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.

Figure 1

IFC in the cingulo-opercular network (a) and right fronto-parietal network (b) in older healthy participants. The clusters significantly related to phasic alerting effects (red) are overlaid on intra-network iFC (blue). The spatial maps are obtained by a combined independent component analysis dual regression approach. Behaviour-iFC associations were tested using a voxel-wise multiple regression, controlling for age, sex, head motion, and education (p < 0.05 FWE corrected at cluster level). The results are presented on a standard anatomical MNI152 template using MRIcroGL (https://www.mccauslandcenter.sc.edu/mricrogl/source); slice numbers in transverse plane are indicated.

Figure 2

Age group differences of associations between phasic alerting effect on visual processing speed and iFC in the cingulo-opercular (a) and right fronto-parietal network (b). Panel a illustrates that the association between phasic alerting effects on visual processing speed and iFC in the cingulo-opercular network is significantly lower in older than in younger adults (p < 0.05 FWE corrected at cluster level, significant cluster in red). Panel b represents an exploratory analysis (p < 0.05 uncorrrected at cluster level) in the right fronto-parietal network. The spatial maps (blue) are obtained by a combined independent component analysis dual regression approach. Behaviour-iFC associations were tested using a voxel-wise multiple regression, controlling for age, sex, head motion, and education. The results are presented on a standard anatomical MNI152 template using MRIcroGL (https://www.mccauslandcenter.sc.edu/mricrogl/source); slice numbers in transverse plane are indicated.

Figure 3

Exemplary trial sequence of the presented TVA-based whole report task (a) and summary of performance in cue and no-cue conditions for a representative healthy older participant (b). Solid curves (mean theo.) depict the best TVA-based fit to acquired data points (mean obs). The dashed line represents the model-based estimate of vSTM storage capacity K; the dotted line represents the model-based estimate of visual processing speed C.