Evaluating the impact of fast-fMRI on dynamic functional connectivity in an event-based paradigm

PLoS One. 2018 Jan 22;13(1):e0190480. doi: 10.1371/journal.pone.0190480. eCollection 2018.

Abstract

The human brain is known to contain several functional networks that interact dynamically. Therefore, it is desirable to analyze the temporal features of these networks by dynamic functional connectivity (dFC). A sliding window approach was used in an event-related fMRI (visual stimulation using checkerboards) to assess the impact of repetition time (TR) and window size on the temporal features of BOLD dFC. In addition, we also examined the spatial distribution of dFC and tested the feasibility of this approach for the analysis of interictal epileptiforme discharges. 15 healthy controls (visual stimulation paradigm) and three patients with epilepsy (EEG-fMRI) were measured with EPI-fMRI. We calculated the functional connectivity degree (FCD) by determining the total number of connections of a given voxel above a predefined threshold based on Pearson correlation. FCD could capture hemodynamic changes relative to stimulus onset in controls. A significant effect of TR and window size was observed on FCD estimates. At a conventional TR of 2.6 s, FCD values were marginal compared to FCD values using sub-seconds TRs achievable with multiband (MB) fMRI. Concerning window sizes, a specific maximum of FCD values (inverted u-shape behavior) was found for each TR, indicating a limit to the possible gain in FCD for increasing window size. In patients, a dynamic FCD change was found relative to the onset of epileptiform EEG patterns, which was compatible with their clinical semiology. Our findings indicate that dynamic FCD transients are better detectable with sub-second TR than conventional TR. This approach was capable of capturing neuronal connectivity across various regions of the brain, indicating a potential to study the temporal characteristics of interictal epileptiform discharges and seizures in epilepsy patients or other brain diseases with brief events.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain / diagnostic imaging*
  • Brain / physiopathology
  • Brain Mapping
  • Case-Control Studies
  • Electroencephalography
  • Epilepsy / diagnostic imaging*
  • Epilepsy / physiopathology
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Middle Aged
  • Young Adult

Grants and funding

This work was supported by the Werner Reichardt Centre for Integrative Neuroscience (CIN grant: Pool-Project 2012-10) and the DFG (CIN EXC 307) for NF. Support for SV was provided by the Swiss National Science Foundation grant 320030-169198. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We also acknowledge support by the Open Access Publication Funds of the Göttingen University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.