Effects of chewing on cognitive processing speed

In recent years, chewing has been discussed as producing effects of maintaining and sustaining cognitive performance. We have reported that chewing may improve or recover the process of working memory; however, the mechanisms underlying these phenomena are still to be elucidated. We investigated the effect of chewing on aspects of attention and cognitive processing speed, testing the hypothesis that this effect induces higher cognitive performance. Seventeen healthy adults (20–34 years old) were studied during attention task with blood oxygenation level-dependent functional (fMRI) at 3.0 T MRI. The attentional network test (ANT) within a single task fMRI containing two cue conditions (no cue and center cue) and two target conditions (congruent and incongruent) was conducted to examine the efficiency of alerting and executive control. Participants were instructed to press a button with the right or left thumb according to the direction of a centrally presented arrow. Each participant underwent two back-to-back ANT sessions with or without chewing gum, odorless and tasteless to remove any effect other than chewing. Behavioral results showed that mean reaction time was significantly decreased during chewing condition, regardless of speed-accuracy trade-off, although there were no significant changes in behavioral effects (both alerting and conflict effects). On the other hand, fMRI analysis revealed higher activations in the anterior cingulate cortex and left frontal gyrus for the executive network and motor-related regions for both attentional networks during chewing condition. These results suggested that chewing induced an increase in the arousal level and alertness in addition to an effect on motor control and, as a consequence, these effects could lead to improvements in cognitive performance.     

Brain functions associated with verbal working memory tasks among young males with alcohol use disorders

This study aimed to investigate the differences in brain functions during verbal working memory between individuals with alcohol use disorders (AUD) and normal controls. fMRI was used to scan brain activations associated with verbal working memory while participants performed 2-back and 0-back tasks. A total of 21 young male college students participated in the study. Eleven of those who clinically met the criteria for AUD were assigned to the AUD group, whereas ten demographically similar subjects who were social drinkers but not AUD were assigned to the normal control group. The AUD group showed less activation in bilateral frontal and precentral, left superior temporal, left superior parietal, and left cerebellar cortex during the 2-back task relative to 0-back task compared to the normal control group. In contrast, the control group showed less activation only in the right uncus than the AUD group. These results suggest that subjects with AUD present abnormality in brain functioning during verbal working memory.     

Executive functions and extraversion

Executive functions and extraversion have been linked to similar neurological substrates. Participants were tested on a variety of tasks that assessed performance on three components of executive functioning (i.e., shifting, updating, and inhibition) and two measures of extraversion (Eysenck Personality Questionnaire-Revised and Carver and White’s BIS/BAS scales). More extraverted participants showed different patterns of executive function performance than the more introverted participants. Extraverts performed best on more difficult tasks and on updating tasks. Conversely, introverts performed best on set shifting tasks. These results suggest that executive functioning strengths differ based on degree of extraversion.     

Neurocognitive development and externalizing problems: the role of inhibitory control deficits from 4 to 6 years

Executive processes have been posited as important regulators of externalizing problems (EP), but there has been little research on the relation between executive dysfunction and EP in early childhood. During the preschool period, maturation of the prefrontostriatal circuitry parallels increases in inhibitory control (IC). Poor IC development could result in elevated levels of aggressive, disruptive, and impulsive behavior. In this investigation, the development of the relation between IC and EP was examined in preschool and early elementary school children using the Day/Night and Tapping tasks. Children with more EP made more incorrect responses on both IC tasks, consistently across age and sex. The associations between EP and response latencies differed across children, however, with longer latencies on the Tapping task being most characteristic for boys with high levels of EP. This association was not apparent for girls. Two prominent aspects of early EP, aggressive and inattentive behavior, showed only weak unique associations with IC performance. These findings imply that diminished IC accompanies elevated EP as early as the preschool years, and that this decrement persists into the elementary school-age years for both girls and boys, and that accuracy and response latency may confer different information about the development of IC.     

Dissociable contributions of the left and right posterior medial orbitofrontal cortex in motivational control of goal-directed behavior

Several findings from both human neuroimaging and nonhuman primate studies suggest that the posterior medial orbitofrontal cortex (OFC) may be critical for the motivational control of goal-directed behavior. The present study was conducted to clarify the role of the left and right posterior medial OFC in that function by examining the effects of focal unilateral lesions to this region on the performance on an incentive working memory task. The study covered patients who had undergone surgery for an ACoA aneurysm and normal control subjects (C). The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) posterior part of the gyrus rectus, and without such a resection (GR−). Participants performed a 2-back working memory task under three motivational conditions (penalty, reward, and no-incentive). The C group performed worse in the penalty condition and better in the reward condition as compared to the no-incentive condition. Similar results were obtained for the GR− group. Performance of the LGR+ group did not depend on incentive manipulations, whereas the RGR+ group performed better in both the penalty and reward conditions than in the no-incentive condition. The results show that the posterior medial OFC is involved in the motivational modulation of working memory performance. Our findings also suggest that the left posterior medial OFC plays a crucial role in this function, whereas the right posterior medial OFC is particularly involved in the processing of the punishing aspect of salient events and it probably mediates in guiding behavior on the basis of negative outcomes of action.     

Self-regulation during a single performance episode: Mood-as-information in the absence of formal feedback

This investigation used a daily diary methodology to examine goal revision and effort allocation processes over a single, 2-weeks performance episode in which individuals prepared for a course exam. Growth curve modeling revealed that daily goal exhibited a curvilinear trend in which it was stable and relatively high at the beginning of the time period, but rapidly declined as the exam approached. Daily effort exhibited a trend opposite of the goal trend, remaining low and relatively stable at the beginning and increasingly rapidly as the exam approached. Current mood predicted daily goal revision, with positive mood being positively related to goal revision and negative mood being negatively related to goal revision. The traits of behavioral activation system (BAS) sensitivity and behavioral inhibition system (BIS) sensitivity moderated within-person relationships of positive and negative mood with goal revision. Simultaneous and lagged relationships among mood, goals, and daily effort were also examined.     

Supporting children’s counterfactual thinking with alternative modes of responding

To speculate about counterfactual worlds, children need to ignore what they know to be true about the real world. Prior studies yielding individual differences data suggested that counterfactual thinking may be related to overcoming prepotent responses. In two experiments, we manipulated how 3- to 5-year-olds responded to counterfactual conditional and syllogism tasks. In Experiment 1 (N = 39), children’s performance improved on both conditional and syllogism tasks when they responded with an arrow rather than pointing with a finger. In Experiment 2 (N = 42), 3- and 4-year-olds benefited from both an arrow manipulation and, separately, the introduction of a delay before responding. We suggest that both manipulations help children to overcome an impulsive prepotent response to counterfactual questions arising from a default assumption that information about the past is true.     

Contributions of modern measurement theory to measuring executive function in early childhood: An empirical demonstration

This study demonstrates the merits of evaluating a newly developed battery of executive function tasks, designed for use in early childhood, from the perspective of item response theory (IRT). The battery was included in the 48-month assessment of the Family Life Project, a prospective longitudinal study of 1292 children oversampled from low-income and African American families. IRT models were applied to a select set of tasks to demonstrate empirically (a) a principled method for item evaluation, including the utility of item characteristic curves; (b) how to explicitly test whether the measurement properties of executive function tasks are invariant across mutually exclusive subgroups of youths; (c) how the precision of measurement of a given task can vary according to underlying child ability; and (d) the utility of using IRT-based versus percentage correct scores. Results are discussed with respect to the importance of developing psychometrically sound and scalable instruments that facilitate the measurement of interindividual differences in intraindividual change of executive function across the early childhood period.     

Individual differences in growth in executive function across the transition to school predict externalizing and internalizing behaviors and self-perceived academic success at 6 years of age

Building on an existing latent variable analysis of executive function (EF) in children (N = 191, 57% boys and 43% girls) making the transition to school (Hughes et al. (2010), Developmental Neuropsychology, vol. 35, pp. 20-36), the current study both documented average developmental improvements from 4 to 6 years of age and examined individual differences in EF growth in relation to latent factors for two sets of child outcome measures at 6 years: (a) first-grade teachers’ ratings of emotional symptoms, hyperactivity, and conduct/peer problems and (b) children’s self-perceived academic and social competencies. With effects of concurrent verbal ability and EF controlled, variation in EF slopes across the transition to school predicted variation in latent constructs for (a) all four problem behavior subscales and (b) children’s self-reported academic (but not social) competence. These findings underscore the clinical and educational significance of early individual differences in EF and highlight the value of adopting a developmental perspective.     

Two is better than one, but mine is better than ours: Preschoolers’ executive function during co-play

The current study investigated how playing with another individual may influence 3- and 4-year-olds’ executive function in the Less-Is-More (LIM) task, where children point to the tray with the smaller amount of treats so as to obtain the larger amount of treats in the other tray. In Experiment 1, 35 Singaporean children were tested with a self version and a co-player-split version of the LIM task. Results showed that children appeared to be less impulsive when playing with a co-player than when playing individually. Experiment 2 further investigated how the intention of the co-player, collective profit oriented versus individual profit oriented, may influence children’s executive function. In total, 96 children were tested with a self version, a co-player-share version, and a co-player-opponent version. Results showed that the co-playing facilitation effect appeared in only the co-player-opponent version. Together, the results of the current study showed that when preschoolers play with an individual who shares a common goal with them, they may become more efficient in executive control.