A scoping review and critique of the Input-Output subtyping dimension of spatial neglect.

Spatial neglect is a common and debilitating disorder after stroke whereby individuals have difficulty reporting, orienting, and/or responding to the contralesional side of space. Given the heterogeneity of neglect symptom presentation, various neglect subtypes have been proposed to better characterize the disorder. This review focuses on the distinction between Input neglect (i.e., difficulty perceiving and/or attending to contralesional stimuli) and Output neglect (i.e., difficulty planning and/or executing movements toward contralesional stimuli). Conceptualizations of Input and Output neglect have varied considerably. We provide a novel summary of the terminology, measurement approaches, and neural correlates of these subtypes. A protocol detailing our systematic scoping review strategy is registered on the Open Science Framework (https://osf.io/bvtxf/). For feasibility and greater comparability across studies, we limited our inclusion criteria to tasks focused on visual stimuli and upper-limb movements. A total of 110 articles were included in the review. Subtyping tasks were categorized based on whether they mainly manipulated aspects of the input (i.e., congruence of visual input with motor output, presence of visual input) or the output (i.e., modality, goal, or direction of output) to produce an Input-Output subtype dissociation. We used our review results to identify four main critiques of this literature: 1) lack of consistency/clarity in conceptual models; 2) methodological issues of dissociating Input and Output subtypes; 3) a need for updated neural theories; and 4) barriers to clinical application. We discuss the lessons learned from this subtyping dimension that can be applied to future research on neglect subtype assessment and treatment.

Internal consistency and reliability of the lifetime and modified current cognitive activity questionnaires and their association with cognitive performance: a six-year follow up of the Brain in Motion study.

INTRODUCTION: Cognitive activity questionnaires could provide insight into neurocognitive reserve. The Lifetime Cognitive Activities Questionnaire (LCAQ) assesses cognitive activities at four stages of life. The Modified Current Cognitive Activities Questionnaire (CCAQ) assesses current cognitive activities. We examined the construct validity, internal consistency, test-retest reliability, and stability of these questionnaires throughout the Brain in Motion (BIM) study and their relationship with cognitive performance. METHODS: The LCAQ, Montreal Cognitive Assessment (MoCA), and neuropsychological battery were administered at the initial pre-intervention and six-year follow-up. The CCAQ was administered at five timepoints. Construct validity of the CCAQ/LCAQ was assessed using proxies of cognitive engagement (educational attainment and the North American Adult Reading Test [NAART]). Cronbach alpha analysis determined internal consistency. LCAQ reliability was established by comparing the pre-intervention and six-year follow-up. CCAQ reliability was determined by comparing both pre-intervention assessments, correlations throughout BIM determined stability. A multiple linear regression investigated the associations between cognitive engagement and cognitive domains derived from a principal component analysis. RESULTS: MoCA scores at the initial pre-intervention (27.49 ± 1.46) and six-year follow up (26.53 ± 2.08). The LCAQ and CCAQ correlated with educational attainment and the NAART. The LCAQ (n = 266) produced an alpha of 0.90 (20 items). The CCAQ (n = 261) resulted in an alpha of 0.71 (25 items). LCAQ scores (n = 94) at the initial pre-intervention and six-year follow-up were correlated. CCAQ (n = 94) scores at the initial pre-intervention correlated with scores at all five other timepoints. The multiple linear regression revealed associations between the CCAQ and verbal memory/attention. The NAART was associated with processing speed, concept formation, and verbal memory/attention. CONCLUSIONS: In the absence of cognitive decline, these questionnaires exhibit significant construct validity, internal consistency, test-retest reliability, and the CCAQ displayed stability. The NAART and CCAQ were associated with neuropsychological performance. Our findings support future use of these questionnaires and exemplify the neuroprotective role of cognitive engagement.

Investigating premotor reaching biases after prism adaptation.

Prism adaptation (PA) is both a visuomotor learning task and potential treatment for spatial neglect after stroke. While PA's aftereffects can improve neglect symptoms, therapeutic benefits vary across individuals, possibly due to differences in neglect subtypes. Neglect symptoms can be described along an information processing pathway, yielding perceptual (input) and premotor (output) neglect subtypes. There is some evidence that PA mainly benefits persons with premotor neglect. We investigated whether PA modulates the premotor stage of information processing by examining whether PA could induce a premotor bias in healthy adults. We measured perceptual and premotor biases using a speeded reach task that compares the initiation time of leftward and rightward reaches to lateralized targets from different hand start positions. Using a randomized mixed experimental design, 30 right-handed healthy adults completed this speeded reach task before and after either left-shifting (n = 15) or right-shifting (n = 15) PA. As hypothesized, left-shifting PA speeded initiation time specifically for reaches in the rightward direction, regardless of target location (p = .02, ηp2 = .18), suggesting that PA induced a premotor bias in the direction of the prism aftereffect. These findings have implications for PA's underlying mechanisms, which can inform visuomotor learning theories and PA's use as a treatment for spatial neglect.

Cognitive Training to Enhance Aphasia Therapy (Co-TrEAT): A Feasibility Study.

Persons with aphasia (PWA) often have deficits in cognitive domains such as working memory (WM), which are negatively correlated with recovery, and studies have targeted WM deficits in aphasia therapy. To our knowledge, however, no study has examined the efficacy of multi-modal training which includes both WM training and targeted language therapy. This pilot project examined the feasibility and preliminary efficacy of combining WM training and naming therapy to treat post-stroke PWA. Chronic PWA were randomly assigned to either the a) Phonological Components Analysis (PCA) and WM intervention (WMI) condition (i.e., a computerized adaptive dual n-back task), or b) PCA and active control condition (WMC). Participants received face-to-face PCA therapy 3 times/week for 5 weeks, and simultaneously engaged in WM training or the active control condition five times/week, independently at home. Six PWA were enrolled, 3 in each condition. Feasibility metrics were excellent for protocol compliance, retention rate and lack of adverse events. Recruitment was less successful, with insufficient participants for group analyses. Participants in the WMI (but not the WMC) condition demonstrated a clinically significant (i.e., > 5 points) improvement on the Western Aphasia Battery- Aphasia Quotient (WAB-R AQ) and Boston Naming Test after therapy. Given the small sample size, the performance of two individuals, matched on age, education, naming accuracy pre-treatment, WAB-R AQ and WM abilities was compared. Participant WMI-3 demonstrated a notable increase in WM training performance over the course of therapy; WMC-2 was the matched control. After therapy, WMI-3's naming accuracy for the treated words improved from 30 to 90% (compared to 30-50% for WMC-2) with a 7-point WAB-R AQ increase (compared to 3 for WMC-2). Improvements were also found for WMI-3 but not for WMC-2 on ratings of communicative effectiveness, confidence and some conversation parameters in discourse. This feasibility study demonstrated excellent results for most aspects of Co-TrEAT. Recruitment rate, hampered by limited resources, must be addressed in future trials; remotely delivered aphasia therapy may be a possible solution. Although no firm conclusions can be drawn, the case studies suggest that WM training has the potential to improve language and communication outcomes when combined with aphasia therapy.

Can prism adaptation effects generalize to wheelchair maneuvering?

BACKGROUND: While prism adaptation (PA) has been recognized as a promising tool for treating spatial neglect, implementation as a standard treatment in clinical care has been lagging. Limited evidence for the generalization of after-effects to everyday activities has been a barrier towards implementation. OBJECTIVES: This study examined whether a home-friendly standardized PA protocol (Peg-the-Mole, PTM) induces after-effects that can transfer to wheelchair maneuvering. We also examined the impact of using constant (1 starting hand position) or variable (3 starting hand positions) training conditions on the transfer of after-effects to wheelchair maneuvering. METHODS: Sixty participants were randomly assigned to one of four PTM conditions: 1) prisms/constant training; 2) prisms/variable training; 3) sham goggles/constant training; 4) sham goggles/variable training. RESULTS: The use of PTM with rightward shifting prisms induced after-effects on proprioceptive and visual pointing outcome tasks. Groups using PTM with prism goggles showed a leftward shift in their position within a wheelchair course and a reduction in the number of right-sided collisions. The training condition did not have an impact on the transfer of after-effects to wheelchair driving. CONCLUSION: PTM is a clinically appealing PA protocol that induces after-effects that can transfer to an everyday activity relevant to patients with neglect.

Role of aging and working memory in performance on a naturalistic visual search task.

Studying age-related changes in working memory (WM) and visual search can provide insights into mechanisms of visuospatial attention. In visual search, WM is used to remember previously inspected objects/locations and to maintain a mental representation of the target to guide the search. We sought to extend this work, using aging as a case of reduced WM capacity. The present study tested whether various domains of WM would predict visual search performance in both young (n = 47; aged 18-35 yrs) and older (n = 48; aged 55-78) adults. Participants completed executive and domain-specific WM measures, and a naturalistic visual search task with (single) feature and triple-conjunction (three-feature) search conditions. We also varied the WM load requirements of the search task by manipulating whether a reference picture of the target (i.e., target template) was displayed during the search, or whether participants needed to search from memory. In both age groups, participants with better visuospatial executive WM were faster to locate complex search targets. Working memory storage capacity predicted search performance regardless of target complexity; however, visuospatial storage capacity was more predictive for young adults, whereas verbal storage capacity was more predictive for older adults. Displaying a target template during search diminished the involvement of WM in search performance, but this effect was primarily observed in young adults. Age-specific interactions between WM and visual search abilities are discussed in the context of mechanisms of visuospatial attention and how they may vary across the lifespan.

Ankle-foot orthoses improve walking but do not reduce dual-task costs after stroke.

BACKGROUND: Cognitive-motor interference, as measured by dual-task walking (performing a mental task while walking), affects many clinical populations. Ankle-foot orthoses (AFOs) are lower-leg splints prescribed to provide stability to the foot and ankle, as well as prevent foot drop, a gait deficit common after stroke. AFO use has been shown to improve gait parameters such as speed and step time, which are often negatively impacted by dual-task walking. OBJECTIVES: Our objective was to establish whether AFOs could protect against cognitive-motor interference, as measured by dual-task walking, following post-stroke hemiplegia. METHODS: A total of 21 individuals with post-stroke hemiplegia that use an AFO completed a dual-task walking paradigm in the form of a 2 (walking with vs. without a concurrent cognitive task) by 2 (walking with vs. without an AFO) repeated-measures design. Changes to both motor and cognitive performance were analyzed. RESULTS: The results suggest that the use of an AFO improves gait overall in both single- and dual-task walking, particularly with respect to stride regularity, but there were no interactions to suggest that AFOs reduce the cognitive-motor dual-task costs themselves. A lack of differences in cognitive performance during dual-task walking with and without the AFO suggests that the AFO's benefit to motor performance cannot be attributed to task prioritization. CONCLUSIONS: These data support the use of AFOs to improve certain gait parameters for post-stroke hemiplegia, but AFOs do not appear to protect against cognitive-motor interference during dual-task walking. Future research should pursue alternate therapeutics for ameliorating task-specific declines under cognitively demanding circumstances.

Current clinical practice in the screening and diagnosis of spatial neglect post-stroke: Findings from a multidisciplinary international survey.

Spatial neglect has profound implications for quality of life after stroke, yet we lack consensus for screening/diagnosing this heterogeneous syndrome. Our first step in a multi-stage research programme aimed to determine which neglect tests are used (within four categories: cognitive, functional, neurological and neuroimaging/neuromodulation), by which stroke clinicians, in which countries, and whether choice is by professional autonomy or institutional policy. 454 clinicians responded to an online survey: 12 professions (e.g., 39% were occupational therapists) from 33 countries (e.g., 38% from the UK). Multifactorial logistic regression suggested inter-professional differences but fewer differences between countries (Italy was an outlier). Cognitive tests were used by 82% (particularly by psychologists, cancellation and drawing were most popular); 80% used functional assessments (physiotherapists were most likely). 20% (mainly physicians, from Italy) used neuroimaging/ neuromodulation. Professionals largely reported clinical autonomy in their choices. Respondents agreed on the need for a combined approach to screening and further training. This study raises awareness of the translation gap between theory and practice. These findings lay an important foundation to subsequent collaborative action between clinicians, researchers and stroke survivors to reach consensus on screening and diagnostic measures. The immediate next step is a review of the measures' psychometric properties.

Genetic Risk, Vascular Function, and Subjective Cognitive Complaints Predict Objective Cognitive Function in Healthy Older Adults: Results From the Brain in Motion Study.

Aging is associated with subjective memory complaints. Approximately half of those with subjective memory complaints have objective cognitive impairment. Previous studies have provided evidence of an association between genetic risk for Alzheimer's disease (AD) and dementia progression. Also, aging is a significant risk factor for vascular pathology that may underlie at least some of the cognitive changes. This study investigates the relative contribution of subjective cognitive complaints (SCC), vascular function, and genetic risk for dementia in predicting objective cognitive performance. Multiple regression and relative importance analysis were used to investigate the relative contribution of vascular function, self-reported SCC, and dementia genetic risk, in predicting objective cognition in a sample of 238 healthy community-dwelling older adults. Age, sex, premorbid cognitive abilities, subjective verbal memory complaints, higher cerebrovascular blood flow during submaximal exercise, and certain dementia risk alleles were significant predictors of worse objective verbal memory performance (p < 0.001, R 2 = 35.2-36.4%). Using relative importance analysis, subjective verbal memory complaints, and certain dementia risk alleles contributed more variance than cerebrovascular measures. These results suggest that age-related changes in memory in healthy older adults can be predicted by subjective memory complaints, genetic risk, and to a lesser extent, cerebrovascular function.

Visual Feedback Modulates Aftereffects and Electrophysiological Markers of Prism Adaptation.

Prism adaptation (PA) is both a model for visuomotor learning and a promising treatment for visuospatial neglect after stroke. The task involves reaching for targets while prism glasses horizontally displace the visual field. Adaptation is hypothesized to occur through two processes: strategic recalibration, a rapid self-correction of pointing errors; and spatial realignment, a more gradual adjustment of visuomotor reference frames that produce prism aftereffects (i.e., reaching errors upon glasses removal in the direction opposite to the visual shift). While aftereffects can ameliorate neglect, not all patients respond to PA, and the neural mechanisms underlying successful adaptation are unclear. We investigated the feedback-related negativity (FRN) and the P300 event-related potential (ERP) components as candidate markers of strategic recalibration and spatial realignment, respectively. Healthy young adults wore prism glasses and performed memory-guided reaching toward vertical-line targets. ERPs were recorded in response to three different between-subject error feedback conditions at screen-touch: view of hand and target (Experiment 1), view of hand only (Experiment 2), or view of lines to mark target and hand position (view of hand occluded; Experiment 3). Conditions involving a direct view of the hand-produced stronger aftereffects than indirect hand feedback, and also evoked a P300 that decreased in amplitude as adaptation proceeded. Conversely, the FRN was only seen in conditions involving target feedback, even when aftereffects were smaller. Since conditions producing stronger aftereffects were associated with a phase-sensitive P300, this component may index a "context-updating" realignment process critical for strong aftereffects, whereas the FRN may reflect an error monitoring process related to strategic recalibration.

Aerobic exercise improves cognition and cerebrovascular regulation in older adults.

OBJECTIVE: To test the hypothesis that aerobic exercise is associated with improvements in cognition and cerebrovascular regulation, we enrolled 206 healthy low-active middle-aged and older adults (mean ± SD age 65.9 ± 6.4 years) in a supervised 6-month aerobic exercise intervention and assessed them before and after the intervention. METHODS: The study is a quasi-experimental single group pre/postintervention study. Neuropsychological tests were used to assess cognition before and after the intervention. Transcranial Doppler ultrasound was used to measure cerebral blood flow velocity. Cerebrovascular regulation was assessed at rest, during euoxic hypercapnia, and in response to submaximal exercise. Multiple linear regression was used to examine the association between changes in cognition and changes in cerebrovascular function. RESULTS: The intervention was associated with improvements in some cognitive domains, cardiorespiratory fitness, and cerebrovascular regulation. Changes in executive functions were negatively associated with changes in cerebrovascular resistance index (CVRi) during submaximal exercise (ß = -0.205, p = 0.013), while fluency improvements were positively associated with changes in CVRi during hypercapnia (ß = 0.106, p = 0.03). CONCLUSION: The 6-month aerobic exercise intervention was associated with improvements in some cognitive domains and cerebrovascular regulation. Secondary analyses showed a novel association between changes in cognition and changes in cerebrovascular regulation during euoxic hypercapnia and in response to submaximal exercise.

Development of the Halifax Visual Scanning Test: A New Measure of Visual-Spatial Neglect for Personal, Peripersonal, and Extrapersonal Space.

OBJECTIVES: Visual-spatial neglect is a common attentional disorder after right-hemisphere stroke and is associated with poor rehabilitation outcomes. The presence of neglect symptoms has been reported to vary across personal, peripersonal, and extrapersonal space. Currently, no measure is available to assess neglect severity equally across these spatial regions and may be missing subsets of symptoms or patients with neglect entirely. We sought to provide initial construct validity for a novel assessment tool that measures neglect symptoms equally for these spatial regions: the Halifax Visual Scanning Test (HVST). METHODS: In Study I, the HVST was compared to conventional measures of neglect and functional outcome scores (wheelchair navigation) in 15 stroke inpatients and 14 healthy controls. In Study II, 19 additional controls were combined with the control data from Study I to establish cutoffs for impairment. Patterns of neglect in the stroke group were examined. RESULTS: In Study I, performance on all HVST subtests were correlated with the majority of conventional subtests and wheelchair navigation outcomes. In Study II, neglect-related deficits in visual scanning showed dissociations across spatial regions. Four inpatients exhibited symptoms of neglect on the HVST that were not detected on conventional measures, one of which showed symptoms in personal and extrapersonal space exclusively. CONCLUSIONS: The HVST appears a useful measure of neglect symptoms in different spatial regions that may not be detected with conventional measures and that correlates with functional wheelchair performance. Preliminary control data are presented and further research to add to this normative database appears warranted.

Synergistic Benefits of Combined Aerobic and Cognitive Training on Fluid Intelligence and the Role of IGF-1 in Chronic Stroke.

BACKGROUND: Paired exercise and cognitive training have the potential to enhance cognition by "priming" the brain and upregulating neurotrophins. METHODS: Two-site randomized controlled trial. Fifty-two patients >6 months poststroke with concerns about cognitive impairment trained 50 to 70 minutes, 3× week for 10 weeks with 12-week follow-up. Participants were randomized to 1 of 2 physical interventions: Aerobic (>60% VO2peak using <10% body weight-supported treadmill) or Activity (range of movement and functional tasks). Exercise was paired with 1 of 2 cognitive interventions (computerized dual working memory training [COG] or control computer games [Games]). The primary outcome for the 4 groups (Aerobic + COG, Aerobic + Games, Activity + COG, and Activity + Games) was fluid intelligence measured using Raven's Progressive Matrices Test administered at baseline, posttraining, and 3-month follow-up. Serum neurotrophins collected at one site (N = 30) included brain-derived neurotrophic factor (BDNF) at rest (BDNFresting) and after a graded exercise test (BDNFresponse) and insulin-like growth factor-1 at the same timepoints (IGF-1rest, IGF-1response). RESULTS: At follow-up, fluid intelligence scores significantly improved compared to baseline in the Aerobic + COG and Activity + COG groups; however, only the Aerobic + COG group was significantly different (+47.8%) from control (Activity + Games -8.5%). Greater IGF-1response at baseline predicted 40% of the variance in cognitive improvement. There was no effect of the interventions on BDNFresting or BDNFresponse; nor was BDNF predictive of the outcome. CONCLUSIONS: Aerobic exercise combined with cognitive training improved fluid intelligence by almost 50% in patients >6 months poststroke. Participants with more robust improvements in cognition were able to upregulate higher levels of serum IGF-1 suggesting that this neurotrophin may be involved in behaviorally induced plasticity.

Clock Drawing Test in acute stroke and its relationship with long-term functional and cognitive outcomes.

Objective: The Clock Drawing Test (CDT) is commonly used as a screening tool for the assessment of dementia. The association between the CDT in acute stroke and long-term functional and cognitive outcomes in this population is unknown. The present prospective study is the first to examine if CDT scores in the acute stage after stroke are related to long-term outcomes and to compare the predictive ability of two scoring systems in a large sample of stroke patients. Method: A total of 340 patients admitted to an acute stroke unit were included in the present study. Separate stepwise multiple linear regression analyses were performed with eight independent variables (demographic/pre-stroke variables - age, sex, premorbid functioning; stroke-related variables - stroke severity, localization; cognitive variables - Orientation Test, CDT [2 scoring systems]), and four dependent variables administered one year post-stroke (Barthel Index, modified Rankin Scale, Reintegration to Normal Living index, Global Deterioration Scale). Results: Although both CDT scoring methods were related to all long-term outcome measures, the more comprehensive scoring system was the only baseline variable that significantly explained the variance in outcome measures in all four multiple regression models. Conclusion: Performance on the CDT in acute stroke is related to long-term outcomes including patients' degree of independence in performing activities of daily living, the degree to which they achieved reintegration into daily occupations, and the degree of cognitive decline observed one-year post-stroke. Future studies are needed to clarify the nature of the relationship between different CDT scoring systems and post-stroke outcomes.

Acute Sleep Restriction Has Differential Effects on Components of Attention.

Inadequate nightly sleep duration can impair daytime functioning, including interfering with attentional and other cognitive processes. Current models posit that attention is a complex function regulated by several separate, but interacting, neural systems responsible for vigilance, orienting, and executive control. However, it is not clear to what extent each of these underlying component processes is affected by sleep loss. The purpose of this study was to evaluate the effects of acute sleep restriction on these attentional components using the Dalhousie Computerized Attention Battery (DalCAB). DalCAB tasks were administered to healthy women (aged 19-25 years) on two consecutive mornings: once after a night with 9 h time in bed (TIB), and once again after either another night with 9 h TIB (control condition, n = 19) or after a night with 3 h TIB (sleep restriction condition, n = 20). Self-ratings of sleepiness and mood were also obtained following each sleep condition. Participants showed increases in self-reported sleepiness and fatigue after the second night only in the sleep restriction group. Sleep restriction primarily affected processing speed on tasks measuring vigilance; however, performance deficits were also observed on some measures of executive function (e.g., go/no-go task, flanker task, working memory). Tasks assessing orienting of attention were largely unaffected. These results indicate that acute sleep restriction has differential effects on distinct components of attention, which should be considered in modeling the impacts of sleep loss on the underlying attentional networks.

The effects of prism adaptation on daily life activities in patients with visuospatial neglect: a systematic review.

Studies that have investigated prism adaptation (PA) effects on symptoms of visuospatial neglect have primarily used neuropsychological tests as outcome measures. An important question that remains to be answered is whether PA effects translate into improvements in patients' daily life activities. In the present review, we examined systematically the evidence for the effect of PA treatment on daily life activities in patients with neglect. Two authors independently assessed the methodological quality of 25 intervention and 1 follow-up studies using validated scales. PA effects were evaluated for reading/writing, activities of daily living (ADL) direct tests, ADL questionnaires, and navigation tests. Studies were evaluated as being of excellent (n = 1), good (n = 12), fair (n = 10), or poor (n = 3) quality. Among the 26 articles, a total of 32 measurements showed significant PA effects (one measurement from a study of excellent quality, 17 from studies of good quality, 10 from studies of fair quality, four from studies of poor quality), whereas non-significant effects were found in 15 measurements (two from a study of excellent quality, three from studies of good quality, eight from studies of fair quality, two from studies of poor quality). There is some evidence suggesting that PA can improve daily functioning, particularly as measured by reading/writing and ADL direct tests. The impact of several variables on PA effects should be investigated further including sample heterogeneity and time since injury.

Is performance on probed serial recall tasks in schizophrenia related to duration of Attentional Blink?

Schizophrenia is associated with a deficit in working memory, with the degree of working memory impairment related to the level of social and occupational functioning. This study tests the hypothesis that the working memory deficits in individuals with schizophrenia can be explained by slow processing of visual stimuli, as measured by the attentional blink (AB) task. Individuals with schizophrenia (SC) and controls (HC) were recruited from an early intervention service for psychosis and the local community. Data from 16 SC (11M/5F, mean = 26.4 yo) and 20 age-matched HC (11M/9F, mean = 25.8 yo) were analyzed. Each subject performed an AB task to determine their AB duration, defined as the lag to reach their plateau performance (ltpp). As expected, mean AB duration in the SC group (575 ms) was significantly slower than HC (460 ms; p = 0.007). Recall accuracy of the SC group on a working memory task, a 6-item probed serial recall task (PSR), was reduced compared to the HC group at a standard interstimulus interval (ISI) (p = 0.002). When the individual's AB duration was then used to adjust the ISI on the PSR task to three relative ISI rates (Slow (2 × ltpp), Medium (ltpp) and Fast (1/2 × ltpp)), performance on the PSR task was affected by group, position and ISI and qualified by an ISI ∗ position (p = 0.001) and a trend to a triple interaction (p = 0.054). There was main effect of group at all ISIs, but group ∗ position interaction only at Slow ISI (p = 0.01). Our interpretation of the results is that absolute ISI, rather than ISI relative to AB duration, affected performance.

Methods for validating chronometry of computerized tests.

Determining the speed at which a task is performed (i.e., reaction time) can be a valuable tool in both research and clinical assessments. However, standard computer hardware employed for measuring reaction times (e.g., computer monitor, keyboard, or mouse) can add nonrepresentative noise to the data, potentially compromising the accuracy of measurements and the conclusions drawn from the data. Therefore, an assessment of the accuracy and precision of measurement should be included along with the development of computerized tests and assessment batteries that rely on reaction times as the dependent variable. This manuscript outlines three methods for assessing the temporal accuracy of reaction time data (one employing external chronometry). Using example data collected from the Dalhousie Computerized Attention Battery (DalCAB) we discuss the detection, measurement, and correction of nonrepresentative noise in reaction time measurement. The details presented in this manuscript should act as a cautionary tale to any researchers or clinicians gathering reaction time data, but who have not yet considered methods for verifying the internal chronometry of the software and or hardware being used.

Promoting brain health through exercise and diet in older adults: a physiological perspective.

The rise in incidence of age-related cognitive impairment is a global health concern. Ageing is associated with a number of changes in the brain that, collectively, contribute to the declines in cognitive function observed in older adults. Structurally, the ageing brain atrophies as white and grey matter volumes decrease. Oxidative stress and inflammation promote endothelial dysfunction thereby hampering cerebral perfusion and thus delivery of energy substrates and nutrients. Further, the development of amyloid plaques and neurofibrillary tangles contributes to neuronal loss. Of interest, there are substantial inter-individual differences in the degree to which these physical and functional changes impact upon cognitive function as we grow older. This review describes how engaging in physical activity and cognitive activities and adhering to a Mediterranean style diet promote 'brain health'. From a physiological perspective, we discuss the effects of these modifiable lifestyle behaviours on the brain, and how some recent human trials are beginning to show some promise as to the effectiveness of lifestyle behaviours in combating cognitive impairment. Moreover, we propose that these lifestyle behaviours, through numerous mechanisms, serve to increase brain, cerebrovascular and cognitive reserve, thereby preserving and enhancing cognitive function for longer.