Nathan E. Yanasak

Exercise Improves Executive Function and Achievement and Alters Brain Activation in Overweight Children: A Randomized, Controlled Trial

OBJECTIVEnThis experiment tested the hypothesis that exercise would improve executive function.nnnDESIGNnSedentary, overweight 7- to 11-year-old children (N = 171, 56% girls, 61% Black, M ± SD age = 9.3 ± 1.0 years, body mass index [BMI] = 26 ± 4.6 kg/m², BMI z-score = 2.1 ± 0.4) were randomized to 13 ± 1.6 weeks of an exercise program (20 or 40 min/day), or a control condition.nnnMAIN OUTCOME MEASURESnBlinded, standardized psychological evaluations (Cognitive Assessment System and Woodcock-Johnson Tests of Achievement III) assessed cognition and academic achievement. Functional MRI measured brain activity during executive function tasks.nnnRESULTSnIntent to treat analysis revealed dose-response benefits of exercise on executive function and mathematics achievement. Preliminary evidence of increased bilateral prefrontal cortex activity and reduced bilateral posterior parietal cortex activity attributable to exercise was also observed.nnnCONCLUSIONnConsistent with results obtained in older adults, a specific improvement on executive function and brain activation changes attributable to exercise were observed. The cognitive and achievement results add evidence of dose-response and extend experimental evidence into childhood. This study provides information on an educational outcome. Besides its importance for maintaining weight and reducing health risks during a childhood obesity epidemic, physical activity may prove to be a simple, important method of enhancing aspects of childrens mental functioning that are central to cognitive development. This information may persuade educators to implement vigorous physical activity.

An 8-Month Randomized Controlled Exercise Trial Alters Brain Activation During Cognitive Tasks in Overweight Children

Children who are less fit reportedly have lower performance on tests of cognitive control and differences in brain function. This study examined the effect of an exercise intervention on brain function during two cognitive control tasks in overweight children.

Basal ganglia-thalamocortical circuitry disruptions in schizophrenia during delayed response tasks.

BACKGROUNDnSchizophrenia is characterized by executive functioning deficits, presumably mediated by prefrontal cortex dysfunction. For example, schizophrenia participants show performance deficits on ocular motor delayed response (ODR) tasks, which require both inhibition and spatial working memory for correct performance.nnnMETHODSnThe present functional magnetic resonance imaging (fMRI) study compared neural activity of 14 schizophrenia and 14 normal participants while they performed ODR tasks.nnnRESULTSnSchizophrenia participants generated: 1) more trials with anticipatory saccades (saccades made during the delay period), 2) memory saccades with longer latencies, and 3) memory saccades of decreased accuracy. Increased blood oxygenation level-dependent (BOLD) signal changes were observed in both groups in ocular motor circuitry (e.g., supplementary eye fields [SEF], lateral frontal eye fields [FEF], inferior parietal lobule [IPL], cuneus, and precuneus). The normal, but not the schizophrenia, group demonstrated BOLD signal changes in dorsolateral prefrontal regions (right Brodmann area [BA] 9 and bilateral BA 10), medial FEF, insula, thalamus, and basal ganglia. Correlations between percentage of anticipatory saccade trials and BOLD signal changes were more similar between groups for subcortical regions and less similar for cortical regions.nnnCONCLUSIONSnThese results suggest that executive functioning deficits in schizophrenia may be associated with dysfunction of the basal ganglia-thalamocortical circuitry, evidenced by decreased prefrontal cortex, basal ganglia, and thalamus activity in the schizophrenia group during ODR task performance.

An 8-month exercise intervention alters frontotemporal white matter integrity in overweight children.

In childhood, excess adiposity and low fitness are linked to poor academic performance, lower cognitive function, and differences in brain structure. Identifying ways to mitigate obesity-related alterations is of current clinical importance. This study examined the effects of an 8-month exercise intervention on the uncinate fasciculus, a white matter fiber tract connecting frontal and temporal lobes. Participants consisted of 18 unfit, overweight 8- to 11-year-old children (94% Black) who were randomly assigned to either an aerobic exercise (nu2009=u200910) or a sedentary control group (nu2009=u20098). Before and after the intervention, all subjects participated in a diffusion tensor MRI scan. Tractography was conducted to isolate the uncinate fasciculus. The exercise group showed improved white matter integrity as compared to the control group. These findings are consistent with an emerging literature suggesting beneficial effects of exercise on white matter integrity.

Improved Frontoparietal White Matter Integrity in Overweight Children Is Associated with Attendance at an After-School Exercise Program

Aerobic fitness is associated with white matter integrity (WMI) in adults as measured by diffusion tensor imaging (DTI). This study examined the effect of an 8-month exercise intervention on WMI in children. Participants were 18 sedentary, overweight (BMI ≥85th percentile) 8- to 11-year-old children (94% Black), randomly assigned to either an aerobic exercise (n = 10) or sedentary attention control group (n = 8). Each group was offered an instructor-led after-school program every school day for approximately 8 months. Before and after the program, all subjects participated in DTI scans. Tractography was conducted to isolate the superior longitudinal fasciculus and investigate whether the exercise intervention affected WMI in this region. There was no group by time interaction for WMI in the superior longitudinal fasciculus. There was a group by time by attendance interaction, however, such that higher attendance at the exercise intervention, but not the control intervention, was associated with increased WMI. Heart rate and the total dose of exercise correlated with WMI changes in the exercise group. In the overall sample, increased WMI was associated with improved scores on a measure of attention and improved teacher ratings of executive function. This study indicates that participating in an exercise intervention improves WMI in children as compared to a sedentary after-school program.

AN EIGHT MONTH RANDOMIZED CONTROLLED EXERCISE INTERVENTION ALTERS RESTING STATE SYNCHRONY IN OVERWEIGHT CHILDREN

Children with low aerobic fitness have altered brain function compared to higher-fit children. This study examined the effect of an 8-month exercise intervention on resting state synchrony. Twenty-two sedentary, overweight (body mass index ≥85th percentile) children 8-11 years old were randomly assigned to one of two after-school programs: aerobic exercise (n=13) or sedentary attention control (n=9). Before and after the 8-month programs, all subjects participated in resting state functional magnetic resonance imaging scans. Independent components analysis identified several networks, with four chosen for between-group analysis: salience, default mode, cognitive control, and motor networks. The default mode, cognitive control, and motor networks showed more spatial refinement over time in the exercise group compared to controls. The motor network showed increased synchrony in the exercise group with the right medial frontal gyrus compared to controls. Exercise behavior may enhance brain development in children.

SCHIZOPHRENIA AND RED LIGHT: fMRI EVIDENCE FOR A NOVEL BIOBEHAVIORAL MARKER

Previous research has demonstrated the ability of diffuse red light to suppress activity in the magnocellular (M) visual pathway. An earlier psychophysical study found that a subset of nonpsychotic relatives of persons with schizophrenia showed the opposite effect when compared to healthy adults (), suggesting a novel biobehavioral marker for the disorder. The present study attempted to replicate and explore the mechanism for this effect using fMRI. Results provide physiological evidence that the M pathway response to red light is in the opposite direction than expected in a subset of nonpsychotic relatives of persons with schizophrenia.

Functional magnetic resonance imaging examination of the magnocellular visual pathway in nonpsychotic relatives of persons with schizophrenia

Physiological research with monkeys and psychophysical research with humans has demonstrated the ability of diffuse red light to suppress activity in the magnocellular (M) visual pathway. In contrast, a previous psychophysical study found that a subset of nonpsychotic relatives of persons with schizophrenia showed the opposite effect, suggesting a novel biobehavioral marker for the disorder. Other research suggests that persons with schizophrenia have a dysfunctional M pathway under neutral (non-red) light conditions. However, it does not appear that these findings have been explored with physiological methods in nonpsychotic relatives, which would provide support for genetic contributions. The current study used physiological methodology to explore whether, as a group: 1) healthy adults show suppression of the M pathway in response to diffuse red light; 2) nonpsychotic relatives of persons with schizophrenia have a dysfunctional M pathway under neutral light conditions; and 3) nonpsychotic relatives of persons with schizophrenia have a differential M pathway response to red light. Functional magnetic resonance imaging (fMRI) was used to investigate a group of 13 nonpsychotic relatives of persons with schizophrenia and 11 controls. Moving concentric rings were presented on both red and green backgrounds to stimulate the M pathway. The fMRI signal strength in bilateral cortical region V5 (MT) was measured as a marker of M pathway functioning. Statistically significant results were limited to measures of fMRI signal in right hemisphere V5 relative to signal from bilateral V5, and suggested that: 1) the control group had reduced M pathway activity in response to diffuse red light; 2) the relative group had a hypoactive M pathway; and 3) a subset of the relatives had the opposite M pathway response to diffuse red light. The differential M pathway response to red light in the relatives remained a statistical trend after controlling for M pathway signal from the neutral (green) background condition. Results provide preliminary evidence that genetic risk for schizophrenia is related to a hypoactive M pathway and an independent differential response (increase in activity) of the M pathway to red light. These features may be more evident in the right hemisphere when examining cortical region V5.

The relationship between uncinate fasciculus white matter integrity and verbal memory proficiency in children

During childhood, verbal learning and memory are important for academic performance. Recent functional MRI studies have reported on the functional correlates of verbal memory proficiency, but few have reported the underlying structural correlates. The present study sought to test the relationship between fronto-temporal white matter integrity and verbal memory proficiency in children. Diffusion weighted images were collected from 17 Black children (age 8–11 years) who also completed the California Verbal Learning Test. To index white matter integrity, fractional anisotropy values were calculated for bilateral uncinate fasciculus. The results revealed that low anisotropy values corresponded to poor verbal memory, whereas high anisotropy values corresponded to significantly better verbal memory scores. These findings suggest that a greater degree of myelination and cohesiveness of axonal fibers in uncinate fasciculus underlie better verbal memory proficiency in children.

Deciphering spousal intentions: An fMRI study of couple communication

Several relational theories suggest that advice, particularly advice in areas important to the self, may be cognitively processed differently than other types of support (e.g., nondirective support) or low importance advice. Little is known, however, about the neurocognitive substrates of such complex social behaviors. We hypothesized that the Superior Temporal Sulcus (STS) and the Medial Prefrontal Cortex (MPFC), cortical regions previously linked to Theory of Mind (ToM), would be more active for high than low importance advice. Results indicated that high importance advice was associated with greater activation in the left MPFC and bilaterally in the STS. Similar results were obtained when compared to positive comments. These findings indicate that when given advice individuals may be attempting to infer motivation.