Biology subjects

Brass, M.

Publications and source records attributed to Brass, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Parallel control of conjunctive and compositional representations supports dynamic task preparation

People can dynamically and adaptively update task goals in the face of task uncertainty. In this fMRI study, we aimed to investigate the modulation of neural task representations that subserve such flexible task control. On each trial, we asked people to perform one of nine image categorization tasks. During task preparation, participants had to actively infer varying levels of task uncertainty and dynamically modulate their task preparation accordingly. Multivariate pattern analyses demonstrated dissociable uncertainty-driven modulations of conjunctive and compositional task representations in the right frontoparietal network. Specifically, different sub-regions showed diminished conjunctive task representations when task uncertainty increased during task preparation. At the same time, we observed an active maintenance of compositional task representations, suggesting an adaptive cognitive strategy in facilitating compositional task reconfiguration. These findings suggest a mechanism of parallel control on conjunctive and compositional representations that allows for maximizing the advantages of both representational formats, offering new insights into the neural mechanisms underpinning human flexible task preparation.

neuroscience↗

bioRxiv2025

Interpersonal Synchrony and Implicit Identification

The transformative effects of interpersonal synchrony on reshaping the relationship between the self and the group by fostering self-other blurring are well-documented. However, these findings largely rely on self-reported measures, leaving aspects of the self inaccessible to explicit measures unexplored. We combined the Implicit Association Task (IAT) with conventional explicit evaluations of self-other blurring to examine how experiences of synchronous movement may also swiftly shape implicit measures indicative of self-other blurring. In three online experiments participants experienced synchronous movement as opposed to no movement (Experiment 1) or unpredictable movement (Experiment 2) or asynchronous movement (Experiment 3) with virtually presented agents. Our data indicate that synchronous movement led to higher levels of self-other blurring on the Inclusion of Other in Self (IOS) scale and implicit self-concept evaluations on the IAT. Participants demonstrated a preference for associating self-related words with images of the synchronous group, while associating other-related words with images from the no-movement, unpredictable, and asynchronous movement groups. This suggests that experiencing synchronous movement with a group influences implicit semantic self-associations. These findings suggest that interpersonal synchrony may alter self-concept at both an embodied and semantic level, extending beyond conscious affiliation. Our combined methodology offers a deeper insight into the impact of synchronous experiences on self-constructs and social relationships.

animal behavior and cognition↗

bioRxiv2024

Shared Rhythm to Shared Vision: Synchronous Marching increases Conformity on Perceptual Decision making

Previous research on synchronous movement rituals have found that it increased prosocial propensity toward the synchronised group and reliance on the group opinions. However, whether basic cognitive processes such as perceptual decision-making are affected by synchronous movement remains unexplored. In this novel virtual reality experiment, we examined whether marching synchronously with a group can induce greater informational conformity on an unrelated perceptual task (forced choice random dot motion). We found higher degree of conformity following synchronised marching during low stimulus information. This finding indicates that synchronised movement induces minimal group membership expressed via increased self-other blurring and conformity. Thus, participation in movement-based rituals has the capacity to change our perception of the world to align more closely with the synchronised group.

animal behavior and cognition↗

bioRxiv2024

Coordinated social interactions are supported by integrated neural representations

Joint actions are defined as coordinated interactions of two or more agents towards a shared goal, often requiring different and complementary individual contributions. However, how humans can successfully act together without the interfering effects of observing incongruent movements is still largely unknown. It has been proposed that interpersonal predictive processes are at play to allow the formation of a Dyadic Motor Plan, encompassing both agents shares. Yet, direct empirical support for such an integrated motor plan is still limited. In this study, we aimed at testing the properties of these anticipated representations. We collected EEG data while human participants (N = 36; 27 females) drew shapes simultaneously to a virtual partner, in two social contexts: either they had to synchronize and act jointly, or they performed the movements alongside, but independently. We adopted a multivariate approach to show that the social context influenced how the upcoming action of the partner is anticipated during the interval preceding the movement. We found evidence that acting jointly induces an encoding of the partners action that is strongly intertwined with the participants action, supporting the hypothesis of an integrative motor plan in joint but not in parallel actions.

neuroscience↗

bioRxiv2023

Concurrent response and action effect representations across the somatomotor cortices during novel task preparation.

Instructions allow us to fulfill novel and complex tasks on the first try. This skill has been linked to preparatory brain signals that encode upcoming demands in advance, facilitating novel performance. To deepen insight into these processes, we explored whether instructions pre-activated task-relevant motoric and perceptual neural states. Critically, we addressed whether these representations anticipated activity patterns guiding overt sensorimotor processing, which could reflect that internally simulating novel tasks facilitates the preparation. To do so, we collected functional magnetic resonance imaging data while female and male participants encoded and implemented novel stimulus-response associations. Participants also completed localizer tasks designed to isolate the neural representations of the mappings-relevant motor responses, perceptual consequences, and stimulus categories. Using canonical template tracking, we identified whether and where these sensorimotor representations were pre-activated. We found that response-related templates were encoded in advance in regions linked with action control, entailing not only the instructed responses but also their somatosensory consequences. This result was particularly robust in primary motor and somatosensory cortices. While, following our predictions, we found a systematic decrease in the irrelevant stimulus templates representational strength compared to the relevant ones, this difference was due to below-zero estimates linked to the irrelevant category activity patterns. Overall, our findings reflect that instruction processing relies on the sensorimotor cortices to anticipate motoric and kinesthetic representations of prospective action plans, suggesting the engagement of motor imagery during novel task preparation. More generally, they stress that the somatomotor system could participate with higher-level frontoparietal regions during anticipatory task control.

neuroscience↗

bioRxiv2023

Hebbian learning of stimulus-response associations using transcranial magnetic stimulation

Classical conditioning states that the systematic co-occurrence of a neutral stimulus with an unconditioned stimulus can cause the neutral stimulus to, over time, evoke the same response as the unconditioned stimulus. On a neural level, Hebbian learning suggests that this type of learning occurs through changes in synaptic plasticity when two neurons are simultaneously active, resulting in increased connectivity between them. Inspired by learning theories, we here investigated whether the mere co-activation of visual stimuli and stimulation of the primary motor cortex using transcranial magnetic stimulation (TMS) would result in stimulus-response associations that can impact future behaviour. During a learning phase, we repeatedly paired the presentation of a specific colour (but not other colours) with a TMS pulse over the motor cortex. Next, participants performed a two-alternative forced choice task where they had to categorize simple shapes and we studied whether the shapes task-irrelevant colour (and its potentially associated involuntary motor activity) affected the required motor response. Participants showed more errors on incongruent trials for stimuli that were previously paired with high intensity TMS pulses, but only when tested on the same day. Using a drift diffusion model for conflict tasks, we further demonstrate that this interference occurred early, and gradually increased as a function of associated TMS intensity. Taken together, our findings show that the human brain can learn stimulus-response associations using externally induced motor cortex stimulation.

neuroscience↗

bioRxiv2022

EEG frequency tagging evidence of intact social interaction recognition in adults with autism

To explain the social difficulties in autism, a large amount of research has been conducted on the neural correlates of social perception. However, this research has mostly used basic social stimuli (e.g. eyes, faces, hands, single agent), not resembling the complexity of what we encounter in our daily social lives, and as such, the situations people with autism experience difficulties in. A more complex stimulus that we do come across often and is also highly relevant for social functioning is that of third-party social interactions. Here, we investigated if individuals with and without autism process third-party social interactions differently. More specifically, we measured neural responses to social scenes depicting either social interaction or not with an electroencephalogram (EEG) frequency tagging task and compared these responses between adults with and without autism (N = 61). The results revealed an enhanced response to social scenes with interaction, replicating previous findings in a neurotypical sample (Oomen et al., 2022). Crucially, this effect was found in both groups with no difference between them. This suggest that social interaction recognition is not anomalous in adults with autism and cannot explain the social difficulties adults with autism experience. Lay abstractPeople with autism have social difficulties and are thought to experience the world differently. To better understand these differences, research has studied how the brain of people with and without autism processes social stimuli. However, this research has mostly used basic social stimuli (e.g. eyes, faces, hands, and single agents). Such stimuli do not resemble the complexity of daily life, where we typically do not come across isolated body parts, but instead have to make sense of complex social scenes with multiple people. To do so, it is imperative that we are able to recognize social interaction. Hence, if social interaction processing is anomalous, this could have pervasive consequences for social functioning more generally. Here, we used brain imaging to test if adults with autism process social interaction scenes differently than adults without autism. In line with previous findings from a neurotypical sample (Oomen et al. (2022), we found that social scenes depicting interaction elicited stronger brain responses than social scenes not depicting interaction. Crucially, this effect was found in both groups with no difference between them. These findings suggest that the fundamental process of social interaction recognition is not anomalous in adults with autism.

neuroscience↗

bioRxiv2022

Effects of experiencing CS-US pairings on instructed fear reversal

Fear learning allows us to identify and anticipate aversive events, and adapt our behavior accordingly. This is often thought to rely on associative learning mechanisms where an initially neutral conditioned stimulus (CS) is repeatedly paired with an aversive unconditioned stimulus (US), eventually leading to the CS also being perceived as aversive and threatening. Importantly, however, humans also show verbal fear learning. Namely, they have the ability to change their responses to stimuli rapidly through verbal instructions about CS-US pairings. Past research on the link between experience-based and verbal fear learning indicated that verbal instructions about a reversal of CS-US pairings can fully override the effects of previously experienced CS-US pairings, as measured through fear ratings, skin conductance, and fear-potentiated startle. However, it remains an open question whether such instructions can also annul memory traces in the brain. Here, we used a fear reversal paradigm in conjunction with representational similarity analysis of fMRI data to test whether verbal instructions fully override the effects of experienced CS-US pairings in fear-related brain regions or not. Previous research suggests that only the right amygdala should show lingering representations of previously experienced threat (a so-called "Pavlovian trace"). Unexpectedly, we found evidence for the residual effect of prior CS-US experience to be much more widespread than anticipated, in the amygdala but also cortical regions like the dorsal anterior cingulate or dorso-lateral prefrontal cortex. This finding shines a new light on the interaction of different fear learning mechanisms, at times with unexpected consequences.

neuroscience↗

bioRxiv2022

Theta-phase connectivity between medial prefrontal and posterior areas underlies novel instructions implementation

Implementing novel instructions is a complex and uniquely human cognitive ability, that requires the rapid and flexible conversion of symbolic content into a format that enables the execution of the instructed behavior. Preparing to implement novel instructions, as opposed to their mere maintenance, involves the activation of the instructed motor plans, and the binding of the action information to the specific context in which this should be executed. Recent evidence and prominent computational models suggest that this efficient configuration of the system might involve a central role of frontal theta oscillations in establishing top-down long-range synchronization between distant and task-relevant brain areas. In the present EEG study (human subjects, 30 females, 4 males), we demonstrate that proactively preparing for the implementation of novels instructions, as opposed to their maintenance, involves a strengthened degree of connectivity in the theta frequency range between medial prefrontal and motor/visual areas. Moreover, we replicated previous results showing oscillatory features associated specifically with implementation demands, and extended on them demonstrating the role of theta oscillations in mediating the effect of task demands on behavioral performance. Taken together, these findings support our hypothesis that the modulation of connectivity patterns between frontal and task-relevant posterior brain areas is a core factor in the emergence of a behavior-guiding format from novel instructions. Significance statementEveryday life requires the use and manipulation of currently available information to guide behavior and reach specific goals. In the present study we investigate how the same instructed content elicits different neural activity depending on the task being performed. We show that medial prefrontal theta oscillations are larger when novel instructions have to be implemented, rather than simply maintained. Crucially, connectivity between medial prefrontal cortex and posterior areas is strengthened during instructions implementation, suggesting that theta oscillations play a role in setting up a dynamic and flexible network of task-relevant regions optimized for the execution of the instructed behavior.

neuroscience↗

bioRxiv2021

Adaptive coding of stimulus information in human fronto-parietal cortex during visual classification

The neural mechanisms of how frontal and parietal brain regions support flexible adaptation of behavior remain poorly understood. Here, we used functional magnetic resonance imaging (fMRI) and model-based representational similarity analysis (RSA) to investigate frontoparietal representations of stimulus information during visual classification under varying task demands. Based on prior research, we predicted that increasing perceptual task difficulty should lead to more categorical coding of stimulus information, and that exemplar-level stimulus coding would be restricted to posterior, sensory brain regions. Counter to our expectations, however, we found frontoparietal regions encoded exemplar-level stimulus information. Interestingly, the anterior intraparietal sulcus (aIPS) encoded stimuli equally well regardless of perceptual difficulty, and these representations were directly related to choice behavior (proportion of guessing). Overall, these findings reveal unexpected exemplar-level stimulus coding in frontoparietal cortex, and highlight the role of aIPS in supporting adaptive behavior.

neuroscience↗

bioRxiv2021

Implicit agency is related to gamma power changes in an automatic imitation task

Often we have a feeling that we can control effects in the external world through our actions. The role of action processing associated with this implicit form of agency is still not clear. In this study, we used automatic imitation and electroencephalography to investigate neural oscillations associated with action processing and its possible contribution to implicit agency. Brain activity was recorded while participants performed actions (congruent or incongruent with a displayed finger movement) which subsequently triggered an outcome (a tone). We used a time estimation task to measure intentional binding (an index of implicit agency). We observed a decrease of alpha, beta and gamma power for congruent compared to incongruent actions and increased theta power for incongruent compared to congruent actions. Crucially, participants who showed greater intentional binding for congruent versus incongruent actions also presented greater gamma power differences. Alpha, beta and theta power were modulated by congruency but were unrelated to intentional binding. Our study suggests that an increased implicit agency for facilitated actions is associated with changes in gamma power. Our study also contributes to a characterization of neural oscillations in automatic imitation.

neuroscience↗

bioRxiv2020

Faster model updating in autism during early sensory processing

BackgroundRecent theories of autism propose that a core deficit in autism would be a less context-sensitive weighting of prediction errors. There is also first support for this hypothesis on an early sensory level. However, an open question is whether this decreased context-sensitivity is caused by faster updating of ones model of the world (i.e. higher weighting of new information), proposed by predictive coding theories, or slower model updating. Here, we differentiated between these two hypotheses by investigating how first impressions shape the mismatch negativity (MMN), reflecting early sensory prediction error processing. MethodsAn autism and matched control group (both n=27) were compared on the multi-timescale MMN paradigm, in which tones were presented that were either standard (frequently occurring) or deviant (rare), and these roles reversed every block. A well-replicated observation is that the initial model (i.e. the standard and deviant sound in the first block) influences MMN amplitudes in later blocks. If autism is characterized by faster model updating, we hypothesized that their MMN amplitudes would be less influenced by the initial context. ResultsWe found that MMN responses in the autism group did not differ between the initial deviant and initial standard sounds as they did in the control group. ConclusionsThese results show that individuals with autism are less influenced by initial contexts, confirming that autism is characterized by faster updating of sensory models, as proposed by predictive coding accounts of autism.

neuroscience↗

bioRxiv2020

NEURAL OSCILLATIONS DISSOCIATE BETWEEN MAINTENANCE AND PROCEDURALIZATION OF NOVEL INSTRUCTIONS

Humans are capable of flexibly converting symbolic instructions into novel behaviors. Previous evidence and theoretical models suggest that the implementation of a novel instruction requires the reformatting of its declarative content into an action-oriented code optimized for the execution of the instructed behavior. While neuroimaging research focused on identifying the brain areas involved in such a process, the temporal and electrophysiological mechanisms remain poorly understood. These mechanisms, however, can provide information about the specific cognitive processes that characterize the proceduralization of information. In the present study, we recorded EEG activity while we asked participants to either simply maintain declaratively the content of novel S-R mappings or to proactively prepare for their implementation. By means of time-frequency analyses, we isolated the oscillatory features specific to the proceduralization of instructions. Implementation of the instructed mappings elicited stronger theta activity over frontal electrodes and suppression in mu and beta activity over central electrodes. On the contrary, activity in the alpha band, which has been shown to track the attentional deployment to task-relevant items, showed no differences between tasks. Together, these results support the idea that proceduralization of information is characterized by specific component processes such as orchestrating complex task settings and configuring the motor system that are not observed when instructions are held in a declarative format. HighlightsO_LIFrontal theta power is increased during instructions implementation C_LIO_LIAttentional orienting in WM is analogous across maintenance and implementation C_LIO_LIInstructions implementation involves motor recruitment C_LI

neuroscience↗

bioRxiv2019

Frontoparietal action-oriented codes support novel task set implementation

A key aspect of human cognitive flexibility concerns the ability to convert complex symbolic instructions into novel behaviors. Previous research proposes that this transformation is supported by two neurocognitive states: an initial declarative maintenance of task knowledge, and an implementation state necessary for optimal task execution. Furthermore, current models predict a crucial role of frontal and parietal brain regions in this process. However, whether declarative and procedural signals independently contribute to implementation remains unknown. We report the results of an fMRI experiment in which participants executed novel instructed stimulus-response associations. We then used a pattern-tracking procedure to quantify the contribution of format-unique signals during instruction implementation. This revealed independent procedural and declarative representations of novel S-Rs in frontoparietal areas, prior to execution. Critically, the degree of procedural activation predicted subsequent behavioral performance. Altogether, our results suggest an important contribution of frontoparietal regions to the neural architecture that regulates cognitive flexibility.

neuroscience↗

bioRxiv2019

Metacognitive awareness of difficulty in action selection: the role of the cingulo-opercular network

The question whether and how we are able to monitor our own cognitive states (metacognition) has been a matter of debate for decades. Do we have direct access to our cognitive processes or can we only infer them indirectly based on their consequences? In the current study, we wanted to investigate the brain circuits that underlie the metacognitive experience of fluency in action selection. To manipulate action-selection fluency we used a subliminal response priming paradigm. On each trial, both male and female human participants additionally engaged in the metacognitive process of rating how hard they felt it was to respond to the target stimulus. Despite having no conscious awareness of the prime, results showed that participants rated incompatible trials (during which subliminal primes interfered with the required response) to be more difficult than compatible trials (where primes facilitated the required response) reflecting metacognitive awareness of difficulty. This increased sense of subjective difficulty was mirrored by increased activity in the rostral cingulate zone (RCZ) and the anterior insula, two regions that are functionally closely connected. Importantly, this reflected activations that were unique to subjective difficulty ratings and were not explained by reaction times or prime-response compatibility. We interpret these findings in light of a possible grounding of the metacognitive judgement of fluency in action selection in interoceptive signals resulting from increased effort.

neuroscience↗

bioRxiv2019

Defining the neural correlates of spontaneous theory of mind (ToM): An fMRI mega-analytic investigation

There is a major debate in the theory of mind (ToM) field, concerning whether spontaneous and explicit ToM are based on the same or two distinct cognitive systems. While there is extensive research on the neural correlates of explicit ToM, revealing consistent activation of the temporo-parietal junction (TPJ) and medial prefrontal cortex (mPFC), few studies investigated spontaneous ToM, with conflicting results, probably due to having small samples of participants. Here, we implemented a mega-analytic approach by pooling data from three fMRI studies, to achieve enough statistical power to better define the neurocognitive mechanisms underlying spontaneous ToM. Participants watched videos in which an agent acquires a true or false belief about the location of a ball. By analysing the blood-oxygen level dependent signal during the belief formation phase for false versus true beliefs, we found a cluster of activation in the right, and to a lesser extent, left posterior parietal cortex spanning the TPJ, but no mPFC activation. Region of interest (ROI) analysis on bilateral TPJ and mPFC confirmed these results and added evidence to the content-selectivity for false beliefs with positive content and asymmetry in laterality of the spontaneous ToM system. Interestingly, the whole brain analysis, supported by an overlap with brain maps, revealed maximum activation in areas involved in visuospatial working memory and attention switching functions, such as the supramarginal gyrus, the middle temporal gyrus, and the inferior frontal gyrus. Taken together, these findings suggest that spontaneous and explicit ToM rely on partially overlapping brain systems. However, spontaneous ToM tasks also show clear differences with explicit ToM tasks.

neuroscience↗

bioRxiv2019

I believe, therefore I am: Effects of self-control beliefs on behavioral and electrophysiological markers of inhibitory and emotional attention control

In this study, a placebo/nocebo neuro-stimulation procedure was employed to investigate if expectations about self-control can influence self-control exertion. More specifically, we recorded behavioral and electrophysiological responses in an emotional antisaccade task in a between-subjects design, in which one group was led to believe that self-control was enhanced (MSC group) and the other that self-control was weakened (LSC group). This set-up allowed to investigate both response and emotional inhibition, as well as different stages at which control can be exerted during task performance, using Event-Related Potential (ERP) methods. Results showed that the bogus neuro-stimulation indeed installed the expectation of respectively better or worse self-control capacity, as well as the retrospective evaluation at the end of the experiment that the neuro-stimulation changed their self-control in that direction. Participants in the MSC compared to the LSC group showed higher accuracy in trials in which inhibitory control was necessary (antisaccade trials). ERP results showed no effect of the placebo/nocebo manipulation at the level of attention and inhibitory control. In sum, this study showed that high-order cognitive processes are not immune to the influence of expectations induced by a placebo/nocebo procedure, and shows that instructions alone can induce a placebo/nocebo effect in cognitive functioning.

neuroscience↗

bioRxiv2018

Spontaneous mentalizing after early interpersonal trauma: Evidence for hypoactivation of the temporoparietal junction

Experience of interpersonal trauma and violence alters self-other distinction and mentalizing abilities (also known as theory of mind, or ToM), yet little is known about their neural correlates. This fMRI study assessed temporoparietal junction (TPJ) activation, an area strongly implicated in interpersonal processing, during spontaneous mentalizing in 35 adult women with histories of childhood physical, sexual, and/or emotional abuse (childhood abuse; CA) and 31 women without such experiences (unaffected comparison; UC). Participants watched movies during which an agent formed true or false beliefs about the location of a ball, while participants always knew the true location of the ball. As hypothesized, right TPJ activation was greater for UC compared to CA for false versus true belief conditions. However, posttraumatic stress symptomatology (PTSS) appeared to play a role in driving the neural effect. In addition, CA showed increased functional connectivity relative to UC between the rTPJ and dorsomedial prefrontal cortex. Finally, the agents false belief about the presence of the ball speeded participants response (ToM index), but without group differences. These findings highlight that experiencing early interpersonal trauma can alter brain areas involved in the neural processing of ToM and perspective-taking during adulthood.

neuroscience↗