Biology subjects

Spronkers, F. S.

Publications and source records attributed to Spronkers, F. S..

4 recordsLinked to original sources

bioRxiv2026

Dopamine modulates striatal activity when controlling the output of working memory

Cognitive control depends on capacity-limited mechanisms that require selection. Working memory (WM) therefore relies on an input-gate to filter information into WM and an output-gate to transform current WM representations into a prioritised state to guide behaviour. According to current theory, such WM gating processes are modulated by dopamine in the striatum, yet empirical evidence for this hypothesis remains sparse. We fill this gap by directly testing the role of dopamine for both WM input-and output-gating in a double-blind, placebo-controlled within-subject fMRI study (N = 34; 23 female, 11 male human subjects), using a 400 mg oral dose of the dopamine D2 receptor antagonist sulpiride. In our cued delayed-response task, which separated input-from output-gating, sulpiride altered neural activity in the striatum during output-gating. This effect was accompanied by a sulpiride-induced de-crease in the neural stimulus selectivity of gated sensory representations in visual association cortex, with greater decreases in stimulus selectivity correlating with reduced behavioural accuracy in the task. Together, the results establish a role for striatal dopamine during the control of cortical outflow of WM. Significance StatementTo act on a goal, the brain holds information in mind and brings the important parts into focus to guide what we do next. Scientists believe that this "selection" process involves dopamine, a chemical messenger, in a brain area called the striatum. We tested this by giving people a drug that alters dopamine activity in the brain. The drug changed how the striatum reacted when people selected information from memory. It also made the brains visual areas represent this information less clearly, and this change affected peoples behaviour. Therefore, we conclude that dopamine in the striatum plays a role when our brain controls which information in working memory is sent to other parts of the brain to guide actions.

neuroscience↗

bioRxiv2025

Dissecting the contribution of recent reward versus recent performance history on cognitive effort allocation

An extensive body of literature has shown that humans tend to avoid expending cognitive effort, just like for physical effort or financial resources. How then, do we decide whether to put this effort in? Decision-making not only involves choosing our actions, but also the meta-decision of how much cognitive effort to invest in making this choice, weighing the costs of cognitive effort against potential rewards. Popular recent theories, grounded in the field of reinforcement learning, suggest that this cost-benefit trade-off can be informed by the opportunity costs of effort investment, which the brain may approximate by the estimated average reward rate per unit time. It follows from intuition that in a low reward environment, investing cognitive resources in the task at hand will less likely lead to missed opportunities. Recent studies provided support for this idea, showing that people exert more cognitive effort when reward rate is low. Here, we replicate one of the key previous findings but provide an important nuance to this result. Cognitive effort allocation was better explained by participants recent performance history (i.e. accuracy rate) than average reward rate. In combination with the observation that participants were insensitive to the reward currently at stake, this invites a reinterpretation of these previous findings and suggests the need for further studies to assess whether environmental richness may indeed serve as a heuristic to modulate cognitive effort allocation.

neuroscience↗

bioRxiv2019

Localizing the multiple-demand frontoparietal network in individual subjects

The frontoparietal multiple-demand (MD) control network plays a key role in goal-directed behavior. Recent developments of multivoxel pattern analysis (MVPA) for fMRI data allow for more fine-grained investigations into the functionality and properties of brain systems. In particular, MVPA in the MD network was used to gain better understanding of control processes such as attentional effects, adaptive coding, and representation of multiple task-relevant features, but overall low decoding levels have limited its use for this network. A common practice of applying MVPA is by investigating pattern discriminability within a region-of-interest (ROI) using a template mask, thus ensuring that the same brain areas are studied in all participants. This approach offers high sensitivity, but does not take into account differences between individuals in the spatial organization of brain regions. An alternative approach uses independent localizer data for each subject to select the most responsive voxels and define individual ROIs within the boundaries of a group template. Such an approach allows for a refined and targeted localization based on the unique pattern of activity of individual subjects while ensuring that functionally similar brain regions are studied for all subjects. In the current study we tested whether using individual ROIs leads to changes in decodability of task-related neural representations as well as univariate activity across the MD network compared to when using a group template. We used three localizer tasks to separately define subject-specific ROIs: spatial working memory, verbal working memory, and a Stroop task. We then systematically assessed univariate and multivariate results in a separate rule-based criterion task. All the localizer tasks robustly recruited the MD network and evoked highly reliable activity patterns in individual subjects. Consistent with previous studies, we found a clear benefit of the subject-specific ROIs for univariate results from the criterion task, with increased activity in the individual ROIs based on the localizers data, compared to the activity observed when using the group template. In contrast, there was no benefit of the subject-specific ROIs for the multivariate results in the form of increased discriminability, as well as no cost of reduced discriminability. Both univariate and multivariate results were similar in the subject-specific ROIs defined by each of the three localizers. Our results provide important empirical evidence for researchers in the field of cognitive control for the use of individual ROIs in the frontoparietal network for both univariate and multivariate analysis of fMRI data, and serve as another step towards standardization and increased comparability across studies.

neuroscience↗

bioRxiv2019

Effects of mid-frontal brain stimulation on sustained attention

Sustained attention is defined as the ability to maintain attention over longer periods of time, which typically declines with time on task (i.e., the vigilance decrement). Previous studies have suggested an important role for the dorsomedial prefrontal cortex (mPFC) in sustained attention. In two experiments, we aimed to enhance sustained attention by applying transcranial electrical current stimulation over the mPFC during a sustained attention task. In the first experiment, we applied transcranial direct current stimulation (tDCS) in a between-subject design (n=97): participants received either anodal, cathodal, or sham stimulation. Contrary to our prediction, we found no effect of stimulation on the vigilance decrement. In the second experiment, participants received theta and alpha transcranial alternating current stimulation (tACS) in two separate sessions (n=47, within-subject design). Here, we found a frequency-dependent effect on the vigilance decrement, such that contrary to our expectation, participants performance over time became worse after theta compared to alpha stimulation. However, this result needs to be interpreted with caution given that this effect could be driven by differential side effects between the two stimulation frequencies. To conclude, across two studies, we were not able to reduce the vigilant decrement using tDCS or theta tACS.

neuroscience↗