Right-lateralized fronto-parietal network and phasic alertness in healthy aging

Abstract

Phasic alerting cues temporarily increase the brain's arousal state. In younger and older participants, visual processing speed in a whole report task, estimated based on the theory of visual attention, is higher in cue than no-cue conditions. The present study assessed whether older participants' ability to profit from warning cues is related to intrinsic functional connectivity (iFC) in the cingulo-opercular and/ or right fronto-parietal network. We acquired resting-state functional magnetic resonance imaging data from 31 older participants. By combining an independent component analysis and dual regression, we investigated iFC in both networks. A voxel-wise multiple regression in older participants yielded that higher phasic alerting effects on visual processing speed were significantly related to lower right fronto-parietal network iFC. This result supports a particular role of the right fronto-parietal network in maintaining phasic alerting capabilities in aging. We then compared healthy older participants to a previously reported sample of healthy younger participants to assess whether behaviour-ifc relationships are age group specific. The comparison revealed that the association between phasic alerting and cingulo-opercular network iFC is significantly lower in older than in younger adults.Phasic alertness refers to momentary enhancements of the brain's "state of readiness" due to warning cues 1 . Previous studies, using a whole report task with briefly presented letter arrays and parametric modelling of report performance based on the theory of visual attention (TVA) 2 , demonstrated that perceptual speed of visual processing is enhanced by visual 3 and auditory warning cues 4 . Furthermore, auditory alerting was shown to be effective in both healthy younger and older participants 5 . Concerning neural correlates underlying phasic alerting effects in younger adults, we found that the individual cueing benefits were significantly related to intrinsic functional connectivity (iFC) in the cingulo-opercular network (CON) 6 . IFC refers to spatial patterns of correlated blood oxygen level dependent (BOLD) signal with a frequency of 0.01-0.1 Hz over time 7 . These BOLD fluctuations can be measured using resting-state functional magnetic resonance imaging (rs-fMRI).With respect to older adults, it is unclear whether their preserved phasic alertness response relies on the same intrinsic brain network as in younger adults or a different one. Reviewing the importance of right-hemispheric structures for cognitive reserve 8 , Robertson suggested that the integrity and functional connectivity of the right fronto-parietal network (rFPN) is decisive for the late-life maintenance of attentional abilities and, especially, alertness functions 9,10 . He summarized evidence for a close, bidirectional relationship of the availability of noradrenaline provided by the locus coeruleus, which is decisive for the ability to increase arousal 11,12 , and the integrity of the right fronto-parietal network in aging individuals. The m...

Alertness Training Increases Visual Processing Speed in Healthy Older Adults

“…Thus, when all stimuli are task relevant, as in whole-report paradigms, increased alertness will boost all processing rates, resulting in a proportional increase in VPS. Consistent with this, other findings have shown that VPS increases following psychostimulant intake (Finke et al, 2010) and phasic alerting cues (Haupt, Ruiz-Rizzo, Sorg, & Finke, 2020), in which alerting-cue intensity monotonically increased only the VPS parameter C and not other TVA parameters (Petersen, Petersen, Bundesen, Vangkilde, & Habekost, 2017). Thus, we hypothesized that targeted, computerized tonic-alertness training would also increase VPS in healthy older adults.…”

“…The linkage identified between higher CON functional connectivity and higher VPS gain from a longer term intervention differs from functional connectivity–VPS benefit relationships established in previous studies on the effects of short-term auditory phasic-alertness cues. In these studies, higher cuing gains were found to be related to lower CON functional connectivity in younger adults and to lower functional connectivity in the right frontoparietal network in older adults (Haupt et al, 2020). The discrepancies between the current findings and these results might reflect differences in the brain systems underlying phasic and intrinsic alertness functions.…”

Visual processing speed is linked to functional connectivity between right frontoparietal and visual networks

“…For each frequency bin, we obtained the ICs' spatial cross‐correlation values with resting‐state network templates (Allen et al., 2011) using FSL's fslcc command (https://surfer.nmr.mgh.harvard.edu/pub/dist/freesurfer/tutorial_packages/OSX/fsl_501/src/avwutils/fslcc.cc). As we were interested only in networks previously shown relevant for VPS (Haupt et al., 2020; Ruiz‐Rizzo et al., 2018), we selected the two ICs, as defined in Allen et al., (2011), that showed the highest correlation coefficients with, correspondingly, COn (Allen et al's Salience, IC 55), RFPn (Allen et al's IC 60), and visual networks (Allen et al's IC 39, IC 46, IC 48, IC 59, IC 64, and IC 67). Note that we did not exhaustively select all brain networks relevant for attention (e.g., the dorsal attention network or the bilateral executive control network) but only those that have been specifically associated with VPS.…”

Combining Gamma With Alpha and Beta Power Modulation for Enhanced Cortical Mapping in Patients With Focal Epilepsy

“…Most patients performed well in the task, however, one patient performed poorly and withdrew early from the experiment. This experience prompted us to question how well ECoG mapping would perform in a less demanding task, which might be particularly relevant when applying ECoG mapping in pediatric populations, patients with low general cognitive ability (Ruiz-Rizzo et al, 2018 or patients who are otherwise unable or unwilling to engage in demanding cognitive testing (Haupt et al, 2020;Ruiz-Rizzo et al, 2020). Our cognitive experiment included a passive condition in which the same auditory stimuli were presented without any explicit task.…”