The effect of visual target presence and age on antisaccade performance.

Antisaccade and prosaccade (PS) performance were studied in a large cohort of females (age range 42-74 yr). Antisaccade performance was assessed in two variants of the task, a "traditional" antisaccade (TA) task, in which no visual stimuli were present at the saccade goal, and a visually guided antisaccade (VGA) task, in which small visual stimuli were present at the possible saccade goals prior to the imperative visual stimulus. Directional error frequency was similar in the two antisaccade tasks. However, reaction time (RT) was ∼33 ms longer in the VGA task than in the TA task. Across participants, the average saccade amplitudes of prosaccades and TAs were both correlated with those of VGAs but not with each other. TAs had a hypermetria that increased with age. Saccade amplitude variability was much higher for TAs than for PSs and VGAs. Saccade polar angle variability was low for all three tasks. Age diminished performance with modest task dependence, except for an increase in TA hypermetria. These results suggest that the generation of antisaccade directional errors does not depend on visual target presence at the saccade goal, that antisaccade RT can be affected by target presence, that age can increase saccade hypermetria in the absence of visual guidance, and that visually guided antisaccades are governed by distinct voluntary and visually guided saccade mechanisms. Moreover, these results suggest that an understanding of human motor performance benefits from the use of a participant pool with a larger age range than that used in most studies.NEW & NOTEWORTHY This study uses a visually guided antisaccade (VGA) task to determine whether poor performance in a large middle-aged participant pool on an antisaccade task results from problems with executive control or voluntary saccade generation. Spatial and temporal attributes of saccade performance as a function of task and age are analyzed comprehensively. Correlational analysis is used to determine how VGAs are governed jointly by voluntary and visually guided movement mechanisms.

Polygenic risk scores for schizophrenia are associated with oculomotor endophenotypes.

BACKGROUND: Schizophrenia is a heterogeneous disorder with substantial heritability. The use of endophenotypes may help clarify its aetiology. Measures from the smooth pursuit and antisaccade eye movement tasks have been identified as endophenotypes for schizophrenia in twin and family studies. However, the genetic basis of the overlap between schizophrenia and these oculomotor markers is largely unknown. Here, we tested whether schizophrenia polygenic risk scores (PRS) were associated with oculomotor performance in the general population. METHODS: Analyses were based on the data of 2956 participants (aged 30-95) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Genotyping was performed on Omni-2.5 exome arrays. Using summary statistics from a recent meta-analysis based on the two largest schizophrenia genome-wide association studies to date, we quantified genetic risk for schizophrenia by creating PRS at different p value thresholds for genetic markers. We examined associations between PRS and oculomotor performance using multivariable regression models. RESULTS: Higher PRS were associated with higher antisaccade error rate and latency, and lower antisaccade amplitude gain. PRS showed inconsistent patterns of association with smooth pursuit velocity gain and were not associated with saccade rate during smooth pursuit or performance on a prosaccade control task. CONCLUSIONS: There is an overlap between genetic determinants of schizophrenia and oculomotor endophenotypes. Our findings suggest that the mechanisms that underlie schizophrenia also affect oculomotor function in the general population.

Cerebral blood flow and immediate and sustained executive function benefits following single bouts of passive and active exercise.

Passive exercise occurs when an individual's limbs are moved via an external force and is a modality that increases cerebral blood flow (CBF) and provides an immediate postexercise executive function (EF) benefit. To our knowledge, no work has examined for how long passive exercise benefits EF. Here, healthy young adults (N = 22; 7 female) used a cycle ergometer to complete three 20-min conditions: passive exercise (via mechanically driven flywheel), a traditional light intensity (37 W) "active" exercise condition (i.e., via volitional pedalling) and a non-exercise control condition. An estimate of CBF was obtained via transcranial Doppler ultrasound measurement of middle cerebral artery blood velocity (MCAv) and antisaccades (i.e., saccade mirror-symmetrical to a target) were completed prior to and immediately, 30- and 60-min following each condition to assess EF. Passive and active exercise increased MCAv; however, the increase was larger in the latter condition. In terms of antisaccades, passive and active exercise provided an immediate postexercise reaction time benefit. At the 30-min assessment, the benefit was observed for active but not passive exercise and neither produced a benefit at the 60-min assessment. Thus, passive exercise provided an evanescent EF "boost" and is a finding that may reflect a smaller cortical hemodynamic response.

Assessing anxiety-linked impairment in attentional control without eye-tracking: The masked-target antisaccade task.

Contemporary cognitive theories of anxiety and attention processing propose that heightened levels of anxiety vulnerability are associated with a decreasing ability to inhibit the allocation of attention towards task-irrelevant information. Existing performance-based research has most often used eye-movement assessment variants of the antisaccade paradigm to demonstrate such effects. Critically, however, eye-movement assessment methods are limited by expense, the need for expert training in administration, and limited mobility and scalability. These barriers have likely led to researchers' use of suboptimal methods of assessing the relationship between attentional control and anxiety vulnerability. The present study examined the capacity for a non-eye-movement-based variant of the antisaccade task, the masked-target antisaccade task (Guitton et al., 1985), to detect anxiety-linked differences in attentional control. Participants (N = 342) completed an assessment of anxiety vulnerability and performed the masked-target antisaccade task in an online assessment session. Greater levels of anxiety vulnerability predicted poorer performance on the task, consistent with findings observed from eye-movement methods and with cognitive theories of anxiety and attention processing. Results also revealed the task to have high internal reliability. Our findings indicate that the masked-target antisaccade task provides a psychometrically reliable, low-cost, mobile, and scalable assessment of anxiety-linked differences in attentional control.

Oral Administration of Oxytocin, Like Intranasal Administration, Decreases Top-Down Social Attention.

BACKGROUND: The neuropeptide oxytocin (OXT) modulates social cognition by increasing attention to social cues and may have therapeutic potential for impaired social attention in conditions such as autism spectrum disorder. Intranasal administration of OXT is widely used to examine the drug's functional effects in both adults and children and is assumed to enter the brain directly via this route. However, OXT can also influence brain function through increased blood concentrations, and we have recently shown that orally (lingual) administered OXT also modulates neural responses to emotional faces and may be better tolerated for therapeutic use. Here, we examine whether 24 IU OXT administered orally can facilitate social attention. METHODS: In a randomized, placebo-controlled pharmacologic study, we used a validated emotional antisaccade eye-tracking paradigm to explore the effects of oral OXT on bottom-up and top-down attention processing in 80 healthy male participants. RESULTS: Our findings showed that in terms of top-down attention, oral OXT increased errors for both social (angry, fearful, happy, sad, and neutral emotion faces) and nonsocial stimuli (oval shapes) in the antisaccade condition but increased response latencies only in the social condition. It also significantly reduced post-task state anxiety, but this reduction was not correlated with task performance. A comparison with our previous intranasal OXT study using the same task revealed that both routes have a similar effect on increasing antisaccade errors and response latencies and on reducing state anxiety. CONCLUSIONS: Overall, our findings suggest that oral administration of OXT produces similar effects on top-down social attention control and anxiety to intranasal administration and may therefore have therapeutic utility.

The unidirectional prosaccade switch-cost: no evidence for the passive dissipation of an oculomotor task-set inertia.

Cognitive flexibility is a core component of executive function and supports the ability to 'switch' between different tasks. Our group has examined the cost associated with switching between a prosaccade (i.e., a standard task requiring a saccade to veridical target location) and an antisaccade (i.e., a non-standard task requiring a saccade mirror-symmetrical to veridical target) in predictable (i.e., AABB) and unpredictable (e.g., AABAB…) switching paradigms. Results have shown that reaction times (RTs) for a prosaccade preceded by an antisaccade (i.e., task-switch trial) are longer than when preceded by its same task-type (i.e., task-repeat trial), whereas RTs for antisaccade task-switch and task-repeat trials do not differ. The asymmetrical switch-cost has been attributed to an antisaccade task-set inertia that proactively delays a subsequent prosaccade (i.e., the unidirectional prosaccade switch-cost). A salient question arising from previous work is whether the antisaccade task-set inertia passively dissipates or persistently influences prosaccade RTs. Accordingly, participants completed separate AABB (i.e., A = prosaccade, B = antisaccade) task-switching conditions wherein the preparation interval for each trial was 'short' (1000-2000 ms; i.e., the timeframe used in previous work), 'medium' (3000-4000 ms) and 'long' (5000-6000 ms). Results demonstrated a reliable prosaccade switch-cost for each condition (ps < 0.02) and two one-sided test statistics indicated that switch cost magnitudes were within an equivalence boundary (ps < 0.05). Hence, null and equivalence tests demonstrate that an antisaccade task-set inertia does not passively dissipate and represents a temporally persistent feature of oculomotor control.

Antisaccade, a predictive marker for freezing of gait in Parkinson's disease and gait/gaze network connectivity.

Freezing of gait is a challenging sign of Parkinson's disease associated with disease severity and progression and involving the mesencephalic locomotor region. No predictive factor of freezing has been reported so far. The primary objective of this study was to identify predictors of freezing occurrence at 5 years. In addition, we tested whether functional connectivity of the mesencephalic locomotor region could explain the oculomotor factors at baseline that were predictive of freezing onset. We performed a prospective study investigating markers (parkinsonian signs, cognitive status and oculomotor recordings, with a particular focus on the antisaccade latencies) of disease progression at baseline and at 5 years. We identified two groups of patients defined by the onset of freezing at 5 years of follow-up; the 'Freezer' group was defined by the onset of freezing in the ON medication condition during follow-up (n = 17), while the 'non-Freezer' group did not (n = 8). Whole brain resting-state functional MRI was recorded at baseline to determine how antisaccade latencies were associated with connectivity of the mesencephalic locomotor region networks in patients compared to 25 age-matched healthy volunteers. Results showed that, at baseline and compared to the non-Freezer group, the Freezer group had equivalent motor or cognitive signs, but increased antisaccade latencies (P = 0.008). The 5-year course of freezing of gait was correlated with worsening antisaccade latencies (P = 0.0007). Baseline antisaccade latencies was also predictive of the freezing onset (χ2 = 0.008). Resting state connectivity of mesencephalic locomotor region networks correlated with (i) antisaccade latency differently in patients and healthy volunteers at baseline; and (ii) the further increase of antisaccade latency at 5 years. We concluded that antisaccade latency is a predictive marker of the 5-year onset of freezing of gait. Our study suggests that functional networks associated with gait and gaze control are concurrently altered during the course of the disease.

Variation in antisaccadic response latencies investigated with the hierarchical LATER process model.

The antisaccade paradigm is frequently applied to measure inhibitory control. Typically, simple, perceptually neutral stimuli are used as cues. Recently, emotional versions of this paradigm have also been employed. In our study, we used both versions of the paradigm. In addition, scrambled faces served to control for stimulus size and emotional valence. We applied a hierarchical extension to the Linear Approach to Threshold Ergodic Rate (LATER) process model, which allows the estimation of two latent cognitive parameters: speed of information accumulation (accretion rate) and the amount of information needed before a saccadic movement (caution threshold). We hypothesized a faster accretion rate and lower caution threshold for circular and scrambled compared to emotional face stimuli as well as meaningful differences between individual emotions. Our results showed a faster accretion rate and lower caution threshold for emotional compared to circular stimuli, though. In contrast, scrambled faces had a lower accretion rate and lower caution threshold. Furthermore, the LATER model uncovered subtle differences between different emotions. Happy faces tend to receive a faster accretion rate and higher caution threshold than neutral ones, while for fearful faces it was the other way around. Our results contradict earlier research on emotional stimuli interfering inhibitory control.

Assessing cognitive flexibility in anorexia nervosa using eye tracking: A registered report.

OBJECTIVE: Cognitive flexibility research in anorexia nervosa (AN) has primarily focused on group differences between clinical and control participants, but research in the general population utilizing the mixed pro- anti-saccade flexibility task has demonstrated individual differences in trait anxiety are a determinant of switching performance, and switching impairments are more pronounced for keypress than saccadic (eye-movement) responses. The aim of the current research is to explore trait anxiety and differences in saccadic and keypress responding as potential determinants of performance on flexibility tasks in AN. METHOD: We will compare performance on the mixed pro- anti-saccade paradigm between female adult participants with a current diagnosis of AN and matched control participants, observing both saccadic and keypress responses while controlling for trait anxiety (State - Trait Anxiety Inventory) and spatial working memory (Corsi Block Tapping Test). Associations with eating disorder-related symptoms (Eating Disorder Examination Questionnaire), flexibility in everyday life (Eating Disorder Flexibility Index), and the Clinical Perfectionism Questionnaire will also be assessed. RESULTS: Data which controls for individual differences in trait anxiety and assesses flexibility at both the task- and response-set level may be used to more accurately understand differences in performance on cognitive flexibility tasks by participants with AN. DISCUSSION: Clarifying the effects of trait anxiety on flexibility, and differences between task- and response-set switching may advance our understanding of how cognitive flexibility relates to flexibility in everyday life and improve translation to therapeutic approaches. PUBLIC SIGNIFICANCE STATEMENT: This research will compare performance on a flexibility task between participants with anorexia nervosa (AN) and controls while observing their eye-movements to examine whether trait anxiety and type of response (eye-movement and keypress) are associated with performance. This data may improve our understanding of why participants with AN perform more poorly on cognitive flexibility tasks, and how poor cognitive flexibility relates to eating disorder-related issues with flexibility in everyday life.

Increased Subthalamic Nucleus Deep Brain Stimulation Amplitude Impairs Inhibitory Control of Eye Movements in Parkinson's Disease.

BACKGROUND AND OBJECTIVES: Bilateral subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson's disease (PD) can have detrimental effects on eye movement inhibitory control. To investigate this detrimental effect of bilateral STN DBS, we examined the effects of manipulating STN DBS amplitude on inhibitory control during the antisaccade task. The prosaccade error rate during the antisaccade task, that is, directional errors, was indicative of impaired inhibitory control. We hypothesized that as stimulation amplitude increased, the prosaccade error rate would increase. MATERIALS AND METHODS: Ten participants with bilateral STN DBS completed the antisaccade task on six different stimulation amplitudes (including zero amplitude) after a 12-hour overnight withdrawal from antiparkinsonian medication. RESULTS: We found that the prosaccade error rate increased as stimulation amplitude increased (p < 0.01). Additionally, prosaccade error rate increased as the modeled volume of tissue activated (VTA) and STN overlap decreased, but this relationship depended on stimulation amplitude (p = 0.04). CONCLUSIONS: Our findings suggest that higher stimulation amplitude settings can be modulatory for inhibitory control. Some individual variability in the effect of stimulation amplitude can be explained by active contact location and VTA-STN overlap. Higher stimulation amplitudes are more deleterious if the active contacts fall outside of the STN resulting in a smaller VTA-STN overlap. This is clinically significant as it can inform clinical optimization of STN DBS parameters. Further studies are needed to determine stimulation amplitude effects on other aspects of cognition and whether inhibitory control deficits on the antisaccade task result in a meaningful impact on the quality of life.

Effects of pupillary light and darkness reflex on the generation of pro- And anti-saccades.

Saccades are often directed toward a stimulus that provides useful information for observers to navigate the visual world. The quality of visual signals of a stimulus is influenced by global luminance, and the pupil constricts or dilates after a luminance increase or decrease, respectively, to optimize visual signals for further information processing. Although luminance level changes regularly in the real environment, saccades are mostly studied in the luminance-unchanged setup. Whether pupillary responses triggered by global luminance changes modulate saccadic behavior are yet to be explored. Through varying background luminance level in an interleaved pro- and anti-saccade paradigm, we investigated the modulation of pupillary luminance responses on the generation of reflexive and voluntary saccades. Subjects were instructed to either automatically look at the peripheral stimulus (pro-saccade) or to suppress the automatic response and voluntarily look in the opposite direction from the stimulus (anti-saccade). Level of background luminance was increased (light), decreased (dark), or unchanged (control) during the instructed fixation period. Saccade reaction time distributions of correct pro- and anti-saccades in the light and dark conditions were differed significantly from those in the control condition. Moreover, the luminance condition modulated saccade kinematics, showing reduced performances in the light condition than in the control condition, particularly in pro-saccades. Modeling results further suggested that both pupil diameter and pupil size derivative significantly modulated saccade behavior, though effect sizes were small and mainly mediated by intersubject differences. Together, our results demonstrated the influence of pupillary luminance responses on the generation of pro- and anti-saccades.

Antisaccades in Parkinson's Disease: A Meta-Analysis.

The usefulness of eye-tracking tasks as potential biomarkers for motor or cognitive disease burden in Parkinson's disease (PD) has been subject of debate for many years. Several studies suggest that the performance in the antisaccade task may be altered in patients with PD and associated with motor disease severity or executive dysfunction. In this meta-analysis, random effects models were used to synthesize the existing evidence on antisaccade error rates and latency in PD. Furthermore, meta-regressions were performed to assess the role of motor and cognitive disease severity, dopaminergic medication and methodological factors. Additionally, the impact of acute levodopa administration and activation of deep brain stimulation was evaluated in two separate sub-analyses.This meta-analysis confirms that antisaccade latency and error rate are significantly increased in PD. Disease duration, Unified Parkinson's disease rating scale score and Hoehn and Yahr stage mediate the effect of PD on antisaccade latency with higher motor burden being associated with increased antisaccade latency.Acute administration of levodopa had no significant effects on antisaccade performance in a small number of eligible studies. Deep brain stimulation in the subthalamic nucleus, on the other hand, may alter the speed accuracy trade-off supporting an increase of impulsivity following deep brain stimulation in PD.According to the results of the meta-analysis, antisaccade latency may provide a potential marker for disease severity and progression in PD which needs further confirmation in longitudinal studies.

Using multivariate endophenotypes to identify psychophysiological mechanisms associated with polygenic scores for substance use, schizophrenia, and education attainment.

BACKGROUND: To better characterize brain-based mechanisms of polygenic liability for psychopathology and psychological traits, we extended our previous report (Liu et al. Psychophysiological endophenotypes to characterize mechanisms of known schizophrenia genetic loci. Psychological Medicine, 2017), focused solely on schizophrenia, to test the association between multivariate psychophysiological candidate endophenotypes (including novel measures of θ/δ oscillatory activity) and a range of polygenic scores (PGSs), namely alcohol/cannabis/nicotine use, an updated schizophrenia PGS (containing 52 more genome-wide significant loci than the PGS used in our previous report) and educational attainment. METHOD: A large community-based twin/family sample (N = 4893) was genome-wide genotyped and imputed. PGSs were constructed for alcohol use, regular smoking initiation, lifetime cannabis use, schizophrenia, and educational attainment. Eleven endophenotypes were assessed: visual oddball task event-related electroencephalogram (EEG) measures (target-related parietal P3 amplitude, frontal θ, and parietal δ energy/inter-trial phase clustering), band-limited resting-state EEG power, antisaccade error rate. Principal component analysis exploited covariation among endophenotypes to extract a smaller number of meaningful dimensions/components for statistical analysis. RESULTS: Endophenotypes were heritable. PGSs showed expected intercorrelations (e.g. schizophrenia PGS correlated positively with alcohol/nicotine/cannabis PGSs). Schizophrenia PGS was negatively associated with an event-related P3/δ component [ß = -0.032, nonparametric bootstrap 95% confidence interval (CI) -0.059 to -0.003]. A prefrontal control component (event-related θ/antisaccade errors) was negatively associated with alcohol (ß = -0.034, 95% CI -0.063 to -0.006) and regular smoking PGSs (ß = -0.032, 95% CI -0.061 to -0.005) and positively associated with educational attainment PGS (ß = 0.031, 95% CI 0.003-0.058). CONCLUSIONS: Evidence suggests that multivariate endophenotypes of decision-making (P3/δ) and cognitive/attentional control (θ/antisaccade error) relate to alcohol/nicotine, schizophrenia, and educational attainment PGSs and represent promising targets for future research.

Response Inhibition Deficits in Women with the FMR1 Premutation are Associated with Age and Fall Risk.

One in 113-178 females worldwide carry a premutation allele on the FMR1 gene. The FMR1 premutation is linked to neurocognitive and neuromotor impairments, although the phenotype is not fully understood, particularly with respect to age effects. This study sought to define oculomotor response inhibition skills in women with the FMR1 premutation and their association with age and fall risk. We employed an antisaccade eye-tracking paradigm to index oculomotor inhibition skills in 35 women with the FMR1 premutation and 28 control women. The FMR1 premutation group exhibited longer antisaccade latency and reduced accuracy relative to controls, indicating deficient response inhibition skills. Longer response latency was associated with older age in the FMR1 premutation and was also predictive of fall risk. Findings highlight the utility of the antisaccade paradigm for detecting early signs of age-related executive decline in the FMR1 premutation, which is related to fall risk. Findings support the need for clinical prevention efforts to decrease and delay the trajectory of age-related executive decline in women with the FMR1 premutation during midlife.

Combined antisaccade task and transcranial direct current stimulation to increase response inhibition in binge eating disorder.

Binge eating disorder (BED) is associated with deficient response inhibition. Malfunctioning response inhibition is linked to hypoactivation of the dorsolateral prefrontal cortex (dlPFC), where excitability could be increased by anodal transcranial direct current stimulation (tDCS). Response inhibition can be assessed using an antisaccade task which requires supressing a dominant response (i.e. saccade) towards a newly appearing picture in the visual field. We performed a double-blind, randomised, placebo-controlled proof-of-concept-study in which we combined a food-modified antisaccade task with tDCS in people with BED. We expected task learning and modulatory tDCS effects. Sixteen people were allocated to a 1 mA condition, 15 people to a 2 mA condition. Each participant underwent the food-modified antisaccade task at three measurement points: baseline without stimulation, anodal verum and sham stimulation at the right dlPFC in a crossover design. The error rate and the latencies of correct antisaccades decreased over time. No tDCS effect on the error rate could be observed. Compared to sham stimulation, 2 mA tDCS decreased the latencies of correct antisaccades, whereas 1 mA tDCS increased it. Self-reported binge eating episodes were reduced in the 2 mA condition, while there was no change in the 1 mA condition. Participants demonstrated increased response inhibition capacities by a task learning effect concerning the error rate and latencies of correct antisaccades over time as well as a nonlinear tDCS effect represented by ameliorated latencies in the 2 mA and impaired latencies in the 1 mA condition. The reduction of binge eating episodes might indicate a transfer effect to everyday life. Given that the reduction in binge eating was observed before tDCS administration, this effect could not be the result of neuromodulation. Randomized clinical trials are needed to fully understand this reduction, and to explore the efficacy of a combined antisaccade and tDCS training for BED.

Do emotional stimuli interfere with response inhibition? evidence from the antisaccade paradigm.

When it comes to measuring cognitive control and inhibition, the antisaccade paradigm is a popular task to apply. Usually, simple, perceptually and affectively neutral stimuli, e.g. white circles, are used. Recently, researchers also employed a version of the paradigm displaying emotional faces. Differences in cognitive processing due to stimulus size and emotional valence have not been investigated yet. Thus, in the present study, we applied both versions of the antisaccade paradigm in a healthy sample. In addition, we used scrambled faces to control for stimulus size and emotional valence. We hypothesised slower reaction times and higher error rates for emotional face stimuli compared to circular and scrambled ones as well as significant differences between individual emotions. In contrast to our hypotheses, results showed faster reaction times fewer errors for emotional faces compared to circular and scrambled stimuli. Furthermore, ANOVA models showed no meaningful differences between different emotions. Our study shows specific patterns in inhibitory control due to stimulus size and valence in an antisaccade eye-tracking task.

Increased cerebral blood flow supports a single-bout postexercise benefit to executive function: evidence from hypercapnia.

A single bout of aerobic exercise improves executive function; however, the mechanism for the improvement remains unclear. One proposal asserts that an exercise-mediated increase in cerebral blood flow (CBF) enhances the efficiency of executive-related cortical structures. To examine this, participants completed separate 10-min sessions of moderate- to heavy-intensity aerobic exercise, a hypercapnic environment (i.e., 5% CO2), and a nonexercise and nonhypercapnic control condition. The hypercapnic condition was included because it produces an increase in CBF independent of metabolic demands. An estimate of CBF was achieved via transcranial Doppler ultrasound and near-infrared spectroscopy that provided measures of middle cerebral artery blood velocity (BV) and deoxygenated hemoglobin (HHb), respectively. Exercise intensity was adjusted to match participant-specific changes in BV and HHb associated with the hypercapnic condition. Executive function was assessed before and after each session via antisaccades (i.e., saccade mirror-symmetrical to a target) because the task is mediated via the same executive networks that demonstrate task-dependent modulation following single and chronic bouts of aerobic exercise. Results showed that hypercapnic and exercise conditions were associated with comparable BV and HHb changes, whereas the control condition did not produce a change in either metric. In terms of antisaccade performance, the exercise and hypercapnic, but not control, conditions demonstrated improved postcondition reaction times (RT), and the magnitude of the hypercapnic and exercise-based increase in estimated CBF was reliably related to the postcondition improvement in RT. Accordingly, results evince that an increase in CBF represents a candidate mechanism for a postexercise improvement in executive function.NEW & NOTEWORTHY Single-bout aerobic exercise "boosts" executive function, and increased cerebral blood flow (CBF) has been proposed as a mechanism for the benefit. In this study, participants completed 10 min of aerobic exercise and 10 min of inhaling a hypercapnic gas, a manipulation known to increase CBF independently of metabolic demands. Both exercise and hypercapnic conditions improved executive function for at least 20 min. Accordingly, an increase in CBF is a candidate mechanism for the postexercise improvement in executive function.

Mapping neural dynamics underlying saccade preparation and execution and their relation to reaction time and direction errors.

Our ability to control and inhibit automatic behaviors is crucial for negotiating complex environments, all of which require rapid communication between sensory, motor, and cognitive networks. Here, we measured neuromagnetic brain activity to investigate the neural timing of cortical areas needed for inhibitory control, while 14 healthy young adults performed an interleaved prosaccade (look at a peripheral visual stimulus) and antisaccade (look away from stimulus) task. Analysis of how neural activity relates to saccade reaction time (SRT) and occurrence of direction errors (look at stimulus on antisaccade trials) provides insight into inhibitory control. Neuromagnetic source activity was used to extract stimulus-aligned and saccade-aligned activity to examine temporal differences between prosaccade and antisaccade trials in brain regions associated with saccade control. For stimulus-aligned antisaccade trials, a longer SRT was associated with delayed onset of neural activity within the ipsilateral parietal eye field (PEF) and bilateral frontal eye field (FEF). Saccade-aligned activity demonstrated peak activation 10ms before saccade-onset within the contralateral PEF for prosaccade trials and within the bilateral FEF for antisaccade trials. In addition, failure to inhibit prosaccades on anti-saccade trials was associated with increased activity prior to saccade onset within the FEF contralateral to the peripheral stimulus. This work on dynamic activity adds to our knowledge that direction errors were due, at least in part, to a failure to inhibit automatic prosaccades. These findings provide novel evidence in humans regarding the temporal dynamics within oculomotor areas needed for saccade programming and the role frontal brain regions have on top-down inhibitory control.

A single bout of moderate intensity exercise improves cognitive flexibility: evidence from task-switching.

Executive function entails the core components of response  inhibition, working memory and cognitive flexibility. An accumulating literature has shown that a single bout of exercise improves the response inhibition  and working memory components of executive function; however, limited work has examined a putative exercise-related improvement to cognitive flexibility. To address this limitation, Experiment 1 entailed a 20-min session of moderate intensity aerobic exercise (via cycle ergometer), and pre- and post-exercise cognitive flexibility was examined via a task-switching paradigm involving alternating pro- and antisaccades (AABB: A = prosaccade, B = antisaccade). In Experiment 2, participants sat on the cycle ergometer without exercising (i.e., rest break) and the same AABB paradigm was examined pre- and post-break. We used an AABB pro- and antisaccade paradigm because previous work has shown that a prosaccade preceded by an antisaccade exhibits a reliable-and large magnitude-increase in reaction time, whereas the converse switch does not (i.e., the unidirectional prosaccade switch-cost). Experiment 1 showed a unidirectional prosaccade switch-cost pre-exercise (p = .012)-but not post-exercise (p = .30), and a two one-sided t test indicated that the latter comparison was within an equivalence boundary (p < .01). In contrast, Experiment 2 revealed a unidirectional prosaccade switch-cost at pre- and post-break assessments (ps < .01). Accordingly, our results indicate that a single bout of exercise improves cognitive flexibility and provides convergent evidence that exercise improves global components of executive function.

Differential benefits of olanzapine on executive function in schizophrenia patients: Preliminary findings.

OBJECTIVE: Schizophrenia patients show executive function (EF) impairments in voluntary orienting as measured by eye-movements. We tested 14 inpatients to investigate the effects of the antipsychotic olanzapine on EF, as measured by antisaccade eye-movement performance. METHODS: Patients were tested at baseline (before olanzapine), 3-5 days post-medication, and 12-14 days post-medication. Patients were also assessed on the Positive and Negative Syndrome Scale (PANSS) to measure the severity of schizophrenia-related symptoms, and administered the Stroop task, a test of EF. Nine matched controls were also tested on the antisaccade and Stroop. RESULTS: Both groups showed improvement on Stroop and antisaccade; however, the schizophrenia group improved significantly more on antisaccade, indicating an additional benefit of olanzapine on EF performance. Patients with poorer baseline antisaccade performance (High-Deficit) showed significantly greater improvement on the antisaccade task than patients with better baseline performance (Low-Deficit), suggesting that baseline EF impairment predicts the magnitude of cognitive improvement with olanzapine. These subgroups showed significant and equivalent improvement on PANSS scores, indicating that improvement on the antisaccade task with olanzapine was not a result of differences in magnitude of clinical improvement. CONCLUSIONS: This preliminary study provides evidence that olanzapine may be most advantageous for patients with greater baseline EF deficits.