Anterior Prefrontal Activation Research Articles

Anterior prefrontal brain activity during emotion control predicts resilience to post-traumatic stress symptoms.

Regulating social emotional actions is essential for coping with life stressors and is associated with control by the anterior prefrontal cortex (aPFC) over the amygdala. However, it remains unclear to what extent prefrontal emotion regulation capacities contribute to resilience against developing post-traumatic stress disorder (PTSD) symptoms. Here, 185 police recruits who experienced their core trauma in the line of duty participated ina prospective longitudinal study. Pre-and post-trauma, they performed a well-established functionalMRI approach-avoidance task, mapping impulsive and controlled emotional actions. Higher baseline aPFC, dorsal and medial frontal pole activity was related to lower PTSD-symptoms after trauma exposure.aPFC activity predicted symptom development over and above self-reported and behavioral measures. Trauma-exposure, but not trauma-symptoms, predicted amygdala activation at follow-up. These findings suggest that prefrontal emotion regulation activity predicts increased resilience against developing post-traumatic stress symptoms, and may provide fruitful starting points for prediction and intervention studies.

Abnormal dorsal attention network activation in memory impairment after traumatic brain injury.

Memory impairment is a common, disabling effect of traumatic brain injury. In healthy individuals, successful memory encoding is associated with activation of the dorsal attention network as well as suppression of the default mode network. Here, in traumatic brain injury patients we examined whether: (i) impairments in memory encoding are associated with abnormal brain activation in these networks; (ii) whether changes in this brain activity predict subsequent memory retrieval; and (iii) whether abnormal white matter integrity underpinning functional networks is associated with impaired subsequent memory. Thirty-five patients with moderate-severe traumatic brain injury aged 23-65 years (74% males) in the post-acute/chronic phase after injury and 16 healthy control subjects underwent functional MRI during performance of an abstract image memory encoding task. Diffusion tensor imaging was used to assess structural abnormalities across patient groups compared to 28 age-matched healthy controls. Successful memory encoding across all participants was associated with activation of the dorsal attention network, the ventral visual stream and medial temporal lobes. Decreased activation was seen in the default mode network. Patients with preserved episodic memory demonstrated increased activation in areas of the dorsal attention network. Patients with impaired memory showed increased left anterior prefrontal activity. White matter microstructure underpinning connectivity between core nodes of the encoding networks was significantly reduced in patients with memory impairment. Our results show for the first time that patients with impaired episodic memory show abnormal activation of key nodes within the dorsal attention network and regions regulating default mode network activity during encoding. Successful encoding was associated with an opposite direction of signal change between patients with and without memory impairment, suggesting that memory encoding mechanisms could be fundamentally altered in this population. We demonstrate a clear relationship between functional networks activated during encoding and underlying abnormalities within the structural connectome in patients with memory impairment. We suggest that encoding failures in this group are likely due to failed control of goal-directed attentional resources.

Functionally Dissociable Influences on Learning Rate in a Dynamic Environment

Maintaining accurate beliefs in a changing environment requires dynamically adapting the rate at which one learns from new experiences. Beliefs should be stable in the face of noisy data but malleable in periods of change or uncertainty. Here we used computational modeling, psychophysics, and fMRI to show that adaptive learning is not a unitary phenomenon in the brain. Rather, it can be decomposed into three computationally and neuroanatomically distinct factors that were evident in human subjects performing a spatial-prediction task: (1) surprise-driven belief updating, related to BOLD activity in visual cortex; (2) uncertainty-driven belief updating, related to anterior prefrontal and parietal activity; and (3) reward-driven belief updating, a context-inappropriate behavioral tendency related to activity in ventral striatum. These distinct factors converged in a core system governing adaptive learning. This system, which included dorsomedial frontal cortex, responded to all three factors and predicted belief updating both across trials and across individuals.

Comparison of different spatial transformations applied to EEG data: A case study of error processing

The purpose of this paper is to compare the effects of different spatial transformations applied to the same scalp-recorded EEG data. The spatial transformations applied are two referencing schemes (average and linked earlobes), the surface Laplacian, and beamforming (a distributed source localization procedure). EEG data were collected during a speeded reaction time task that provided a comparison of activity between error vs. correct responses. Analyses focused on time–frequency power, frequency band-specific inter-electrode connectivity, and within-subject cross-trial correlations between EEG activity and reaction time. Time–frequency power analyses showed similar patterns of midfrontal delta–theta power for errors compared to correct responses across all spatial transformations. Beamforming additionally revealed error-related anterior and lateral prefrontal beta-band activity. Within-subject brain–behavior correlations showed similar patterns of results across the spatial transformations, with the correlations being the weakest after beamforming. The most striking difference among the spatial transformations was seen in connectivity analyses: linked earlobe reference produced weak inter-site connectivity that was attributable to volume conduction (zero phase lag), while the average reference and Laplacian produced more interpretable connectivity results. Beamforming did not reveal any significant condition modulations of connectivity. Overall, these analyses show that some findings are robust to spatial transformations, while other findings, particularly those involving cross-trial analyses or connectivity, are more sensitive and may depend on the use of appropriate spatial transformations.

An fMRI Study for Prototype Position Effect of Insight in Scientific Inventional Problem-Solving

When people encounter problems, they typically go through a period of puzzlement and require inspiration from other aspects of life to solve these problems. Friedrich Kekule, for example, discovered the molecular structure of benzene after dreaming of two serpents caught in each other's tails, which formed a circle on a distinctive ring. Archimedes derived insight into the relationship between weight and volume when he noticed displaced water in a bathtub. Numerous major inventions in history have been based on bionic imitation, in which biological systems are applied to the creation of artificial devices and machines. In most previous studies, creativity has been investigated primarily through divergent thinking tasks and insightful problem solving. For example, by comparing the alternative uses task and intelligence-related tasks, different patterns of electrophysiological brain activity and a stronger level of anterior prefrontal brain activation were observed. Although these findings aid the understanding of creativity, whether the progression of scientific invention is identical to the processes discussed in the above-mentioned studies remains unclear. Specifically, the process of prototype position effect of insight in scientific innovation has not been directly addressed. To explore the neural mechanism for prototype position effect of insight in scientific innovation, we selected 40 novel scientific innovation problems (to which scientists have undergone actually but college students did not know the answers) as the material and used fMRI technique for the experiments. Zhang Qinglin proposed that in reality, insight should be caused by "prototypal events activation"; it suggests that the key to solving insight problems is to activate the "prototypal event" correctly and gain "key heuristic information" under experimental conditions.Based on Zhang's hypothesis, this study was designed to explore the neural mechanism governing the act of catching inspiration in scientific innovation. In order to test these hypotheses, we adopted "five to five" paradigm. In this study, the prototype position contains former-problem (problem guide) and former-prototype. The participants were divided into two groupes. First groupes, the participants were asked to investigate 40 post-prototype inventional problems. Second groupes were opposite, the participants were asked to study 40 former-problem inventional problems. The instruments used in the experiments were 40 inventional problems and SPSS 17.0 was used for the statistical analyses. Behavior date showed the mean inventional problem-solving score for former-problem was higher than for former-prototype. And our fMRI data showed that the left middle temporal gyrus、left middle frontal gyrus were significantly activated when college students successfully caught inspiration under former-problem condition; left cingulate gyrus and left middle frontal gyrus were significantly activated when college students successfully solve the problem in the case of former-prototype condition. To the best of our knowledge, this work is the first fMRI study to investigate the brain activation of critical cognitive processes (automatic activation for catching inspiration) behind scientific innovation. Moreover, the real-life scientific innovations used in the experiments have higher ecological validity than the tasks (riddles, remote association tasks, and so on) used in previous studies. That is, the fMRI results can provide valuable insight into the neural basis of catching inspiration.

The effects of physical activity on functional MRI activation associated with cognitive control in children: a randomized controlled intervention

This study used functional magnetic resonance imaging (fMRI) to examine the influence of a 9-month physical activity program on task-evoked brain activation during childhood. The results demonstrated that 8- to 9-year-old children who participated in 60+ min of physical activity, 5 days per week, for 9 months, showed decreases in fMRI brain activation in the right anterior prefrontal cortex coupled with within-group improvements in performance on a task of attentional and interference control. Children assigned to a wait-list control group did not show changes in brain function. Furthermore, at post-test, children in the physical activity group showed similar anterior frontal brain patterns and incongruent accuracy rates to a group of college-aged young adults. Children in the wait-list control group still differed from the young adults in terms of anterior prefrontal activation and performance at post-test. There were no significant changes in fMRI activation in the anterior cingulate cortex (ACC) for either group. These results suggest that physical activity during childhood may enhance specific elements of prefrontal cortex function involved in cognitive control.

Increased left anterior insular and inferior prefrontal activity in post-stroke mania

BackgroundPost-stroke mania is an infrequent complication after stroke, and the mechanisms underlying this disorder remain unclear. Although a contralesional release phenomenon has been implicated in post-stroke mania, empirical findings are lacking.Case presentationWe present a case report of post stroke mania. Single photon emission tomography (SPECT) was performed twice, during the manic state and during the remitted euthymic state. The first SPECT study performed during the manic state demonstrated hypoperfusion in the right temporal and frontal regions due to right putaminal hemorrhage. It also showed hyperperfusion in the inferior lateral prefrontal lobe, the temporal lobe, and the medial and lateral parts of the parietal lobe in the left hemisphere. The second SPECT study performed during the euthymic state demonstrated moderate improvement in the hypoperfusion in the right fronto-temporal regions. Furthermore, compared to the findings on the first SPECT study, the second study showed that the focal hyperperfusion in the anterior insular cortex, inferior lateral prefrontal lobes, and superior-middle temporal gyrus in the left hemisphere had vanished.ConclusionIncreased left inferior prefrontal and anterior insular activity and reduced extensive right fronto-temporal lobe activity are involved in the development of post-stroke mania.

Role for Presupplementary Motor Area in Inhibition of Cognitive Set Interference

Proactive interference (PI), which is formed through repetition of certain behavior and lasts for a while, needs to be inhibited in order for subsequent behavior to prevail over the antecedent one. Although the inhibitory mechanisms in the pFC have been reported that are recruited long after one behavior is updated to another, very little is known about the inhibitory mechanisms that are recruited immediately after the update. The WCST was modified in the present fMRI study such that inhibition of PI could be examined both immediately after and long after update of behavior. Use of "dual-match" stimuli allowed us to compare two types of trials where inhibition of PI was and was not required (control and release trials, respectively). Significant activation was observed in the left pre-SMA during control versus release trials. The pre-SMA activation was selective to PI inhibition required immediately after update of behavior, which exhibited marked contrast to the left anterior prefrontal activation selective to PI inhibition required long after the update. These results reveal dissociable inhibitory mechanisms in these two regions that are recruited in the different temporal contexts of the inhibitory demands imposed during performance of the task.

Amygdalar modulation of frontotemporal connectivity during the inkblot test

Unique and unusual responses to inkblot stimuli evoked by emotionally vulnerable psychiatric patients have been considered as examples of interference of emotion with perceptual processes. However, few studies have investigated the interaction between emotion-related and perception-related neural circuits during performance of the inkblot test. In our recent studies using the inkblot stimuli, enlargement of the amygdala was revealed in association with frequent production of unique responses to the inkblot stimuli. Additionally, our studies demonstrated right temporopolar activation associated with the production of unique responses, as well as left anterior prefrontal and bilateral occipitotemporal activation associated with the production of typical responses. On the basis of these results, we hypothesized that the amygdala is involved in modulation of the connectivity among the frontotemporal regions identified in the activation analysis. To address this issue, we performed a functional connectivity analysis of functional magnetic resonance imaging data, using physiophysiological interaction implemented in Statistical Parametric Mapping 2 (SPM2). This analysis revealed that the amygdala imposed a positive modulation on the connection from the anterior prefrontal region to the temporopolar region, and a negative modulation on the connection from the temporopolar region to the occipitotemporal regions. These results suggest that interference of emotion affects perception during the inkblot test.

116. Anterior prefrontal activity associated with pleasant and unpleasant emotions: A study with event-related near-infrared spectroscopy

116. Anterior prefrontal activity associated with pleasant and unpleasant emotions: A study with event-related near-infrared spectroscopy

A parametric relief signal in human ventrolateral prefrontal cortex

People experience relief whenever outcomes are better than they would have been, had an alternative course of action been chosen. Here we investigated the neuronal basis of relief with functional resonance imaging in a choice task in which the outcome of the chosen option and that of the unchosen option were revealed sequentially. We found parametric activation increases in anterior ventrolateral prefrontal cortex with increasing relief (chosen outcomes better than unchosen outcomes). Conversely, anterior ventrolateral prefrontal activation was unrelated to the opposite of relief, increasing regret (chosen outcomes worse than unchosen outcomes). Furthermore, the anterior ventrolateral prefrontal activation was unrelated to primary gains and increased with relief irrespective of whether the chosen outcome was a loss or a gain. These results suggest that the anterior ventrolateral prefrontal cortex encodes a higher-order reward signal that lies at the core of current theories of emotion.

Increased Left Prefrontal Activation During Staring/Mutism Episodes in a Patient With Resistant Catatonic Schizophrenia: A Near Infrared Spectroscopy Study

To present the first near infrared spectroscopy (NIRS) study of a patient with resistant catatonic schizophrenia during residual episodes of catatonia-related symptoms. Functional imaging studies generally point to a decreased cortical activation in catatonic patients, with the notable exception of increased orbitofrontal/medial prefrontal activity elicited by negative stimuli. Cortical activity of the left anterior prefrontal area was recorded with a Techen 4 x 4 NIRS apparatus. Four episodes of staring/mutism were recorded and averaged. Compared with normal activity, these episodes were characterized by increased cortical activation. Within its methodologic limitations, the present observation suggests that increased anterior prefrontal activation in catatonic patients is not specific to negative stimuli. Known functions of the anterior prefrontal cortex such as self monitoring, reallocation of attention, or conflict resolution might underlie these findings. These also attest to the potential of NIRS for functional imaging of vulnerable subjects.

Preparation for integration: the role of anterior prefrontal cortex in working memory

The execution of complex working memory tasks often requires various cognitive control operations on stored content. Here we focus on the integration operation - defined as merging the outcome of subtask processing with additional information actively maintained before and during subtask execution. In prior work, we identified the anterior prefrontal cortex as critical for integration during mental arithmetic. Here we replicate and extend these results in an adapted mental arithmetic task that enabled examination of the detailed temporal dynamics of the anterior prefrontal activation. We find that this region is involved in the preparation for integration, possibly by ensuring that goal-relevant information is maintained in an accessible form, while at the same time protected from subtask interference.

Differential Anterior Prefrontal Activation during the Recognition Stage of a Spatial Working Memory Task

Neuroimaging studies commonly show widespread activations in the prefrontal cortex during various forms of working memory and long-term memory tasks. However, the anterior prefrontal cortex (aPFC, Brodmann area 10) has been mainly associated with retrieval in episodic memory, and its role in working memory is less clear. We conducted an event-related functional magnetic resonance imaging study to examine brain activations in relation to recognition in a spatial delayed-recognition task. Similar to the results from previous findings, several frontal areas were strongly activated during the recognition phase of the task, including the aPFC, the lateral PFC and the anterior cingulate cortex. Although the aPFC was more active during the recognition phase, it was also active during the delay phase of the spatial working memory task. In addition, the aPFC showed greater activity in response to negative probes (non-targets) than to positive probes (targets). While our analyses focused on examining signal changes in the aPFC, other prefrontal regions showed similar effects and none of the areas were more active in response to the positive probes than to the negative probes. Our findings support the conclusion that the aPFC is involved in working memory and particularly in processes that distinguish target and non-target stimuli during recognition.

The neural basis for novel semantic categorization

We monitored regional cerebral activity with BOLD fMRI during acquisition of a novel semantic category and subsequent categorization of test stimuli by a rule-based strategy or a similarity-based strategy. We observed different patterns of activation in direct comparisons of rule- and similarity-based categorization. During rule-based category acquisition, subjects recruited anterior cingulate, thalamic, and parietal regions to support selective attention to perceptual features, and left inferior frontal cortex to helps maintain rules in working memory. Subsequent rule-based categorization revealed anterior cingulate and parietal activation while judging stimuli whose conformity with the rules was readily apparent, and left inferior frontal recruitment during judgments of stimuli whose conformity was less apparent. By comparison, similarity-based category acquisition showed recruitment of anterior prefrontal and posterior cingulate regions, presumably to support successful retrieval of previously encountered exemplars from long-term memory, and bilateral temporal-parietal activation for perceptual feature integration. Subsequent similarity-based categorization revealed temporal-parietal, posterior cingulate, and anterior prefrontal activation. These findings suggest that large-scale networks support relatively distinct categorization processes during the acquisition and judgment of semantic category knowledge.

Towards an understanding of gait control: brain activation during the anticipation, preparation and execution of foot movements

While a detailed understanding of brain activity with hand movements has developed, less is known about the functional anatomy of motor control for foot movements. Here we have used fMRI to define brain activity associated with unilateral foot extension and flexion, component movements of gait. We studied brain responses to visually cued active and passive movements and periods of either preparation (before active movement) or anticipation (before passive movement) with a pseudo-randomized block design. A mixed-effects ( n = 12) contrast of the active movement condition vs. rest identified brain activation in regions including the medial wall of the primary sensorimotor cortex, consistent with expected somatotopy. Medial wall activation during passive movement vs. rest was less intense and localized to the same region. Frontal and association cortices were more active during preparation or anticipation periods than during the movements themselves. A contrast of preparation to move vs. active movement showed significant activation in the medial frontal and frontopolar gyri and the precuneus. Contrast of the anticipation of movement with the passive movement condition revealed activation in the dorsal premotor cortex and precuneus. Our study thus provides evidence for somatotopy in multiple functional regions in the motor control network. The anterior prefrontal activity is involved in the preparation for cued movement with distinct regions of the medial motor cortex (including SMA and CMA) preferentially involved in motor program planning and execution. This direct characterization of brain activation patterns associated with foot movements promises use of fMRI for the functional analysis of pathologies of gait.

Neural correlates of self-reflection.

The capacity to reflect on one's sense of self is an important component of self-awareness. In this paper, we investigate some of the neurocognitive processes underlying reflection on the self using functional MRI. Eleven healthy volunteers were scanned with echoplanar imaging using the blood oxygen level-dependent contrast method. The task consisted of aurally delivered statements requiring a yes-no decision. In the experimental condition, participants responded to a variety of statements requiring knowledge of and reflection on their own abilities, traits and attitudes (e.g. 'I forget important things', 'I'm a good friend', 'I have a quick temper'). In the control condition, participants responded to statements requiring a basic level of semantic knowledge (e.g. 'Ten seconds is more than a minute', 'You need water to live'). The latter condition was intended to control for auditory comprehension, attentional demands, decision-making, the motoric response, and any common retrieval processes. Individual analyses revealed consistent anterior medial prefrontal and posterior cingulate activation for all participants. The overall activity for the group, using a random-effects model, occurred in anterior medial prefrontal cortex (t = 13.0, corrected P = 0.05; x, y, z, 0, 54, 8, respectively) and the posterior cingulate (t = 14.7, P = 0.02; x, y, z, -2, -62, 32, respectively; 967 voxel extent). These data are consistent with lesion studies of impaired awareness, and suggest that the medial prefrontal and posterior cingulate cortex are part of a neural system subserving self-reflective thought.

Left Anterior Prefrontal Activation Increases with Demands to Recall Specific Perceptual Information

Results from neuroimaging studies have led to competing theories regarding the contributions of prefrontal regions to memory formation and retrieval. To investigate this issue, we used event-related functional magnetic resonance imaging to assess prefrontal activation during encoding and retrieval of pictures of objects. Responses to studied and unstudied objects at retrieval were compared between two tests with differing demands for the specificity of information to be retrieved (source vs old-new recognition). Results showed that bilateral ventral [Brodmann's areas (BA) 44, 45, and 47] and right dorsal (BA 9) prefrontal regions were activated during both encoding and retrieval, but activity in these regions was not reliably modulated by the specificity of information to be retrieved. A region in left anterior prefrontal cortex (BA 10/46) was reliably activated during retrieval trials, and activation in this region increased with demands to retrieve perceptually detailed information about studied objects. Our results show that left anterior prefrontal cortex is engaged during the monitoring and evaluation of specific memory characteristics at retrieval-a process critical for accurate episodic remembering.

Hemispheric Activation of Anterior and Inferior Prefrontal Cortex during Verbal Encoding and Recognition: A PET Study of Healthy Volunteers

Evidence of bilateral prefrontal activation during memory encoding and retrieval has increased attention given to anatomical subdivisions within the prefrontal cortex. The current study examined anterior and inferior aspects of the prefrontal cortex to determine their degree of functional and hemispheric overlap during encoding and recognition. Cerebral blood flow of 25 healthy volunteers was measured using PET 15O-water methods during four conditions: resting baseline, sequential finger movement, word encoding, and word recognition. Resting and motor images were averaged to provide a single reference that was subtracted from encoding and recognition using statistical parametric mapping (SPM96). Memory conditions were also subtracted from each other to identify differences in regional activity. Subjects performed well (86% correct) and had a slightly conservative response bias. Baseline subtraction from encoding revealed focal activation of left inferior prefrontal cortex (area 45) without significant contralateral activation. Recognition minus baseline subtraction produced a focal right anterior prefrontal activation (areas 9 and 10) that was not present in the left hemisphere. Bilateral effects were seen in area 45 during recognition. Subtraction of memory tasks from each other did not reveal any areas of greater activity during encoding. However, the recognition task produced greater activation in right area 9 extending into the anterior cingulate. Greater activity during recognition was also observed in left insula and bilateral visual integration areas. These results are discussed in relation to the prevailing model of prefrontal hemispheric asymmetry during episodic memory.

The Role of the Right Anterior Prefrontal Cortex in Episodic Retrieval

Regional brain activity was measured with H215O PET while participants attempted to complete word-stem and word-fragment retrieval cues with previously studied words. The retrieval cue manipulation was employed to gain control over the monitoring operations associated with evaluating the episodic status of alternative cue completions. These operations were more constrained for fragments, which had fewer possible completions than each corresponding stem. In one condition (zero target), during the scanning interval none of the cues could be completed with studied items, whereas in another condition (high target), 80% of cues belonged to studied items. Relative to baseline tasks, right anterior prefrontal activity was greater for stems than for fragments in the zero target condition. The target density manipulation did not modulate right anterior prefrontal activity, but was associated with increased activity in right dorsolateral prefrontal cortex. These findings are consistent with the proposal that the right anterior prefrontal cortex supports monitoring operations during episodic retrieval tasks. In addition, the findings add to evidence suggesting that the dorsolateral and anterior right prefrontal cortex make functionally distinct contributions to episodic retrieval.