Processing of fMRI-related anxiety and information flow between brain and body revealed a preponderance of oscillations at 0.15/0.16 Hz

Abstract

Slow oscillations of different center frequencies and their coupling play an important role in brain-body interactions. The crucial question analyzed by us is, whether the low frequency (LF) band (0.05–0.15 Hz) or the intermediate frequency (IMF) band (0.1–0.2 Hz) is more eminent in respect of the information flow between body (heart rate and respiration) and BOLD signals in cortex and brainstem. A recently published study with the LF band in fMRI-naïve subjects revealed an intensive information flow from the cortex to the brainstem and a weaker flow from the brainstem to the cortex. The comparison of both bands revealed a significant information flow from the middle frontal gyrus (MFG) to the precentral gyrus (PCG) and from brainstem to PCG only in the IMF band. This pattern of directed coupling between slow oscillations in the cortex and brainstem not only supports the existence of a pacemaker-like structure in brainstem, but provides first evidence that oscillations centered at 0.15/0.16 Hz can also emerge in brain networks. BOLD oscillations in resting states are dominating at ~ 0.08 Hz and respiratory rates at ~ 0.32 Hz. Therefore, the frequency component at ~ 0.16 Hz (doubling-halving 0.08 Hz or 0.32 Hz) is of special interest, because phase coupled oscillations can reduce the energy demand.

Respiration-entrained brain oscillations in healthy fMRI participants with high anxiety

“…The fast BOLD oscillations in the amygdala are centered at ~ 0.32 Hz and the slow oscillations in the PCG (ROI 1), MFG (ROI 7), medial frontal cortex (ROI 23) and brain stem (ROIs 93, 99) centered at ~ 0.16 Hz. While the former oscillations may be related to a downward information flow, the latter may have its origin in the brainstem pacemaker exhibiting an upward flow (Pfurtscheller et al 17 ). Both information flows are important, because they contribute to a power increase in the LF and HF band of the HRV, an important prerequisite for successful emotional regulation 26 .…”

“…Respiration and the electrocardiogram (ECG) were recorded inside the scanner. Details about the exact timing see 16 , 17 .…”

“…Participants were naïve to the purpose of the study, had no former MRI experience and were without any record of neurological or psychiatric disorders (assessed by self-report). From these 23 participants with fMRI-related anxiety already two publications are ble in Scientific Reports 16 , 17 which focused on the two low frequency bands of 0.05–0.15 Hz and 0.1–0.2 Hz. In this paper we studied the high frequency band 0.2–0.4 Hz in a group of ten fMRI participants with the highest anxiety scores (AS).…”

“…Epochs of 40 s were used for the analysis, and the bootstrap approach was employed for the statistics. More details can may be found in 16 , 17 .…”

“…The base for DTF is a multivariate autoregressive (MVAR) model, which is fitted simultaneously to the physiological signals including BOLD recording from prefrontal cortex and brainstem. This method of processing was already successfully applied to cardiac beat-to-beat interval (RRI) time courses, respiration and BOLD data in the low frequency (LF) bands of 0.05–0.15 Hz and 0.1–0.2 Hz 16 , 17 .…”