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Cognitive control in context: Neural, functional, and social mechanisms of metacontrol

Periodic Reporting for period 2 - Metacontrol (Cognitive control in context: Neural, functional, and social mechanisms of metacontrol)

Reporting period: 2018-06-01 to 2019-11-30

Human behavior is particularly flexible, which allows us to adapt to continuously changing conditions and situations. How is that possible, how do we achieve this flexibility? The project METACONTROL assumes that humans can perceive, decide, and act under different mental modes—metacontrol modes as we call them. Sometimes they tend to be more persistent, keeping and following their current goal even under challenging conditions, but sometimes they can also be more flexible, which may include trading one’s current goal for another, more promising one. The goal of the project is to characterize and better understand the mental set allowing us to be persistent or flexible and study the conditions under which people tend to be more persistent and when they are more flexible. Part of this goal consists in the attempt to study the brain processes involved in being persistent or flexible, and in creating mathematical models that allow us to predict when people are persistent or flexible, in which individuals tend to be more persistent or more flexible overall. Finally, the project aims to characterize the consequences of being persistent or flexible with respect to human performance and social interaction.
The first period of the project yielded five interesting findings.

First, we found that individuals are not very consistent with respect to the degree of persistence and flexibility across different tasks. Previous research has shown that some people are better at tasks that require persistence (e.g. tasks in which irrelevant but misleading information needs to be ignored) while others are better at tasks that call for flexibility (e.g. brainstorming) because of their individual genetic predisposition and/or their cultural background. This might suggest that some people tend to be more persistent in all tasks that they work on while others are more flexible. However, this expectation was not confirmed by a larger study in which the same individuals perform various tasks. And yet, individuals were consistent across tasks with respect to their overall performance. This suggests that each task requires a different degree of persistence or flexibility, and people are able to adjust to that degree; but some are better to adjust than others and can thus switch between persistence and flexibility in a more adaptive fashion.

Second, we found first evidence that this kind of adaptivity (i.e. the ability to switch between persistence and flexibility in a task-specific fashion) might be related to serotonin, a human neurotransmitter that is also involved in the feeling of happiness and in depression. We had the opportunity to test individuals participating in a session in which psychedelic truffles were consumed—a practice that is legal in the Netherlands. Consuming such truffles increases the individual level of serotonin, which we found to improve performance in both tasks that require persistence in tasks that require flexibility. A follow-up study failed to confirm these findings but a smaller dosage might be an explanation. Another follow-up study has been run in the findings are currently analyzed. While we need to await confirmation, a positive result might suggest that the balance between persistence and flexibility is achieved by processes that rely on serotonin.

Third, we carried out a meta-analysis of previous studies in humans and non-human animals to identify and characterize the neural source of persistence and flexibility. There is strong evidence that both persistence and flexibility rely on dopamine, another human neurotransmitter. Flexibility relies on the striatal dopaminergic pathway, which is an evolutionary old pathway deep in the brain that is driven by activity of the substantia nigra, a small brain system. Persistence relies on the frontal dopaminergic pathway, which is evolutionary a younger and driven by activity in the ventral tegmental area, in other brain system. Given that we want to monitor or the activities in these two dopaminergic pathways online, we were interested to better understand and localize the substantia nigra and the ventral tegmental area. However, while the former is well defined anatomically, the latter is surprisingly difficult to demarcate, and there is considerable variability in the literature which brain systems are actually part of the ventral tegmental area. We collaborate with Prof. Birte Forstmann at the University of Amsterdam to tackle that problem by using a probabilistic brain atlas. The article reporting this Atlas will be reported in a few weeks.

Fourth, we found behavioral evidence that persistence and flexibility modes have a strong impact on information processing, but only in some tasks. We use particular meditation techniques to induce more persistent or more flexible metacontrol modes, and test how this changes the way people perform particular tasks. Interestingly, such changes could only be found in tasks that require the retrieval of information from memory but not in tasks that rely on perceptually available information only. This suggests that metacontrol modes operate by changing the way we control the information that we retrieve from memory: when in a more persistent mode, we restrict this retrieval to the information that we really need but when in a more flexible mode, we also allow associated but not necessarily relevant information to be retrieved. The latter is not optimal when high concentration and focus is needed but very useful to get new ideas.

Fifth, we found first evidence that metacontrol parameters can be conditioned to external stimuli and be transferred from one task to another, even if the two tasks are very different (far-transfer). While there was some evidence that metacontrol biases towards persistence or flexibility used or induced in one task can affect performance in the same task thereafter, we predicted that far-transfer to entirely different tasks should be possible. We were able to provide evidence that this is possible, even though more research to bolster that claim is necessary and underway.
The next steps of the project will consist in visualizing the brain processes involved in persistence and flexibility by means of brain imaging, online monitoring the brain processes during changes from persistence to flexibility, or vice versa, to better understand the reasons why memory retrieval is the target of metacontrol modes, to find out which environmental cues help us to become more persistent or flexible, depending on the situational challenges, to analyze how cultural factors create individual tendencies to be more persistent or more flexible, and to determine the social implications of being persistent or being flexible. Piloting and planning of these studies will be completed in June 2019.

With respect to the starting point of the entire project, the following unexpected trends have emerged and are likely to be further developed and substantiated until the end of the project.

First, the neuroanatomical underpinnings of metacontrol might turn out to be less well structured than we have originally expected. The idea that persistence might be driven by the frontal dopaminergic pathway originating in VTA and flexibility might be driven by the nigrostriatal pathway might have been too simplistic, because VTA and substantia nigra activity might be more integrated in humans than it has been found in animals. It might be this integration that has humans allowed to take a major phylogenetic step that is associated with the development of cognitive-control functions.

Second, whereas culturally induced individual metacontrol state biases may be visible in very loosely structured tasks, they seem to give way to metacontrol states that are tailored to the current task to a degree that is stronger than originally expected. This calls for a concept that we have coined “adaptivity”, the ability to quickly adjust metacontrol states to the present task.

Third, the specific metacontrol states may be much more integrated with the particular tasks they are used for than originally expected. Carrying out a task may automatically re-invoke the metacontrol state that is best suiting this task, or at least the state that has been most frequently used to carry out this task.

Fourth, other neurotransmitters than dopamine may contribute to the establishment of particular metacontrol states.