Left Frontal Activity Research Articles

Significant Head Motion Can Cause Either Hypermetabolic or Hypometabolic Cerebral Activity on 18F-FDG PET/CT

We report 2 separate cases with significant head motion causing apparent hypometabolic and hypermetabolic cerebral activity on FDG PET/CT. Case 1 is a 57-year-old man with facial numbness status post chemotherapy for mantle cell lymphoma. Restaging attenuation-corrected PET showed increased left frontal region activity, whereas nonattenuation-corrected PET demonstrated evidence of patient motion with normal physiologic left frontal cortical activity. Case 2 is a 78-year-old man with history of malignant melanoma. Attenuation-corrected PET/CT demonstrated diffusely decreased activity in the left cerebral hemisphere, whereas nonattenuation-corrected PET showed significant head motion with intact cortical activity.

Approach-related left prefrontal EEG asymmetry predicts muted error-related negativity

In two studies, we used electroencephalography (EEG) to test whether approach-motivation-related brain activity would predict reduced sensitivity to negative outcomes. In both studies, participants (Study 1, N=26; Study 2, N=56) were first recorded for baseline EEG to measure approach-related left frontal EEG activity. They then completed either the color-naming Stroop task (Study 1) or the Multi-Source Interference Task (Study 2) to measure error-related negativity (ERN), an event-related potential that has been associated with aversive motivation and distress. In both studies, higher leftward frontal EEG asymmetry predicted reduced ERN amplitude. Hierarchical regression analyses of the separate frontal nodes that comprised the asymmetry score further showed that left frontal activity predicted reduced ERN amplitude whereas right frontal activity predicted greater ERN amplitude. Results have implications for understanding emotion and motivation and for understanding the personal resilience associated with approach motivated states.

Left inferior frontal activations depending on the canonicity determined by the argument structures of ditransitive sentences: an MEG study.

To elucidate the relationships between syntactic and semantic processes, one interesting question is how syntactic structures are constructed by the argument structure of a verb, where each argument corresponds to a semantic role of each noun phrase (NP). Here we examined the effects of possessivity [sentences with or without a possessor] and canonicity [canonical or noncanonical word orders] using Japanese ditransitive sentences. During a syntactic decision task, the syntactic structure of each sentence would be constructed in an incremental manner based on the predicted argument structure of the ditransitive verb in a verb-final construction. Using magnetoencephalography, we found a significant canonicity effect on the current density in the left inferior frontal gyrus (IFG) at 530–550 ms after the verb onset. This effect was selective to canonical sentences, and significant even when the precedent NP was physically identical. We suggest that the predictive effects associated with syntactic processing became larger for canonical sentences, where the NPs and verb were merged with a minimum structural distance, leading to the left IFG activations. For monotransitive and intransitive verbs, in which structural computation of the sentences was simpler than that of ditransitive sentences, we observed a significant effect selective to noncanonical sentences in the temporoparietal regions during 480–670 ms. This effect probably reflects difficulty in semantic processing of noncanonical sentences. These results demonstrate that the left IFG plays a predictive role in syntactic processing, which depends on the canonicity determined by argument structures, whereas other temporoparietal regions would subserve more semantic aspects of sentence processing.

EEG brain wave band differentiation during a eustress state of humor associated mirthful laughter compared to a distress state

Humor associated mirthful laughter, a novel eustress state, and a distress state differentially modulates neuroendocrine, immune, and psychological mood states. We used the 9 channel B‐Alert X10® EEG system with power spectral density (PSD), computed for left and right hemispheres, to determine if EEG metrics differentiated between a humor eustress state and a distress state. Eight video trial EEG sessions (states ‐ humor eustress vs. distress) were run on 2 individuals. Absolute PSD was used for the analysis of frontal theta (3–7Hz), alpha (8–12Hz), and beta (13–29Hz) of the left (F3) and right (F4) hemispheres. Using 10 sec epochs, ANOVA confirmed the humor state increased PSD across theta, p < .05; and alpha, p < .01. The opposite was true for beta where the eustress decreased PSD, p < .05. For differences between hemispheres, using 1‐way ANOVA, significant right‐left differences occurred across state for frontal theta, p < .05 and frontal alpha, p < .05. Significance was also found in the parietal for alpha, p < .05, but not for theta. PSD shows 1) both theta and alpha have greater left frontal (F3) EEG activity during the humor eustress state, which is associated with positive affect; and 2) right‐left hemispheric differentiation. In conclusion, PSDs computed for the left and right frontal hemispheres, using B‐Alert X10® EEG activity, differentiates a humor eustress state from a distress state.

Imaging language networks before and after anterior temporal lobe resection: Results of a longitudinal fMRI study

SummaryPurpose: Anterior temporal lobe resection (ATLR) controls seizures in up to 70% of patients with intractable temporal lobe epilepsy (TLE) but, in the language dominant hemisphere, may impair language function, particularly naming. Functional reorganization can occur within the ipsilateral and contralateral hemispheres. We investigated reorganization of language in left-hemisphere–dominant patients before and after ATLR; whether preoperative functional magnetic resonance imaging (fMRI) predicts postoperative naming decline; and efficiency of postoperative language networks.Methods: We studied 44 patients with TLE due to unilateral hippocampal sclerosis (24 left) on a 3T GE-MRI scanner. All subjects performed language fMRI and neuropsychological testing preoperatively and again 4 months after left or right ATLR.Key Findings: Postoperatively, individuals with left TLE had greater bilateral middle/inferior frontal fMRI activation and stronger functional connectivity from the left inferior/middle frontal gyri to the contralateral frontal lobe than preoperatively, and this was not observed in individuals with right TLE. Preoperatively, in left and right TLE, better naming correlated with greater preoperative left hippocampal and left frontal activation for verbal fluency (VF). In left TLE, stronger preoperative left middle frontal activation for VF was predictive of greater decline in naming after ATLR. Postoperatively, in left TLE with clinically significant naming decline, greater right middle frontal VF activation correlated with better postoperative naming. In patients without postoperative naming decline, better naming correlated with greater activation in the remaining left posterior hippocampus. In right TLE, naming ability correlated with left hippocampal and left and right frontal VF activation postoperatively.Significance: In left TLE, early postoperative reorganization to the contralateral frontal lobe suggests multiple systems support language function. Postoperatively, ipsilateral recruitment involving the posterior hippocampal remnant is important for maintaining language, and reorganization to the contralateral hemisphere is less effective. Preoperative left middle frontal activation for VF was predictive of naming decline in left TLE after ATLR.

An Integrative Assessment of the Psychophysiologic Alterations in Young Women With Recurrent Major Depressive Disorder

Alterations in neuroelectrical activities coincide with major depressive disorder (MDD). This study examines the pattern of cerebral activity and cardiac autonomic parameters of euthymic women with recurrent MDD. Resting electroencephalograms and electrocardiograms were recorded from 20 women with MDD receiving escitalopram and 40 matched and healthy women. We computed frontal alpha asymmetry to evaluate the interhemispheric balance. Parameters of heart rate variability were extracted to assess cardiac autonomic control. Sample entropy was used to assess the complexity of neurocardiac dynamics. The relationship between cardiovagal activity and alpha electroencephalogram was examined with a coherence analysis. Multivariable analysis of variance revealed a differential pattern of psychophysiologic variables between MDD patients and controls (p = .03). MDD was associated with a tendency toward lower left frontal activity (-0.06 [standard deviation = 0.14] versus 0.04 [0.17] lnμV(2), p = .04). Discriminant analysis demonstrated more right frontal activation, a lower high-frequency heart rate power spectrum, and a higher ratio of the low- to high-frequency heart rate power spectrum in patients with MDD compared with controls. Residual depressive symptoms (r = -0.09 to 0.11, p = .63-.99) and escitalopram dosage (r = -0.09 to 0.28, p = .22-.84) were not correlated with autonomic measures. Coherence between normalized high-frequency component of the heart rate power spectrum and alpha power was not significant (F3, p = .27; F4, p = .16). Euthymic women with recurrent MDD have a distinctive psychophysiologic profile. This profile may reflect altered frontal activation and a reduced cardiovagal tone in depression.

Cardiovascular and electrocortical markers of anger and motivation during a simulated driving task

The experience of anger may have consequences for the long-term health of the individual. The psychophysiological manifestation of anger can vary in response to the motivational context of anger provocation. The current study was designed to investigate how motivational context (challenge vs. threat) influenced the cardiovascular system and frontal EEG asymmetry. 29 male participants completed a simulated driving journey with a fixed time schedule. Anger was induced by exposing participants to traffic delays at an early (challenge) and later point (threat) on the simulated route. A number of dependent variables were recorded, including 32 channels of EEG, measures of cardiovascular impedance, blood pressure and fEMG activity from the corrugator supercilii. The results indicated that traffic delays significantly increased blood pressure, heart rate, TPR and corrugator activity whilst reducing the relative level of left frontal activation in the EEG. However, there was little evidence for a consistent distinction between the early (challenge) and late (threat) introduction of traffic delay. The consequences of these findings for capturing the cardiovascular and electrocortical responses to anger induction are discussed.

Asymmetric frontal brain activity and parental rejection predict altruistic behavior: Moderation of oxytocin effects

Asymmetric frontal brain activity has been widely implicated in reactions to emotional stimuli and is thought to reflect individual differences in approach–withdrawal motivation. Here, we investigate whether asymmetric frontal activity, as a measure of approach–withdrawal motivation, also predicts charitable donations after a charity’s (emotion-eliciting) promotional video showing a child in need is viewed, in a sample of 47 young adult women. In addition, we explore possibilities for mediation and moderation, by asymmetric frontal activity, of the effects of intranasally administered oxytocin and parental love withdrawal on charitable donations. Greater relative left frontal activity was related to larger donations. In addition, we found evidence of moderation: Low levels of parental love withdrawal predicted larger donations in the oxytocin condition for participants showing greater relative right frontal activity. We suggest that when approach motivation is high (reflected in greater relative left frontal activity), individuals are generally inclined to take action upon seeing someone in need and, thus, to donate money to actively help out. Only when approach motivation is low (reflected in less relative left/greater relative right activity) do empathic concerns affected by oxytocin and experiences of love withdrawal play an important part in deciding about donations.

Bi-frontal direct current stimulation affects delay discounting choices

In delay discounting tasks, participants decide between receiving a certain amount of money now or a larger sum sometime in the future. This study investigated the effects of transcranial direct current stimulation on delay discounting. Participants made delay discounting choices while receiving a bi-frontal stimulation of right-hemisphere anodal/left-hemisphere cathodal, left-hemisphere anodal/right-hemisphere cathodal, and sham stimulation, in three separate sessions. When the difference between the alternatives was 10% or more, participants generally preferred to wait for the larger sum. Nevertheless, there were more choices of smaller “immediate” gains, instead of the larger delayed options, when the left dorsolateral prefrontal cortex (DLPFC) was facilitated and the right DLPFC inhibited, compared to the sham stimulation. These observations indicate the significant role of the prefrontal cortex in delay discounting choices, and demonstrate that increased left frontal activation combined with decreased right frontal activation can alter decision-making by intensifying a tendency to choose immediate gains.

Frontal EEG asymmetry moderates the effects of stressful life events on internalizing symptoms in children at familial risk for depression

This study examined whether frontal alpha electroencephalographic (EEG) asymmetry moderates the association between stressful life events and depressive symptoms in children at familial risk for depression. Participants included 135 children ages 6 to 13, whose mothers had either a history of depression or no history of major psychiatric conditions. Frontal EEG was recorded while participants watched emotion-eliciting films. Symptoms and stressful life events were obtained via the Child Behavior Check List and a clinical interview, respectively. High-risk children displayed greater relative right lateral frontal activation (F7/F8) than their low-risk peers during the films. For high-risk children, greater relative left lateral frontal activation moderated the association between stressful life events and internalizing symptoms. Specifically, greater relative left lateral frontal activation mitigated the effects of stress in at-risk children.

Spatio-temporal localisation of attentional orienting to gaze and peripheral cues

Another person's eye gaze often triggers our attention such that we follow their direction of gaze. We investigated how the neural mechanisms for processing eye-gaze and spatial attention interact using magnetoencephalography (MEG) in young adults. In a cueing paradigm, a face was presented centrally with left or right averted eye-gaze serving as the directional cue in the eye-gaze condition. In the peripheral cue condition, the face with a straight gaze was presented with a cue stimulus appearing on the left or right of the face. Cue validity was 50%. MEG was recorded during the two conditions and event-related beamforming was used to determine the timing and location of the brain activity related to the two types of cueing. The MEG data indicated that generally the network of activation in response to our two cue types was similar. In contrast, MEG responses to the targets demonstrated one main peak at 286–306ms for the eye-gaze cue condition while two peaks were found at 238–258ms and 286–306ms for the peripheral cue condition. Activation was also consistently larger for the invalid than valid trials. Source images for the invalid minus valid contrasts for the 238–258ms window showed significant activation only in the peripheral cueing condition, in the left temporoparietal junction and left inferior frontal gyrus. In the 286–306ms window, both conditions showed left medial frontal activations. Thus, peripheral cues showed more rapid neural processing than the eye-gaze cues, with the second component being common to both, reflecting in part common processing. We suggest that attentional processing was maximal in the left hemisphere, as the right hemisphere was likely engaged in processing the face information.

Relationship maintenance and biases on the line bisection task: Attractive alternatives, asymmetrical cortical activity, and approach–avoidance motivation

People in long-term romantic relationships possess relationship maintenance mechanisms designed to protect against the temptation of desirable relationship alternatives. The current research examined the link between relationship maintenance mechanisms and an index of neurologically based approach/avoidance motivation. Participants completed a line bisection task that yields measures of asymmetric activity in the right and left frontal cortices; such activity is thought to reflect people's level of approach/avoidance motivation. Compared to single participants, participants in committed relationships displayed relatively less left visual field bias on the line bisection task (indicative of greater left frontal cortical activation and greater cognitive avoidance motivation) in response to available, attractive opposite-sex targets. Decreased left visual field bias was particularly pronounced among individuals with moderate levels of relationship commitment — those expected to display the highest levels of relationship maintenance. These findings provide insight into perceptual, motivational, and neurological processes that may help people avoid tempting relationship alternatives.

Infant physiological and behavioral responses to loss of maternal attention to a social-rival

Previous research has found that infants respond with more negative/protest as well as approach-type behaviors in response to the loss of maternal attention to a social-rival as compared to a non-social item. The purpose of the current research was to conceptually replicate the maternal inattention research with a different population and to extend on it by examining the relationships between infants' emotional responses and their temperament and physiology (brain activity). A baseline measure of infant EEG was collected after which mother–infant dyads (n = 30) participated in two mother-ignoring conditions. Infants demonstrated more approach-style responses (maternal-directed gaze, proximity, and touch), higher reactivity levels (increased arousal, aggression, and disorganization), and more negative affect in the social-rival relative to the nonsocial condition. Approach-style (jealousy) responses were predictive of the infants' greater left frontal baseline EEG activity. Maternal reports of an infant's temperamental sociability and approach were not related to frontal EEG but several temperamental characteristics were associated with approach style responses during the social-rival condition. These findings collectively point to the emotion of jealousy in infants, as only during the social rival condition were associations between approach style responses and negative affect as well as left frontal EEG activity uncovered.

Revealing the Functional Neuroanatomy of Intrinsic Alertness Using fMRI: Methodological Peculiarities

Clinical observations and neuroimaging data revealed a right-hemisphere fronto-parietal-thalamic-brainstem network for intrinsic alertness, and additional left fronto-parietal activity during phasic alertness. The primary objective of this fMRI study was to map the functional neuroanatomy of intrinsic alertness as precisely as possible in healthy participants, using a novel assessment paradigm already employed in clinical settings. Both the paradigm and the experimental design were optimized to specifically assess intrinsic alertness, while at the same time controlling for sensory-motor processing. The present results suggest that the processing of intrinsic alertness is accompanied by increased activity within the brainstem, thalamus, anterior cingulate gyrus, right insula, and right parietal cortex. Additionally, we found increased activation in the left hemisphere around the middle frontal gyrus (BA 9), the insula, the supplementary motor area, and the cerebellum. Our results further suggest that rather minute aspects of the experimental design may induce aspects of phasic alertness, which in turn might lead to additional brain activation in left-frontal areas not normally involved in intrinsic alertness. Accordingly, left BA 9 activation may be related to co-activation of the phasic alertness network due to the switch between rest and task conditions functioning as an external warning cue triggering the phasic alertness network. Furthermore, activation of the intrinsic alertness network during fixation blocks due to enhanced expectancy shortly before the switch to the task block might, when subtracted from the task block, lead to diminished activation in the typical right hemisphere intrinsic alertness network. Thus, we cautiously suggest that – as a methodological artifact – left frontal activations might show up due to phasic alertness involvement and intrinsic alertness activations might be weakened due to contrasting with fixation blocks, when assessing the functional neuroanatomy of intrinsic alertness with a block design in fMRI studies.

Adverse Rearing Environments and Neural Development in Children: The Development of Frontal Electroencephalogram Asymmetry

Children raised in institutional settings experience marked deprivation in social and environmental stimulation. This deprivation may disrupt brain development in ways that increase risk for psychopathology. Differential hemispheric activation of the frontal cortex is an established biological substrate of affective style that is associated with internalizing psychopathology. Previous research has never characterized the development of frontal electroencephalogram asymmetry in children or evaluated whether adverse rearing environments alter developmental trajectories. A sample of 136 children (mean age = 23 months) residing in institutions in Bucharest, Romania, and a sample of community control subjects (n = 72) participated. Half of institutionalized children were randomized to a foster care intervention. Electroencephalogram data were acquired at study entry and at ages 30, 42, and 96 months. A structured diagnostic interview of psychiatric disorders was completed at 54 months. Children exhibited increases in right relative to left hemisphere frontal activation between the second and fourth years of life, followed by an increase in left relative to right hemisphere activation. Children reared in institutions experienced a prolonged period of increased right hemisphere activation and a blunted rebound in left frontal activation. Foster care placement was associated with improved developmental trajectories but only among children placed before 24 months. The development trajectory of frontal electroencephalogram asymmetry in early childhood predicted internalizing symptoms at 54 months. Exposure to adverse rearing environments can alter brain development, culminating in heightened risk for psychopathology. Interventions delivered early in life have the greatest potential to mitigate the long-term effects of these environments.

Search asymmetry, sustained attention, and response inhibition

In the present experiment, we used search asymmetry to test whether the sustained attention to response task is a better measure of response inhibition or sustained attention. Participants performed feature present and feature absent target detection tasks using either a sustained attention to response task (SART; high Go low No-Go) or a traditionally formatted task (TFT; high No-Go low Go) response format. In addition to performance, we employed functional near infrared spectroscopy (fNIRS) to measure lateral cerebral oxygenation levels and self-reports of Tense Arousal, Energetic Arousal, task related and unrelated thoughts occurring during the tasks. Detections were lower and reaction times longer in the feature absent search than the feature present search regardless of response format. Detections were lower, but reaction times shorter in the SART than the TFT regardless of feature search. Greater right than left frontal hemisphere activation occurred in the SART than the TFT. In addition, the SART was more fatiguing based on self-reports than the TFT, but there were no differences in Task-Unrelated Thoughts across task conditions. Overall, the results suggest the SART places high response inhibition, not necessarily sustained attention, demands on participants.

Neural correlates of metonymy resolution

Metonymies are exemplary models for complex semantic association processes at the sentence level. We investigated processing of metonymies using event-related functional magnetic resonance imaging (fMRI). During an 1.5 Tesla fMRI scan, 14 healthy subjects (12 female) read 124 short German sentences with either literal (like “Africa is arid”), metonymic (“Africa is hungry”), or nonsense (“Africa is woollen”) content. Sentences were constructed so that they obey certain grammatical, semantic, and plausibility conditions and were matched for word frequency, semantic association, length and syntactic structure. We concentrated on metonymies that were not yet fossilised; we also examined a wide variety of metonymic readings. Reading metonymies relative to literal sentences revealed signal changes in a predominantly left-lateralised fronto-temporal network with maxima in the left and right inferior frontal as well as left middle temporal gyri. Left inferior frontal activation may reflect both inference processes and access to world knowledge during metonymy resolution.

The synchronization of spontaneous BOLD activity predicts extraversion and neuroticism

There is an increasing body of evidence pointing to a relationship between personality and brain markers. The purpose of this study was to identify the associations between personality dimensions of extraversion and neuroticism and the local synchronization of spontaneous blood oxygen level-dependent (BOLD) activity assessed by regional homogeneity (ReHo) approach. Our results revealed the significant negative correlation between neuroticism and ReHo in the left middle frontal gyrus, providing evidence for the left frontal activation involved in pleasant emotion. ReHo was correlated negatively with extraversion in the medial prefrontal cortex (MPFC), an important portion of the default mode network (DMN), thus further indicating the relationship between DMN and personality. In addition, ReHo in the insula, cerebellum and cingulate gyrus was correlated positively with extraversion, suggesting the associations between individual difference in extraversion and specific brain regions involved in affective processing. These findings shed light on the important relationship between the synchronization of spontaneous fluctuations and personality dimensions of extraversion and neuroticism, which provide further evidence for the neural underpinning of individual difference in personality traits.

Speech Facilitation by Left Inferior Frontal Cortex Stimulation

SummaryElectrophysiological studies in humans and animals suggest that noninvasive neurostimulation methods such as transcranial direct current stimulation (tDCS) can elicit long-lasting [1], polarity-dependent [2] changes in neocortical excitability. Application of tDCS can have significant and selective behavioral consequences that are associated with the cortical location of the stimulation electrodes and the task engaged during stimulation [3–8]. However, the mechanism by which tDCS affects human behavior is unclear. Recently, functional magnetic resonance imaging (fMRI) has been used to determine the spatial topography of tDCS effects [9–13], but no behavioral data were collected during stimulation. The present study is unique in this regard, in that both neural and behavioral responses were recorded using a novel combination of left frontal anodal tDCS during an overt picture-naming fMRI study. We found that tDCS had significant behavioral and regionally specific neural facilitation effects. Furthermore, faster naming responses correlated with decreased blood oxygen level-dependent (BOLD) signal in Broca's area. Our data support the importance of Broca's area within the normal naming network and as such indicate that Broca's area may be a suitable candidate site for tDCS in neurorehabilitation of anomic patients, whose brain damage spares this region.

Prefrontal asymmetry and parent-rated temperament in infants.

Indicators of temperament appear early in infancy and remain relatively stable over time. Despite a great deal of interest in biological indices of temperament, most studies of infant temperament rely on parental reports or behavioral tasks. Thus, the extent to which commonly used temperament measures relate to potential biological indicators of infant temperament is still relatively unknown. The current experiment examines the relationship between a common parental report measure of temperament – the Infant Behavior Questionnaire – Revised (IBQ-R) – and measures of frontal EEG asymmetry in infants. We examined associations between the subscales of the IBQ-R and frontal EEG asymmetry scores recorded during a combined series of neutral attentional and putatively emotional recording conditions in infants between 7 and 9 months of age. We predicted that approach-related subscales of the IBQ-R (e.g., Approach, Soothability) would be related to greater left prefrontal asymmetry, while withdrawal-related subscales (e.g., Distress to Limitations, Fear, Falling Reactivity, Perceptual Sensitivity) would be related to greater right prefrontal asymmetry. In the mid- and lateral-frontal regions, Approach, Distress to Limitations, Fear, Soothability, and Perceptual Sensitivity were generally associated with greater left frontal activation (rs≥.23, ps<0.05), while only Falling Reactivity was associated with greater right frontal activation (rs≤−.44, ps<0.05). Results suggest that variability in frontal EEG asymmetry is robustly associated with parental report measures of temperament in infancy.