impulsive risk taking behavior.

Decision making in juvenile myoclonic epilepsy.

Recent neuroimaging studies have reported structural and functional brain abnormalities in patients with juvenile myoclonic epilepsy (JME), which may also involve cortical and subcortical networks that are important for decision making. This study is the first attempt to examine decision making in JME. Twenty-two patients with JME (median age 26.00, range 18-50) and 33 healthy controls (median age 26.00, range 18-57) participated in the study. For the JME group, the median age at seizure onset was 14.00 years (range 1-20); the median epilepsy duration was 11.50 years (range 3-45). Eleven patients (50 %) had pharmacoresistant seizures. All participants completed the Iowa Gambling Task (IGT), a widely used standard task of decision making. In this task, contingencies are not explained and feedback on previous decisions has to be used in order to learn to choose the advantageous alternatives. In the IGT, patients with JME showed difficulty in learning to choose advantageously compared to healthy controls. Difficulty was enhanced for the patients with pharmacoresistant seizures. A correlation analysis revealed an association between decision-making performance of patients with JME and executive functions. Results indicate that patients with JME have difficulty in making advantageous decisions and that persistence of seizures might be a critical factor for cognitive functioning. Findings of this study add a new aspect to the neuropsychological profile of JME. Difficulty in decision making may impair functioning of patients with JME in everyday life and affect their adherence to treatment plans.

Executive functions in chronic mesial temporal lobe epilepsy.

There is no consensus as to whether mesial temporal lobe epilepsy (MTLE) leads to executive function deficits. In this study, we adopted an extensive neuropsychological test battery and assessed different executive functions in chronic, unilateral MTLE. Performance of MTLE patients was compared with that of healthy peers and with normative data. Several MTLE patients had scores below cut-off or below the 10th percentile of normative data. Scores of the whole patient group were overall in the average range of normative data. Relative to controls, MTLE patients performed poorly in tests of working memory, cognitive flexibility, categorical verbal fluency, set-shifting, categorization, and planning. These findings raise an important methodological issue as they suggest that executive function deficits in chronic MTLE may be individually variable and that their assessment should include different tests. Deficits in chronic MTLE are not limited to temporal lobe functions, such as memory, but may extend to extra temporal cognitive domains, such as executive functions.

Decision making under ambiguity and under risk in mesial temporal lobe epilepsy.

Decision making is essential in everyday life. Though the importance of the mesial temporal lobe in emotional processing and feedback learning is generally recognized, decision making in mesial temporal lobe epilepsy (mTLE) is almost unexplored so far. Twenty-eight consecutive epilepsy patients with drug resistant mTLE and fifty healthy controls performed decision tasks under initial ambiguity (participants have to learn by feedback to make advantageous decisions) and under risk (advantageous choices may be made by estimating risks and by rational strategies). A subgroup analysis compared the performance of patients affected by MRI-verified abnormalities of the hippocampus or amygdala. The effect of lesion side was also assessed. In decision under ambiguity, mTLE patients showed marked deficits and did not improve over the task. Patients with hippocampus abnormality and patients with amygdala abnormality showed comparable deficits. No difference was found between right and left TLE groups. In decision under risk, mTLE patients performed at the same level as controls. Results suggest that mTLE patients have difficulties in learning from feedback and in making decisions in uncertain, ambiguous situations. By contrast, they are able to make advantageous decisions when full information is given and risks, possible gains and losses are exactly defined.