Biology subjects

Heekeren, H. R.

Publications and source records attributed to Heekeren, H. R..

6 recordsLinked to original sources

bioRxiv2021

Effects of non-invasive brain stimulation on visual perspective taking: A meta-analytic study

Visual perspective taking (VPT) is a critical ability required by complex social interaction. Non-invasive brain stimulation (NIBS) has been increasingly used to examine the causal relationship between brain activity and VPT, yet with heterogeneous results. In the current study, we conducted two meta-analyses to examine the effects of NIBS of the right temporoparietal junction (rTPJ) or dorsomedial prefrontal cortex (dmPFC) on VPT, respectively. We performed a comprehensive literature search to identify qualified studies, and computed the standardized effect size (ES) for each combination of VPT level (Level-1: visibility judgment; Level-2: mental rotation) and perspective (self and other). Thirteen studies (rTPJ: 12 studies, 23 ESs; dmPFC: 4 studies, 14 ESs) were included in the meta-analyses. Random-effects models were used to generate the overall effects. Subgroup analyses for distinct VPT conditions were also performed. We found that rTPJ stimulation significantly improved participants visibility judgment from the allocentric perspective, whereas its effects on other VPT conditions are negligible. Stimulation of dmPFC appeared to influence Level-1 performance from the egocentric perspective, although it was only based on a small number of studies. Notably, contrary to some theoretical models, we did not find strong evidence that these regions are involved in Level-2 VPT with a higher requirement of mental rotation. These findings not only advanced our understanding of the causal roles of the rTPJ and dmPFC in VPT, but also revealed the efficacy of NIBS on VPT is relatively small. Researchers should also be cautious about the potential publication bias and selective reporting.

neuroscience↗

bioRxiv2021

Parallel representation of context and multiple context-dependent values in ventro-medial prefrontal cortex

Value representations in ventromedial prefrontal-cortex (vmPFC) are known to guide the choice between options. But the value of an option can be different in different task contexts. Goal-directed behavior therefore requires to know the current context and associated values of options, and to flexibly switch between value representations in a task-dependent manner. We tested whether task-relevant and -irrelevant values influence behavior and asked whether both values are represented together with context signals in vmPFC. Thirty-five participants alternated between tasks in which stimulus color or motion predicted rewards. As expected, neural activity in vmPFC and choices were largely driven by task-relevant values. Yet, behavioral and neural analyses indicate that participants also retrieved the values of irrelevant features, and computed which option would have been best in the alternative context. Investigating the probability distributions over values and contexts encoded in multivariate fMRI signals, we find that vmPFC maintains representations of the current context, i.e. task state, the value associated with it, and the hypothetical value of the alternative task state. Crucially, we show that evidence for irrelevant value signals in vmPFC relates to behavior on multiple levels, competes with expected value signals, and interacts with task state representations. Our results thus suggest that different value representations are represented in parallel and imply a link between neural representations of task states, their associated values and their influence on behavior. This sheds new light on vmPFCs role in decision making, bridging between a hypothesized role in mapping observations onto the task states of a mental map, and computing value expectations for alternative states.

neuroscience↗

bioRxiv2021

Category-specific item encoding in the medial temporal lobe and beyond: The role of reward.

Forming new memories is a fundamental part of human life, and the medial temporal lobe (MTL) is central to memory formation. Recent research suggests that within MTL, the perirhinal and parahippocampal cortices (PRC, PHC) process object and scene memory, respectively, whereas the hippocampus (HC) is agnostic to stimulus category. It is unclear, however, whether MTL category specificity extends to item encoding. Furthermore, MTL does not act in isolation: Reward-related memories are formed in interplay with the dopaminergic midbrain (substantia nigra/ventral tegmental area, SNVTA) and amygdala (AMY), but it is unclear whether reward modulates neural item encoding in a category-specific way. To address these questions, we had 39 healthy volunteers (27 for all memory-based analyses) undergo functional magnetic resonance imaging while they solved an incidental encoding task, which paired objects or scenes with high or low reward, followed by a next-day surprise recognition test. Behaviourally, high reward preferably enhanced object memory. Importantly, neural activity in PRC and PHC reflected item encoding of objects and scenes, respectively. Moreover, AMY encoding effects were selective for high-reward objects, with a similar pattern in PRC. SNVTA and HC showed no clear evidence of item encoding. The behavioural and neural asymmetry of reward-related encoding effects may be conveyed through an anterior-temporal memory system, including AMY and PRC, potentially in interplay with the ventromedial prefrontal cortex (vmPFC).

neuroscience↗

bioRxiv2021

The neural basis of effort valuation: A meta-analysis of functional magnetic resonance imaging studies

Choosing how much effort to expend is a critical for everyday decisions. While effort-based decision-making is altered in common psychopathologies and many neuroimaging studies have been conducted to examine how effort is valued, it remains unclear where the brain processes effort-related costs and integrates them with rewards. Using meta-analyses of combined maps and coordinates of functional magnetic resonance imaging (fMRI) studies (total N = 22), we showed that raw effort demands consistently activated the pre-supplementary motor area (pre-SMA). In contrast, the net value of effortful reward consistently activated regions, such as the ventromedial prefrontal cortex (vmPFC) and ventral striatum (VS), that have been previously implicated in value integration in other cost domains. The opposite activation patterns of the pre-SMA and vmPFC imply a double dissociation of these two regions, in which the pre-SMA is involved in pure effort cost representation and the vmPFC in net value integration. These findings advance our understanding of the neural basis of effort-related valuation and reveal potential brain targets to treat motivation-related disorders.

neuroscience↗

bioRxiv2020

Belief states and categorical-choice biases determine reward-based learning under perceptual uncertainty

In natural settings, learning and decision making often takes place under considerable perceptual uncertainty. Here we investigate the computational principles that govern reward-based learning and decision making under perceptual uncertainty about environmental states. Based on an integrated perceptual and economic decision-making task where unobservable states governed the reward contingencies, we analyzed behavioral data of 52 human participants. We formalized perceptual uncertainty with a belief state that expresses the probability of task states based on sensory information. Using several Bayesian and Q-learning agent models, we examined to which degree belief states and categorical-choice biases determine human learning and decision making under perceptual uncertainty. We found that both factors influenced participants behavior, which was similarly captured in Bayesian-inference and Q-learning models. Therefore, humans dynamically combine uncertain perceptual and reward information during learning and decision making, but categorical choices substantially modulate this integration. The results suggest that categorical commitments to the most likely state of the environment may generally give rise to categorical biases on learning under uncertainty.

neuroscience↗

bioRxiv2019

GLAMbox: A Python toolbox for investigating the association between gaze allocation and decision behaviour

Recent empirical findings have indicated that gaze allocation plays a crucial role in simple decision behaviour. Many of these findings point towards an influence of gaze allocation onto the speed of evidence accumulation in an accumulation-to-bound decision process (resulting in generally higher choice probabilities for items that have been looked at longer). Further, researchers have shown that the strength of the association between gaze and choice behaviour is highly variable between individuals, encouraging future work to study this association on the individual level. However, only few decision models exist that easily allow studying the gaze-choice association on the individual level, due to the high cost of developing and implementing them. The model space is particularly scarce for choice sets with more than two choice alternatives. Here, we present GLAMbox, a Python-based toolbox that is built upon PyMC3 and allows the easy application of the gaze-weighted linear accumulator model (GLAM) to experimental choice data. The GLAM assumes gaze-dependent evidence accumulation in a linear stochastic race that extends to decision scenarios with many choice alternatives. GLAMbox enables Bayesian parameter estimation of the GLAM for individual, pooled or hierarchical models, provides an easy-to-use interface to predict choice behaviour and visualize choice data, and benefits from all of PyMC3s Bayesian statistical modeling functionality. Further documentation, resources and the toolbox itself are available at https://github.com/glamlab/glambox.

neuroscience↗