Activity In Frontal Cortex Research Articles

Modulation of brain activation during executive functioning in autism with citalopram

Adults with autism spectrum disorder (ASD) are frequently prescribed selective serotonin reuptake inhibitors (SSRIs). However, there is limited evidence to support this practice. Therefore, it is crucial to understand the impact of SSRIs on brain function abnormalities in ASD. It has been suggested that some core symptoms in ASD are underpinned by deficits in executive functioning (EF). Hence, we investigated the role of the SSRI citalopram on EF networks in 19 right-handed adult males with ASD and 19 controls who did not differ in gender, age, IQ or handedness. We performed pharmacological functional magnetic resonance imaging to compare brain activity during two EF tasks (of response inhibition and sustained attention) after an acute dose of 20 mg citalopram or placebo using a randomised, double-blind, crossover design. Under placebo condition, individuals with ASD had abnormal brain activation in response inhibition regions, including inferior frontal, precentral and postcentral cortices and cerebellum. During sustained attention, individuals with ASD had abnormal brain activation in middle temporal cortex and (pre)cuneus. After citalopram administration, abnormal brain activation in inferior frontal cortex was ‘normalised’ and most of the other brain functional differences were ‘abolished’. Also, within ASD, the degree of responsivity in inferior frontal and postcentral cortices to SSRI challenge was related to plasma serotonin levels. These findings suggest that citalopram can ‘normalise’ atypical brain activation during EF in ASD. Future trials should investigate whether this shift in the biology of ASD is maintained after prolonged citalopram treatment, and if peripheral measures of serotonin predict treatment response.

Focused Representation of Successive Task Episodes in Frontal and Parietal Cortex.

Complex cognition is dynamic, with each stage of a task requiring new cognitive processes appropriately linked to stimulus or other content. To investigate control over successive task stages, we recorded neural activity in lateral frontal and parietal cortex as monkeys carried out a complex object selection task, with each trial separated into phases of visual selection and learning from feedback. To study capacity limitation, complexity was manipulated by varying the number of object targets to be learned in each problem. Different task phases were associated with quasi-independent patterns of activity and information coding, with no suggestion of sustained activity linked to a current target. Object and location coding were largely parallel in frontal and inferior parietal cortex, though frontal cortex showed somewhat stronger object representation at feedback, and more sustained location coding at choice. At both feedback and choice, coding precision diminished as task complexity increased, matching a decline in performance. We suggest that, across successive task steps, there is radical but capacity-limited reorganization of frontoparietal activity, selecting different cognitive operations linked to their current targets.

Interhemispherically dynamic representation of an eye movement-related activity in mouse frontal cortex.

Cortical plasticity is fundamental to motor recovery following cortical perturbation. However, it is still unclear how this plasticity is induced at a functional circuit level. Here, we investigated motor recovery and underlying neural plasticity upon optogenetic suppression of a cortical area for eye movement. Using a visually-guided eye movement task in mice, we suppressed a portion of the secondary motor cortex (MOs) that encodes contraversive eye movement. Optogenetic unilateral suppression severely impaired contraversive movement on the first day. However, on subsequent days the suppression became inefficient and capability for the movement was restored. Longitudinal two-photon calcium imaging revealed that the regained capability was accompanied by an increased number of neurons encoding for ipsiversive movement in the unsuppressed contralateral MOs. Additional suppression of the contralateral MOs impaired the recovered movement again, indicating a compensatory mechanism. Our findings demonstrate that repeated optogenetic suppression leads to functional recovery mediated by the contralateral hemisphere.

I'm tired and feel like drinking: Viewing alcohol cues after exerting self-control increases approach motivation among individuals lower in alcohol sensitivity.

Exerting self-control depletes capacity for future self-control, which can promote greater alcohol use. However, certain populations may be more susceptible to these effects of depleted self-control capacity. For example, individuals with lower alcohol sensitivity (i.e., requiring more drinks to experience the effects of alcohol) are a high-risk group who are likely to engage in hazardous alcohol use and develop an alcohol use disorder. Those lower in alcohol sensitivity also exhibit heightened motivational reactivity in response to alcohol-related cues, which may be enhanced following exertion of self-control. However, whether drinkers lower in alcohol sensitivity are at higher risk for exhibiting greater motivations toward alcohol-related cues after exerting self-control is unclear. The current research examined the role of alcohol sensitivity in predicting approach motivation following exertion of self-control. It was expected drinkers exerting self-control would exhibit greater orientation toward rewarding cues, particularly after viewing alcohol-related cues. However, we predicted this pattern would be most prominent among drinkers lower in alcohol sensitivity. Experiment 1 supported these hypotheses, with lower alcohol sensitivity predicting greater approach motivation among drinkers required to exert self-control prior to viewing alcohol-related compared to neutral cues. Experiment 2 aimed to replicate these findings by assessing asymmetrical frontal cortical activation, an index of approach motivation. Drinkers with lower alcohol sensitivity exhibited greater relative left frontal cortical activation, consistent with approach motivation, while viewing alcohol-related cues following exertion of self-control. Results have implications for interventions aimed at identifying those at risk for greater alcohol motivations during states of mental exhaustion. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Alcohol exposure in utero disrupts cortico-striatal coordination required for behavioral flexibility

Deficits in behavioral flexibility are a hallmark of multiple psychiatric, neurological, and substance use disorders. These deficits are often marked by decreased function of the prefrontal cortex (PFC); however, the genesis of such executive deficits remains understudied. Here we report how the most preventable cause of developmental disability, in utero exposure to alcohol, alters cortico-striatal circuit activity leading to impairments in behavioral flexibility in adulthood. We utilized a translational touch-screen task coupled with in vivo electrophysiology in adult mice to examine single unit and coordinated activity of the lateral orbital frontal cortex (OFC) and dorsolateral striatum (DS) during flexible behavior. Prenatal alcohol exposure (PAE) decreased OFC, and increased DS, single unit activity during reversal learning and altered the number of choice responsive neurons in both regions. PAE also decreased coordinated activity within the OFC and DS as measured by oscillatory field activity and altered spike-field coupling. Furthermore, PAE led to sustained connectivity between regions past what was seen in control animals. These findings suggest that PAE causes altered coordination within and between the OFC and DS, promoting maladaptive perseveration. Our model suggests that in optimally functioning mice OFC disengages the DS and updates the newly changed reward contingency, whereas in PAE animals, aberrant and persistent OFC to DS signaling drives behavioral inflexibility during early reversal sessions. Together, these findings demonstrate how developmental exposure alters circuit-level activity leading to behavioral deficits and suggest a critical role for coordination of neural timing during behaviors requiring executive function.

Network-Targeted, Multi-site Direct Cortical Stimulation Enhances Working Memory by Modulating Phase Lag of Low-Frequency Oscillations

Working memory is mediated by the coordinated activation of frontal and parietal cortices occurring in the theta and alpha frequency ranges. Here, we test whether electrically stimulating frontal and parietal regions at the frequency of interaction is effective in modulating working memory. We identify working memory nodes that are functionally connected in theta and alpha frequency bands and intracranially stimulate both nodes simultaneously in participants performing working memory tasks. We find that in-phase stimulation results in improvements in performance compared to sham stimulation. In addition, in-phase stimulation results in decreased phase lag between regions within working memory network, while anti-phase stimulation results in increased phase lag, suggesting that shorter phase lag in oscillatory connectivity may lead to better performance. The results support the idea that phase lag may play a key role in information transmission across brain regions. Thus, brain stimulation strategies to improve cognition may require targeting multiple nodes of brain networks.

Effortful control of motivation, not withdrawal motivation, relates to greater right frontal asymmetry

Past models of frontal asymmetry have associated greater relative right frontal cortical activity with greater withdrawal motivation and greater relative left frontal cortical activity with greater approach motivation. However, this traditional model of frontal asymmetry leaves little to no room for the control processes that engage and regulate these emotional and motivational systems. A growing body of literature suggests that greater relative right frontal activation may be associated with greater regulatory control (Gable et al. 2018). However, this work confounded regulatory control and motivational direction. The current studies sought to test the competing hypotheses that currently exist in the literature by examining whether greater right frontal activation is more closely associated with regulatory control or withdrawal motivation. In Study 1, participants listened to negative and neutral sounds while suppressing their emotional reactions or listening naturally. Greater relative right frontal activation during the sound clips was associated with participants' reported effort when attempting to suppress their motivational responses to negative stimuli. Greater relative right frontal activation did not relate to experiencing negative affect. In Study 2, participants could win money by looking at a negative or neutral image or escape from looking at them for no reward. Greater relative right frontal activation was associated with looking at the negative pictures longer when there was a possibility of reward, but not when the possibility of reward was absent. Together, these studies suggest that it is the affective control of emotion rather than negative affect driving greater relative right frontal asymmetry. Additionally, these studies suggest that motivational conflicts engage effortful control.

Interaction Effect of Sex and Body Mass Index on Gray Matter Volume.

Objective: Few studies have investigated sex differences in brain structure associated with body mass index (BMI), and the related findings are inconsistent. In this study, we aimed to investigate the effect of sex × BMI interactions on gray matter volume (GMV), and to determine the implications of any structural differences.Methods: The final sample comprised 653 participants (449 women) who were assessed using voxel-based morphology analysis of T1-weighted magnetic resonance images. We used the voxel-based morphometry (VBM) to build a multiple regression model to explore the association between BMI and GMV, and used analysis of variance (ANOVA) to explore the BMI × sex interaction on GMV. A subset of 410 participants (291 women) underwent whole brain resting-state functional connectivity (rsFC) analysis to investigate sex differences in the seed (interaction) region. The cluster with a significant effect in the previous ANOVA analysis was used as a seed.Results: A significant BMI × sex interaction was observed in the left anterior cingulate cortex (ACC), while GMV was negatively correlated with BMI in men but not in women. The rsFC between the left ACC and the caudate was lower in men than in women. Within the entire sample, the insula, caudate, and medial frontal cortex activities were negatively correlated with BMI while the cerebellum and postcentral gyrus activities were positively correlated with BMI.Conclusions: Our findings address the interaction effect of BMI and sex on GM alterations. We found that the GMV in men seemed to be more likely to change with BMI than women, and the left ACC may be the reason for the increase in BMI of men, but not women.

Saccadic Eye Movements in Young-Onset Parkinson’s Disease - A BOLD fMRI Study

ABSTRACTThe objective of the present study was to understand control of saccadic eye movements in patients with young onset Parkinson’s disease (YOPD) where onset of disease symptoms appears early in life (<40 years of age). Functional magnetic resonance imaging (fMRI) was performed in patients with YOPD and control subjects while they performed saccadic tasks, which consisted of a reflexive task and another task that required inhibitory control of eye movements (Go-NoGo task). Functional imaging related to saccadic eye movements in this group of patients has not been widely reported. A 1.5T MR scanner was used for structural and functional imaging. Analysis of blood-oxygen-level-dependent (BOLD) fMRI was performed using Statistical Parametric Mapping (SPM) software and compared in patients and controls. In patients with YOPD greater activation was seen significantly in the middle frontal gyrus, medial frontal gyrus, angular gyrus, cingulate gyrus, precuneus and cerebellum, when compared with the control group, during the saccadic tasks. Gap and overlap protocols revealed differential activation patterns. The abnormal activation during reflexive saccades was observed in the overlap condition, while during Go-NoGo saccades in the gap condition. The results suggest that impaired circuitry in patients with YOPD results in recruitment of more cortical areas. This increased frontal and parietal cortical activity possibly reflects compensatory mechanisms for impaired cognitive and saccadic circuitry.

Word recognition and future language skills in 14-month-old infants

Children show remarkable progress in word learning in the second year of life. This language growth coincides with the vocabulary spurt and the development of domain-general cognition, e.g., attention that facilitates perceptual processing. Evidence suggests that language growth depends on increasing processing efficiency and underlying neuronal specialization. We used magnetoencephalography (MEG) to characterize neural activity following familiar and unfamiliar words in 14-month-old infants and related measures of neural activity to prospective measures of vocabulary growth. MEG source modeling revealed a broadly distributed network in bilateral frontal, temporal and parietal cortex that distinguished word classes between 150–900 ms after word onset. Analysis of correlations between outcome measurements and strength of neural activity revealed that in the interval 150–300 ms after word onset, the magnitude of neural activation in the right inferior frontal cortex for familiar words was positively correlated with vocabulary size at 18, 21, 24, 27 and 30 months of age. We argue that increased activity to familiar words may reflect more efficient discriminatory processing by the most skilled language learners who develop a larger vocabulary one year later.Children show remarkable progress in word learning in the second year of life. This language growth coincides with the vocabulary spurt and the development of domain-general cognition, e.g., attention that facilitates perceptual processing. Evidence suggests that language growth depends on increasing processing efficiency and underlying neuronal specialization. We used magnetoencephalography (MEG) to characterize neural activity following familiar and unfamiliar words in 14-month-old infants and related measures of neural activity to prospective measures of vocabulary growth. MEG source modeling revealed a broadly distributed network in bilateral frontal, temporal and parietal cortex that distinguished word classes between 150–900 ms after word onset. Analysis of correlations between outcome measurements and strength of neural activity revealed that in the interval 150–300 ms after word onset, the magnitude of neural activation in the right inferior frontal cortex for familiar words was positively correla...

The effect of ethnicity and team membership on face processing: a cultural neuroscience perspective.

In-ethnicity bias, as one of the in-group biases, is widespread in different cultures, interfering with cross-ethnicity communication. Recent studies have revealed that an in-ethnicity bias can be reduced by an in-team bias caused by the membership in a mixed-ethnicity team. However, the neural correlates of different in-group biases are still not clear, especially regarding possible cultural differences. A total of 44 participants (20 Chinese and 24 Germans) were recruited and completed a social categorization fMRI-task, categorizing faces according to their ethnicity and a learned team membership. Our behavioral results revealed both in-ethnicity and in-team bias in German participants, but not in Chinese participants. Our imaging results, however, showed both biases across all participants, as reflected in increased dorsal medial frontal cortex (MFC) activation for in-ethnicity, as well as in-team categorizations, while activation in ventral MFC was higher for in-ethnicity faces in Chinese participants than in the German participants. Our results highlight the importance of the dorsal MFC for in-group categorization across cultures and suggest that cultures might modulate in-group biases.

Cognitive remediation therapy modulates intrinsic neural activity in patients with major depression.

Cognitive impairment is a core feature of major depressive disorder (MDD). Cognitive remediation may improve cognition in MDD, yet so far, the underlying neural mechanisms are unclear. This study investigated changes in intrinsic neural activity in MDD after a cognitive remediation trial. In a longitudinal design, 20 patients with MDD and pronounced cognitive deficits and 18 healthy controls (HC) were examined using resting-state functional magnetic resonance imaging. MDD patients received structured cognitive remediation therapy (CRT) over 5 weeks. The whole-brain fractional amplitude of low-frequency fluctuations was computed before the first and after the last training session. Univariate methods were used to address regionally-specific effects, and a multivariate data analysis strategy was employed to investigate functional network strength (FNS). MDD patients significantly improved in cognitive function after CRT. Baseline comparisons revealed increased right caudate activity and reduced activity in the left frontal cortex, parietal lobule, insula, and precuneus in MDD compared to HC. In patients, reduced FNS was found in a bilateral prefrontal system at baseline (p < 0.05, uncorrected). In MDD, intrinsic neural activity increased in right inferior frontal gyrus after CRT (p < 0.05, small volume corrected). Left inferior parietal lobule, left insula, left precuneus, and right caudate activity showed associations with cognitive improvement (p < 0.05, uncorrected). Prefrontal network strength increased in patients after CRT, but this increase was not associated with improved cognitive performance. Our findings support the role of intrinsic neural activity of the prefrontal cortex as a possible mediator of cognitive improvement following CRT in MDD.

Prenatal exposure to glycol ethers and motor inhibition function evaluated by functional MRI at the age of 10 to 12 years in the PELAGIE mother-child cohort

BackgroundPregnant women are ubiquitously exposed to organic solvents, such as glycol ethers. Several studies suggest potential developmental neurotoxicity following exposure to glycol ethers with a lack of clarity of possible brain mechanisms. ObjectivesWe investigated the association between urinary levels of glycol ethers of women during early pregnancy and motor inhibition function of their 10- to 12-year-old children by behavioral assessment and brain imaging. MethodsExposure to glycol ethers was assessed by measuring six metabolites in urine (<19 weeks of gestation) of 73 pregnant women of the PELAGIE mother-child cohort (France). Maternal urinary levels were classified as low, medium, or high. Children underwent functional magnetic resonance imaging (fMRI) examinations during which motor inhibition function was assessed with a Go/No-Go task. Analyses were performed using linear regression for task performance and generalized linear mixed-effect models for brain activation, FWER-corrected for multiple testing at the spatial cluster level. Confounders were considered by restriction and a priori adjustment. ResultsHigher maternal butoxyacetic acid (BAA) urinary concentrations were associated with poorer child performance (β = −1.1; 95% CI: −1.9, −0.2 for high vs low). There was also a trend for ethoxyacetic acid (EAA) towards poorer performance (β = −0.3; 95% CI: −0.7, 0.01). Considering inhibition demand, there were increased activity in occipital regions in association with moderate EAA (left cuneus) and moderate methoxyacetic acid (MAA) (right precuneus). When children succeeded to inhibit, high ethoxyethoxyacetic acid (EEAA) and moderate phenoxyacetic acid (PhAA) levels were associated with differential activity in frontal cortex, involved in inhibition network. DiscussionPrenatal urinary levels of two glycol ether metabolites were associated with poorer Go/No-Go task performance. Differential activations were observed in the brain motor inhibition network in relation with successful inhibition, but not with cognitive demand. Nevertheless, there is no consistence between performance indicators and cerebral activity results. Other studies are highly necessary given the ubiquity of glycol ether exposure.

Decoding Changes of Mind in Voluntary Action-Dynamics of Intentional Choice Representations.

Voluntary actions rely on appropriate flexibility of intentions. Usually, we should pursue our goals, but sometimes we should change goals if they become too costly to achieve. Using functional magnetic resonance imaging, we investigated the neural dynamics underlying the capacity to change one's mind based on new information after action onset. Multivariate pattern analyses revealed that in visual areas, neural representations of intentional choice between 2 visual stimuli were unchanged by additional decision-relevant information. However, in fronto-parietal cortex, representations changed dynamically as decisions evolved. Precuneus, angular gyrus, and dorsolateral prefrontal cortex encoded new externally cued rewards/costs that guided subsequent changes of mind. Activity in medial frontal cortex predicted changes of mind when participants detached from externally cued evidence, suggesting a role in endogenous decision updates. Finally, trials with changes of mind were associated with an increase in functional connectivity between fronto-parietal areas, allowing for integration of various endogenous and exogenous decision components to generate a distributed consensus about whether to pursue or abandon an initial intention. In conclusion, local and global dynamics of choice representations in fronto-parietal cortex allow agents to maintain the balance between adapting to changing environments versus pursuing internal goals.

Low intensity white noise improves performance in auditory working memory task: An fMRI study

Research suggests that white noise may facilitate auditory working memory performance via stochastic resonance. Stochastic resonance is quantified by plotting cognitive performance as a function of noise intensity. The plot would appear as an inverted U-curve, that is, a moderate noise is beneficial for performance whereas too low and too much noise attenuates performance. However, knowledge about the optimal signal-to-noise ratio (SNR) needed for stochastic resonance to occur in the brain, particularly in the neural network of auditory working memory, is limited and demand further investigation. In the present study, we extended previous works on the impact of white noise on auditory working memory performance by including multiple background noise levels to map out the inverted U-curve for the stochastic resonance. Using functional magnetic resonance imaging (fMRI), twenty healthy young adults performed a word-based backward recall span task under four signal-to-noise ratio conditions: 15, 10, 5, and 0-dB SNR. Group results show significant behavioral improvement and increased activation in frontal cortices, primary auditory cortices, and anterior cingulate cortex in all noise conditions, except at 0-dB SNR, which decreases activation and performance. When plotted as a function of signal-to-noise ratio, behavioral and fMRI data exhibited a noise-benefit inverted U-shaped curve. Additionally, a significant positive correlation was found between the activity of the right superior frontal gyrus (SFG) and performance in 5-dB SNR. The predicted phenomenon of SR on auditory working memory performance is confirmed. Findings from this study suggest that the optimal signal-to-noise ratio to enhance auditory working memory performance is within 10 to 5-dB SNR and that the right SFG may be a strategic structure involved in enhancement of auditory working memory performance.

Topography and timing of activity in right inferior frontal cortex and anterior insula for stopping movement

Topography and timing of activity in right inferior frontal cortex and anterior insula for stopping movement

Neural indices of listening effort in noisy environments

Listening in a noisy environment is challenging for individuals with normal hearing and can be a significant burden for those with hearing impairment. The extent to which this burden is alleviated by a hearing device is a major, unresolved issue for rehabilitation. Here, we found adult users of cochlear implants (CIs) self-reported listening effort during a speech-in-noise task that was positively related to alpha oscillatory activity in the left inferior frontal cortex, canonical Broca’s area, and inversely related to speech envelope coherence in the 2–5 Hz range originating in the superior-temporal plane encompassing auditory cortex. Left frontal cortex coherence in the 2–5 Hz range also predicted speech-in-noise identification. These data demonstrate that neural oscillations predict both speech perception ability in noise and listening effort.

Cortico-Thalamic Circuit Model for Bottom-Up and Top-Down Mechanisms in General Anesthesia Involving the Reticular Activating System

: General anesthesia is a widely used medical procedure. However, its underlying physiological mechanisms are still unknown. Current research has identified bottom-up mechanisms in the brain involving subcortical sleep-promoting and arousal structures and top-down mechanisms comprising corticocortical and corticothalamic circuits. The current work presents a neural model considering both mechanisms. Its numerical simulation yields frontal and occipital cortical activity that exhibits the characteristic spectral changes as observed experimentally. In addition, increasing the anesthetic level enhances local synchrony and weakens distant synchrony. This represents a fragmentation of the brain as observed in experimental data under anesthesia.

Reduced Visual and Frontal Cortex Activation During Visual Working Memory in Grapheme-Color Synaesthetes Relative to Young and Older Adults.

The sensory recruitment model envisages visual working memory (VWM) as an emergent property that is encoded and maintained in sensory (visual) regions. The model implies that enhanced sensory-perceptual functions, as in synaesthesia, entail a dedicated VWM-system, showing reduced visual cortex activity as a result of neural specificity. By contrast, sensory-perceptual decline, as in old age, is expected to show enhanced visual cortex activity as a result of neural broadening. To test this model, young grapheme-color synaesthetes, older adults and young controls engaged in a delayed pair-associative retrieval and a delayed matching-to-sample task, consisting of achromatic fractal stimuli that do not induce synaesthesia. While a previous analysis of this dataset (Pfeifer et al., 2016) has focused on cued retrieval and recognition of pair-associates (i.e., long-term memory), the current study focuses on visual working memory and considers, for the first time, the crucial delay period in which no visual stimuli are present, but working memory processes are engaged. Participants were trained to criterion and demonstrated comparable behavioral performance on VWM tasks. Whole-brain and region-of-interest-analyses revealed significantly lower activity in synaesthetes’ middle frontal gyrus and visual regions (cuneus, inferior temporal cortex), respectively, suggesting greater neural efficiency relative to young and older adults in both tasks. The results support the sensory recruitment model and can explain age and individual WM-differences based on neural specificity in visual cortex.

EEG coherence in theta, alpha, and beta bands in frontal regions and executive functions

Executive functions are higdevel cognitive processes that make possible the formation of flexible and adaptive goal-directed behaviors and the frontal lobes regulate these functions. The purpose of this study was to investigate the relationship between frontal EEG coherence in theta, alpha, and beta bands and executive functions in adults. A sample of 168 students (Mage = 25.44 years, SD = 4.52) were included in this study. EEG records were recorded at the psychology laboratory of Mohaghegh Ardabili University (Iran), then intrahemispheric and interhemispheric coherence of frontal regions were analyzed using the NeuroGuide software. The participants were asked to fill in the Adult Executive Skills Questionnaire. Correlational results showed that there is a positive relationship between executive functions and EEG coherence in theta, alpha, and beta bands in frontal regions of the left hemisphere, EEG coherence of alpha and beta bands in frontal regions of the right hemisphere and EEG coherence of alpha band between frontal regions of the two hemispheres. The results of the regression analysis also revealed that coherence of alpha, beta, and theta bands between left and right frontal regions and coherence of beta and theta bands in the left frontal regions predict executive functions. These results indicate that the common activity of frontal cortex, especially the left hemisphere, is associated with executive functions and cognitive control.