Neural Differentiation is Moderated by Age in Scene-Selective, But Not Face-Selective, Cortical Regions

Abstract

The aging brain is characterized by neural dedifferentiation, an apparent decrease in the functional selectivity of category-selective cortical regions. Age-related reductions in neural differentiation have been proposed to play a causal role in cognitive aging. Recent findings suggest, however, that age-related dedifferentiation is not equally evident for all stimulus categories and, additionally, that the relationship between neural differentiation and cognitive performance is not moderated by age. In light of these findings, in the present experiment, younger and older human adults (males and females) underwent fMRI as they studied words paired with images of scenes or faces before a subsequent memory task. Neural selectivity was measured in two scene-selective (parahippocampal place area (PPA) and retrosplenial cortex (RSC)] and two face-selective [fusiform face area (FFA) and occipital face area (OFA)] regions using both a univariate differentiation index and multivoxel pattern similarity analysis. Both methods provided highly convergent results, which revealed evidence of age-related reductions in neural dedifferentiation in scene-selective but not face-selective cortical regions. Additionally, neural differentiation in the PPA demonstrated a positive, age-invariant relationship with subsequent source memory performance (recall of the image category paired with each recognized test word). These findings extend prior findings suggesting that age-related neural dedifferentiation is not a ubiquitous phenomenon, and that the specificity of neural responses to scenes is predictive of subsequent memory performance independently of age.

Effects of age on goal-dependent modulation of episodic memory retrieval

“…'Reinstatement indices' based on the resulting single-trial β-weights in each sceneselective ROI, separately for the trials of the two retrieval tasks, were computed in a manner akin to a previously described 'differentiation index' Srokova et al, 2020;Voss et al, 2008;Zebrowitz et al, 2016). The reinstatement index operationalizes retrieval-related reinstatement of scene information in terms of an effect size by computing the difference between the mean BOLD response associated with test words studied over scene backgrounds versus words studied over scrambled backgrounds, and then dividing the difference by pooled standard deviation:…”

“…Pattern similarity analysis (PSA) was performed to complement the analyses of the univariate reinstatement index (cf. Srokova et al, 2020). Scene reinstatement was operationalized in terms of shared neural patterns between test trials and a scene-specific voxel-wise profile derived from the functional localizer.…”

The Retrieval-related Anterior shift is Moderated by Age and Correlates with Memory Performance

“…Behavioral performance and neuropsychological test performance have been reported previously (Srokova et al, 2020; Hill et al, 2021) and are only briefly summarized below. With regards to neuropsychological test performance, younger adults outperformed older adults on the CVLT Short Delay – Free recall, CVLT recognition – False alarms, WMS Logical Memory I and II, SDMT, Trails A and B, and Raven’s matrices.…”

A Functional MRI Paradigm for Efficient Mapping of Memory Encoding Across Sensory Conditions

“…Within the visual condition, we chose to present faces and spatial scenes, motivated by work on face-selective and scene-selective brain regions (Kanwisher et al, 1997 ; Epstein and Kanwisher, 1998 ; Gazzaley et al, 2005 ; Collins and Dickerson, 2019 ). Further, those stimuli seemed to show differences in age-related reductions in neural dedifferentiation, which makes them interesting for longitudinal studies (Srokova et al, 2020 ). To select auditory stimuli on a similar level of specificity, we chose voice and environmental stimuli motivated by previous work on voice-selective brain regions (Belin et al, 2000 , 2002 ; Pernet et al, 2015 ; Agus et al, 2017 ; Zäske et al, 2017 ; Aglieri et al, 2018 ).…”