Changes in the Intranetwork and Internetwork Connectivity of the Default Mode Network and Olfactory Network in Patients with COVID-19 and Olfactory Dysfunction
Hui Zhang, T. Chung, Fergus Kai-Chuen Wong, I. Hung, H. Mak
Brain Science April 1, 2022 DOI: 10.3390/brainsci12040511 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case-control functional MRI study Peer reviewed |
|---|---|
| Sample size | 35 |
| Population | 13 healthy controls and 22 patients with COVID-19-related olfactory dysfunction |
| Measures | butanol threshold test (BTT), functional magnetic resonance imaging (fMRI) connectivity measures |
| Topics | Default mode network |
| Key findings | COVID-19 patients with olfactory dysfunction showed significantly higher intranetwork connectivity in the default mode network and higher internetwork connectivity between the olfactory network and default mode network compared with healthy controls, while olfactory network intranetwork connectivity did not differ significantly between groups. Butanol threshold test scores correlated significantly with olfactory network intranetwork connectivity. The authors propose that these connectivity increases may compensate for olfactory and well-being deficits. |
Abstract
Olfactory dysfunction (OD) is a common symptom in coronavirus disease 2019 (COVID-19) patients. Moreover, many neurological manifestations have been reported in these patients, suggesting central nervous system involvement. The default mode network (DMN) is closely associated with olfactory processing. In this study, we investigated the internetwork and intranetwork connectivity of the DMN and the olfactory network (ON) in 13 healthy controls and 22 patients presenting with COVID-19-related OD using independent component analysis and region of interest functional magnetic resonance imaging (fMRI) analysis. There was a significant correlation between the butanol threshold test (BTT) and the intranetwork connectivity in ON. Meanwhile, the COVID-19 patients with OD showed significantly higher intranetwork connectivity in the DMN, as well as higher internetwork connectivity between ON and DMN. However, no significant difference was found between groups in the intranetwork connectivity within ON. We postulate that higher intranetwork functional connectivities compensate for the deficits in olfactory processing and general well-being in COVID-19 patients. Nevertheless, the compensation process in the ON may not be obvious at this stage. Our results suggest that resting-state fMRI is a potentially valuable tool to evaluate neurosensory dysfunction in COVID-19 patients.
Comparable studies
Other observational and cohort studies on default mode network, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| A default mode of brain function Normal adult human brain | 2001 | Observational study | |
| Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network Healthy subjects | 2008 | Observational cohort | |
| Meditation experience is associated with increased cortical thickness Participants with extensive Insight meditation experience and matched controls | 2005 | Observational cohort | n = 20 |
| Meditation experience is associated with differences in default mode network activity and connectivity Experienced meditators and matched meditation-naive controls | 2011 | Observational cohort | |
| The precuneus/posterior cingulate cortex plays a pivotal role in the default mode network: Evidence from a partial correlation network analysis Healthy subjects | 2008 | Observational study |
Citations in the library
Cites 3
- The default mode network: where the idiosyncratic self meets the shared social world Nature Reviews Neuroscience January 22, 2021
- Internal and external attention and the default mode network Neuroimage January 18, 2017
- Default Mode Network (DMN) Deactivation during Odor-Visual Association Human Brain Mapping October 27, 2016