Biology subjects

Pasvanis, S.

Publications and source records attributed to Pasvanis, S..

7 recordsLinked to original sources

bioRxiv2024

Menopause status and sex affect memory for spatial context information and white matter microstructure at midlife

Decline in spatial context memory emerges in midlife, the time when most females transition from pre-to post-menopause. Recent evidence suggests that, among post-menopausal females, advanced age is associated with functional brain alterations and lower spatial context memory. However, it is unknown whether similar effects are evident for white matter (WM) and, moreover, whether such effects contribute to sex differences at midlife. To address this, we conducted a study on 96 cognitively unimpaired middle-aged adults (30 males, 32 pre-menopausal females, 34 post-menopausal females). Spatial context memory was assessed using a face-location memory paradigm, while WM microstructure was assessed using diffusion tensor imaging. Behaviorally, advanced age was associated with lower spatial context memory in post-menopausal females but not pre-menopausal females or males. Additionally, advanced age was associated with microstructural variability in predominantly frontal WM (e.g., anterior corona radiata, genu of corpus callosum), which was related to lower spatial context memory among post-menopausal females. Our findings suggest that post-menopausal status enhances vulnerability to age effects on the brains WM and episodic memory.

neuroscience↗

bioRxiv2023

The influence of chronological age and menopause status on the functional neural correlates of spatial context memory in middle-aged females.

Reductions in the ability to encode and retrieve past experiences in rich spatial contextual detail (episodic memory) are apparent by midlife - a time when most females experience spontaneous menopause. Yet, little is known about how menopause status affects episodic memory-related brain activity at encoding and retrieval in middle-aged pre- and post-menopausal females, and whether any observed group differences in brain activity and memory performance correlate with chronological age within group. We conducted an event-related task fMRI study of episodic memory for spatial context to address this knowledge gap. Multivariate behavioral partial least squares (PLS) was used to investigate how chronological age and retrieval accuracy correlated with brain activity in 31 premenopausal (age range: 39.55 - 53.30 yrs, Mage = 44.28 yrs, SDage = 3.12 yrs) and 41 postmenopausal females (age range: 46.70 to 65.14 yrs, Mage = 57.56 yrs, SDage = 3.93 yrs). We found that postmenopausal status, and advanced age within post-menopause, was associated with lower spatial context memory. The fMRI analysis showed that only in postmenopausal females, advanced age was correlated with decreased activity in occipitotemporal, parahippocampal, and inferior parietal during encoding and retrieval, and poorer spatial context memory performance. In contrast, only premenopausal females exhibited an overlap in encoding and retrieval activity in angular gyrus, midline cortical regions, and prefrontal cortex, which correlated with better spatial context retrieval accuracy. These results highlight how menopause status and chronological age, nested within menopause group, affect episodic memory and its neural correlates at midlife. Significance StatementThis is the first fMRI study to examine how pre- and post-menopause status affects the neural correlates of episodic memory encoding and retrieval, and how chronological age contributes to any observed group similarities and differences. We found that both menopause status (endocrine age) and chronological age affect spatial context memory and its neural correlates. Menopause status directly affected the direction of age- and performance-related correlations with brain activity in inferior parietal, parahippocampal and occipitotemporal cortices across encoding and retrieval. Moreover, we found that only premenopausal females exhibited cortical reinstatement of encoding-related activity in midline cortical, prefrontal, and angular gyrus, at retrieval. This suggests that spatial context memory abilities may rely on distinct brain systems at pre-compared to post-menopause.

neuroscience↗

bioRxiv2021

Sex differences in age- and episodic memory-related effects on task-based functional connectivity

Aging is associated with episodic memory decline and changes in functional brain connectivity. Understanding whether and how biological sex influences age- and memory performance-related functional connectivity has important theoretical and clinical implications for our understanding of brain and cognitive aging. Yet, little is known about the effect of sex on neurocognitive aging. Here, we scanned 161 healthy adults between 19-76 yrs of age in an event-related functional magnetic resonance imaging (fMRI) study of face-location spatial context memory. Adults were scanned while performing easy and difficult versions of the task at both encoding and retrieval. We used multivariate whole-brain partial least squares (PLS) connectivity to test the hypothesis that there are sex differences in age- and episodic memory performance-related functional connectivity. We examined how individual differences in age and retrieval accuracy correlated with task-related connectivity. We then repeated this analysis after disaggregating the data by self-reported sex. We found that increased encoding and retrieval-related connectivity within the dorsal attention network (DAN), and between DAN and frontoparietal network (FPN) and visual networks, was positively correlated to retrieval accuracy and negatively correlated with age in both sexes. We also observed sex differences in age- and performance-related functional connectivity: i) greater between-network integration was apparent at both levels of task difficulty in women only, and ii) increased DAN-DMN connectivity with age was observed in men and was correlated with poorer memory performance. Therefore, the neural correlates of age-related episodic memory decline differ in women and men and has important theoretical and clinical implications for the cognitive neuroscience of memory, aging and dementia prevention.

neuroscience↗

bioRxiv2019

APOE4 status is related to differences in memory-related brain function in asymptomatic older adults: Baseline analysis of the PREVENT-AD task fMRI dataset

Episodic memory decline is one of the earliest symptoms of late-onset Alzheimers Disease (AD) and older adults with the apolipoprotein E e4 (+APOE4) genetic risk factor for AD may exhibit altered patterns of memory-related brain activity years prior to initial symptom onset. In the current study we report the baseline episodic memory task fMRI results from the PRe-symptomatic EValuation of Experimental or Novel Treatments for Alzheimers Disease (PREVENT-AD) study in Montreal, Canada, in which 327 healthy older adults, within 15 years of the parents conversion to AD, were scanned. During the task fMRI protocol volunteers were scanned as they encoded and retrieved object-location spatial source associations. The task was designed to discriminate between brain activity related to successful spatial source recollection and failures in spatial source recollection, with memory for only item (object) memory. Multivariate task-related partial least squares (task PLS) was used to test the hypothesis that +APOE4 adults with a family history of AD would exhibit altered patterns of brain activity in the recollection-related memory network, comprised of medial frontal, parietal and medial temporal cortices, compared to APOE4 non-carriers (-APOE4). We also tested for group differences in the correlation between event-related brain activity and memory performance in +APOE4 compared to -APOE4 adults using behavioral-PLS (B-PLS). We found group similarities in memory performance and in task-related brain activity in the recollection network. However, the B-PLS results indicated there were group differences in brain activity-behavior correlations in ventral occipito-temporal, medial temporal, and medial prefrontal cortices during episodic encoding. These findings are consistent with previous literature on the influence of APOE4 on brain activity and provide new perspective on potential gene-based differences in brain-behavior relationships in people with parental history of AD. Future research should further investigate the potential to distinguish risk of AD development based on memory performance and associated patterns of brain activity.

neuroscience↗

bioRxiv2019

Sex differences in the neural correlates of age-related episodic memory decline

Aging is associated with episodic memory decline and alterations in memory-related brain function. However, it remains unclear if age-related memory decline is associated with similar patterns of brain aging in women and men. In the current task fMRI study, we tested the hypothesis that there are sex differences in the effect of age and memory performance on brain activity during episodic encoding and retrieval of face-location associations (spatial context memory). Forty-one women and 41 men between the ages of 21 to 76 years participated in this study. Between-group multivariate partial least squares (PLS) analysis of the fMRI data was conducted to directly test for sex-group differences and similarities in age-related and performance-related patterns of brain activity. Our behavioural analysis indicated no significant sex differences in retrieval accuracy on the fMRI tasks. In relation to performance effects, we observed similarities and differences in how retrieval accuracy related to brain activity in women and men. Both sexes activated dorsal and lateral prefrontal cortex (PFC), inferior parietal cortex (IPC) and left parahippocampal gyrus (PHG) at encoding and this supported subsequent memory performance. However, there were sex differences in retrieval activity in these same regions and in lateral occipital-temporal and ventrolateral PFC. In relation to age effects, we observed sex differences in the effect of age on memory-related activity within PFC, IPC, PHG and lateral occipital-temporal cortices. Overall, our findings suggest that the neural correlates of age-related spatial context memory decline differ in women compared to men.

neuroscience↗

bioRxiv2019

Age- and reserve-related increases in fronto-parietal and anterior hippocampal activity during episodic encoding predict subsequent memory

Remembering associations between encoded items and their contextual setting is a feature of episodic memory. Although this ability deteriorates with age in general, there is substantial variability in how older individuals perform on episodic memory tasks. This variability may stem from genetic and/or environmental factors related to reserve, allowing some individuals to compensate for age-related decline through differential recruitment of brain regions. In this fMRI study, we tested predictions related to reserve and compensation in a large adult lifespan sample (N=154). We used multivariate Behaviour Partial Least Squares (B-PLS) analysis to examine how age, retrieval accuracy, and a proxy measure of reserve, impacted brain activity patterns during spatial and temporal context encoding and retrieval. Reserve modulated age-related compensatory brain responses in ventral visual, temporal, and fronto-parietal regions during memory encoding as a function of task demands. Activity in inferior parietal, medial temporal, and ventral visual regions were strongly impacted by age at encoding and retrieval, but were also related to individual differences in reserve. Our findings are consistent with the concepts of reserve and compensation and suggest that reserve may mitigate age-related decline by modulating compensatory brain responses in the aging brain.

neuroscience↗

bioRxiv2017

Family history and APOE4 risk for Alzheimer’s Disease impact the neural correlates of episodic memory by early midlife

Episodic memory impairment is a consistent, pronounced deficit in pre-clinical stages of late-onset Alzheimers disease (AD). Individuals with risk factors for AD exhibit altered brain function several decades prior to the onset of AD-related symptoms. In the current event-related fMRI study of spatial context memory we tested the hypothesis that middle-aged adults (MA; 40-58yrs) with a family history of late onset AD (MA+FH), or a combined +FH and apolipoprotein E {varepsilon}4 allele risk factors for AD (MA+FH+APOE4), will exhibit differences in encoding and retrieval-related brain activity, compared to - FH-APOE4 MA controls. We also hypothesized that the two at-risk MA groups will exhibit distinct patterns of correlation between brain activity and memory performance, compared to controls. To test these hypotheses we conducted multivariate task, and behavior, partial least squares analysis of fMRI data obtained during successful context encoding and retrieval. Our results indicate that even though there were no significant group differences in context memory performance, there were significant differences in brain activity and brain-behavior correlations involving hippocampus, left angular gyrus, cingulate, and precuneus in MA with AD risk factors, compared to controls. In addition, we observed that brain activity and brain-behavior correlations in anterior-medial PFC and in ventral visual cortex differentiated the two MA risk groups from each other, and from MAcontrols. This is the first study to show that there are differences in the brain areas engaged during context memory encoding and retrieval in middle-aged adults with +FH and +APOE-4 risk factors for late onset AD, compared to controls.

neuroscience↗