Stroop interference, hemodynamic response and aging: An event-related fMRI study

Not All Stroop-Type Tasks Are Alike: Assessing the Impact of Stimulus Material, Task Design, and Cognitive Demand via Meta-analyses Across Neuroimaging Studies

The Stroop effect is one of the most often studied examples of cognitive conflict processing. Over time, many variants of the classic Stroop task were used, including versions with different stimulus material, control conditions, presentation design, and combinations with additional cognitive demands. The neural and behavioral impact of this experimental variety, however, has never been systematically assessed. We used activation likelihood meta-analysis to summarize neuroimaging findings with Stroop-type tasks and to investigate whether involvement of the multiple-demand network (anterior insula, lateral frontal cortex, intraparietal sulcus, superior/inferior parietal lobules, midcingulate cortex, and pre-supplementary motor area) can be attributed to resolving some higher-order conflict that all of the tasks have in common, or if aspects that vary between task versions lead to specialization within this network. Across 133 neuroimaging experiments, incongruence processing in the color-word Stroop variant consistently recruited regions of the multiple-demand network, with modulation of spatial convergence by task variants. In addition, the neural patterns related to solving Stroop-like interference differed between versions of the task that use different stimulus material, with the only overlap between color-word, emotional picture-word, and other types of stimulus material in the posterior medial frontal cortex and right anterior insula. Follow-up analyses on behavior reported in these studies (in total 164 effect sizes) revealed only little impact of task variations on the mean effect size of reaction time. These results suggest qualitative processing differences among the family of Stroop variants, despite similar task difficulty levels, and should carefully be considered when planning or interpreting Stroop-type neuroimaging experiments.

Positive effects of brisk walking and Tai Chi on cognitive function in older adults: An fNIRS study

Exercise has shown to have beneficial effects on cognition in older adults. The purpose of this study was to investigate the cortical hemodynamic responses during the word-color Stroop test (WCST) prior and after acute walking and Tai Chi exercise by functional near-infrared spectroscopy (fNIRS). Twenty participants (9 males, mean age 62.8 ± 5.2), first underwent a baseline WCST test, after which they took three WCST tests in a randomized order, (a) after sitting rest (control), (b) after 6 minutes performing Tai Chi Quan, and (c) after a bout of 6 minutes brisk walking. During these four WCST tests cortical hemodynamic changes in the prefrontal area were monitored with fNIRS. Both brisk walking and Tai Chi enhanced hemodynamic activity during the Stroop incongruent tasks, leading to improved cognitive performance (quicker reaction time). Brisk walking induced a greater hemodynamic activity in the right dorsolateral prefrontal cortex (DLPFC) and ventrolateral prefrontal cortex (VLPFC) area, whereas Tai Chi induced a greater bilateral hemodynamic activity in the DLPFC and VLPFC areas. The present study provided empirical evidence of enhanced hemodynamic response in task- specific regions of the brain that can be achieved by a mere six minutes of brisk walking or Tai Chi in older adults.

Inhibition and Heart Rate Variability in Experimentally Induced Pain

Introduction

Pain is a complex experience that requires executive functions (EFs) to be processed. The autonomic outcome of the neural networks involved in the cognitive evaluation of pain is reflected by heart rate variability (HRV), an index of self-regulation abilities. Although some results suggest a relationship between HRV, EFs, and pain, studies focusing on this three-way relationship are still scarce.

Objective

This study aims to investigate the relationship between pain, cognitive, and autonomic mechanisms, hypothesizing an association between resting HRV and both cognitive and motor inhibition as indices of executive functioning. This relationship was investigated after an experimental-induced pain.

Methods

Seventy-six young adults were exposed to the Cold Pressure Arm Warp to induce experimental pain. HRV was collected, and cognitive tasks were administered to assess executive performance.

Results

The results showed that (1) HRV indices significantly increased during pain stimulation, (2) cognitive inhibition was positively correlated with vagal indices and with pain parameters, (3) both inhibition tasks significantly predicted pain threshold while the performance on the Stroop Task predicted pain tolerance.

Conclusion

Results suggest a three-way relationship. Further research would focus on the role of HRV and cognitive strategies in pain management in chronic pain conditions.

Global effects of aging on the hemodynamic response function in the human brain

In functional magnetic resonance imaging, the hemodynamic response function (HRF) is a transient, stereotypical response to local changes in cerebral hemodynamics and oxygen metabolism due to briefly (< 4 s) evoked neural activity. Accordingly, the HRF is often used as an impulse response with the assumption of linearity in data analysis. In cognitive aging studies, it has been very common to interpret differences in brain activation as age-related changes in neural activity. Contrary to this assumption, however, evidence has accrued that normal aging may also significantly affect the vasculature, thereby affecting cerebral hemodynamics and metabolism, confounding interpretation of fMRI aging studies. In this study, use was made of a multisensory stimulus to evoke the HRF in ~ 87% of cerebral cortex in cognitively intact adults with ages ranging from 22-75 years. The stimulus evokes both positive and negative HRFs, which were characterized using model-free parameters in native-space coordinates. Results showed significant age trends in HRF parameter distributions in terms of both amplitudes (e.g., peak amplitude and CNR) and temporal dynamics (e.g., full-width-at-half-maximum). This work sets the stage for using HRF methods as a biomarker for age-related pathology.

Modulating prospective memory and attentional control with high-definition transcranial current stimulation: Study protocol of a randomized, double-blind, and sham-controlled trial in healthy older adults

The ability to remember future intentions (i.e., prospective memory) is influenced by attentional control. At the neuronal level, frontal and parietal brain regions have been related to attentional control and prospective memory. It is debated, however, whether more or less activity in these regions is beneficial for older adults' performance. We will test that by systematically enhancing or inhibiting activity in these regions with anodal or cathodal high-definition transcranial direct current stimulation in older adults. We will include n = 105 healthy older volunteers (60-75 years of age) in a randomized, double-blind, sham-controlled, and parallel-group design. The participants will receive either cathodal, anodal, or sham high-definition transcranial direct current stimulation of the left or right inferior frontal gyrus, or the right superior parietal gyrus (1mA for 20 min). During and after stimulation, the participants will complete tasks of attentional control and prospective memory. The results of this study will clarify how frontal and parietal brain regions contribute to attentional control and prospective memory in older healthy adults. In addition, we will elucidate the relationship between attentional control and prospective memory in that age group. The study has been registered with ClinicalTrials.gov on the 12th of May 2021 (trial identifier: NCT04882527).

Cytoarchitectonic mapping of the human frontal operculum-New correlates for a variety of brain functions

The human frontal operculum (FOp) is a brain region that covers parts of the ventral frontal cortex next to the insula. Functional imaging studies showed activations in this region in tasks related to language, somatosensory, and cognitive functions. While the precise cytoarchitectonic areas that correlate to these processes have not yet been revealed, earlier receptorarchitectonic analysis resulted in a detailed parcellation of the FOp. We complemented this analysis by a cytoarchitectonic study of a sample of ten postmortem brains and mapped the posterior FOp in serial, cell-body stained histological sections using image analysis and multivariate statistics. Three new areas were identified: Op5 represents the most posterior area, followed by Op6 and the most anterior region Op7. Areas Op5-Op7 approach the insula, up to the circular sulcus. Area 44 of Broca's region, the most ventral part of premotor area 6, and parts of the parietal operculum are dorso-laterally adjacent to Op5-Op7. The areas did not show any interhemispheric or sex differences. Three-dimensional probability maps and a maximum probability map were generated in stereotaxic space, and then used, in a first proof-of-concept-study, for functional decoding and analysis of structural and functional connectivity. Functional decoding revealed different profiles of cytoarchitectonically identified Op5-Op7. While left Op6 was active in music cognition, right Op5 was involved in chewing/swallowing and sexual processing. Both areas showed activation during the exercise of isometric force in muscles. An involvement in the coordination of flexion/extension could be shown for the right Op6. Meta-analytic connectivity modeling revealed various functional connections of the FOp areas within motor and somatosensory networks, with the most evident connection with the music/language network for Op6 left. The new cytoarchitectonic maps are part of Julich-Brain, and publicly available to serve as a basis for future analyses of structural-functional relationships in this region.

Intrinsic functional brain connectivity is resilient to chronic hypoperfusion caused by unilateral carotid artery stenosis

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Unilateral internal carotid artery stenosis leads to chronic cerebral hypoperfusion.

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rsfMRI functional connectivity is well-compensated in asymptomatic ICA stenosis.

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Functional network properties remain stable before and after revascularization.

Introduction

Chronic cerebral hypoperfusion caused by asymptomatic high-grade stenosis of the internal carotid artery (ICA) has been associated with impaired cognitive function. Only few studies exist on underlying changes of functional connectivity (FC).

Methods

20 patients with unilateral high-grade ICA stenosis without MRI lesions and 25 aged-match controls underwent resting-state functional MRI (rsfMRI) and neuropsychological assessment. Patients were examined within ten days before and 6–10 weeks after surgical or interventional revascularization of carotid stenosis. We examined mean resting-state FC ipsi- and contralateral to stenosis and network topology using graph-theoretical measures.

Results

At baseline, intrahemispheric FC was similar for patients and healthy controls. After revascularization mean FC increased moderately without an effect on network topology. Patients performed worse in TMT B and Stroop test, while performance in global screening tests for dementia (Mini Mental Status Examination, DemTect) were comparable. Test results did not improve after revascularization.

Conclusion

In our study population, we find no effect of chronic hypoperfusion on FC and global cognitive function, although we observe minor impairments in processing speed and mental flexibility. The subtle increase of FC after revascularization could indicate excessive upregulation after restoration of perfusion. However, it might as well be a coincidental finding due to the limited sample size.

Abnormal EEG Signal Energy in the Elderly: A Wavelet Analysis of Event-related Potentials During a Stroop Task

BACKGROUND

Previous work showed that elderly with excess in theta activity in their resting state electroencephalogram (EEG) are at higher risk of cognitive decline than those with a normal EEG. By using event-related potentials (ERP) during a counting Stroop task, our prior work showed that elderly with theta excess have a large P300 component compared with normal EEG group. This increased activity could be related to a higher EEG signal energy used during this task.

NEW METHOD

By wavelet analysis applied to ERP obtained during a counting Stroop task we quantified the energy in the different frequency bands of a group of elderly with altered EEG.

RESULTS

In theta and alpha bands, the total energy was higher in elderly subjects with theta excess, specifically in the stimulus categorization window (258-516 ms). Both groups solved the task with similar efficiency.

COMPARISON WITH EXISTING METHODS

The traditional ERP analysis in elderly compares voltage among conditions and groups for a given time windows, while the frequency composition is not usually examined. We complemented our previous ERP analysis using a wavelet methodology. Furthermore, we showed the advantages of wavelet analysis over Short Time Fourier Transform when exploring EEG signal during this task.

CONCLUSIONS

The higher EEG signal energy in ERP might reflect undergoing neurobiological mechanisms that allow the elderly with theta excess to cope with the cognitive task with similar behavioral results as the normal EEG group. This increased energy could promote a metabolic and cellular dysregulation causing a greater decline in cognitive function.

Neural regions associated with gain-loss frequency and average reward in older and younger adults

Research on the biological basis of reinforcement-learning has focused on how brain regions track expected value based on average reward. However, recent work suggests that humans are more attuned to reward frequency. Furthermore, older adults are less likely to use expected values to guide choice than younger adults. This raises the question of whether brain regions assumed to be sensitive to average reward, like the medial and lateral PFC, also track reward frequency, and whether there are age-based differences. Older (60-81 years) and younger (18-30 years) adults performed the Soochow Gambling task, which separates reward frequency from average reward, while undergoing fMRI. Overall, participants preferred options that provided negative net payoffs, but frequent gains. Older adults improved less over time, were more reactive to recent negative outcomes, and showed greater frequency-related activation in several regions, including DLPFC. We also found broader recruitment of prefrontal and parietal regions associated with frequency value and reward prediction errors in older adults, which may indicate compensation. The results suggest greater reliance on average reward for younger adults than older adults.

Cognitive Control Promotes Either Honesty or Dishonesty, Depending on One's Moral Default

Cognitive control is crucially involved in making (dis)honest decisions. However, the precise nature of this role has been hotly debated. Is honesty an intuitive response, or is will power needed to override an intuitive inclination to cheat? A reconciliation of these conflicting views proposes that cognitive control enables dishonest participants to be honest, whereas it allows those who are generally honest to cheat. Thus, cognitive control does not promote (dis)honesty per se; it depends on one's moral default. In the present study, we tested this proposal using electroencephalograms in humans (males and females) in combination with an independent localizer (Stroop task) to mitigate the problem of reverse inference. Our analysis revealed that the neural signature evoked by cognitive control demands in the Stroop task can be used to estimate (dis)honest choices in an independent cheating task, providing converging evidence that cognitive control can indeed help honest participants to cheat, whereas it facilitates honesty for cheaters.SIGNIFICANCE STATEMENT Dishonesty causes enormous economic losses. To target dishonesty with interventions, a rigorous understanding of the underlying cognitive mechanisms is required. A recent study found that cognitive control enables honest participants to cheat, whereas it helps cheaters to be honest. However, it is evident that a single study does not suffice as support for a novel hypothesis. Therefore, we tested the replicability of this finding using a different modality (EEG instead of fMRI) together with an independent localizer task to avoid reverse inference. We find that the same neural signature evoked by cognitive control demands in the localizer task can be used to estimate (dis)honesty in an independent cheating task, establishing converging evidence that the effect of cognitive control indeed depends on a person's moral default.

The Aging Brain and Executive Functions Revisited: Implications from Meta-analytic and Functional-Connectivity Evidence

Healthy aging is associated with changes in cognitive performance, including executive functions (EFs) and their associated brain activation patterns. However, it has remained unclear which EF-related brain regions are affected consistently, because the results of pertinent neuroimaging studies and earlier meta-analyses vary considerably. We, therefore, conducted new rigorous meta-analyses of published age differences in EF-related brain activity. Out of a larger set of regions associated with EFs, only left inferior frontal junction and left anterior cuneus/precuneus were found to show consistent age differences. To further characterize these two age-sensitive regions, we performed seed-based resting-state functional connectivity (RS-FC) analyses using fMRI data from a large adult sample with a wide age range. We also assessed associations of the two regions' whole-brain RS-FC patterns with age and EF performance. Although our results largely point toward a domain-general role of left inferior frontal junction in EFs, the pattern of individual study contributions to the meta-analytic results suggests process-specific modulations by age. Our analyses further indicate that the left anterior cuneus/precuneus is recruited differently by older (compared with younger) adults during EF tasks, potentially reflecting inefficiencies in switching the attentional focus. Overall, our findings question earlier meta-analytic results and suggest a larger heterogeneity of age-related differences in brain activity associated with EFs. Hence, they encourage future research that pays greater attention to replicability, investigates age-related differences in deactivation, and focuses on more narrowly defined EF subprocesses, combining multiple behavioral assessments with multimodal imaging.

Neural correlates of the improvement of cognitive performance resulting from enhanced sense of competence: A magnetoencephalography study

The alterations in neural activity related to the improvement of cognitive performance, which would be leading to better academic performance, remain poorly understood. In the present study, we assessed neural activity related to the improvement of task performance resulting from academic rewards. Twenty healthy male volunteers participated in this study. All participants performed four sessions of a 1-back-Stroop task under both target and control conditions. An image indicating that the task performance of each participant was above average and categorized as being at almost the highest level was presented immediately after each session under the target condition, whereas a control image did not indicate task performance. Neural activity during the 1-back-Stroop task was recorded by magnetoencephalography. The correction rate of the 1-back-Stroop task in the final session relative to that in the first under the target condition was increased compared with the control condition. Correlation analysis revealed that the decreases in alpha band power in right Brodmann’s area (BA) 47 and left BA 7 were positively associated with the increased correction rate caused by the target condition. These findings are expected to contribute to a better understanding of the neural mechanisms underlying the improvement of cognitive performance.

Impact of age and cyclooxygenase inhibition on the hemodynamic response to acute cognitive challenges

Structural and functional changes in the cerebral vasculature occur with advancing age, which may lead to impaired neurovascular coupling (NVC) and cognitive decline. Cyclooxygenase (COX) inhibition abolishes age-related differences in cerebrovascular reactivity, but it is unclear if COX inhibition impacts NVC. The purpose of this study was to examine the influence of aging on NVC before and after COX inhibition. Twenty-three young (age = 25 ± 4 yr) and 21 older (age = 64 ± 5 yr) adults completed two levels of difficulty of the Stroop and n-back tests before and after COX inhibition. Middle cerebral artery blood velocity (MCAv) was measured using transcranial Doppler ultrasound and mean arterial blood pressure (MAP) was measured using a finger cuff. Hemodynamic variables were measured at rest and in response to cognitive challenges. During the Stroop test, older adults demonstrated a greater increase in MCAv (young: 2.2 ± 6.8% vs. older: 5.9 ± 5.8%; P = 0.030) and MAP (young: 2.0 ± 4.9% vs. older: 4.8 ± 4.9%; P = 0.036) compared with young adults. There were no age-related differences during the n-back test. COX inhibition reduced MCAv by 30% in young and 26% in older adults (P < 0.001 for both). During COX inhibition, there were no age-related differences in the percent change in MCAv or MAP in response to the cognitive tests. Our results show that older adults require greater increases in MCAv and MAP during a test of executive function compared with young adults and that any age-related differences in NVC were abolished during COX inhibition. Collectively, this suggests that aging is associated with greater NVC necessary to accomplish a cognitive task.

Ageing and multisensory integration: A review of the evidence, and a computational perspective

The processing of multisensory signals is crucial for effective interaction with the environment, but our ability to perform this vital function changes as we age. In the first part of this review, we summarise existing research into the effects of healthy ageing on multisensory integration. We note that age differences vary substantially with the paradigms and stimuli used: older adults often receive at least as much benefit (to both accuracy and response times) as younger controls from congruent multisensory stimuli, but are also consistently more negatively impacted by the presence of intersensory conflict. In the second part, we outline a normative Bayesian framework that provides a principled and computationally informed perspective on the key ingredients involved in multisensory perception, and how these are affected by ageing. Applying this framework to the existing literature, we conclude that changes to sensory reliability, prior expectations (together with attentional control), and decisional strategies all contribute to the age differences observed. However, we find no compelling evidence of any age-related changes to the basic inference mechanisms involved in multisensory perception.

Stroop switching card test: brief screening of executive functions across the lifespan

This study aimed to: (1) propose a novel version of the Stroop switching test, namely the Stroop Switching Card Test (SSCT), to assess the overall efficiency of executive functions (EF) and its underlying cognitive processes (conflict resolution and conflict adaptation); (2) examine the utility of the SSCT in the assessment of EF in different age groups (age range 15-75 years), compare its results with standard neuropsychological tests (SNT), and (3) examine the contribution of both the processing speed and cognitive reserve on the performance of all used tests. The SSCT showed more sensitivity to detect subtle executive dysfunction in the middle age (~50 years). Going further, the SSCT revealed a progressive decline in conflict adaptation over two life periods. The first period of decline started at ~50 years and the second at~ 65 years. The processing speed and cognitive reserve had a prominent role in our results, notably in SSCT.

Age-Related Changes in the Neural Processes of Reward-Directed Action and Inhibition of Action

Aging is associated with structural and functional brain changes which may impact the regulation of motivated behaviors, including both action and inhibition of action. As behavioral regulation is often exercised in response to reward, it remains unclear how aging may influence reward-directed action and inhibition of action differently. Here we addressed this issue with the functional magnetic resonance imaging data of 72 participants (aged 21-74) performing a reward go/no-go (GNG) task with approximately 2/3 go and 1/3 no-go trials. The go and no-go success trials were rewarded with a dollar or a nickel, and the incorrect responses were penalized. An additional block of the GNG task without reward/punishment served as the control to account for age-related slowing in processing speed. The results showed a prolonged response time (RT) in rewarded (vs. control) go trials with increasing age. Whole-brain multiple regressions of rewarded (vs. control) go trials against age and RT both revealed an age-related reduced activity of the anterior insula, middle frontal gyrus, and rostral anterior cingulate cortex. Furthermore, activity from these regions mediated the relationship between age and go performance. During rewarded (vs. control) no-go trials, age was associated with increased accuracy rate but decreased activation in the medial superior frontal and postcentral gyri. As these regions also exhibited age-related activity reduction during rewarded go, the finding suggests aging effects on common brain substrates that regulate both action and action inhibition. Taken together, age shows a broad negative modulation on neural activations but differential effects on performance during rewarded action and inhibition of action.

Brain networks mediating the influence of background music on selective attention

Prevalent across societies and times, music has the ability to enhance attention, a property relevant to clinical applications, but the underlying brain mechanisms remain unknown. It is also unclear whether music produces similar or differential effects with advancing age. Here, we used event-related functional magnetic resonance imaging to investigate the influence of music exposure evoking four types of emotions on distinct attentional components measured with a modified attention network test, across 19 young (21 ± 2.6) and 33 old participants (72 ± 5.4). We then determined whether music-related effects differed across age groups and whether they were associated with particular acoustic features. Background music during selective attention requiring distractor conflict resolution was associated with faster response times and greater activations of fronto-parietal areas during happy and high-arousing music, whereas sad and low-valence music was associated with slower responses and greater occipital recruitment. Shifting and altering components of attention were unaffected. The influence of music on performance and brain networks was similar between age groups. These behavioral and neuroimaging results demonstrate the importance of affective music dimensions, particularly arousal, in enhancing selective attention processes. This study adds novel support to the benefits of music in the rehabilitation of attention functions.

Age-Related Decreases in Interhemispheric Resting-State Functional Connectivity and Their Relationship With Executive Function

Age-related alterations of functional brain networks contribute to cognitive decline. Current theories indicate that age-related intrinsic brain functional reorganization may be a critical marker of cognitive aging. Yet, little is known about how intrinsic interhemispheric functional connectivity changes with age in adults, and how this relates to critical executive functions. To address this, we examined voxel-mirrored homotopic connectivity (VMHC), a metric that quantifies interhemispheric communication, in 93 healthy volunteers (age range: 19-85) with executive function assessment using the Delis-Kaplan Executive Function System (D-KEFS) scales. Resting functional MRI data were analyzed to assess VMHC, and then a multiple linear regression model was employed to evaluate the relationship between age and the whole-brain VMHC. We observed age-related reductions in VMHC of ventromedial prefrontal cortex (vmPFC) and hippocampus in the medial temporal lobe subsystem, dorsal anterior cingulate cortex and insula in salience network, and inferior parietal lobule in frontoparietal control network. Performance on the color-word inhibition task was associated with VMHC of vmPFC and insula, and VMHC of vmPFC mediated the relationship between age and CWIT inhibition reaction times. The percent ratio of correct design scores in design fluency test correlated positively with VMHC of the inferior parietal lobule. The current study suggests that brain interhemispheric functional alterations may be a promising new avenue for understanding age-related cognitive decline.

Study Protocol: Does an Acute Intervention of High-Intensity Physical Exercise Followed by a Brain Training Video Game Have Immediate Effects on Brain Activity of Older People During Stroop Task in fMRI?-A Randomized Controlled Trial With Crossover Design

Background: Elderly people are affected by processes leading to decline in various aspects of daily living that impair their quality of life. Regarding neurological aspects, executive functions have been shown to be valuable for daily life and to slow decline during aging. Most intervention studies intended to improve cognitive functions during aging specifically address long-term destructive processes and countermeasures. However, to an increasing degree, studies also investigate the acute benefits that prove to be useful for daily life, such as physical exercise or video games in the form of exercise video gaming (“exergaming”). Because little is known about the change in cognitive ability following acute intervention of a combination of physical exercise and video gaming, especially for older people, this work is designed as an attempt to address this matter.

Methods: This study is a randomized crossover controlled trial to test the response to an acute bout of high-intensity physical exercise followed by a short session with a brain training (Brain Age) video game in physically active and cognitively healthy older adults (60–70 years). The response is measured using Stroop task performance (cognitive task for executive function) and related brain activity assessed with functional magnetic resonance imaging (fMRI). The control conditions are low-intensity physical exercise and Tetris for video gaming.

Discussion: This study is intended to provide insight into the alteration of executive function and its related brain activity from an acute intervention with a combination of physical exercise and video gaming in older people. The protocol might not be implementable in daily life to improve cognitive abilities. However, the results can support future studies that investigate cognition and the combination of physical exercise and video gaming. Moreover, it can provide real-life implications.

Trial registration: This trial was registered in The University Hospital Medical Information Network Clinical Trials Registry (UMIN000033054). Registered 19 July 2018, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000037687.

Neuropsychological functions of verbal recall and psychomotor speed significantly affect pain tolerance

Background

Effects from cognitive performance on pain tolerance have been documented, however, sample sizes are small and confounders often overlooked. We aimed to establish that performance on neuropsychological tests was associated with pain tolerance, controlling for salient confounders.

Methods

This was a cross‐sectional study nested within the Tromsø‐6 survey. Neuropsychological test performance and the cold pressor test were investigated in 4,623 participants. Due to significant interaction with age, participants were divided into three age groups (<60, ≥60 to <70 and ≥70 years). Cox proportional hazard models assessed the relationship between neuropsychological tests and cold pressure pain tolerance, using hand‐withdrawal as event. The fully adjusted models controlled for sex, education, BMI, smoking status, exercise, systolic blood pressure, sleep problems and mental distress.

Results

In the adjusted models, participants aged ≥70 years showed a decreased hazard of hand withdrawal of 18% (HR 0.82, 95% CI (0.73, 0.92) per standard deviation on immediate verbal recall, and a decreased hazard of 23% (HR 0.77, 95% CI (0.65, 0.08) per standard deviation on psychomotor speed. Participants aged ≥60 to <70 years had a significant decreased hazard of 11% (HR 0.89, 95% CI (0.80, 0.98) per standard deviation on immediate word recall. In participants aged <60 years, there was a decreased hazard of 14% (HR 0.86 95% CI: 0.76, 0.98), per standard deviation on psychomotor speed.

Conclusion

Better performance on neuropsychological tests increased pain tolerance on the cold pressor test. These exposure effects were present in all age groups.

Significance

This paper describes substantial associations between cognitive functioning and cold pressor tolerance in 4,623 participants. Reduced psychomotor speed and poor verbal recall gave greater odds for hand‐withdrawal on the cold pressor task. The associations were stronger in older participants, indicating an interaction with age.

Cognitive Load Affects Speech Motor Performance Differently in Older and Younger Adults

Purpose The aim of this study was to determine the impact of cognitive load imposed by a speech production task on the speech motor performance of healthy older and younger adults. Response inhibition, selective attention, and working memory were the primary cognitive processes of interest. Method Twelve healthy older and 12 healthy younger adults produced multiple repetitions of 4 sentences containing an embedded Stroop task in 2 cognitive load conditions: congruent and incongruent. The incongruent condition, which required participants to suppress orthographic information to say the font colors in which color words were written, represented an increase in cognitive load relative to the congruent condition in which word text and font color matched. Kinematic measures of articulatory coordination variability and movement duration as well as a behavioral measure of sentence production accuracy were compared between groups and conditions and across 3 sentence segments (pre-, during-, and post-Stroop). Results Increased cognitive load in the incongruent condition was associated with increased articulatory coordination variability and movement duration, compared to the congruent Stroop condition, for both age groups. Overall, the effect of increased cognitive load was greater for older adults than younger adults and was greatest in the portion of the sentence in which cognitive load was manipulated (during-Stroop), followed by the pre-Stroop segment. Sentence production accuracy was reduced for older adults in the incongruent condition. Conclusions Increased cognitive load involving response inhibition, selective attention, and working memory processes within a speech production task disrupted both the stability and timing with which speech was produced by both age groups. Older adults' speech motor performance may have been more affected due to age-related changes in cognitive and motoric functions that result in altered motor cognition.

A Revised Mental Energy Hypothesis of the g Factor in Light of Recent Neuroscience

The article proposes a revised mental energy hypothesis for the emergence of the g factor. Charles E. Spearman interpreted the g factor as a kind of domain-general mental energy. Nowadays, it is known that the energy currency of organisms is the chemical energy transporter adenosine triphosphate (ATP). ATP is produced by complex metabolic processes (mainly by glucose oxidation), and most of it in the human brain is used for neural signaling. There are substantial individual differences in the metabolic properties of the brain, which lead to different levels of energy production. It is thereby proposed to place more emphasis on individual differences of metabolic functions in intelligence research. Neuroscientific findings suggest that increased brain metabolism and, therefore, higher energy-production levels facilitate better performance on different cognitive tasks. These findings are not in conflict with the refined neural efficiency hypothesis. In addition, building on Dennis Garlick’s proposal that neural plasticity is the core process underlying the development of the g factor, it is illustrated why ATP is crucial for neural plasticity. Taken together, the direct effects of level of energy production on cognitive performance and the relations with neural plasticity suggest an important role in the emergence of the g factor.

Age-related changes in attention control and their relationship with gait performance in older adults with high risk of falls

BACKGROUND

Falls are the leading cause of injury-related deaths in the elderly worldwide. Both gait impairment and cognitive decline have been shown to constitute major fall risk factors. However, further investigations are required to establish a more precise link between the influence of age on brain systems mediating executive cognitive functions and their relationship with gait disturbances, and thus help define novel markers and better guide remediation strategies to prevent falls.

METHODS

Event-related functional magnetic resonance imaging (fMRI) was used to evaluate age-related effects on the recruitment of executive control brain network in selective attention task, as measured with a flanker paradigm. Brain activation patterns were compared between twenty young (21 years ± 2.5) and thirty-four old participants (72 years ± 5.3) with high fall risks. We then determined to what extend age-related differences in activation patterns were associated with alterations in several gait parameters, measured with electronic devices providing a precise quantitative evaluation of gait, as well as with alterations in several aspects of cognitive and physical abilities.

RESULTS

We found that both young and old participants recruited a distributed fronto-parietal-occipital network during interference by incongruent distractors in the flanker task. However, additional activations were observed in posterior parieto-occipital areas in the older relative to the younger participants. Furthermore, a differential recruitment of both the left dorsal parieto-occipital sulcus and precuneus was significantly correlated with higher gait variability. Besides, decreased activation in the right cerebellum was found in the older with poorer cognitive processing speed scores.

CONCLUSIONS

Overall results converge to indicate greater sensitivity to attention interference and heightened recruitment of cortical executive control systems in the elderly with fall risks. Critically, this change was associated with selective increases in gait variability indices, linking attentional control with gait performance in elderly with high risks of falls.

Aging of the frontal lobe

Healthy aging is associated with numerous deficits in cognitive function, which have been attributed to changes within the prefrontal cortex (PFC). This chapter summarizes some of the most prominent cognitive changes associated with age-related alterations in the anatomy and physiology of the PFC. Specifically, aging of the PFC results in deficient aspects of cognitive control, including sustained attention, selective attention, inhibitory control, working memory, and multitasking abilities. Yet, not all cognitive functions associated with the PFC exhibit age-related declines, such as arithmetic, comprehension, emotion perception, and emotional control. Moreover, not all older adults exhibit declines in cognition. Multiple life-course and lifestyle factors, as well as genetics, play a role in the trajectory of cognitive performance across the life span. Thus many adults retain cognitive function well into advanced age. Moreover, the brain remains plastic throughout life and there is increasing evidence that most age-related declines in cognition can be remediated by various methods such as physical exercise, cognitive training, or noninvasive brain stimulation. Overall, because cognitive aging is associated with numerous life-course and lifestyle factors, successful aging likely begins in early life, while maintaining cognition or remediating declines is a life-long process.

Functional magnetic resonance imaging with encoding task in patients with mild cognitive impairment and different severity of leukoaraiosis

Leukoaraiosis is one of the main contributors to mild cognitive impairment due to vascular damage (vascular MCI, VMCI), whose pathophysiology has not been fully elucidated yet. We aimed to shed light on such issue using functional MRI (fMRI). Sixteen patients with VMCI were enrolled and compared with twenty-five patients with MCI but without significant vascular damage (non-vascular MCI, NVMCI) and with fifteen healthy controls (HC). They all underwent fMRI with incidental verbal learning paradigm, using a 3T scanner. Differently from cases with NVMCI (versus HC), VMCI patients presented a higher BOLD activation in the right parieto-occipital cortex and a lower activation in the left superior and middle frontal gyri, anterior cingulum and in left fronto-opercular area when compared to HC. Cortical activation evaluated by fMRI may reflect specific patterns of damage and attempt of compensation in patients with MCI and different severity of leukoaraiosis.

Central artery stiffness is related to cerebral oxygenation hemodynamics during executive function tasks in healthy middle-aged and older adults

Age-related decreases in cognitive function, cerebral perfusion, and vascular function increase the risk of dementia. However, the effects of central artery stiffness on cerebral oxygenation hemodynamics during executive function tasks and executive function remain unclear. The aim of this cross-sectional study was to investigate the relationships among central artery stiffness, cerebral oxygenation hemodynamics during executive function tasks, and executive function in middle-aged and older adults. Sixty-two middle-aged and older adults (age range: 51-79 years) were recruited for this study. For each participant, we measured the carotid artery β-stiffness, oxygenated hemoglobin (oxy-Hb) signal change in the prefrontal cortex during the Stroop task, and Stroop interference time. Correlation analyses revealed that the carotid artery β-stiffness was significantly correlated with the Stroop interference time (r = 0.43, P < 0.001) and with the oxy-Hb signal change in the left (r = -0.38, P = 0.002), but not the right, prefrontal cortex. In addition, the Stroop interference time was significantly correlated with the oxy-Hb signal change in the left (r = -0.42, P = 0.001), but not the right, prefrontal cortex. The participants were divided into the low and high arterial stiffness groups according to the median value. We found that the Stroop interference time was significantly shorter (P = 0.006) and the oxy-Hb signal change in the left prefrontal cortex was significantly larger in the low arterial stiffness group than in the high arterial stiffness group (P = 0.011). In the low, but not the high, arterial stiffness group, the oxy-Hb signal change of the left prefrontal cortex during executive function tasks was significantly larger than the oxy-Hb signal change of the right prefrontal cortex (P = 0.014). These results suggest that increases in central artery stiffness are associated with decreases in oxygenation hemodynamics in the left prefrontal cortex during executive function tasks and reductions in executive function.

Incremental rate of prefrontal oxygenation determines performance speed during cognitive Stroop test: the effect of ageing

Cognitive function declines with age. The underlying mechanisms responsible for the deterioration of cognitive performance, however, remain poorly understood. We hypothesized that an incremental rate of prefrontal oxygenation during a cognitive Stroop test decreases in progress of ageing, resulting in a slowdown of cognitive performance. To test this hypothesis, we identified, using multichannel near-infrared spectroscopy, the characteristics of the oxygenated-hemoglobin concentration (Oxy-Hb) responses of the prefrontal cortex to both incongruent Stroop and congruent word-reading test. Spatial distributions of the significant changes in the three components (initial slope, peak amplitude, and area under the curve) of the Oxy-Hb response were compared between young and elderly subjects. The Stroop interference time (as a difference in total periods for executing Stroop and word-reading test, respectively) approximately doubled in elderly as compared to young subjects. The Oxy-Hb in the rostrolateral, but not caudal, prefrontal cortex increased during the Stroop test in both age groups. The initial slope of the Oxy-Hb response, rather than the peak and area under the curve, had a strong correlation with cognitive performance speed. Taken together, it is likely that the incremental rate of prefrontal oxygenation may decrease in progress of ageing, resulting in a decline in cognitive performance.

Modulation of Cognitive and Emotional Control in Age-Related Mild-to-Moderate Hearing Loss

Progressive hearing loss is a common phenomenon in healthy aging and may affect the perception of emotions expressed in speech. Elderly with mild to moderate hearing loss often rate emotional expressions as less emotional and display reduced activity in emotion-sensitive brain areas (e.g., amygdala). However, it is not clear how hearing loss affects cognitive and emotional control mechanisms engaged in multimodal speech processing. In previous work we showed that negative, task-relevant and -irrelevant emotion modulates the two types of control in younger and older adults without hearing loss. To further explore how reduced hearing capacity affects emotional and cognitive control, we tested whether moderate hearing loss (>30 dB) at frequencies relevant for speech impacts cognitive and emotional control. We tested two groups of older adults with hearing loss (HL; N = 21; mean age = 70.5) and without hearing loss (NH; N = 21; mean age = 68.4). In two EEG experiments participants observed multimodal video clips and either categorized pronounced vowels (cognitive conflict) or their emotions (emotional conflict). Importantly, the facial expressions were either matched or mismatched with the corresponding vocalizations. In both conflict tasks, we found that negative stimuli modulated behavioral conflict processing in the NH but not the HL group, while the HL group performed at chance level in the emotional conflict task. Further, we found that the amplitude difference between congruent and incongruent stimuli was larger in negative relative to neutral N100 responses across tasks and groups. Lastly, in the emotional conflict task, neutral stimuli elicited a smaller N200 response than emotional stimuli primarily in the HL group. Consequently, age-related hearing loss not only affects the processing of emotional acoustic cues but also alters the behavioral benefits of emotional stimuli on cognitive and emotional control, despite preserved early neural responses. The resulting difficulties in the multimodal integration of incongruent emotional stimuli may lead to problems in processing complex social information (irony, sarcasm) and impact emotion processing in the limbic network. This could be related to social isolation and depression observed in the elderly with age-related hearing loss.

Dissociations of cognitive inhibition, response inhibition, and emotional interference: Voxelwise ALE meta-analyses of fMRI studies

Inhibitory control is the stopping of a mental process with or without intention, conceptualized as mental suppression of competing information because of limited cognitive capacity. Inhibitory control dysfunction is a core characteristic of many major psychiatric disorders. Inhibition is generally thought to involve the prefrontal cortex; however, a single inhibitory mechanism is insufficient for interpreting the heterogeneous nature of human cognition. It remains unclear whether different dimensions of inhibitory processes-specifically cognitive inhibition, response inhibition, and emotional interference-rely on dissociated neural systems. We conducted systematic meta-analyses of fMRI studies in the BrainMap database supplemented by PubMed using whole-brain activation likelihood estimation. A total of 66 study experiments including 1,447 participants and 987 foci revealed that while the left anterior insula was concordant in all inhibitory dimensions, cognitive inhibition reliably activated specific dorsal frontal inhibitory system, engaging dorsal anterior cingulate, dorsolateral prefrontal cortex, and parietal areas, whereas emotional interference reliably implicated a ventral inhibitory system, involving the ventral surface of the inferior frontal gyrus and the amygdala. Response inhibition showed concordant clusters in the fronto-striatal system, including the dorsal anterior cingulate region and extended supplementary motor areas, the dorsal and ventral lateral prefrontal cortex, basal ganglia, midbrain regions, and parietal regions. We provide an empirically derived dimensional model of inhibition characterizing neural systems underlying different aspects of inhibitory mechanisms. This study offers a fundamental framework to advance current understanding of inhibition and provides new insights for future clinical research into disorders with different types of inhibition-related dysfunctions.

Two Different Populations within the Healthy Elderly: Lack of Conflict Detection in Those at Risk of Cognitive Decline

During healthy aging, inhibitory processing is affected at the sensorial, perceptual, and cognitive levels. The assessment of event-related potentials (ERPs) during the Stroop task has been used to study age-related decline in the efficiency of inhibitory processes. Studies using ERPs have found that the P300 amplitude increases and the N500 amplitude is attenuated in healthy elderly adults compared to those in young adults. On the other hand, it has been reported that theta excess in resting EEG with eyes closed is a good predictor of cognitive decline during aging 7 years later, while a normal EEG increases the probability of not developing cognitive decline. The behavioral and ERP responses during a Counting-Stroop task were compared between 22 healthy elderly subjects with normal EEG (Normal-EEG group) and 22 healthy elderly subjects with an excess of EEG theta activity (Theta-EEG group). Behaviorally, the Normal-EEG group showed a higher behavioral interference effect than the Theta-EEG group. ERP patterns were different between the groups, and two facts are highlighted: (a) the P300 amplitude was higher in the Theta-EEG group, with both groups showing a P300 effect in almost all electrodes, and (b) the Theta-EEG group did not show an N500 effect. These results suggest that the diminishment in inhibitory control observed in the Theta-EEG group may be compensated by different processes in earlier stages, which would allow them to perform the task with similar efficiency to that of participants with a normal EEG. This study is the first to show that healthy elderly subjects with an excess of theta EEG activity not only are at risk of developing cognitive decline but already have a cognitive impairment.

The Influence of Negative Emotion on Cognitive and Emotional Control Remains Intact in Aging

Healthy aging is characterized by a gradual decline in cognitive control and inhibition of interferences, while emotional control is either preserved or facilitated. Emotional control regulates the processing of emotional conflicts such as in irony in speech, and cognitive control resolves conflict between non-affective tendencies. While negative emotion can trigger control processes and speed up resolution of both cognitive and emotional conflicts, we know little about how aging affects the interaction of emotion and control. In two EEG experiments, we compared the influence of negative emotion on cognitive and emotional conflict processing in groups of younger adults (mean age = 25.2 years) and older adults (69.4 years). Participants viewed short video clips and either categorized spoken vowels (cognitive conflict) or their emotional valence (emotional conflict), while the visual facial information was congruent or incongruent. Results show that negative emotion modulates both cognitive and emotional conflict processing in younger and older adults as indicated in reduced response times and/or enhanced event-related potentials (ERPs). In emotional conflict processing, we observed a valence-specific N100 ERP component in both age groups. In cognitive conflict processing, we observed an interaction of emotion by congruence in the N100 responses in both age groups, and a main effect of congruence in the P200 and N200. Thus, the influence of emotion on conflict processing remains intact in aging, despite a marked decline in cognitive control. Older adults may prioritize emotional wellbeing and preserve the role of emotion in cognitive and emotional control.

Functional imaging of cognition in an old-old population: A case for portable functional near-infrared spectroscopy

In this study, functional near-infrared spectroscopy (fNIRS) was used to record brain activation during cognitive testing in older individuals (88±6yo; N = 19) living in residential care communities. This population, which is often associated with loss of personal independence due to physical or cognitive decline associated with aging, is also often under-represented in neuroscience research because of a limited means to participate in studies which often take place in large urban or university centers. In this study, we demonstrate the feasibility and initial results using a portable 8-source by 4-detector fNIRS system to measure brain activity from participants within residential care community centers. Using fNIRS, brain signals were recorded during a series of computerized cognitive tests, including a Symbol Digit Coding test (SDC), Stroop Test (ST), and Shifting Attention Test (SAT). The SDC and SAT elicited greater activity in the left middle frontal region of interest. Three components of the ST produced increases in the right middle frontal and superior frontal, and left superior frontal regions. An association between advanced age and increased activation in the right middle frontal region was observed during the incongruent ST. Although none of the participants had clinical dementia based on the short portable mental status questionnaire, the group performance was slightly below age-normed values on these cognitive tests. These results demonstrate the capability for obtaining functional neuroimaging measures in residential settings, which ultimately may aid in prognosis and care related to dementia in older adults.

Verbal memory in breast cancer patients treated with chemotherapy with doxorubicin and cyclophosphamide

Memory is one of the crucial human cognitive functions, and deficits in memory processes may lead to difficulties in everyday functioning. The aim of this study was to analyse the effect of anthracycline-based adjuvant chemotherapy (AC) used in breast cancer treatment on verbal memory and learning. We also evaluated the relationship between verbal memory and psychological, somatic and socio-demographic factors. The study was carried out on a group of 31 women with early breast cancer treated with adjuvant chemotherapy and 30 healthy controls. The patients underwent neuropsychological assessment using the Rey Auditory Verbal Learning Test at three time points: before chemotherapy, mid-chemotherapy and post-chemotherapy. The examination in the controls was conducted at the same time intervals. We found an association between AC-schema chemotherapy and deficits in delayed memory. A deterioration in performance after treatment was observed in 19% of patients. The results showed no deterioration of immediate memory or the verbal learning process. Moreover, a positive relationship was shown between the level of education, physical fitness and the functioning of verbal memory. The results of the study also indicate that age and hormonal status are factors that may increase the possibility of deficits in verbal memory after AC-schema chemotherapy.

Age-Related Shift in Neuro-Activation during a Word-Matching Task

Growing evidence from the neuroscience of aging suggests that executive function plays a pivotal role in maintaining semantic processing performance. However, the presumed age-related activation changes that sustain executive semantic processing remain poorly understood. The aim of this study was to explore the executive aspects of semantic processing during a word-matching task with regard to age-related neuro-functional reorganization, as well as to identify factors that influence executive control profiles. Twenty younger and 20 older participants underwent fMRI scanning. The experimental task was based on word-matching, wherein visual feedback was used to instruct participants to either maintain or switch a semantic-matching rule. Response time and correct responses were assessed for each group. A battery of cognitive tests was administrated to all participants and the older group was divided into two subgroups based on their cognitive control profiles. Even though the percentage of correct responses was equivalent in the task performance between both groups and within the older groups, neuro-functional activation differed in frontoparietal regions with regards to age and cognitive control profiles. A correlation between behavioral measures (correct responses and response times) and brain signal changes was found in the left inferior parietal region in older participants. Results indicate that the shift in age-related activation from frontal to parietal regions can be viewed as another form of neuro-functional reorganization. The greater reliance on inferior parietal regions in the older compared to the younger group suggests that the executive control system is still efficient and sustains semantic processing in the healthy aging brain. Additionally, cognitive control profiles underlie executive ability differences in healthy aging appear to be associated with specific neuro-functional reorganization throughout frontal and parietal regions. These findings demonstrate that changes in neural support for executive semantic processing during a word-matching task are not only influenced by age, but also by cognitive control profile.

White Matter Hyperintensity Load Modulates Brain Morphometry and Brain Connectivity in Healthy Adults: A Neuroplastic Mechanism?

White matter hyperintensities (WMHs) are acquired lesions that accumulate and disrupt neuron-to-neuron connectivity. We tested the associations between WMH load and (1) regional grey matter volumes and (2) functional connectivity of resting-state networks, in a sample of 51 healthy adults. Specifically, we focused on the positive associations (more damage, more volume/connectivity) to investigate a potential route of adaptive plasticity. WMHs were quantified with an automated procedure. Voxel-based morphometry was carried out to model grey matter. An independent component analysis was run to extract the anterior and posterior default-mode network, the salience network, the left and right frontoparietal networks, and the visual network. Each model was corrected for age, global levels of atrophy, and indices of brain and cognitive reserve. Positive associations were found with morphometry and functional connectivity of the anterior default-mode network and salience network. Within the anterior default-mode network, an association was found in the left mediotemporal-limbic complex. Within the salience network, an association was found in the right parietal cortex. The findings support the suggestion that, even in the absence of overt disease, the brain actuates a compensatory (neuroplastic) response to the accumulation of WMH, leading to increases in regional grey matter and modified functional connectivity.

Brain atrophy can introduce age-related differences in BOLD response

Use of functional magnetic resonance imaging (fMRI) in studies of aging is often hampered by uncertainty about age-related differences in the amplitude and timing of the blood oxygenation level dependent (BOLD) response (i.e., hemodynamic impulse response function (HRF)). Such uncertainty introduces a significant challenge in the interpretation of the fMRI results. Even though this issue has been extensively investigated in the field of neuroimaging, there is currently no consensus about the existence and potential sources of age-related hemodynamic alterations. Using an event-related fMRI experiment with two robust and well-studied stimuli (visual and auditory), we detected a significant age-related difference in the amplitude of response to auditory stimulus. Accounting for brain atrophy by circumventing spatial normalization and processing the data in subjects' native space eliminated these observed differences. In addition, we simulated fMRI data using age differences in brain morphology while controlling HRF shape. Analyzing these simulated fMRI data using standard image processing resulted in differences in HRF amplitude, which were eliminated when the data were analyzed in subjects' native space. Our results indicate that age-related atrophy introduces inaccuracy in co-registration to standard space, which subsequently appears as attenuation in BOLD response amplitude. Our finding could explain some of the existing contradictory reports regarding age-related differences in the fMRI BOLD responses. Hum Brain Mapp 38:3402-3414, 2017. © 2017 Wiley Periodicals, Inc.

Resting-state connectivity and modulated somatomotor and default-mode networks in Huntington disease

AIMS

To analyze brain functional connectivity in the somatomotor and default-mode networks (DMNs) of patients with Huntington disease (HD), its relationship with gray matter (GM) volume loss, and functional changes after pridopidine treatment.

METHODS

Ten patients and ten untreated controls underwent T1-weighted imaging and resting-state functional magnetic resonance imaging (fMRI); four patients were also assessed after 3 months of pridopidine treatment (90 mg/d). The seed-based functional connectivity patterns from the posterior cingulate cortex and the supplementary motor area (SMA), considered cortical hubs of the DMN and somatomotor networks, respectively, were computed. FMRIB Software Library voxel-based morphometry measured GM volume.

RESULTS

Patients had GM volume decrease in all cortical and subcortical areas of the somatomotor network with preservation of the SMA, and increased somatomotor and DMN connectivity. In DMN structures, functional connectivity impairment preceded volume loss. Pridopidine reduced the intensity of these aberrant connections.

CONCLUSION

The abnormal connectivity of the somatomotor and DMN observed in HD patients may represent an early dysfunction marker, as it preceded volume loss in DMN. Pridopidine reduced connectivity of these networks in all four treated patients, suggesting that connectivity is sensitive to treatment response.

The Disconnected Brain and Executive Function Decline in Aging

Higher order speeded cognitive abilities depend on efficient coordination of activity across the brain, rendering them vulnerable to age reductions in structural and functional brain connectivity. The concept of "disconnected aging" has been invoked, suggesting that degeneration of connections between distant brain regions cause cognitive reductions. However, it has not been shown that changes in cognitive functions over time can be explained by simultaneous changes in brain connectivity. We followed 119 young and middle-aged (23-52 years) and older (63-86 years) adults for 3.3 years with repeated assessments of structural and functional brain connectivity and executive functions. We found unique age-related longitudinal reductions in executive function over and above changes in more basic cognitive processes. Intriguingly, 82.5% of the age-related decline in executive function could be explained by changes in connectivity over time. While both structural and functional connectivity changes were related to longitudinal reductions in executive function, only structural connectivity change could explain the age-specific decline. This suggests that the major part of the age-related reductions in executive function can be attributed to micro- and macrostructural alterations in brain connectivity. Although correlational in nature, we believe the present results constitute evidence for a "disconnected brain" view on cognitive aging.

Inhibition and Switching in Healthy Aging: A Longitudinal Study

OBJECTIVES

Discrepant findings of age-related effects between cross-sectional and longitudinal studies on executive function (EF) have been described across different studies. The aim of the present study was to examine longitudinal age effects on inhibition and switching, two key subfunctions of EF, calculated from results on the Color Word Interference Test (CWIT).

METHODS

One hundred twenty-three healthy aging individuals (average age 61.4 years; 67% women) performed the CWIT up to three times, over a period of more than 6 years. Measures of inhibition, switching, and combined inhibition and switching were analyzed. A longitudinal linear mixed effects models analysis was run including basic CWIT conditions, and measures of processing speed, retest effect, gender, education, and age as predictors.

RESULTS

After taking all predictors into account, age added significantly to the predictive value of the longitudinal models of (i) inhibition, (ii) switching, and (iii) combined inhibition and switching. The basic CWIT conditions and the processing speed measure added to the predictive value of the models, while retest effect, gender, and education did not.

CONCLUSIONS

The present study on middle-aged to older individuals showed age-related decline in inhibition and switching abilities. This decline was retained even when basic CWIT conditions, processing speed, attrition, gender, and education were controlled. (JINS, 2017, 23, 90-97).

Effects of reaction time variability and age on brain activity during Stroop task performance

Variability in reaction time during task performance may reflect fluctuations in attention and cause reduced performance in goal-directed tasks, yet it is unclear whether the mechanisms behind this phenomenon change with age. Using fMRI, we tested young and cognitively healthy older adults with the Stroop task to determine whether aging affects the neural mechanisms underlying intra-individual reaction time variability. We found significant between-group differences in BOLD activity modulated by reaction time. In older adults, longer reaction times were associated with greater activity in frontoparietal attentional areas, while in younger adults longer reaction times were associated with greater activity in default mode network areas. Our results suggest that the neural correlates of reaction time variability change with healthy aging, reinforcing the concept of functional plasticity to maintain high cognitive function throughout the lifespan.

Age differences in behavioral and neural correlates of proactive interference: Disentangling the role of overall working memory performance

Reliable performance in working memory (WM) critically depends on the ability to resist proactive interference (PI) from previously relevant WM contents. Both WM performance and PI susceptibility are subject to cognitive decline at older adult age. However, the behavioral and neural processes underlying these co-evolving developmental changes and their potential interdependencies are not yet understood. Here, we investigated PI using a recent-probes WM paradigm and functional MRI in a cross-sectional sample of younger (n=18, 10 female, 23.4 ± 2.7 years) and older adults (n=18, 10 female, 70.2 ± 2.7 years). As expected, older adults showed lower WM performance and higher PI susceptibility than younger adults. Resolution of PI activated a mainly bilateral frontal network across all participants. Significant interactions with age indicated reduced neural activation in older adults for PI resolution. A second analysis in a selection of younger and older adults (n=12 each) with matched WM performance also revealed significant differences in PI between both age groups and - on a descriptive level - again a hypo-activation of the older adults' PI network. But the differential effect of age on the neural PI effects did not reach significance in this smaller sample most likely to the reduced statistical power. However, given the highly similar patterns in both the overall and the WM-matched samples, we propose that the hypo-activation of the PI network in the older adults may not be attributable to age-related differences in overall WM performance, hence suggesting that higher PI susceptibility in older adult age does not directly depend on their lower WM performance.

Mindful Aging: The Effects of Regular Brief Mindfulness Practice on Electrophysiological Markers of Cognitive and Affective Processing in Older Adults

There is growing interest in the potential benefits of mindfulness meditation practices in terms of counteracting some of the cognitive effects associated with aging. Pursuing this question, the aim of the present study was to investigate the influence of mindfulness training on executive control and emotion regulation in older adults, by means of studying behavioral and electrophysiological changes. Participants, 55 to 75 years of age, were randomly allocated to an 8-week mindful breath awareness training group or an active control group engaging in brain training exercises. Before and after the training period, participants completed an emotional-counting Stroop task, designed to measure attentional control and emotion regulation processes. Concurrently, their brain activity was measured by means of 64-channel electroencephalography. The results show that engaging in just over 10 min of mindfulness practice five times per week resulted in significant improvements in behavioral (response latency) and electrophysiological (N2 event-related potential) measures related to general task performance. Analyses of the underlying cortical sources (Variable Resolution Electromagnetic Tomography, VARETA) indicate that this N2-related effect is primarily associated with changes in the right angular gyrus and other areas of the dorsal attention network. However, the study did not find the expected specific improvements in executive control and emotion regulation, which may be due to the training instructions or the relative brevity of the intervention. Overall, the results indicate that engaging in mindfulness meditation training improves the maintenance of goal-directed visuospatial attention and may be a useful strategy for counteracting cognitive decline associated with aging.

An updated Italian normative dataset for the Stroop color word test (SCWT)

The Stroop color and word test (SCWT) is widely used to evaluate attention, information processing speed, selective attention, and cognitive flexibility. Normative values for the Italian population are available only for selected age groups, or for the short version of the test. The aim of this study was to provide updated normal values for the full version, balancing groups across gender, age decades, and education. Two kinds of indexes were derived from the performance of 192 normal subjects, divided by decade (from 20 to 90) and level of education (4 levels: 3-5; 6-8; 9-13; >13 years). They were (i) the correct answers achieved for each table in the first 30 s (word items, WI; color items, CI; color word items, CWI) and (ii) the total time required for reading the three tables (word time, WT; color time, CT; color word time, CWT). For each index, the regression model was evaluated using age, education, and gender as independent variables. The normative data were then computed following the equivalent scores method. In the regression model, age and education significantly influenced the performance in each of the 6 indexes, whereas gender had no significant effect. This study confirms the effect of age and education on the main indexes of the Stroop test and provides updated normative data for an Italian healthy population, well balanced across age, education, and gender. It will be useful to Italian researchers studying attentional functions in health and disease.

The association between aerobic fitness and cognitive function in older men mediated by frontal lateralization

Previous studies have shown that higher aerobic fitness is related to higher cognitive function and higher task-related prefrontal activation in older adults. However, a holistic picture of these factors has yet to be presented. As a typical age-related change of brain activation, less lateralized activity in the prefrontal cortex during cognitive tasks has been observed in various neuroimaging studies. Thus, this study aimed to reveal the relationship between aerobic fitness, cognitive function, and frontal lateralization. Sixty male older adults each performed a submaximal incremental exercise test to determine their oxygen intake (V·O2) at ventilatory threshold (VT) in order to index their aerobic fitness. They performed a color-word Stroop task while prefrontal activation was monitored using functional near infrared spectroscopy. As an index of cognitive function, Stroop interference time was analyzed. Partial correlation analyses revealed significant correlations among higher VT, shorter Stroop interference time and greater left-lateralized dorsolateral prefrontal cortex (DLPFC) activation when adjusting for education. Moreover, mediation analyses showed that left-lateralized DLPFC activation significantly mediated the association between VT and Stroop interference time. These results suggest that higher aerobic fitness is associated with cognitive function via lateralized frontal activation in older adults.

Hemodynamic responses on prefrontal cortex related to meditation and attentional task

Recent neuroimaging studies state that meditation increases regional cerebral blood flow (rCBF) in the prefrontal cortex (PFC). The present study employed functional near infrared spectroscopy (fNIRS) to evaluate the relative hemodynamic changes in PFC during a cognitive task. Twenty-two healthy male volunteers with ages between 18 and 30 years (group mean age ± SD; 22.9 ± 4.6 years) performed a color-word stroop task before and after 20 min of meditation and random thinking. Repeated measures ANOVA was performed followed by a post hoc analysis with Bonferroni adjustment for multiple comparisons between the mean values of “During” and “Post” with “Pre” state. During meditation there was an increased in oxy-hemoglobin (ΔHbO) and total hemoglobin (ΔTHC) concentration with reduced deoxy-hemoglobin (ΔHbR) concentration over the right prefrontal cortex (rPFC), whereas in random thinking there was increased ΔHbR with reduced total hemoglobin concentration on the rPFC. The mean reaction time (RT) was shorter during stroop color word task with concomitant reduction in ΔTHC after meditation, suggestive of improved performance and efficiency in task related to attention. Our findings demonstrated that meditation increased cerebral oxygenation and enhanced performance, which was associated with activation of the PFC.