Investigating mechanisms of fast BOLD responses: The effects of stimulus intensity and of spatial heterogeneity of hemodynamics
| Autor: | Jonathan R. Polimeni, Jingyuan E. Chen, Bruce R. Rosen, Nina E. Fultz, Gary H. Glover, Laura D. Lewis |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Adult
Male Brain activity and meditation Haemodynamic response Computer science Cognitive Neuroscience media_common.quotation_subject Neurosciences. Biological psychiatry. Neuropsychiatry Stimulus (physiology) computer.software_genre Somatosensory system behavioral disciplines and activities Young Adult Task intensity Voxel Fast fMRI Canonical model Humans Contrast (vision) Resting state Nonlinearity Visual Cortex media_common Brain Mapping Resting state fMRI Hemodynamic response function High spatial resolution Hemodynamics Middle Aged Magnetic Resonance Imaging Neurology Female Neuroscience computer RC321-571 |
| Zdroj: | NeuroImage, Vol 245, Iss, Pp 118658-(2021) |
| ISSN: | 1095-9572 |
| Popis: | Recent studies have demonstrated that fast fMRI can track neural activity well above the temporal limit predicted by the canonical hemodynamic response model. While these findings are promising, the biophysical mechanisms underlying these fast fMRI phenomena remain underexplored. In this study, we discuss two aspects of the hemodynamic response, complementary to several existing hypotheses, that can accommodate faster fMRI dynamics beyond those predicted by the canonical model. First, we demonstrate, using both visual and somatosensory paradigms, that the timing and shape of hemodynamic response functions (HRFs) vary across graded levels of stimulus intensity-with lower-intensity stimulation eliciting faster and narrower HRFs. Second, we show that as the spatial resolution of fMRI increases, voxel-wise HRFs begin to deviate from the canonical model, with a considerable portion of voxels exhibiting faster temporal dynamics than predicted by the canonical HRF. Collectively, both stimulus/task intensity and image resolution can affect the sensitivity of fMRI to fast brain activity, which may partly explain recent observations of fast fMRI signals. It is further noteworthy that, while the present investigations focus on fast neural responses, our findings suggest that a revised hemodynamic model may benefit the many fMRI studies using paradigms with wide ranges of contrast levels (e.g., resting or naturalistic conditions) or with modern, high-resolution MR acquisitions. |
| Databáze: | OpenAIRE |
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