Adrian G Fischer

• PhD
• PostDoc Position at Freie Universität Berlin

Adapting to errors quickly is essential for survival. Reaction slowing after errors is commonly observed but whether this slowing is adaptive or maladaptive is unclear. Here, we analyse a large dataset from a flanker task using two complementary approaches: a multistage drift-diffusion model, and the lateralisation of EEG beta power as a time-resol...

Optimal decision-making employs short-term rewards and abstract long-term information based on which of these is deemed relevant. Employing short-vs. long-term information is associated with different learning mechanisms, yet neural evidence showing that these two are dissociable is lacking. Here we demonstrate that long-term, inference-based belie...

The ability to learn not only from experienced but also from merely fictive outcomes without direct rewarding or punishing consequences should improve learning and resulting value-guided choice. Using an instrumental learning task in combination with multiple single-trial regression of predictions derived from a computational reinforcement-learning...

Neuroscientists have been puzzled by the fact that acute administration of a selective serotonin reuptake inhibitor (SSRI) produces results that are, at times, compatible with either decreases or increases in serotonergic neurotransmission. Furthermore, the underlying cause of the delayed onset of antidepressant effects of SSRI treatment has remain...

Successful goal-directed behavior critically depends on performance monitoring, a set of cognitive and affective functions determining whether adaptive control is needed and, if so, which type and magnitude is required. Knowledge of the brain structures involved in such a process has grown enormously, although the time course of performance-monitor...

A prominent account of decision-making assumes that information is accumulated until a fixed response threshold is crossed. However, many decisions require weighting of information appropriately against time. Collapsing response thresholds are a mathematically optimal solution to this decision problem. However, our understanding of the neurocomputa...

Deficits in reward learning are core symptoms across many mental disorders. Recent work suggests that such learning impairments arise by a diminished ability to use reward history to guide behaviour, but the neuro-computational mechanisms through which these impairments emerge remain unclear. Moreover, limited work has taken a transdiagnostic appro...

Performance monitoring (PM) is a vital component of adaptive behavior and known to be influenced by motivation. We examined effects of potential gain (PG) and loss avoidance (LA) on neural correlates of PM at different processing stages, using a task with trial-based changes in these motivational contexts. Findings suggest more attention is allocat...

Performance monitoring (PM) is a vital component of adaptive behavior and known to be influenced by motivation. We examined effects of potential gain (PG) and loss avoidance (LA) on neural correlates of PM at different processing stages, using a task with trial-based changes in motivational context. Findings suggest more attention is allocated to t...

A prominent account of decision-making assumes that information is accumulated until a fixed response threshold is crossed. However, many everyday decisions require weighting of information appropriately against time. Collapsing response thresholds are a mathematically optimal solution to this decision problem. However, evidence in favour of dynami...

Optimal decision making in complex environments requires dynamic learning from unexpected events. To speed up learning, we should heavily weight information that indicates state-action-outcome contingency changes and ignore uninformative fluctuations in the environment. Often, however, unrelated information is hard to ignore and can potentially bia...

Under high cognitive demands, older adults tend to resort to simpler, habitual, or model-free decision strategies. This age-related shift in decision behavior has been attributed to deficits in the representation of the cognitive maps, or state spaces, necessary for more complex model-based decision-making. Yet, the neural mechanisms behind this sh...

The feedback-related negativity (FRN) is a well-established electrophysiological correlate of feedback-processing. However, there is still an ongoing debate whether the FRN is driven by negative or positive reward prediction errors (RPE), valence of feedback, or mere surprise. Our study disentangles independent contributions of valence, surprise, a...

We typically slow down after committing an error, an effect termed post-error slowing (PES). Traditionally, PES has been calculated by subtracting post-correct from post-error RTs. Dutilh et al. ( Journal of Mathematical Psychology, 56 (3), 208-216, 2012), however, showed PES values calculated in this way are potentially biased. Therefore, they pro...

Humans are confronted with dynamic environments which require to sequentially decide between exploitation and exploration. According to the marginal value theorem, current reward rates need to be continuously compared with potential future rewards to determine the opportunity cost of staying or leaving. We developed the Gold-treasure-task (GTT) in...

Background: Symptoms of obsessive-compulsive disorder (OCD) are partly related to impaired cognitive control processes and theta modulations constitute an important electrophysiological marker for cognitive control processes such as signaling negative performance feedback in a fronto-striatal network. Deep brain stimulation (DBS) targeting the ante...

Optimal decision making in complex environments requires dynamic learning from unexpected events. To speed up learning, we should heavily weight information that indicates state-action-outcome contingency changes and ignore uninformative fluctuations in the environment. Often, however, unrelated information is hard to ignore and can potentially bia...

When under high cognitive demand older adults tend to resort to simpler, model-free decision strategies. This age-related shift in decision behaviour has been attributed to deficits in the representation of the cognitive maps, or state spaces, necessary for more complex model-based decision-making. Yet, the neural mechanism behind this shift remain...

Research suggests that working memory (WM) has an important role in instrumental learning in changeable environments when reinforcement histories of multiple options must be tracked. Working memory capacity (WMC) not only reflects the ability to maintain items, but also to update and shield items against interference in a context-dependent manner;...

Objective: Tourette syndrome is a neurodevelopmental disorder putatively associated with a hyperdopaminergic state. Therefore, it seems plausible that excessive dopamine transmission in Tourette syndrome alters the ability to learn based on rewards and punishments. We tested whether Tourette syndrome patients exhibited altered reinforcement learni...

Reinforcement learning (RL) theory states that learning is driven by prediction errors (PEs)—the discrepancy between the predicted and actual outcome of an action. When participants learn from their own actions, PEs correlate with the feedback‐related negativity (FRN), but it is not clear if the FRN reflects a PE in observational learning. We use a...

We are capable of planning ahead by incorporating dynamic factors influencing future choices. In this issue of Neuron, Kolling et al. (2018) present fMRI results of a novel task that demonstrates how humans evaluate alternative environments by prospectively incorporating their characteristics over time and account for their own decision tendencies....

The specific role of serotonin and its interplay with dopamine (DA) in adaptive, reward guided behavior as well as drug dependance, still remains elusive. Recently, novel methods allowed cell type specific anatomical, functional and interventional analyses of serotonergic and dopaminergic circuits, promising significant advancement in understanding...

The error-related negativity (ERN or Ne) is increasingly being investigated as a marker discriminating interindividual factors and moves toward a surrogate marker for disorders or interventions. Although reproducibility and validity of neuroscientific and psychological research has been criticized, clear data on how different quantification methods...

Sexual dimorphisms have been observed in many species, including humans, and extend to the prevalence and presentation of important mental disorders associated with performance monitoring malfunctions. However, precisely which underlying differences between genders contribute to the alterations observed in psychiatric diseases is unknown. Here, we...

Serotonin (5-HT) has been hypothesized to be implicated in performance monitoring by promoting behavioral inhibition in the face of aversive events. However, it is unclear whether this is restricted to external (punishment) or includes internal (response errors) events. The aim of the current study was to test whether higher 5-HT levels instigate i...

Humans flexibly weight incoming evidence when updating beliefs and adjusting behavior. In the current issue of Neuron, McGuire et al. (2014) show how distinct neuronal correlates of main factors underlying this weight-ing converge on a common mechanism driving belief updates. An essential question when evaluating ev-idence for one's beliefs in a ch...

Following recent advances in neuromodulation therapy for mental disorders, we treated one patient with severe alcohol addiction with deep brain stimulation (DBS) of the nucleus accumbens (NAc). Before and one year following the surgery, we assessed the effects of DBS within the NAc on the addiction as well as on psychometric scores and electrophysi...