Biology subjects

Mobbs, D.

Publications and source records attributed to Mobbs, D..

7 recordsLinked to original sources

bioRxiv2024

Adaptive Safety Coding in the Prefrontal Cortex

Pivotal to self-preservation is the ability to identify when we are safe and when we are in danger. Previous studies have focused on safety estimations based on the features of external threats and do not consider how the brain integrates other key factors, including estimates about our ability to protect ourselves. Here we examine the neural systems underlying the online dynamic encoding of safety. The current preregistered study used two novel tasks to test four facets of safety estimation: Safety Prediction, Meta-representation, Recognition, and Value Updating. We experimentally manipulated safety estimation changing both levels of external threats and self-protection. Data were collected in two independent samples (behavioral N=100; fMRI N=30). We found consistent evidence of subjective changes in the sensitivity to safety conferred through protection. Neural responses in the ventromedial prefrontal cortex (vmPFC) tracked increases in safety during all safety estimation facets, with specific tuning to protection. Further, informational connectivity analyses revealed distinct hubs of safety coding in the posterior and anterior vmPFC for external threats and protection, respectively. These findings reveal a central role of the vmPFC for coding safety.

neuroscience↗

bioRxiv2024

Unethical amnesia brain: Memory and metacognitive distortion induced by dishonesty

Unethical actions and decisions may distort human memory in two aspects: memory accuracy and metacognition. However, the neural and computational mechanisms underlying the metacognition distortion caused by repeated dishonesty remain largely unknown. Here, we performed two fMRI studies, including one replication study, with an information-sending task in the scanner. The main moral decision task in the scanner involves consistency and reward as two main factors, combined with a pre-scan and post-scan memory test together with mouse tracking. With multiple dimensions of metrics to measure metacognition, we test whether the inter-subject metacognition change correlates with how participants trade off consistency and reward. We find that the compression of representational geometry of reward in the orbitofrontal cortex (OFC) is correlated with both immediate and delayed metacognition changes. Also, the functional connectivity between the dorsolateral prefrontal cortex (DLPFC) and the left temporoparietal junction (lTPJ) under dishonest responses can predict both immediate and delayed metacognition changes in memory. These results suggest that decision-making, emotion, and memory-related brain regions together play a key role in metacognition change after immoral action, shedding light on the neural mechanism of the complex interplay between moral decisions, cognitive processes, and memory distortion. I did that, says my memory. I could not have done that, says my pride, and remains inexorable. Eventually - the memory yields. --Nietzsche[1]

neuroscience↗

bioRxiv2024

An intracranial dissection of human escape circuits

Predators attack at different spatiotemporal scales, spurring prey to elicit escape responses that range from simple motor reactions and strategic planning that involve more complex cognitive processes. Recent work in humans suggests that escape relies on two distinct circuits: the reactive and cognitive fear circuits. However, the specific involvement of these two circuits in different stages of human escaping remains poorly characterized. In this study, we recorded intracranial electroencephalography (iEEG) from epilepsy patients while they performed a modified flight initiation distance (FID) task. We found brain regions in the cognitive fear circuit, including the ventromedial prefrontal cortex and hippocampus, encoded the threat level during the information processing stage. The actual escaping stage, especially under rapid attack, prominently activated areas within the reactive fear circuit, including the midcingulate cortex and amygdala. Furthermore, we observed a negative correlation between the high gamma activity (HGA) of the amygdala and the HGA of the vmPFC and HPC under rapid attacks. This indicates that the amygdala may suppress the activity of the cognitive fear circuit under rapid attacks, enabling the organism to react quickly to ensure survival under the imminent threat. These findings highlight the distinct roles of the reactive and cognitive fear circuits in human escaping and provide accounts for the importance of fear in human survival decisions.

neuroscience↗

bioRxiv2021

Resting-state functional connectivity of social brain regions predicts motivated dishonesty

Motivated dishonesty is a typical social behavior varying from person to person. Resting-state fMRI (rsfMRI) is capable of identifying unique patterns from functional connectivity (FC) between brain networks. To identify the relevant neural patterns and build an interpretable model to predict dishonesty, we scanned 8-min rsfMRI before an information-passing task. In the task, we employed monetary rewards to induce dishonesty. We applied both connectome-based predictive modeling (CPM) and region-of-interest (ROI) analysis to examine the association between FC and dishonesty. CPM indicated that the stronger FC between fronto-parietal and default mode networks can predict a higher dishonesty rate. The ROIs were set in the regions involving four cognitive processes (self-reference, cognitive control, reward valuation, and moral regulation). The ROI analyses showed that a stronger FC between these regions and the prefrontal cortex can predict a higher dishonesty rate. Our study offers an integrated model to predict dishonesty with rsfMRI, and the results suggest that the frequent motivated dishonest behavior may require a higher engagement of social brain regions.

neuroscience↗

bioRxiv2020

Neural encoding of socially adjusted value during competitive and hazardous foraging

In group foraging organisms, optimizing the conflicting demands of competitive food loss and safety is critical. We demonstrate that humans select competition avoidant and risk diluting strategies during foraging depending on socially adjusted value. We formulate a mathematically grounded quantification of socially adjusted value in foraging environments and show using multivariate fMRI analyses that socially adjusted value is encoded by mid-cingulate and ventromedial prefrontal cortices, regions that integrate value and action signals.

neuroscience↗

bioRxiv2018

Attentional set to safety recruits the medial prefrontal cortex

During threat assessment, the early detection of danger is highly adaptive, yet the fast orientation towards safety is also key to survival. The present study aimed to explore how the human brain searches for safety by manipulating subjects attentional set to cues associated with shock probability. Subjects were asked to judge random dots motion (RDM) direction and could be shocked for incorrect responses (RDM task) while keeping alert in detecting the shock probability cues (cue detection task). In contrast to the safe condition, where subjects searched for cues associated with no shock probability, incorrect responses to dangerous+ (D+) cues would increase the shock probability and correct responses to dangerous- (D-) cues would decrease shock probability. In the RDM task, results showed that relative to the D+, the safe attentional set resulted in stronger activation in the ventral medial prefrontal cortex (vmPFC), a core region involved in flexible threat assessment and safety signalling. The vmPFC was also recruited by the D-compared to the D + attentional set. In the cue detection task, shorter response times and greater accuracy were observed for D+ compared to D- and safe cues. Correspondingly, at the neural level D+ cues induced increased activity in the frontoparietal attention network including the inferior parietal lobule and intraparietal sulcus. Overall, our findings demonstrate that attentional set for searching safety recruits the vmPFC, while detection of threat elicits activity in the frontoparietal attention network, suggesting a new role for these regions in human defensive survival circuitry.\n\nSignificance StatementWhile early detection of threat is highly adaptive, the fast orientation towards safety is also key to survival. However, little is known about neural mechanisms underlying attentional set to safety. Using a novel dots motion paradigm combined with fMRI, we explored how human brain prepares for safety searching by manipulating subjects attentional set to cues associated with shock probability. Relative to the dangerous attentional set associated with increasing shock probability, the safe attentional set resulted in stronger activity in the ventral medial prefrontal cortex, a core region involved in flexible threat assessment and safety signalling, suggesting a new role for this region in human defensive survival system in encoding stimuli with survival significance.

neuroscience↗

bioRxiv2017

How Cognitive and Reactive Fear Circuits Optimize Escape Decisions in Humans

Flight initiation distance (FID), the distance at which an organism flees from an approaching threat, is an ecological metric of cost-benefit functions of escape decisions. We adapted the FID paradigm to investigate how fast or slow attacking virtual predators constrain escape decisions. We show that rapid escape decisions rely on reactive fear circuits in the periaqueductal gray and midcingulate cortex (MCC), while protracted escape decisions, defined by larger buffer zones, were associated with cognitive fear circuits which include posterior cingulate cortex, hippocampus and the ventromedial prefrontal cortex, circuits implicated in strategic avoidance and behavioral flexibility. Using a Bayesian Decision Model, we further show that optimization of escape decisions under rapid flight were localized to the MCC, a region involved in adaptive motor control, while the hippocampus is implicated in optimizing decisions that update and control slower escape initiation. These results demonstrate an unexplored link between defensive survival circuits and their role in adaptive escape decisions.\n\nSignificanceHumans, like other animals, have evolved a set of circuits whose primary function is survival. In the case of predation, these circuits include reactive fear circuits involved in fast and immediate escape decisions and cognitive fear circuits that are involved in the conscious feeling of threat as well as slow strategic escape. Using neuroimaging combined with computational modeling, we support this differentiation of fear circuits by showing that fast escape decisions are elicited by the periaqueductal gray and MCC, regions involved in reactive flight. Conversely, slower escape decisions rely on the hippocampus, posterior cingulate cortex and prefrontal cortex, a circuit implicated in behavioral flexibility. These results support the role of the defensive survival circuitry in escape decisions and a separation of fear into reactive and cognitive circuits.

neuroscience↗