Executive Control Components Research Articles

The Mental Health from the Self-Regulation Perspective; What Research on Heart Rate Variability Revealed about the Interaction between Self-Regulation and Executive Attention Dysfunction In Acute Kidney Injury And Sex-Specific Implications

Dysfunctional self-regulation has been proposed to be the hallmark of almost all types of poor mental health. Although many prominent researchers have emphasized the role that executive attention control plays in self-regulation, the link between the two in mental health has been less apparent. According to the neurovisceral integration model, cardiac vagal tone, which refers to the parasympathetic influence on the heart at rest, can indicate the functional integrity of self- regulatory systems. A series of recent experiments demonstrate how individual differences in cardiac vagal tone indexed by heart rate variability (HRV) were associated with a varying degree of attentional control to emotional stimuli. The current paper reviewed recent research findings that showed how HRV modulated key components of executive control. These new findings provide evidence linking self-regulatory capacity and executive control, which may play an important role in supporting healthy mental health. American Psychiatric Association defines mental illnesses as “health conditions involving changes in emotion, thinking or behavior (or a combination of these). Mental illnesses are associated with distress and/or problems functioning in social, work or family activities.” 2 Unfortunately, the number of people affected by mental illness is staggering and increasing at an alarming rate. According to the American Psychiatric Association 2 , nearly one in five (19 percent) U.S. adults experience some form of mental illness in a given year. One in 24 (4.1 percent) percent of individuals are being diagnosed with debilitating mental illnesses such as schizophrenia, bipolar disorder, or major depression and one in 12 (8.5 percent) with a substance use disorder. There is a growing body of literature showing that dysfunctional self-regulation is one of the important contributing factors of the etiology and maintenance of various mental illness. 1, 2-6 Self- regulation refers to the ability to regulate cognition, emotion, and behavior to make an adaptive response to meet constantly changing environmental demands, which has been recognized as a key concept that helps understand human development and psychopathologies. 1, 7-9, 10-11 Of particular interest is the link between attention and self-regulation. Attention involves selecting and focusing on information, which shapes and guides thoughts and actions. 10, 12-13 Also, attention plays a critical role in producing self-regulatory responses not only by selecting and focusing on stimuli in the physical environment but also by internally modulating cognitive processes of different information processing. 10

Associations between different components of executive control in childhood and sleep problems in early adolescence: A longitudinal study.

Research has examined the impact of poor sleep on executive control and related abilities, but the inverse relationship has received less attention. Youth completed objective executive control tasks in childhood (N = 208; Mage = 10.03; 50.5% girls) and self-report measures of sleep-wake problems and daytime sleepiness in early adolescence (Mage = 12.00). Poorer interference suppression and flexible shifting abilities both predicted sleep-wake problems, but response inhibition and working memory did not. For daytime sleepiness, interference suppression was the only significant predictor among executive control components. Socioeconomic status did not moderate any of these associations. Findings have implications for targeting specific executive control abilities in childhood to improve sleep outcomes later in development.

Resisting attraction: Individual differences in executive control are associated with subject-verb agreement errors in production.

We propose that attraction errors in agreement production (e.g., the key to the cabinets are missing) are related to two components of executive control: working memory and inhibitory control. We tested 138 children aged 10 to 12, an age when children are expected to produce high rates of errors. To increase the potential of individual variation in executive control skills, participants came from monolingual, bilingual, and bidialectal language backgrounds. Attraction errors were elicited with a picture description task in Dutch and executive control was measured with a digit span task, Corsi blocks task, switching task, and attentional networks task. Overall, higher rates of attraction errors were negatively associated with higher verbal working memory and, independently, with higher inhibitory control. To our knowledge, this is the first demonstration of the role of both working memory and inhibitory control in attraction errors in production. Implications for memory- and grammar-based models are discussed. (PsycINFO Database Record

Action plan interrupted: resolution of proactive interference while coordinating execution of multiple action plans during sleep deprivation

The ability to retain an action plan to execute another is necessary for most complex, goal-directed behavior. Research shows that executing an action plan to an interrupting event can be delayed when it partly overlaps (vs. does not overlap) with the retained action plan. This phenomenon is known as partial repetition costs (PRCs). PRCs reflect proactive interference, which may be resolved by inhibitory, executive control processes. We investigated whether these inhibitory processes are compromised due to one night of sleep deprivation. Participants were randomized to a sleep-deprived group or a well-rested control group. All participants performed an action planning task at baseline after a full night of sleep, and again either after a night of sleep deprivation (sleep-deprived group) or a full night of sleep (control group). In this task, two visual events occurred in a sequence. Participants retained an action plan to the first event in working memory while executing a speeded action to the second (interrupting) event; afterwards, they executed the action to the first event. The two action plans either partly overlapped (required the same hand) or did not (required different hands). Results showed slower responses to the interrupting event during sleep deprivation compared to baseline and the control group. However, the magnitude of the PRCs was no different during sleep deprivation compared to baseline and the control group. Thus, one night of sleep deprivation slowed global responses to the interruption, but inhibitory processes involved in reducing proactive interference while responding to an interrupting event were not compromised. These findings are consistent with other studies that show sleep deprivation degrades global task performance, but does not necessarily degrade performance on isolated, executive control components of cognition. The possibility that our findings involve local as opposed to central inhibition is also discussed.

Differences in Cortical Structure and Functional MRI Connectivity in High Functioning Autism.

Autism spectrum disorders (ASD) represent a complex group of neurodevelopmental conditions characterized by deficits in communication and social behaviors. We examined the functional connectivity (FC) of the default mode network (DMN) and its relation to multimodal morphometry to investigate superregional, system-level alterations in a group of 22 adolescents and young adults with high-functioning autism compared to age-, and intelligence quotient-matched 29 healthy controls. The main findings were that ASD patients had gray matter (GM) reduction, decreased cortical thickness and larger cortical surface areas in several brain regions, including the cingulate, temporal lobes, and amygdala, as well as increased gyrification in regions associated with encoding visual memories and areas of the sensorimotor component of the DMN, more pronounced in the left hemisphere. Moreover, patients with ASD had decreased connectivity between the posterior cingulate cortex, and areas of the executive control component of the DMN and increased FC between the anteromedial prefrontal cortex and areas of the sensorimotor component of the DMN. Reduced cortical thickness in the right inferior frontal lobe correlated with higher social impairment according to the scores of the Autism Diagnostic Interview-Revised (ADI-R). Reduced cortical thickness in left frontal regions, as well as an increased cortical thickness in the right temporal pole and posterior cingulate, were associated with worse scores on the communication domain of the ADI-R. We found no association between scores on the restrictive and repetitive behaviors domain of ADI-R with structural measures or FC. The combination of these structural and connectivity abnormalities may help to explain some of the core behaviors in high-functioning ASD and need to be investigated further.

The salience network and human personality: Integrity of white matter tracts within anterior and posterior salience network relates to the self-directedness character trait

A prevailing topic in personality neuroscience is the question how personality traits are reflected in the brain. Functional and structural networks have been examined by functional and structural magnetic resonance imaging, however, the structural correlates of functionally defined networks have not been investigated in a personality context. By using the Temperament and Character Inventory (TCI) and Diffusion Tensor Imaging (DTI), the present study assesses in a sample of 116 healthy participants how personality traits proposed in the framework of the biopsychosocial theory of personality relate to white matter pathways delineated by functional network imaging. We show that the character trait self-directedness relates to the overall microstructural integrity of white matter tracts constituting the salience network as indicated by DTI-derived measures. Self-directedness has been proposed as the executive control component of personality and describes the tendency to stay focused on the attainment of long-term goals. The present finding corroborates the view of the salience network as an executive control network that serves maintenance of rules and task-sets to guide ongoing behavior.

Verbal fluency performance in Bengali-English bilingual aphasia

Event Abstract Back to Event Verbal fluency performance in Bengali-English bilingual aphasia Abhijeet Patra1 and Arpita Bose1* 1 University of Reading, School of Psychology and Clinical Language Sciences, United Kingdom Introduction: Research has shown that impairments in executive control may influence word production abilities in aphasia[1,2]. However, studies investigating the contribution of lexical retrieval and executive control processes during word production are mostly limited to monolingual aphasia[3,4]. Very little is known about bilinguals with aphasia (BWA). A better approach to understand the relationship between lexical retrieval and executive control processes might be to use a task that simultaneously draw upon these processes. In a verbal fluency task, lexical and executive contribution for semantic and letter fluency conditions are different; semantic fluency largely depends on lexical retrieval abilities, whilst letter fluency largely depends on executive control abilities. Characterisation of verbal fluency performance beyond number of correct responses (CR) (e.g., Fluency Difference Score FDS; cluster size; number of switches; temporal measures such as within- and between-cluster pauses), have enabled researchers to specifically speculate the components of performance that depends on lexical retrieval vs. executive control processes[5,6,7]. Previous research has shown that in semantic fluency, BWA produced fewer CR, smaller cluster sizes, and fewer number of switches compared to bilingual healthy adults (BHA)[5,6]. These studies have emphasised the greater role of lexical processes in performance differences between BWA and BHA. However, in absence of comparison to letter fluency, it remains inconclusive if it is only the lexical processes that are compromised in BWA. We compared semantic and letter fluency conditions between Bengali-English BWA and BHA to determine: a) if poor performance in aphasia is due to lexical retrieval and/or executive control difficulties; b) are the differences more exaggerated on measures which depend heavily on the executive control processes. Bengali is a South-Asian language spoken by 180.5 million speakers in the world[8]. Despite that aphasia research reporting Bengali speakers remain under-presented (only one study)[9]. We attempt to fill this gap in the literature. Methods & Procedure: Semantic (animals, fruits and vegetables) and letter fluency (/p/, /k/, /m/) 60-seconds trails were collected from eight non-fluent Bengali-English BWA and eight Bengali-English BHA in their dominant language (Bengali). The groups were matched for age, gender, years of education, and bilingualism measures (language proficiency, usage, dominance). We measured: CR, FDS ((CR.semantic fluency - CR.letter fluency)/CR.semantic fluency), cluster size, number of switches, within-and between-cluster pause. Results and Discussion: Table 1 presents results summary. Overall, on both fluency conditions, compared to BHA, BWA produced fewer number of CR, had higher FDS, made fewer switches, and had longer between-cluster pauses. These results are indicative of difficulty in the executive control component of the verbal fluency task in addition to their lexical difficulties[4,7]. Both groups performed similarly on cluster size and within-cluster pauses. Fewer number of CR, and fewer switches for BWA are consistent with the literature[5,6]. No difference in cluster size and within-cluster pause suggest similar search strategies used by BWA and BHA while accessing the mental lexicon. Our results demonstrate that inclusion of letter fluency and a full range of verbal fluency measures are necessary to understand the effect of lexical and executive control processes in verbal fluency performance. Acknowledgements We would like to thank all our participants for their time and effort. We also would like to acknowledge Felix trust, UK for the PhD fellowship.

Dissociated Components of Executive Control in Acute Hypobaric Hypoxia.

The neurocognitive effects of acute hypobaric hypoxia are still largely unknown. This study was designed to test the hypothesis that executive control, an important component of cognition, is especially vulnerable to hypoxia. Subjects participated in a simulated hypobaric chamber flight to 5500 m. Four auditory tasks were presented before, during, and after hypoxia: 1) Voice, and 2) Name variant of the Stroop task (both measuring conflict resolution); 3) go/no-go task (GNG; measuring inhibition); and 4) two-choice reaction time task (CRT; which is a noninhibitory control task). The Stroop effect increased during hypoxia: in the Voice Stroop it increased from 49.4 to 83.6 ms for reaction time and from 4.1 to 12.3% for accuracy; in the Name Stroop from 43.5 to 82.9 ms for reaction time (accuracy remained unchanged). Accuracy declined from 82.3 to 75.0% in CRT, and from 85.8 to 77.5% (averaged over stimulus types) in the GNG task. Importantly, accuracy decreased similarly to go and no-go stimuli in the GNG task, revealing unaffected inhibition. The findings suggest that tasks requiring conflict resolution are more likely to be impaired than tasks requiring inhibition of response. Furthermore, our results provide evidence for the distinct nature of inhibitory control functions.Takács E, Czigler I, Pató LG, Balázs L. Dissociated components of executive control in acute hypobaric hypoxia. Aerosp Med Hu Perform. 2017; 88(12):1081-1087.

Binet's Error: Developmental Change and Individual Differences in Intelligence Are Related to Different Mechanisms.

In common with most, if not all, papers in this special issue, I will argue that understanding the nature of developmental change and individual differences in intelligence requires a theory of the mechanisms underlying both factors. Insofar as these mechanisms constitute part of the fundamental architecture of cognition, this is also an exercise in unifying the discipline and research on intelligence in both children and adults. However, I argue that a variety of data support a theory suggesting that developmental change is the province of mechanisms commonly regarded as components of executive functioning or cognitive control, whereas individual differences are constrained by the speed of information processing. Perhaps paradoxically, this leads to the conclusion that Binet’s fundamental insight—that children’s increasing ability to solve problems of increasing difficulty could generate a single scale of intelligence—is wrong. Compounding the paradox, this means that mental age and IQ are not simply two different ways of expressing the same thing, but are related to two different dimensions of g itself.

Posterior-Anterior Brain Maturation Reflected in Perceptual, Motor and Cognitive Performance.

Based on several postmortem morphometric and in vivo imaging studies it has been postulated that brain maturation roughly follows a caudal to rostral direction. In this study, we linked this maturational pattern to psychological function employing a series of well-established behavioral tasks. We addressed three distinct functions and brain regions with a perceptual (contour integration, CI), motor (finger tapping, FT), and executive control (Navon global–local) task. Our purpose was to investigate basic visual integration functions relying on primary visual cortex (V1) in CI; motor coordination function related to primary motor cortex (M1) in FT, and the executive control component, switching, related to the dorsolateral prefrontal region of the brain in the Navon task. 122 volunteer subjects were recruited to participate in this study between the ages of 10 and 20 (females n = 63, males n = 59). Employing conventional statistical methods, we found that 10 and 12 year olds are performing significantly weaker than 20 year olds in all three tasks. In the CI and Navon global–local tasks, even 14 years old perform poorer than adults. We have also investigated the developmental trajectories by fitting sigmoid curves on our data streams. The analysis of the developmental trajectories of the three tasks showed a posterior to anterior pattern in the emergence of the developmental functions with the earliest development in the visual CI task (V1), followed by motor development in the FT task (M1), and cognitive development as measured in the Navon global–local task (DLPC) being the slowest. Gender difference was also present in FT task showing an earlier maturation for girls in the motor domain.

I. EXECUTIVE CONTROL IN EARLY CHILDHOOD.

Executive control (EC) is a central construct in developmental science, although measurement limitations have hindered understanding of its nature and development in young children, relation to social risk, and prediction of important outcomes. Disentangling EC from the foundational cognitive abilities it regulates and that are inherently required for successful executive task completion (e.g., language, visual/spatial perception, and motor abilities) is particularly challenging at preschool age, when these foundational abilities are still developing and consequently differ substantially among children. A novel latent bifactor modeling approach delineated respective EC and foundational cognitive abilities components that undergird executive task performance in a socio demographically stratified sample of 388 preschoolers in a longitudinal, cohort-sequential study. The bifactor model revealed a developmental shift, where both EC and foundational cognitive abilities contributed uniquely to executive task performance at ages 4.5 and 5.25 years, but were not separable at ages 3 and 3.75. Contrary to the view that EC is vulnerable to socio-familial risk, the contributions of household financial and learning resources to executive task performance were not specific to EC but were via their relation to foundational cognitive abilities. EC, though, showed a unique, discriminant relation with hyperactive symptoms late in the preschool period, whereas foundational cognitive abilities did not predict specific dimensions of dysregulated behavior. These findings form the basis for a new, integrated approach to the measurement and conceptualization of EC, which includes dual consideration of the contributions of EC and foundational cognitive abilities to executive task performance, particularly in the developmental context of preschool.

Executive attention networks show altered relationship with default mode network in PD.

Attention dysfunction is a common but often undiagnosed cognitive impairment in Parkinson's disease that significantly reduces quality of life. We sought to increase understanding of the mechanisms underlying attention dysfunction using functional neuroimaging. Functional MRI was acquired at two repeated sessions in the resting state and during the Attention Network Test, for 25 non-demented subjects with Parkinson's disease and 21 healthy controls. Behavioral and MRI contrasts were calculated for alerting, orienting, and executive control components of attention. Brain regions showing group differences in attention processing were used as seeds in a functional connectivity analysis of a separate resting state run. Parkinson's disease subjects showed more activation during increased executive challenge in four regions of the dorsal attention and frontoparietal networks, namely right frontal eye field, left and right intraparietal sulcus, and precuneus. In three regions we saw reduced resting state connectivity to the default mode network. Further, whereas higher task activation in the right intraparietal sulcus correlated with reduced resting state connectivity between right intraparietal sulcus and the precuneus in healthy controls, this relationship was absent in Parkinson's disease subjects. Our results suggest that a weakened interaction between the default mode and task positive networks might alter the way in which the executive response is processed in PD.

Impairment of the executive attention network in premenopausal women with hormone receptor-positive breast cancer treated with tamoxifen

Tamoxifen (TAM) is most commonly prescribed for patients with hormone-sensitive breast cancer and exerts agonistic/antagonistic effects on estrogen receptors throughout the body. Accumulating evidence has revealed that breast cancer patients receiving TAM manifest cognitive dysfunction. However, whether these patients have a global attention deficit or a more selective impairment of specific attention networks remains unknown. In the present study, we sought to explore the attention function of premenopausal women with hormone receptor-positive breast cancer treated with TAM using the attention network test (ANT). The subjects included breast cancer patients receiving TAM (TAM, N=43), breast cancer patients not receiving TAM (non-TAM, N=41), and matched healthy controls (HC, N=46). The subjects completed the ANT and neuropsychological tests, which measure three independent attention networks and executive function performance, respectively. Our results indicated that patients in the TAM group had significant deficits in their executive control component but not in the alerting or orienting components. Moreover, the patients showed poor executive function performance in the neuropsychological tests. Additionally, in the TAM group, significant correlations were found between the decreased efficiency of the executive control component and their reduced performance in executive function tests. This study demonstrates that premenopausal women with hormone receptor-positive breast cancer treated with TAM have impairment of the executive attention network and that this impairment was associated with differences in executive function performance.

Executive control mechanisms in bilingualism: Beyond speed of processing

The question of interest in this study was whether bilingual individuals show superior executive control compared to monolingual participants. Findings are mixed, with studies showing advantage, disadvantage, or no difference between bilingual and monolingual speakers. In this study, we used different experimental conditions to examine implicit learning, resistance to interference, monitoring, and switching, independently. In addition, we matched our monolingual and bilingual participants on baseline response time. Bilingual participants demonstrated faster implicit learning, greater resistance to interference, more efficient switching compared to monolingual participants. The groups did not differ in monitoring. In conclusion, depending on task complexity and on the target executive control component, there are different patterns of bilingual advantage, beyond the global faster processing speed documented in previous studies. Bilingual young adults showed more efficient adjustments of the cognitive system in response to changes in task demands.

Clinical assessment of social cognitive function in neurological disorders.

Social cognition broadly refers to the processing of social information in the brain that underlies abilities such as the detection of others' emotions and responding appropriately to these emotions. Social cognitive skills are critical for successful communication and, consequently, mental health and wellbeing. Disturbances of social cognition are early and salient features of many neuropsychiatric, neurodevelopmental and neurodegenerative disorders, and often occur after acute brain injury. Its assessment in the clinic is, therefore, of paramount importance. Indeed, the most recent edition of the American Psychiatric Association's Diagnostic and Statistical Manual for Mental Disorders (DSM-5) introduced social cognition as one of six core components of neurocognitive function, alongside memory and executive control. Failures of social cognition most often present as poor theory of mind, reduced affective empathy, impaired social perception or abnormal social behaviour. Standard neuropsychological assessments lack the precision and sensitivity needed to adequately inform treatment of these failures. In this Review, we present appropriate methods of assessment for each of the four domains, using an example disorder to illustrate the value of these approaches. We discuss the clinical applications of testing for social cognitive function, and finally suggest a five-step algorithm for the evaluation and treatment of impairments, providing quantitative evidence to guide the selection of social cognitive measures in clinical practice.

Easy to learn, hard to suppress: The impact of learned stimulus–outcome associations on subsequent action control

The inhibition of impulsive response tendencies that conflict with goal-directed action is a key component of executive control. An emerging literature reveals that the proficiency of inhibitory control is modulated by expected or unexpected opportunities to earn reward or avoid punishment. However, less is known about how inhibitory control is impacted by the processing of task-irrelevant stimulus information that has been associated previously with particular outcomes (reward or punishment) or response tendencies (action or inaction). We hypothesized that stimulus features associated with particular action–valence tendencies, even though task irrelevant, would modulate inhibitory control processes. Participants first learned associations between stimulus features (color), actions, and outcomes using an action–valence learning task that orthogonalizes action (action, inaction) and valence (reward, punishment). Next, these stimulus features were embedded in a Simon task as a task-irrelevant stimulus attribute. We analyzed the effects of action–valence associations on the Simon task by means of distributional analysis to reveal the temporal dynamics. Learning patterns replicated previously reported biases; inherent, Pavlovian-like mappings (action–reward, inaction–punishment avoidance) were easier to learn than mappings conflicting with these biases (action–punishment avoidance, inaction–reward). More importantly, results from two experiments demonstrated that the easier to learn, Pavlovian-like action–valence associations interfered with the proficiency of inhibiting impulsive actions in the Simon task. Processing conflicting associations led to more proficient inhibitory control of impulsive actions, similar to Simon trials without any association. Fast impulsive errors were reduced for trials associated with punishment in comparison to reward trials or trials without any valence association. These findings provide insight into the temporal dynamics of task irrelevant information associated with action and valence modulating cognitive control. We discuss putative mechanisms that might explain these interactions.

Inhibition-Induced Forgetting Results from Resource Competition between Response Inhibition and Memory Encoding Processes

Response inhibition is a key component of executive control, but its relation to other cognitive processes is not well understood. We recently documented the "inhibition-induced forgetting effect": no-go cues are remembered more poorly than go cues. We attributed this effect to central-resource competition, whereby response inhibition saps attention away from memory encoding. However, this proposal is difficult to test with behavioral means alone. We therefore used fMRI in humans to test two neural predictions of the "common resource hypothesis": (1) brain regions associated with response inhibition should exhibit greater resource demands during encoding of subsequently forgotten than remembered no-go cues; and (2) this higher inhibitory resource demand should lead to memory encoding regions having less resources available during encoding of subsequently forgotten no-go cues. Participants categorized face stimuli by gender in a go/no-go task and, following a delay, performed a surprise recognition memory test for those faces. Replicating previous findings, memory was worse for no-go than for go stimuli. Crucially, forgetting of no-go cues was predicted by high inhibitory resource demand, as quantified by the trial-by-trial ratio of activity in neural "no-go" versus "go" networks. Moreover, this index of inhibitory demand exhibited an inverse trial-by-trial relationship with activity in brain regions responsible for the encoding of no-go cues into memory, notably the ventrolateral prefrontal cortex. This seesaw pattern between the neural resource demand of response inhibition and activity related to memory encoding directly supports the hypothesis that response inhibition temporarily saps attentional resources away from stimulus processing. Recent behavioral experiments showed that inhibiting a motor response to a stimulus (a "no-go cue") impairs subsequent memory for that cue. Here, we used fMRI to test whether this "inhibition-induced forgetting effect" is caused by competition for neural resources between the processes of response inhibition and memory encoding. We found that trial-by-trial variations in neural inhibitory resource demand predicted subsequent forgetting of no-go cues and that higher inhibitory demand was furthermore associated with lower concurrent activation in brain regions responsible for successful memory encoding of no-go cues. Thus, motor inhibition and stimulus encoding appear to compete with each other: when more resources have to be devoted to inhibiting action, less are available for encoding sensory stimuli.

Shedding light on the effect of priority instructions during dual-task performance in younger and older adults: A fNIRS study

Age-related differences in the ability to perform two tasks simultaneously (or dual-task) have become a major concern in aging neurosciences and have often been assessed with two distinct paradigms; the Psychological Refractory Period (PRP) and the Dual-Task (DT) paradigms. PRP studies assess participants when they give Priority to one task over the other (complete A then B), whereas in DT studies participants give Equal priority to both tasks (complete A and B). The Equal condition could be viewed as adding an executive control component to the task since the participants must spontaneously monitor attention between tasks. In the current study, we assessed the effect of priority instructions (Priority vs. Equal) on the dual-task performance and brain activity of younger (n=16) and older adults (n=19) with functional near infra-red spectroscopy (fNIRS). In younger adults, the Priority condition showed right-sided activation in the prefrontal cortex during DT execution. Older adults showed bilateral frontal activation, yet restrained to specific areas. They showed increased activation in DT vs. single task condition in the left dorsolateral prefrontal cortex (DLPFC) and the bilateral ventrolateral prefrontal cortex (VLPFC). In the Equal condition, the DT condition showed isolated left DLPFC and VLPFC activation in younger adults and widespread bilateral DLPFC activation in older adults. These results suggest that for both older and younger adults, priority effects are associated with distinct patterns of prefrontal activation. Age-related differences also exist in these patterns such that prefrontal activation seems to be more spread out at different sites in older adults when they are instructed to give Equal priority to both tasks.

Postural control system influences intrinsic alerting state.

Numerous studies using dual-task paradigms (postural and cognitive) have shown that postural control requires cognitive resources. However, the influence of postural control on attention components has never been directly addressed. Using the attention network test (ANT), which assesses specifically each of the 3 components of attention-alertness, orientation, and executive control-within a single paradigm, we investigated the effect of postural balance demand on these 3 components. Forty-two participants completed the ANT in 3 postural conditions: (a) supine, a very stable position; (b) sitting on a chair, an intermediate position; and (c) standing with feet lined up heel to toe, a very instable position known as the Romberg position. Our results revealed that the difficulty of postural control does modulate alerting in such a way that it improves with the level of instability of the position. Regarding the orienting and executive control components of attention, performance was not different when participants were standing upright or seated, whereas in the supine position, performance dropped. The strong and specific interaction between postural control and the alerting system suggests that these mechanisms may share parts of the underlying neural circuits. We discuss the possible implication of the locus coeruleus, known to be involved in both postural balance and alerting. Also, our findings concerning orienting and executive control systems suggest that supine posture could have a specific effect on cognitive activities. These effects are discussed in terms of particularities resulting from the supine position.

The Roles of Working Memory Components in Vocabulary Knowledge

This study investigated the relationship between working memory components and receptive and productive vocabulary knowledge. The letter span and backward digit span tasks were used as verbal and nonverbal measures of working memory storage component respectively. The verbal and nonverbal executive control components were measured by the reading span and operation span tasks separately. Measures of receptive and productive vocabulary were frequency-based tests. The results suggested that the executive control component plays a more prominent role in vocabulary knowledge (both receptive and productive) compared to the storage component. In addition, the correlation between working memory components and productive vocabulary was stronger than their correlation with receptive vocabulary. The highest correlation was found between the verbal executive control component and productive vocabulary while the lowest one was identified between the nonverbal storage component and receptive vocabulary. The results highlight how each working memory component plays a role in retrieving vocabulary knowledge.