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Severi Santavirta

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5 papers

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YNIMG Journal 2026 Journal Article

Four-dimensional neural space for moral inference

Jinglu Chen
Severi Santavirta
Vesa Putkinen
Paulo Sérgio Boggio
Lauri Nummenmaa

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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YNICL Journal 2026 Journal Article

Striatal dopamine synthesis capacity in Parkinson’s disease: Effects of age, sex, and body mass index in a large [18F]fluorodopa PET cohort

Tuulia Malén
Jouni Tuisku
Marco Bucci
Severi Santavirta
Valtteri Kaasinen
Sakari Kaasalainen
Janne Isojärvi
Jarmo Hietala

BACKGROUND: F]fluorodopa detects reduced striatal dopamine synthesis capacity in Parkinson's disease (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. MATERIAL, AIMS, AND METHODS: C]raclopride PET scan, and (3) scanner effects and atlas- versus MRI-based quantification approaches. We provide the mean dopamine synthesis brain maps of healthy controls and PD patients in NeuroVault. RESULTS: estimates for most subjects. CONCLUSIONS: Dopamine synthesis capacity is independently affected by PD and demographic factors and correlated between the striatal and thalamic regions in both controls and PD patients. Adjusting for scanner effects in multi-scanner datasets is recommended. When subject-specific MRI is unavailable, atlas-based normalization may be used with caution to prevent major data loss.

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YNICL Journal 2024 Journal Article

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

Tuulia Malén
Severi Santavirta
Sven De Maeyer
Jouni Tuisku
Valtteri Kaasinen
Tuomas Kankare
Janne Isojärvi
Juha Rinne

PURPOSE: Aberrant dopaminergic function is linked with motor, psychotic, and affective symptoms, but studies have typically compared a single patient group with healthy controls. METHODS: R availability within each group. RESULTS: R availability, while this pattern was weaker in violent offenders. Subjects with schizophrenia, pathological gambling, depression, or overweight did not show clear changes in either the regional receptor availability or the interregional correlation. CONCLUSION: We conclude that the dopaminergic changes in neuropsychiatric conditions might not only affect the overall receptor availability but also how coupled regions are across people. The region-specific receptor availability more profoundly links to the motor symptoms, while the between-region coupling might be disrupted in violence.

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YNIMG Journal 2023 Journal Article

Decoding brain basis of laughter and crying in natural scenes

Lauri Nummenmaa
Tuulia Malèn
Sanaz Nazari-Farsani
Kerttu Seppälä
Lihua Sun
Severi Santavirta
Henry K. Karlsson
Matthew Hudson

Laughter and crying are universal signals of prosociality and distress, respectively. Here we investigated the functional brain basis of perceiving laughter and crying using naturalistic functional magnetic resonance imaging (fMRI) approach. We measured haemodynamic brain activity evoked by laughter and crying in three experiments with 100 subjects in each. The subjects i) viewed a 20-minute medley of short video clips, and ii) 30 min of a full-length feature film, and iii) listened to 13.5 min of a radio play that all contained bursts of laughter and crying. Intensity of laughing and crying in the videos and radio play was annotated by independent observes, and the resulting time series were used to predict hemodynamic activity to laughter and crying episodes. Multivariate pattern analysis (MVPA) was used to test for regional selectivity in laughter and crying evoked activations. Laughter induced widespread activity in ventral visual cortex and superior and middle temporal and motor cortices. Crying activated thalamus, cingulate cortex along the anterior-posterior axis, insula and orbitofrontal cortex. Both laughter and crying could be decoded accurately (66-77% depending on the experiment) from the BOLD signal, and the voxels contributing most significantly to classification were in superior temporal cortex. These results suggest that perceiving laughter and crying engage distinct neural networks, whose activity suppresses each other to manage appropriate behavioral responses to others' bonding and distress signals.

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YNIMG Journal 2023 Journal Article

Functional organization of social perception networks in the human brain

Severi Santavirta
Tomi Karjalainen
Sanaz Nazari-Farsani
Matthew Hudson
Vesa Putkinen
Kerttu Seppälä
Lihua Sun
Enrico Glerean

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 movie 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 a large set of social features and 45 of the features were evaluated reliably between annotators. Cluster analysis of the social features revealed that 13 dimensions were sufficient for describing the social perceptual space. Three different analysis methods were used to map the social perceptual processes in the human brain. Regression analysis mapped regional neural response profiles for different social dimensions. Multivariate pattern analysis then established the spatial specificity of the responses and intersubject correlation analysis connected social perceptual processing with neural synchronization. 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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