Biology subjects

Bergstrom, F.

Publications and source records attributed to Bergstrom, F..

8 recordsLinked to original sources

bioRxiv2026

A spatial transmission model for evaluating interventions during highly pathogenic avian influenza outbreaks

During infectious disease outbreaks, epidemiological models can be used to project future outbreak dynamics and to explore scenarios under different control measures. Here, we present the spatially explicit avian influenza transmission model that we developed during the 2026 WiLiMan-ID consortium Highly Pathogenic Avian Influenza Modelling Challenge, which involved evaluating control measures (preventive and reactive culling, confinement and restocking bans) during a hypothetical avian influenza outbreak. We show that the control measures that were expected to reduce transmission effectively varied between different outbreak stages. For example, policy-makers could choose whether to focus culling efforts on: i) faster reactive culling and no preventive culling; or ii) slower reactive culling and preventive culling. Relatively early in the outbreak, when the number of available culling teams was limited, our results indicate that the two culling strategies were projected to lead to similar numbers of premises with notified infections over the following 28 days. Later in the outbreak, with more culling teams available, the second strategy was projected to lead to substantially fewer notified premises than the first strategy. In addition, we demonstrate that whether a strategy is beneficial or detrimental depends on policy-makers' objectives. For example, preventive culling may reduce transmission, but at the cost of culling poultry on premises without infections, illustrating a trade-off between limiting transmission and the cost of interventions. Our results highlight the importance of choosing policy objectives carefully and reassessing interventions at different outbreak stages to ensure that control policies remain appropriate for the current epidemiological situation.

ecology↗

bioRxiv2026

Grasping at the organization of object knowledge: testing different object-related dimensions as organizational principles of ventral temporal cortex.

In our daily lives we encounter a myriad of things with which we might need to interact as we navigate our environment. Mental representations of these things must be computed and stored in our brains to be manipulated to support cognition. How are such representations organized in the brain? Several proposals have been put forth on what the principles of organization of object information in the brain might be: within ventral temporal cortex - regions thought to support object recognition - possible dimensions include the animacy status of target stimuli, their real size, their texture and material properties, and potentially their graspable status, amongst others. Here we used functional magnetic resonance imaging (fMRI) and multivariate approaches to discriminate patterns of activation for different categories of objects to test the role of these dimensions as organizing principles of object information in the brain. We show that pattern discriminability between different categories of objects does not seem to follow differences in their animacy status in any continuous way. Moreover, graspability of the target stimuli and their haptic texture properties are better predictors of representational content within ventral temporal cortex than animacy and real size. These results are in line with recent studies demonstrating the importance of computational contingencies superimposed by bi-directional functional coupling between parietal regions dedicated to the processing of object manipulation and grasping and ventral temporal regions responsible for object recognition, potentially involving material and texture processing.

neuroscience↗

bioRxiv2025

Subliminal risk influences subjective value in the ventromedial prefrontal cortex

The relationship between conscious awareness and decisions has been heavily debated. Here we investigated whether subliminal probabilities are integrated with conscious rewards to form subjective value (SV) representations in the anterior ventral striatum (aVS) and ventromedial prefrontal cortex (vmPFC). Participants played an incentivized competitive game with risky choice to accumulate points across trials in a behavioral and fMRI experiment. The game was a modified attentional-blink paradigm that rendered a probability cue unseen (indicating a 100% or 0% chance to win a risky reward). Following the probability cue, participants chose between a safe (1 point with certainty) or risky option (>1 or 0 points depending on probability cue). The risky reward was either 2 or 5 points, varying across trials. In some trials the probability cue was absent (replaced by a random distractor) and the probability to win the risky reward was 50%. When probability cues were unseen, they did not influence choice, as value-maximizing choice (d) was not greater than chance, but they did influence reaction time in both experiments. Consistent with SV integration, the BOLD signal in aVS and vmPFC was higher for both conscious rewards (high > low) and subliminal probabilities (high > low) and could not be explained by subliminal salience (cue present > absent). Moreover, multivariate pattern similarity between conscious rewards and subliminal probabilities in vmPFC suggest integration into an abstract value representation. Additionally, we found brain-wide subliminal probability and salience effects. Taken together, these results suggest that conscious awareness is not necessary for probability to be integrated with conscious rewards to form an abstract "common currency" SV representation in vmPFC. Additionally, brain-wide subliminal probability and salience effects suggests information can have "global access" without conscious awareness.

neuroscience↗

bioRxiv2024

Multivariate analysis of multimodal brain structure predicts individual differences in risk and intertemporal preference

Large changes to brain structure (e.g., from damage or disease) can explain alterations in behavior. It is therefore plausible that smaller structural differences in healthy samples can be used to better understand and predict individual differences in behavior. Despite the brains multivariate and distributed structure-to-function mapping, most studies have used univariate analyses of individual structural brain measures. Here we used a multivariate approach in a multimodal data set composed of volumetric, surface-based, diffusion-based, and functional resting-state MRI measures to predict reliable individual differences in risk and intertemporal preferences. We show that combining twelve brain structure measures led to better predictions across tasks than using any individual measure, and by examining model coefficients, we visualize the relative contribution of different brain measures from different brain regions. Using a multivariate approach to brain structure-to-function mapping that combines across many brain structure properties, along with reliably measured behavior phenotypes, may increase out-of-sample prediction accuracies and insight into neural underpinnings. Furthermore, this methodological approach may be useful to improve predictions and neural insight across basic, translational, and clinical research fields.

neuroscience↗

bioRxiv2024

Neural and behavioral similarity-driven tuning curves for manipulable objects

In our daily activities, we encounter numerous objects that we successfully distinguish and recognize within a fraction of a second. This holds for coarse distinctions (e.g., cat vs. hammer) but also for more challenging within-category distinctions that require fine-grain analysis (e.g., cat vs. dog). The efficiency of this recognition depends on how the brain organizes object-related information. While several attempts have focused on unravelling large-scale organization principles, research on within-category organization of knowledge is rather limited. Here, we explored the fine-grain organization of object knowledge and investigated whether manipulable objects are organized and represented in terms of their similarity. To accomplish this, different groups of individuals participated in a behavioral and fMRI release from adaptation experiment. Adaptation was induced by presenting different exemplars of a particular object, and release from adaptation was elicited by the presentation of a deviant object. The relationship between adaptation and deviant objects was manipulated into four levels of similarity, measured by feature overlap between these objects. Our findings revealed that increasing object similarity provoked progressively slower reaction times and progressively weaker fMRI release from adaptation. Specifically, we identified similarity-driven tuning curves for the release from adaptation in the medial fusiform, collateral sulcus, parahippocampal gyri, lingual gyri, lateral occipital complex, and occipito-parietal cortex. These results suggest that the processing and representation of objects in the brain and our ability to perform fine discriminations between objects reflect real-world object similarity in a relatively parametric manner.

neuroscience↗

bioRxiv2023

Less cortical complexity in ventromedial prefrontal cortex is associated with a greater preference for risky and immediate rewards

In our everyday lives, we are often faced with situations in which we have to make choices that involve risky or delayed rewards. However, the extent to which we are willing to accept larger risky (over smaller certain) or larger delayed (over smaller immediate) rewards vary across individuals. Here we investigated the relationship between cortical surface complexity in medial prefrontal cortex and individual differences in risky and intertemporal preferences. We found that lower cortical complexity in ventromedial prefrontal cortex (vmPFC) was associated with a greater preference for risky and immediate rewards. In addition to these common structural associations in mPFC, we also found associations between lower cortical complexity and a greater preference for immediate rewards that extended into left dorsomedial prefrontal cortex and right vmPFC. Taken together, the shared association suggests that lower cortical complexity in vmPFC may be a structural marker for individual differences in impulsive behavior.

neuroscience↗

bioRxiv2021

Disentangling hand and tool processing: distal effects of neuromodulation

The neural processing within a brain region that responds to more than one object category can be separated by looking at the horizontal modulations established by that region, which suggests that local representations can be affected by connections to distal areas, in a category-specific way. Here we first wanted to test whether by applying transcranial direct current stimulation (tDCS) to a region thatre sponds both to hands and tools (posterior middle temporal gyrus; pMTG), while participants performed either a hand- or tool-related training task, we would be able to specifically target the trained category, and thereby dissociate the overlapping neural processing. Second, we wanted to see if these effects were limited to the target area or extended to distal but functionally connected brain areas. After each combined tDCS and training session, participants therefore viewed images of tools, hands, and animals, in an fMRI scanner. Using multivoxel pattern analysis, we found that tDCS stimulation to pMTG indeed improved the classification accuracy between tools vs. animals, but only when combined with a tool training task (not a hand training task). However, surprisingly, tDCS stimulation to pMTG also improved the classification accuracy between hands vs. animals when combined with a tool training task (not a hand training task). Our findings suggest that overlapping but functionally-specific networks can be separated by using a category-specific training task together with tDCS - a strategy that can be applied more broadly to other cognitive domains using tDCS - and demonstrates the importance of horizontal modulations in objectcategory representations.

neuroscience↗

bioRxiv2020

A reduced level of consciousness affects non-conscious processes

Being conscious is a profound aspect of human existence, and understanding its function and its inception is considered one of the truly grand scientific challenges. However, the nature of consciousness remains enigmatic, to a large part because "being conscious" can refer to both the content (phenomenology) and the level (arousal) of consciousness, and how these different aspects are related remains unclear. To empirically assess the relation between level and content of consciousness, we manipulated these two aspects by presenting stimuli consciously or non-consciously and by using Propofol sedation, while brain activity was measured using fMRI. We observed that sedation greatly affected non-conscious processes, which starkly contrasts the notion that anesthetics selectively reduce consciousness. Our findings reveal that level and content of consciousness are separate phenomena, and imply that one may need to reconsider what "being conscious" means.

neuroscience↗