Michelle Voss

• University of Iowa

Different tasks of episodic memory (EM) are only moderately correlated with each other. Furthermore, various EM tasks exhibit disproportional relationships with the hippocampus. This study examined the covariance structure of EM tasks and assessed whether this structure relates differently to hippocampal volume (HV) in a sample of 648 cognitively u...

Background Improvement of cognitive functions is often accompanied by changes in brain function after cognitive training in older adults. In this large‐scale dual‐site fMRI study we investigated the effects of BrainHQ cognitive training (CT; ®Posit Science Inc.) and an active control (AC) group on brain activations during a demanding executive cont...

An underlying hypothesis for broad transfer from cognitive training is that the regional brain signals engaged during the training task are related to the transfer tasks. However, it is unclear whether the brain activations elicited from a specific cognitive task can generalize to performance of other tasks, esp. in normal aging where cognitive tra...

Large central arterial stiffness is a risk factor for cerebrovascular damage and subsequent progression of neurodegenerative diseases, including Alzheimer’s disease and dementia. However, arterial stiffness is determined by both the intrinsic components of the arterial wall (structural stiffness) and the load (i.e., arterial blood pressure) exerted...

Objectives Older adult executive function varies widely due to brain and cognitive aging. Variance in older adult executive function is linked to increased response conflict from cognitive and brain aging. Cognitive Reserve (CR) is a theoretical protective mechanism that lessens brain aging’s impact on cognition and is associated with greater educa...

Objectives Cognitive Training (CT) has been investigated as a means of delaying age-related cognitive decline in older adults. However, its impact on biomarkers of age-related structural brain atrophy has rarely been investigated, leading to a gap in our understanding of the linkage between improvements in cognition and brain plasticity. This study...

Background The relationship of cognition and the 24-hour activity cycles (24-HAC), encompassing physical activity, sedentary behaviour, and sleep, in older adults with mild cognitive impairment (MCI) remains uncertain. Distinct combinations of 24-HAC behaviours can characterize unique activity profiles and influence cognition. We aimed to character...

Objective Processing speed declines with age and is a strong predictor of age-related cognitive decline in other domains, and in predicting who will need help with tasks of daily living in later years. Higher cardiorespiratory fitness (CRF) reflects better cardiopulmonary health and is related to maintenance of processing speed and cognition into l...

Previous research has indicated that cardiorespiratory fitness (CRF) is structurally and functionally neuroprotective in older adults. However, questions remain regarding the mechanistic role of CRF on cognitive and brain health. The purposes of this study were to investigate if higher pre‐intervention CRF was associated with greater change in func...

Introduction: Accumulating evidence suggests that increased central, rather than peripheral, blood pressure (BP) may be a better predictor of cardiovascular risk. The shape of the central BP waveform is determined by ventricular-arterial interactions that can be quantified via novel hemodynamic analyses, from which some parameters have been implica...

Central pulse pressure (PP) is the sum of a forward and backward traveling pressure waves which have been associated with cardiovascular disease (CVD) risk. However, previous studies have reported differential findings regarding importance of the forward versus the backward wave for CVD risk. Therefore, we sought to determine the degree to which th...

Physical exercise acutely improves hippocampal-based learning and memory in rodents and humans. While animal studies have mainly offered cellular- and synaptic-level accounts of these effects, human neuroimaging studies show that exercise improves hippocampal-cortical connectivity at the macroscale level. However, the neurophysiological basis for e...

Purpose Studies of the neural underpinnings of bipolar type I disorder have focused on the emotional control network. However, there is also growing evidence for cerebellar involvement, including abnormal structure, function, and metabolism. Here, we sought to assess functional connectivity of the cerebellar vermis with the cerebrum in bipolar diso...

Purpose Aging is associated with a reduction in brain modularity as well as aspects of executive function, namely, updating, shifting, and inhibition. Previous research has suggested that the aging brain exhibits plasticity. Further, it has been hypothesized that broad-based intervention models may be more effective in eliciting overall gains in ex...

Objective: Central artery reservoir pressure and excess pressure (XSP) are associated with cardiovascular disease (CVD) events and mortality. However, sex differences in the trajectory of central reservoir pressure and XSP with advancing age and their relations with vascular markers of subclinical CVD risk are incompletely understood. Therefore, w...

Purpose: Studies of the neural underpinnings of bipolar type I disorder have focused on the emotional control network. However, there is also growing evidence for cerebellar involvement, including abnormal structure, function, and metabolism. Here, we sought to assess functional connectivity of the cerebellum with the cerebrum in bipolar disorder a...

Background Targeted exercise training is a promising strategy for promoting cognitive function and preventing dementia in older age. Despite the utility of exercise as an intervention, variation still exists in exercise-induced cognitive gains and questions remain regarding the type of training (i.e., what), as well as moderators (i.e., for whom) a...

Background: Targeted exercise training is a promising strategy for promoting cognitive function and preventing dementia in older age. Despite the utility of exercise as an intervention, variation still exists in exercise-induced cognitive gains and questions remain regarding the type of training (i.e., what), as well as moderators (i.e., for whom)...

Cerebrovascular reactivity (CVR) to a physiological stimulus is a commonly used surrogate of cerebrovascular health. Cross-sectional studies using Blood Oxygen Level Dependent (BOLD) neuroimaging demonstrated lower BOLD-CVR to hypercapnia among adults with high compared with lower cardiorespiratory fitness (CRF) in contrast to transcranial Doppler...

Physical activity has shown tremendous promise for counteracting cognitive aging, but also tremendous variability in cognitive benefits. We describe evidence for how exercise affects cognitive and brain aging, and whether cardiorespiratory fitness is a key factor. We highlight a brain network framework as a valuable paradigm for the mechanistic ins...

The hippocampus is negatively affected by aging and is critical for spatial navigation. While there is evidence that wayfinding navigation tasks are especially sensitive to preclinical hippocampal deterioration, these studies have primarily used volumetric hippocampal imaging without considering microstructural properties or anatomical variation wi...

White matter deterioration is associated with cognitive impairment in healthy aging and Alzheimer's disease. It is critical to identify interventions that can slow down white matter deterioration. So far, clinical trials have failed to demonstrate the benefits of aerobic exercise on the adult white matter using diffusion Magnetic Resonance Imaging....

Background: While it has been shown that aerobic exercise interventions are well tolerated in participants with the Huntington disease (HD) gene mutation, no study to date has tested whether an aerobic exercise intervention benefits brain structure and function in pre-manifest HD. Objective: In this study we utilized magnetic resonance (MR) imag...

White matter (WM) deterioration is an important mechanism of cognitive decline in healthy aging and dementia. Engaging in aerobic exercise to improve cardiorespiratory fitness (CRF) is considered one of the most promising ways to improve cognitive and brain health in aging. Yet, no randomized controlled trials have reported benefits of aerobic exer...

Aerobic exercise and physical activity (PA) are known to benefit cognition in adulthood. However, a typical older adult spends most of the day sedentary or in light PA, behaviors that are typically poorly captured by questionnaires. To better understand the associations between time spent in different intensities of lifestyle PA and cognition, we m...

Our jobs can provide intellectually and socially enriched environments but also be the source of major psychological and physical stressors. As the average full-time worker spends >8 h at work per weekday and remains in the workforce for about 40 years, occupational experiences must be important factors in cognitive and brain aging. Therefore, we s...

Introduction Resting-state functional connectivity is coherent brain activity in a task-free state that strongly correlates to task-evoked sensory, motor, and higher-order cognitive systems. Certain networks show decreased functional connectivity with aging. Aging is associated with changes in circadian rhythms and sleep-wake cycles. Limited resear...

Previous researchers have reported that aerobic exercise improves cognition in older adults; however, few researchers have examined the role of arousal on improvements in cognition after exercise. The purpose of this study was to understand how changes in arousal acutely affect changes in cognitive performance after a single session of light compar...

The neural mechanisms that support synchrony of conversational behaviors (e.g., word production, turn length) are not well understood. Lesion work has suggested that the ventromedial prefrontal cortex (vmPFC) is important for noncontent speech convergence, which measures if word production becomes more similar across a conversation (Gordon, Tranel,...

Purpose: Previous studies report memory and functional connectivity of memory systems improve acutely after a single aerobic exercise session or with training, suggesting the acute effects of aerobic exercise may reflect initial changes that adapt over time. In this trial, for the first time, we test the proof-of-concept of whether the acute and t...

Declining episodic memory is common among otherwise healthy older adults, in part due to negative effects of aging on hippocampal circuits. However, there is significant variability between individuals in severity of aging effects on the hippocampus and subsequent memory decline. Importantly, variability may be influenced by modifiable protective p...

Objectives: We examined whether a home-based, adaptive cognitive training program would lead to cognitive performance changes on a neuropsychological test battery in cognitively normal older adults. Method: Sixty-eight older adults (age = 70.0, SD=3.74) were randomly assigned to either cognitive training (CT) or an active control group (AC, casu...

Declining episodic memory is common among otherwise healthy older adults, in part due to negative effects of aging on hippocampal circuits. However, there is significant variability between individuals in severity of aging effects on the hippocampus and subsequent memory decline. Importantly, variability may be influenced by modifiable protective p...

Facial affect recognition deficits following traumatic brain injury (TBI) have been well documented, as has their relationship with impairment in several other cognitive domains. However, little is known about the neurobiological mechanisms underlying affect recognition deficits, in particular mechanisms underlying different aspects of facial affec...

Introduction Habitual aerobic exercise is hypothesized to attenuate age‐related declines in cognitive performance mediated in part by alterations in cerebrovascular reactivity (CVR). However, cross‐sectional studies using fMRI blood oxygen level dependent (BOLD) imaging demonstrate paradoxically lower CVR (cerebral blood flow response to experiment...

No medications prevent or reverse age-related cognitive decline. Physical activity (PA) enhances memory in rodents, but findings are mixed in human studies. As a result, exercise guidelines specific for brain health are absent. Here, we re-examine results from human studies, and suggest the use of more sensitive tasks to evaluate PA effects on age-...

There is growing evidence that aerobic exercise protects against age-related cognitive decline and that cardiorespiratory fitness is an important factor for these benefits. Studies also suggest that combining physical activity with cognitive enrichment is beneficial. We further examine these predictions by comparing effects of a nutritional supplem...

Cognitive enhancements following a single bout of exercise are frequently attributed to increases in cerebral blood flow, however to date we have little understanding of the extent to which such bouts of exercise actually even influence cerebral blood flow following the cessation of exercise. To gain such insight, both regional and global changes i...

Age and cortical structure are both associated with cognition, but characterizing this relationship remains a challenge. A popular approach is to use functional network organization of the cortex as an organizing principle for post-hoc interpretations of structural results. In the current study, we introduce two complimentary approaches to structur...

Dataset of average predictions for each subject and network from predictive models. (CSV)

Document containing supplemental figures and tables. Figure A. Distribution of the total number of vertices selected across all 500 fold training sets (5 folds, 100 iterations) and collapsed across all alpha thresholds (.05,.01,.001,.0005,.0001) for each model type. Note, vertices were selected based on their univariate association with cognition....

Dataset containing prediction model results. (CSV)

Dataset containing the composite scores, individual task scores, and summary structural measures across the entire cortex. (XLSX)

Although facial affect recognition deficits are well documented in individuals with moderate-to-severe traumatic brain injury (TBI), little research has examined the neural mechanisms underlying these impairments. Here, we use diffusion tensor imaging (DTI), specifically the scalars fractional anisotropy (FA), mean diffusivity (MD), and radial diff...

Background Healthy aging is associated with a decline in multiple functional domains including perception, attention, short and long-term memory, reasoning, decision-making, as well as cognitive and motor control functions; all of which are significantly modulated by an individual’s level of alertness. The control of alertness also significantly de...

It is well established that many individuals with traumatic brain injury (TBI) are impaired at facial affect recognition, yet little is known about the mechanisms underlying such deficits. In particular, little work has examined whether the breakdown of facial affect recognition abilities occurs at the perceptual level (e.g., recognizing a smile) o...

Background Subtle, but observable, changes in mobility often exist among older adults with mild cognitive impairment (MCI). Notably, these changes are not inconsequential. Therefore, there is a strong interest to better understand the underlying neural correlates of gait slowing among older adults with MCI. In this study, we aimed to characterize p...

Compared with young adults, older adults demonstrate difficulty forming and retrieving episodic memories. One proposed mechanism is that older adults are impaired at binding information into nonoverlapping representations, which is a key function of the hippocampus. The current experiments evaluate age differences in acquiring new memories using a...

One of the keys to understanding scholastic success is to determine the neural processes involved in school performance. The present study is the first to use a whole-brain connectivity approach to explore whether functional connectivity of resting state brain networks is associated with scholastic performance in seventy-four 7- to 9-year-old child...

Illustration of all components in group ICA. We labeled the ICs as: (1) Sensory-Motor Network, (3) Primary Visual Network, (4) Thalamus, (5) Secondary Visual, (6) DAN*, (7) Auditory, (9) Anterior Prefrontal, (10) Corpus Callosum, (11) SAL*, (12) Lateral occipital, (13) Anterior DMN*, (14) Cerebellum/Brainstem, (15) Posterior DMN*, (16) Cerebellum/B...

Individual scholastic achievement-related differences in functional connectivity between each network core and voxels throughout the brain, via a mixed effects whole-brain model using FSL’s flameo. Reading Composite = Word recognition + Reading comprehension. Mathematics Composite = Math Concepts, Applications, and Computation. Written Language Com...

Recent work suggests that the brain can be conceptualized as a network comprised of groups of sub-networks or modules. The extent of segregation between modules can be quantified with a modularity metric, where networks with high modularity have dense connections within modules and sparser connections between modules. Previous work has shown that h...

Evidence from tasks that primarily tap either hippocampal- or striatal-based memory systems suggests that although these systems often compete for control of behavior, aging is associated with greater cooperation between them. This may stem from altered prefrontal cortex function. Here, we use a configural response task designed to engage both memo...

[This corrects the article on p. 344 in vol. 11, PMID: 28713255.].

Vascular cognitive ischaemia (VCI) is the second most common type of cognitive dysfunction worldwide and is due to cerebrovascular disease. While targeted aerobic exercise is a promising approach to delay the progression of VCI by reducing cardiometabolic risk factors, few randomized controlled trials to date have specifically assessed the efficacy...

Impaired mobility is a major concern for older adults and has significant consequences. While the widely accepted belief is that improved physical function underlies the effectiveness of targeted exercise training in improving mobility and reducing falls, recent evidence suggests cognitive and neural benefits gained through exercise may also play a...

Impaired mobility is a major concern for older adults and has significant consequences. While the widely accepted belief is that improved physical function underlies the effectiveness of targeted exercise training in improving mobility and reducing falls, recent evidence suggests cognitive and neural benefits gained through exercise may also play a...

Background: Vascular cognitive impairment (VCI) results from cerebrovascular disease, and worldwide, it is the second most common type of cognitive dysfunction. While targeted aerobic training is a promising approach to delay the progression of VCI by reducing cardiometabolic risk factors, few randomised controlled trials to date have specifically...

Active experiencing is an intervention aimed at attenuating cognitive declines with mindfulness training via an immersive acting program, and has produced promising results in older adults with limited formal education. Yet, the cognitive mechanism(s) of intervention benefits and generalizability of gains across cognitive domains in the course of h...

Functional connectivity, as measured by resting-state fMRI, has proven a powerful method for studying brain systems in the context of behavior, development, and disease states. However, the relationship of functional connectivity to structural connectivity remains unclear. If functional connectivity relies on structural connectivity, then anatomica...

Recent attention has highlighted the importance of reducing sedentary time for maintaining health and quality of life. However, it is unclear how changing sedentary behavior may influence executive functions and self-regulatory strategy use, which are vital for the long-term maintenance of a health behavior regimen. The purpose of this cross-sectio...

Acute exercise enhances inter-networkFC between the ARN and the SAL. A post-hoc seed-based analysis of the right anterior insula during baseline rs-fMRI scans, which exhibited a main effect of exercise condition for FC increase with the ARN (in favor of active exercise, relative to passive exercise, see Fig 4A). The resulting FC map (red-yellow) is...

Acute exercise enhances inter-networkFC between the R ECN and the DAN. In these panels, a post-hoc seed-based analysis was performed in which the originating seed exhibited a main effect of exercise condition for FC increase with the R ECN (in favor of active exercise, relative to passive exercise). (A) Seed-based analysis of the right intraparieta...

Independent components that were excluded from the current analyses. Out of the 6 ICs that were not included in the analyses, 4 of them had a significant spatial correlation with at least one of the Yeo reference networks. IC 1 overlapped with the visual network reference maps. We excluded IC 1 because there was another IC that included both visual...

Correlation between change in heart rate and change in functional connectivity. These voxelwise maps show, for each network, where there was a positive correlation between change in heart rate and change in functional connectivity for the Passive and Active conditions separately for younger adults, older adults, and all subjects.

Data-driven resting-state networks as compared to reference networks. This figure displays the topographical similarity (using spatial cross-correlation) between the resting-state networks derived from our sample (filled-in colormaps) and those from Yeo et al. 2011 (outlined in cyan). Note: Yeo et al. found a bilateral frontoparietal/executive cont...

Correlation between change in heart rate and change in functional connectivity. These voxelwise maps show, for each network, where there was a positive correlation between change in heart rate and change in functional connectivity for the Active and Passive conditions separately for younger adults, older adults, and all subjects.

The variety and availability of casual video games presents an exciting opportunity for applications such as cognitive training. Casual games have been associated with fluid abilities such as working memory (WM) and reasoning, but the importance of these cognitive constructs in predicting performance may change across extended gameplay and vary wit...

This chapter will review the current state of knowledge on the effects of physical and mental (cognitive) training on hippocampal structure and function. We will primarily focus on normal aging and patient populations, though some relevant examples with young adults will also be described. Where possible, we will briefly review relevant research wi...

Degeneration of cerebral white matter (WM), or structural disconnection, is one of the major neural mechanisms driving age-related decline in cognitive functions, such as processing speed. Past cross-sectional studies have demonstrated beneficial effects of greater cardiorespiratory fitness, physical activity, cognitive training, social engagement,...

Although the hippocampus experiences age-related anatomical and functional deterioration, the effects of aging vary across hippocampal-dependent cognitive processes. In particular, whether or not the hippocampus is known to be required for a spatial memory process is not an accurate predictor on its own of whether aging will affect performance. The...

Many studies have shown a positive relationship between physical activity and mental health. In particular, physical activity and cardiovascular fitness have been linked with better cognitive control, learning and memory, and reduced risk for neurodegenerative disease. However, there is still very little understanding of the neural and cerebrovascu...

Although several studies have demonstrated that facial-affect recognition impairment is common following moderate-severe traumatic brain injury (TBI), and that there are diffuse alterations in large-scale functional brain networks in TBI populations, little is known about the relationship between the two. Here, in a sample of 26 participants with T...

Although there is promising evidence that regular physical activity could counteract age-related decline in cognitive and brain function, the mechanisms for this neuroprotection remain unclear. The acute effects of exercise can provide insight into the mechanisms by which the brain adapts to habitual exercise by reflecting transient modulations of...

Objectives: Although it has been well documented that traumatic brain injury (TBI) can result in communication impairment, little work to date has examined the relationship between social communication skills and structural brain integrity in patients with TBI. The aim of the current study was to investigate the association between self- and other...

Impaired mobility, such as falls, may be an early biomarker of subsequent cognitive decline and is associated with subclinical alterations in both brain structure and function. In this 12-month prospective study, we examined whether there are volumetric differences in gray matter and subcortical regions, as well as cerebral white matter, between ol...

Introduction Habitual aerobic exercise training is associated with preserved cognition, higher cerebrovascular reactivity (CVR) via experimental hypercapnia and transcranial Doppler, lower aortic stiffness and higher white matter brain volumes in older adults. However, global CVR assessed via functional magnetic resonance imaging (fMRI) blood oxyge...

Falls are a major health-care concern, and while dual-task performance is widely recognized as being impaired in those at-risk for falls, the underlying neurocognitive mechanisms remain unknown. A better understanding of the underlying mechanisms could lead to the refinement and development of behavioural, cognitive, or neuropharmacological interve...

Studies of patients with brain damage have highlighted a broad neural network of limbic and prefrontal areas as important for adaptive decision-making. However, some patients with damage outside these regions have impaired decision-making behavior, and the behavioral impairments observed in these cases are often attributed to the general variabilit...

Introduction: Higher central elastic artery stiffness is associated with greater brain white matter hyperintensity volume and lower cognitive performance in older adults. However, it is unknown if higher central artery stiffness is related to regional decreases in brain white matter integrity (WMI) and reductions in working memory or processing spe...

White matter structure declines with advancing age and has been associated with a decline in memory and executive processes in older adulthood. Yet, recent research suggests that higher physical activity and fitness levels may be associated with less white matter degeneration in late life, although the tract-specificity of this relationship is not...

The concept of attachment in long-term interpersonal relationships has been linked to relationship outcome and social-emotional health. To date, no relationship between the structural properties of the human amygdala and attachment in romantic relationships (measured through self-reported attachment related anxiety and avoidance) has been described...

Higher cardiorespiratory fitness is associated with better cognitive performance and enhanced brain activation. Yet, the extent to which cardiorespiratory fitness-related brain activation is associated with better cognitive performance is not well understood. In this cross-sectional study, we examined whether the association between cardiorespirato...

Age is often associated with a decline in cognitive abilities that are important for maintaining functional independence, such as learning new skills. Many forms of motor learning appear to be relatively well preserved with age, while learning tasks that involve associative binding tend to be negatively affected. The current study aimed to determin...

Background: Obesity is associated with vascular risk factors that in turn, may increase dementia risk. However, higher body mass index (BMI) in late life may be neuroprotective. The possible neural mechanisms underlying the benefit of higher BMI on cognition in older adults are largely unknown. Thus, we used functional connectivity magnetic resonan...

Higher cardiorespiratory fitness (CRF) and physical activity (PA) in old age are associated with greater brain structural and functional integrity, and higher cognitive functioning. However, it is not known how different aspects of lifestyle such as sedentariness, light PA (LI-PA), or moderate-to-vigorous physical activity (MV-PA) relate to neural...