How uncertain are you? Disentangling expected and unexpected uncertainty in pupil-linked brain arousal during reversal learning.

During decision making, we are continuously faced with two sources of uncertainty regarding the links between stimuli, our actions, and outcomes. On the one hand, our expectations are often probabilistic, that is, stimuli or actions yield the expected outcome only with a certain probability (expected uncertainty). On the other hand, expectations might become invalid due to sudden, unexpected changes in the environment (unexpected uncertainty). Several lines of research show that pupil-linked brain arousal is a sensitive indirect measure of brain mechanisms underlying uncertainty computations. Thus, we investigated whether it is involved in disentangling these two forms of uncertainty. To this aim, we measured pupil size during a probabilistic reversal learning task. In this task, participants had to figure out which of two response options led to reward with higher probability, whereby sometimes the identity of the more advantageous response option was switched. Expected uncertainty was manipulated by varying the reward probability of the advantageous choice option, whereas the level of unexpected uncertainty was assessed by using a Bayesian computational model estimating change probability and resulting uncertainty. We found that both aspects of unexpected uncertainty influenced pupil responses, confirming that pupil-linked brain arousal is involved in model updating after unexpected changes in the environment. Furthermore, high level of expected uncertainty impeded the detection of sudden changes in the environment, both on physiological and behavioral level. These results emphasize the role of pupil-linked brain arousal and underlying neural structures in handling situations in which the previously established contingencies are no longer valid.

Long-term follow-up of patients with obsessive-compulsive disorder treated by anterior capsulotomy: a neuropsychological study.

BACKGROUND: For treatment-refractory Obsessive-Compulsive-Disorder (OCD) patients, anterior capsulotomy is a potential therapy. We investigated what kinds of cognitive deficits treatment-refractory patients have and how anterior capsulotomy modifies their clinical and cognitive profiles. METHODS: Ten treatment-refractory OCD patients were examined in two groups (operated and non-operated) with 5 participants in each group, matched for symptom severity, gender, age and education. The operated group was treated with anterior capsulotomy; the non-operated group was treated only with pharmaco- and psychotherapy. The Yale-Brown Obsessive-Compulsive Rating Scale (Y-BOCS) was used to measure OCD symptoms, and ten neuropsychological tests were used to measure cognitive functioning. RESULTS: In the operated group, the score of Y-BOCS score significantly decreased during the two-year follow-up period. Additionally, we found a significant increase in neuropsychological test scores on the Wechsler Intelligence Test (MAWI), California Sorting Test Part A (CST-A), Stroop Test Interference Score (STR-I), Verbal Fluency Test and Iowa Gambling Test. As a negative result, we observed intrusion errors in the Category Fluency Test. In the non-operated group significant improvement was found in Y-BOCS scores. At follow-up, we found significant differences between the operated and non-operated groups on three neuropsychological tests: Trail Making Test Part B, Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Attention Index and RBANS Language Index, with better performance in the non-operated group. CONCLUSIONS: Both treatment methods (i.e. anterior capsulotomy and pharmaco- and psychotherapy) seem effective in reducing OCD symptoms and cognitive deficits, but, importantly, to different degrees. The clinical and neuropsychological improvements were more impressive in the operated group.