Biology subjects

Santavirta, S.

Publications and source records attributed to Santavirta, S..

At least 19 recordsLinked to original sources

bioRxiv2026

Mapping the brain basis of appraisals and discrete emotions

The Component Process Model of Emotion conceptualizes any emotional episode (e.g., the discrete emotions of sadness, anger, fear, or interest) as being driven by the multiple appraisal components. However, both the specificity of the neural mechanisms underlying appraisal processes and the way these appraisal networks relate to the neural circuits underlying discrete emotions remain unclear. Here we investigated the neural correlates of appraisal processes and compared them with those of discrete emotions. Participants (n = 97) were scanned with functional magnetic resonance imaging (fMRI) while watching short movie clips with varying emotional contents. Intensity for 12 appraisals and 12 basic and epistemic emotions evoked by the movie clips were rated by independent participants (n = 444). The neural responses were modelled with convolved ratings of appraisals and discrete emotions. The results indicated that appraisals and discrete emotions are supported by a shared set of distributed brain regions that extend beyond typically reported emotion-related areas, encompassing perceptual, action-related, and higher-order cognitive systems. Activations were more consistent for and better explained by appraisals versus discrete emotions. Within this network, epistemic emotions elicited less consistent activations than basic emotions, particularly in limbic regions. Our results highlight the functional organization of appraisals and discrete emotions under dynamic and complex conditions and indicate that appraisal theories better explain neural responses than discrete emotion models.

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bioRxiv2025

Attentional reconfiguration during acute and sustained fear

BACKGROUNDFear is a fundamental survival mechanism that both enhances the chances of survival by rapid detection and adaptive responses to potential threat and by optimizing sensory input and cognitive processing. Here we used naturalistic design with eye tracking to map the spatiotemporal dynamics of attention and arousal during fearful events with slow and fast temporal dynamics. METHODS21 participants watched a full-length horror movie while their eye-movements were recoded with eye tracker. Moment-to-moment intensity of sustained fear as well as the onsets of the jump scares (acute fear) were annotated and used to predict gaze parameters (fixation duration & counts, blink frequency, saccade amplitude, pupil size and intersubject synchronization of gaze position). RESULTSAcute fear events led to shortening of fixation duration, suppression of blinking, as well as increase of fixation count, saccade amplitude, and pupil size. Sustained fear was in turn associated with increased pupil size and decrease in blinking and saccade amplitude. These effects remained significant when controlling for luminosity. CONCLUSIONSDuring natural vision both acute and sustained fear cause rapid reconfiguration, state dependent and individual changes in visual attention prioritizing that is accompanied by increased affective arousal.

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bioRxiv2025

Autistic traits modulate neural responses to social signals during natural vision

Impairments in social perception, a hallmark of autism spectrum disorder (ASD), are also evident at subclinical levels in the general population. However, it remains unclear how such variation in autistic traits modulate neural processing of different types of social information. Here, we investigated whether autistic traits in neurotypical individuals are associated with neural responses to a broad array of social perceptual features during viewing naturalistic stimuli using functional magnetic resonance imaging (fMRI). We also tested the generalizability of these effects across two experiments. Ninety-seven participants completed the Autism Spectrum Quotient (AQ) and watched a set of 96 movie clips and a full movie during an fMRI scan. Intensity of 126 social features in the movie stimuli was continuously annotated by independent observers, and 44 most reliably rated features were used to model neural responses. We examined how consistently the responses to each social feature were dependent on the participants AQ scores. Replicable AQ-dependent neural responses to social features were found in both datasets. The temporal cortex and especially the superior temporal gyrus (STG), served as a central "hub" where autistic traits consistently modulated responses to social features across datasets. Different AQ subscales also revealed distinct association patterns in other brain regions. These findings indicate that autism-related traits broadly influence neural processing of naturalistic social signals, providing insight into how characteristics of autistic symptoms relate to socioemotional processing.

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bioRxiv2025

Striatal dopamine synthesis capacity in Parkinson's disease: Effects of age, sex, and body mass index in a large fluorodopa PET cohort

BACKGROUNDIn Parkinsons disease (PD), the degeneration of nigrostriatal dopaminergic neurons leads to motor symptoms. Positron emission tomography (PET) using radioligand [18F]fluorodopa detects reduced striatal dopamine synthesis capacity in PD patients. Demographic factors such as sex and BMI are also associated with dopamine synthesis capacity. The combined contribution of demographic and clinical effects however remains elusive. It also remains unresolved how the dopamine synthesis capacity is correlated between striatal subregions and how the dopamine synthesis capacity and dopamine receptor function across striatal regions are associated with each other in PD patients and healthy controls. MATERIAL, AIMS, AND METHODSFor this retrospective register-based study, we used baseline [18F]fluorodopa PET data acquired at the Turku PET Centre between the years 1988-2016 with three different scanners (Ecat 931, GE Advance, HRRT). The data included scans of 350 adult human subjects, including 132 healthy controls (65 males and 67 females), and 218 PD patients (134 males and 84 females). The primary aim was to simultaneously investigate the effects of PD, age, sex and BMI on regional dopamine synthesis capacity (influx rate constant Kiref quantified with Patlak) using Bayesian linear regression. Secondary aims were to assess interregional correlations of dopamine synthesis capacity, and the association between regional presynaptic dopamine synthesis and postsynaptic dopamine type 2 receptor (D2R) availability in subjects who also had a proximal [11C]raclopride PET scan. RESULTSWe found modest support for age-dependent decline in dopamine synthesis capacity, increased capacity for higher BMIs, and for higher capacity in females versus males. These effects were smaller than the effect of PD status. Dopamine synthesis capacity across regions was correlated in both patients and controls. Support for positive correlation between the synthesis capacity and the D2R was observed in caudate nucleus. CONCLUSIONSPD and demographic effects are independently associated with the striatal dopamine synthesis capacity. The capacity is reduced by PD, decreased through age (particularly after the age of around 50), higher in females versus males, and weakly increased in higher BMIs. Synthesis capacity is correlated between the striatal and thalamic regions in both PD patients and controls. The dopamine synthesis capacity was positively correlated with the D2R availability in caudate. Scanner affects the estimates of dopamine synthesis capacity measured with [18F]fluorodopa PET, and it is preferrable to adjust for such variation in the data.

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bioRxiv2025

GPT-4 accurately predicts human emotions and their neural correlates

Emotions are evoked by both internal and external events related to survival challenges. Recent advances in multimodal large language models ((M)LLMs), such as GPT-4, enable them to accurately analyze and describe complex visual scenes, raising the question whether LLMs can also predict human emotional experiences evoked by similar scenes. Here we asked GPT-4 and humans (N = 519) to provide self-reports of 48 unipolar emotions and aFective dimensions for emotionally evocative videos and images. We evaluated GPT-4s emotion ratings using three natural socio-emotional stimulus datasets: two video datasets (234 and 120 videos) and one image dataset (300 images). We found that GPT-4 can predict emotions of human observers with high accuracy. The multivariate emotion structure (correlation matrices of emotions ratings) converged between GPT-4 and humans and across datasets indicating that GPT-4 ratings for diFerent emotions follow similar structural representations as the human evaluations. Finally, we modeled the brains hemodynamic responses for emotions elicited by videos or images in two fMRI datasets (N = 97) with GPT-4 or human-based emotional evaluations to highlight the usefulness of GPT-4 in neuroscientific research. The results showed that the brains emotion circuits can be mapped with high accuracy using GPT-4 emotion ratings as the stimulation model. In conclusion, GPT-4 can predict human emotion ratings to the extent that GPT-4 ratings can also model the associated neural responses. Our results indicate that LLMs provide novel and scalable tools that have broad potential in emotion research, cognitive and aFective neuroscience, and that it can also have practical applications.

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bioRxiv2025

Four-dimensional neural space for moral inference

Intuitive moral inference enables us to evaluate moral situations and judge their rightness or wrongness. Although Moral Foundations Theory provides a framework for understanding moral inference, its underlying neural basis remains unclear. To capture spontaneous neural activity during moral inference, participants were instructed to watch a film rich in moral content without making explicit judgments while undergoing fMRI scanning. Independent participants evaluated the moment-to-moment presence of twenty moral dimensions in the film. Correlation and consensus cluster analyses revealed four independent main moral dimensions: virtue, vice, hierarchy, and rebellion. While each dimension exhibited unique neural activation patterns, the temporoparietal junction and inferior parietal lobe were activated across all types of moral inference. These findings establish the low-dimensional nature for the neural basis of intuitive moral inference in everyday settings.

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bioRxiv2025

Exposure to bullying engages social distress circuits in the adolescent and adult brain

Despite advances in understanding the psychological and social consequences of peer victimization, the immediate effects of bullying on the central nervous system remain elusive. Here we mapped the neural responses to simulated bullying in adolescents and adults and tested whether these responses are associated with real-life victimization experiences. Fifty-one adolescents aged 11-14 years, and 47 adults underwent a functional MRI (fMRI) while watching first-person videos of bullying (victimization) in the school environment, as well as neutral and positive social interactions in a similar setting. Exposure to bullying versus positive social interaction engaged the socio-emotional and threat response systems, as well as regions related to social cognition, sensory and interoceptive processing, and motor control. These responses were consistent across adolescents and adults and dependent on the current and past victimization experiences of the participants. This large-scale activation of neural systems subserving socioemotional, somatosensory, and interoceptive processing highlights how peer victimization evokes a severe stress and alarm state in the central nervous system.

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bioRxiv2025

Reduced inter-subject functional connectivity during movies in autism: Replicability across cross-national fMRI datasets

BackgroundAutism is a neurodevelopmental disorder characterized by repetitive behaviors and difficulties in social communication and interaction. Previous research has shown that these symptoms are linked to idiosyncratic behavioral and brain activity patterns while viewing natural social events in movies. This study aimed to investigate the replicability of brain activity idiosyncrasy in autistic individuals by comparing their inter-subject functional connectivity (ISFC) with that of neurotypical individuals. MethodsWe tested for ISFC differences between autistic and neurotypical groups using functional magnetic resonance imaging (fMRI) data from two independent datasets from Germany (Nneurotypical = 25, 7 Males, 18 Females; Nautism = 22, 12 Males, 10 Females) and Finland (Nneurotypical = 19, Nautism = 18; All males). Participants watched short movie stimuli, and pairwise ISFCs were computed across 273 brain regions. Group differences were evaluated using subject-wise permutation tests for each dataset. ResultsIn both datasets, the autistic group showed lower ISFCs compared to the neurotypical group, specifically between visual regions (e.g., occipital gyrus, cuneus) and parietal regions (e.g., superior and inferior parietal lobules), as well as between visual regions and frontal regions (e.g., inferior frontal gyrus, precentral gyrus). ISFC was higher in the Finnish autistic group in temporal regions associated with sound and speech processing. ConclusionsThe study confirmed the replicability of reduced ISFCs in autistic individuals during naturalistic movie-watching, especially between visual and parietal/frontal brain regions. These findings reinforce the utility of ISFC and naturalistic movie-watching paradigm in studying neural connectivity alterations in autism.

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bioRxiv2024

Modelling human social vision with cinematic stimuli

Sociability is central for humans. Visual information ranging from low-level physical features (e.g. luminance) to semantic information (e.g. face recognition) and high-level social inference (e.g. emotional valence of social interactions) is constantly sampled for navigating the social world. Here we utilize large-scale eye tracking during natural vision for mapping how different levels of visual information guide the perception of social scenes. In three experiments, participants (N = 166) watched full-length films and short movie clips with varying social content (total duration: 193 minutes) during eye tracking. To model the association between the perceptual features and spatiotemporal eye movement parameters (gaze position, gaze synchronization, pupil size and blinking), we extracted 39 stimulus features from the movies including low-level audiovisual features (e.g. luminance, motion), presence and location of mid-level semantic categories (e.g. faces, objects) and high-level social information (e.g. body movements, pleasantness). Pupil size was modulated by luminance, scene cuts and emotional arousal while gaze position was most accurately predicted by a combination of the presence of human faces, local motion and entropy. Faces and eyes were prioritized over other semantic categories and blinking rate decreased during periods of attentional engagement. Altogether the results show that human social vision is primarily guided by low-level physical features and mid-level semantic categories, while high-level social features such as emotional arousal primarily modulate pupillary responses.

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bioRxiv2024

GPT-4V shows human-like social perceptual capabilities at phenomenological and neural levels

Humans navigate the social world by rapidly perceiving social features from other people and their interaction. Recently, large-language models (LLMs) have achieved high-level visual capabilities for detailed object and scene content recognition and description. This raises the question whether LLMs can infer complex social information from images and videos, and whether the high-dimensional structure of the feature annotations aligns with that of humans. We collected evaluations for 138 social features from GPT-4V for images (N=468) and videos (N=234) that are derived from social movie scenes. These evaluations were compared with human evaluations (N=2254). The comparisons established that GPT-4V can achieve human-like capabilities at annotating individual social features. The GPT-4V social feature annotations also express similar structural representation compared to the human social perceptual structure (i.e., similar correlation matrix over all social feature annotations). Finally, we modeled hemodynamic responses (N=97) to viewing socioemotional movie clips with feature annotations by human observers and GPT-4V. These results demonstrated that GPT-4V based stimulus models can also reveal the social perceptual network in the human brain highly similar to the stimulus models based on human annotations. These human-like annotation capabilities of LLMs could have wide range of real-life applications ranging from health care to business and would open exciting new avenues for phycological and neuroscientific research.

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bioRxiv2024

Reward responses to vicarious feeding depend on BMI

Eating is inherently social for humans. Yet, most neuroimaging studies of appetite and food-induced reward have focused on studying brain responses to food intake or viewing pictures of food alone. Here we used functional magnetic resonance imaging (fMRI) to measure haemodynamic responses to "vicarious" feeding. The subjects (n=97) viewed series of short videos representing naturalistic episodes of social eating intermixed with videos without feeding / appetite related content. Viewing the vicarious feeding (versus control) videos activated motor and premotor cortices, thalamus, and dorsolateral prefrontal cortices, consistent with somatomotor and affective engagement. Responses to the feeding videos were also downregulated as a function of the participants BMI. Altogether these results suggest that seeing others eating engages the corresponding motor and affective programs in the viewers brain, potentially increasing appetite and promoting mutual feeding.

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bioRxiv2023

Taxonomy for human social perception

Every day, humans encounter complex social situations that need to be encoded effectively to allow interaction with others. Yet, principles for organizing the perception of social features from the external world remain poorly characterised. In this large-scale study we investigated the principles of social perception in dynamic scenes. In the primary dataset, we presented 234 movie clips (41 minutes) containing various social situations to 1140 participants and asked them to evaluate the presence of 138 social features in each clip. Analyses of the social feature ratings revealed that some features are perceived categorically (present or absent) and others continuously (intensity) and simple social features requiring immediate response are perceived most consistently across participants. To establish the low-dimensional perceptual organization for social features based on movies, we used principal coordinate analysis and consensus clustering for the feature ratings. These dimension reduction analyses revealed that the social perceptual structure can be modelled with eight main dimensions and that behaviourally relevant perceptual categories emerge from these main dimensions. This social perceptual structure generalized from the perception of unrelated Hollywood movie clips to the perception of a full Finnish movie (70 min), and to the perception of static images (n = 468) and across three independent sets of participants (n = 2254). Based on the results, we propose eight basic dimensions of social perception as a model for rapid social perception where social situations are perceived along eight orthogonal perceptual dimensions (most importantly emotional valence, empathy versus dominance, and cognitive versus physical behaviour).

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bioRxiv2023

Alterations in type 2 dopamine receptors across neuropsychiatric conditions: A large-scale PET cohort

Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls. Here, we investigated the variation in striatal (caudate nucleus, nucleus accumbens, and putamen) and thalamic type 2 dopamine receptor (D2R) availability using [11C]raclopride positron emission tomography (PET) data from a large sample of 437 humans including healthy controls and subjects with Parkinsons disease (PD), antipsychotic-naive schizophrenia, severe violent behavior, pathological gambling, depression, and overweight. We analyzed regional group differences in D2R availability using Bayesian mixed effects modeling. Subjects with PD showed clearest decline in D2R availability. Healthy controls and patients with PD showed high interregional correlation of D2R availability, while this pattern was weaker in schizophrenia, severe violent behavior, and depression. Subjects with pathological gambling or overweight did not show clear changes in either the regional receptor availability or the interregional correlation. We conclude that the dopaminergic changes in neuropsychiatric conditions might not only affect the overall receptor availability but also the connectivity between the regions. The region-specific receptor availability more profoundly links to the motor symptoms, while the between-region connectivity might be disrupted in affective symptoms. HighlightsWe compared human striatal and thalamic type 2 dopamine receptor (D2R) availability between healthy controls, and subjects with Parkinsons disease (PD), antipsychotic-naive schizophrenia, severe violent behavior, pathological gambling, depression, and overweight. We present the mean brain maps of group specific D2R availabilities in NeuroVault (https://neurovault.org; https://identifiers.org/neurovault.collection:12799). Dopamine type 2 receptor availability is lowered in PD in caudate nucleus, nucleus accumbens and thalamus. Antipsychotic-naive schizophrenia, severe violent behavior, and depression were associated with decreased connectivity between the striatal and thalamic D2R availability. Altered regional D2R availability in the striatum and thalamus is linked with motor disorders, while lowered regional connectivity in D2R might relate to affective disturbance.

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bioRxiv2023

Cerebral Topographies of Perceived and Felt Emotions

Emotions modulate behavioral priorities based on exteroceptive and interoceptive inputs, and the related central and peripheral changes may often be experienced subjectively. Yet, it remains unresolved whether the perceptual and subjectively felt components of the emotion processes rely on shared brain mechanisms. We applied functional magnetic resonance imaging, a rich set of emotional movies, and high-dimensional, continuous ratings of perceived and felt emotions depicted in the same movies to investigate their cerebral organization. Eight main dimensions of emotions evoked during natural movie scene perception were represented in the brain across numerous spatial scales and patterns. Perceived and felt emotions generalized both between individuals and between different samples of stimuli depicting the same emotions. The neural affective space demonstrated an anatomical gradient from responses independent of specific emotions in polysensory areas and default mode regions to more localized and emotion-specific discrete processing in subcortical regions. Differences in neural activations during felt and perceived emotions suggest that temporoparietal areas and precuneus have a key role in computing the affective value of the sensory input. This affective value is then transformed into the subjective emotional experience in the anterior prefrontal cortices, cerebellum, and thalamus. Altogether these data reveal the similarities and differences of domain-general and emotion-specific affect networks in the brain during a wide range of perceived and felt emotions.

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bioRxiv2022

Brain glucose metabolism and ageing: A 5-year longitudinal study in a large PET cohort

BackgroundAgeing and clinical factors impact brain glucose metabolism. However, there is a substantial variation of the reported effects on brain glucose metabolism across studies due to the limited statistical power and cross-sectional study designs. MethodsWe retrospectively analyzed data from 441 healthy males (mean 42.8, range 38-50 years) who underwent health check-up program twice at baseline and 5-year follow-up. Health check-up program included 1) brain 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET), 2) anthropometric and body composition measurements, 3) blood samples, and 4) questionnaires for stress and depression. After spatial normalization of brain FDG PET scans, standardized uptake value ratio (SUVR) was measured from 12 region-of-interests. We used hierarchical clustering analysis to reduce their dimensionality before the Bayesian hierarchical modelling. Five clusters were established for predicting regional SUVR; 1) metabolic cluster (body mass index, waist-to-hip ratio, fat percentage, muscle percentage, homeostatic model assessment index-insulin resistance), 2) blood pressure (systolic, diastolic), 3) glucose (fasting plasma glucose level, HbA1c), 4): psychological cluster (stress, depression), and 5) heart rate. The effects of clinical variable clusters on regional SUVR were investigated using Bayesian hierarchical modelling with brms that applies the Markov-Chain Monte Carlo sampling tools. ResultsAll the clinical variables except depression changed during the 5-year follow-up. SUVR decreased in caudate, cingulate, frontal lobe and parietal lobe and increased in cerebellum, hippocampus, occipital lobe, pallidum, putamen, temporal lobe and thalamus. SUVRs of thalamus, pallidum, hippocampus, putamen and parietal lobe were negatively associated with metabolic cluster and the effects of glucose on SUVRs varied across regions. SUVRs of thalamus, hippocampus, cingulate, cerebellum increased and those with occipital lobe decreased with heart rate. The effects of blood pressure and psychological cluster markedly overlapped with zero across regions. ConclusionRegionally selective decline in brain glucose utilization begins already in the middle age, while individual differences in brain glucose metabolism remain stable. In addition to ageing, brain glucose utilization is also associated with metabolic cluster, blood glucose levels and heart rate. These effects are also consistent over the studied period of 5 years in the middle adulthood.

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bioRxiv2022

Neural responses to biological motion distinguish autistic and schizotypal traits in the general population

Difficulties in social interactions are common to both autism and schizophrenia, and contribute to correlated autistic and schizotypal traits in the neurotypical population. It remains unresolved whether this represents a shared etiology or a superficial phenotypic overlap. Both conditions are associated with atypical neural activity in response to the perception of social stimuli, and also decreased neural synchronization between individuals that may prohibit establishing shared experiences. This study sought to establish if neural activity and neural synchronization associated with biological motion perception are differentially associated with autistic and schizotypal traits in the neurotypical population. Participants watched an audiovisual montage of naturalistic social interactions whilst hemodynamic brain activity was measured with fMRI. A separate sample of participants provided a continuous measure of the extent of biological motion, which was used to predict hemodynamic activity. General Linear Model analysis revealed that biological motion perception was associated with neural activity across the action-observation network. However, inter-subject phase synchronization analysis revealed that neural activity synchronized between individuals in occipital and parietal areas, but de-synchronized in temporal and frontal regions. Autistic traits were associated with a decrease in neural activity (precuneus, middle cingulate gyrus) and schizotypal traits were associated with a decrease in neural synchronization (middle and inferior frontal gyri). Biological motion perception elicits convergent and divergent patterns of neural activity and neural synchronization, and are differentially associated with shared traits related with autism and schizophrenia in the general population, suggesting that they originate from different neural mechanisms.

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bioRxiv2022

Accurate sex classification from neural responses to sexual stimuli

Sex differences in brain activity evoked by sexual stimuli remain elusive despite robust evidence for stronger enjoyment of and interest towards sexual stimuli in men than in women. To test whether visual sexual stimuli evoke different brain activity patterns in men and women, we measured haemodynamic brain activity induced by visual sexual stimuli in two experiments in 91 subjects (46 males). In one experiment, the subjects viewed sexual and non-sexual film clips and dynamic annotations for nudity in the clips was used to predict their hemodynamic activity. In the second experiment, the subjects viewed sexual and non-sexual pictures in an event-related design. Males showed stronger activation than females in the visual and prefrontal cortices and dorsal attention network in both experiments. Furthermore, using multivariate pattern classification we could accurately predict the sex of the subject on the basis of the brain activity elicited by the sexual stimuli. The classification generalized across the experiments indicating that the sex differences were consistent. Eye tracking data obtained from an independent sample of subjects (N = 110) showed that men looked longer than women at the chest area of the nude female actors in the film clips. These results indicate that visual sexual stimuli evoke discernible brain activity patterns in men and women which may reflect stronger attentional engagement with sexual stimuli in men than women.

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bioRxiv2021

Functional organization of social perception in the human brain

Humans rapidly extract diverse and complex information from ongoing social interactions, but the perceptual and neural organization of the different aspects of social perception remains unresolved. We showed short film clips with rich social content to 97 healthy participants while their haemodynamic brain activity was measured with fMRI. The clips were annotated moment-to-moment for 112 social features. Cluster analysis revealed that 13 dimensions were sufficient for describing the social perceptual space. Regression analysis was used to map regional neural response profiles to different social features. Multivariate pattern analysis was then utilized to establish the spatial specificity of these responses. The results revealed a gradient in the processing of social information in the brain. Posterior temporal and occipital regions were broadly tuned to most social dimensions and the classifier revealed that these responses showed spatial specificity for social dimensions; in contrast Heschl gyri and parietal areas were also broadly associated with different social signals, yet the spatial patterns of responses did not differentiate social dimensions. Frontal and subcortical regions responded only to a limited number of social dimensions and the spatial response patterns did not differentiate social dimension. Altogether these results highlight the distributed nature of social processing in the brain.

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