Time-dependent scale-free brain dynamics during naturalistic inputs
Environmental processes, such as auditory and visual inputs, often follow power-law distributions with a time-dependent and constantly changing spectral exponent, β(t). However, it remains unclear how the brain’s scale-free dynamics continuously respond to naturalistic inputs, such as by potentially...
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Elsevier
2025-07-01
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| Series: | NeuroImage |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1053811925002587 |
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| author | Philipp Klar Yasir Çatal Gerhard Jocham Robert Langner Georg Northoff |
| author_facet | Philipp Klar Yasir Çatal Gerhard Jocham Robert Langner Georg Northoff |
| author_sort | Philipp Klar |
| collection | DOAJ |
| description | Environmental processes, such as auditory and visual inputs, often follow power-law distributions with a time-dependent and constantly changing spectral exponent, β(t). However, it remains unclear how the brain’s scale-free dynamics continuously respond to naturalistic inputs, such as by potentially alternating instead of static levels of the spectral exponent. Our fMRI study investigates the brain’s dynamic, time-dependent spectral exponent, β(t), during movie-watching, and uses time-varying inter-subject correlation, ISC(t), to assess the extent to which input dynamics are reflected as shared brain activity across subjects in early sensory regions. Notably, we investigate the level of ISC particularly based on the modulation by time-dependent scale-free dynamics or β(t). We obtained three key findings: First, the brain’s β(t) showed a distinct temporal structure in visual and auditory regions during naturalistic inputs compared to the resting-state, investigated in the 7 Tesla Human Connectome Project dataset. Second, β(t) and ISC(t) were positively correlated during naturalistic inputs. Third, grouping subjects based on the Rest-to-Movie standard deviation change of the time-dependent spectral exponent β(t) revealed that the brain’s relative shift from intrinsic to stimulus-driven scale-free dynamics modulates the level of shared brain activity, or ISC(t), and thus the imprinting of inputs on brain activity. This modulation was further supported by the observation that the two groups displayed significantly different β(t)-ISC(t) correlations, where the group with a higher mean of ISC(t) during inputs also exhibited a higher β(t)-ISC(t) correlation in visual and auditory regions. In summary, our fMRI study underscores a positive relationship between time-dependent scale-free dynamics and ISC, where higher spectral exponents correspond to higher degrees of shared brain activity during ongoing audiovisual inputs. |
| format | Article |
| id | doaj-art-2a2778ff4dcb4ae18bcdd03e9da9d49e |
| institution | DOAJ |
| issn | 1095-9572 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | NeuroImage |
| spelling | doaj-art-2a2778ff4dcb4ae18bcdd03e9da9d49e2025-08-20T03:08:54ZengElsevierNeuroImage1095-95722025-07-0131412125510.1016/j.neuroimage.2025.121255Time-dependent scale-free brain dynamics during naturalistic inputsPhilipp Klar0Yasir Çatal1Gerhard Jocham2Robert Langner3Georg Northoff4Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany; Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany; Corresponding author.The Royal’s Institute of Mental Health Research & University of Ottawa. Brain and Mind Research Institute, Centre for Neural Dynamics, Faculty of Medicine, University of Ottawa, 145 Carling Avenue, Rm. 6435, Ottawa, Ontario K1Z 7K4, CanadaFaculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University of Düsseldorf, Düsseldorf, GermanyInstitute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany; Institute of Systems Neuroscience, Heinrich Heine University Düsseldorf, Düsseldorf, GermanyUniversity of Ottawa, Institute of Mental Health Research at the Royal Ottawa Hospital, 145 Carling Avenue, Rm. 6435, Ottawa, Ontario K1Z 7K4, CanadaEnvironmental processes, such as auditory and visual inputs, often follow power-law distributions with a time-dependent and constantly changing spectral exponent, β(t). However, it remains unclear how the brain’s scale-free dynamics continuously respond to naturalistic inputs, such as by potentially alternating instead of static levels of the spectral exponent. Our fMRI study investigates the brain’s dynamic, time-dependent spectral exponent, β(t), during movie-watching, and uses time-varying inter-subject correlation, ISC(t), to assess the extent to which input dynamics are reflected as shared brain activity across subjects in early sensory regions. Notably, we investigate the level of ISC particularly based on the modulation by time-dependent scale-free dynamics or β(t). We obtained three key findings: First, the brain’s β(t) showed a distinct temporal structure in visual and auditory regions during naturalistic inputs compared to the resting-state, investigated in the 7 Tesla Human Connectome Project dataset. Second, β(t) and ISC(t) were positively correlated during naturalistic inputs. Third, grouping subjects based on the Rest-to-Movie standard deviation change of the time-dependent spectral exponent β(t) revealed that the brain’s relative shift from intrinsic to stimulus-driven scale-free dynamics modulates the level of shared brain activity, or ISC(t), and thus the imprinting of inputs on brain activity. This modulation was further supported by the observation that the two groups displayed significantly different β(t)-ISC(t) correlations, where the group with a higher mean of ISC(t) during inputs also exhibited a higher β(t)-ISC(t) correlation in visual and auditory regions. In summary, our fMRI study underscores a positive relationship between time-dependent scale-free dynamics and ISC, where higher spectral exponents correspond to higher degrees of shared brain activity during ongoing audiovisual inputs.http://www.sciencedirect.com/science/article/pii/S1053811925002587Fractal dynamicsScale-free dynamicsSpectral exponentInter-subject correlationISC |
| spellingShingle | Philipp Klar Yasir Çatal Gerhard Jocham Robert Langner Georg Northoff Time-dependent scale-free brain dynamics during naturalistic inputs NeuroImage Fractal dynamics Scale-free dynamics Spectral exponent Inter-subject correlation ISC |
| title | Time-dependent scale-free brain dynamics during naturalistic inputs |
| title_full | Time-dependent scale-free brain dynamics during naturalistic inputs |
| title_fullStr | Time-dependent scale-free brain dynamics during naturalistic inputs |
| title_full_unstemmed | Time-dependent scale-free brain dynamics during naturalistic inputs |
| title_short | Time-dependent scale-free brain dynamics during naturalistic inputs |
| title_sort | time dependent scale free brain dynamics during naturalistic inputs |
| topic | Fractal dynamics Scale-free dynamics Spectral exponent Inter-subject correlation ISC |
| url | http://www.sciencedirect.com/science/article/pii/S1053811925002587 |
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