Inferior Prefrontal Activation Research Articles

Hippocampal and prefrontal processing of network topology to simulate the future

Topological networks lie at the heart of our cities and social milieu. However, it remains unclear how and when the brain processes topological structures to guide future behaviour during everyday life. Using fMRI in humans and a simulation of London (UK), here we show that, specifically when new streets are entered during navigation of the city, right posterior hippocampal activity indexes the change in the number of local topological connections available for future travel and right anterior hippocampal activity reflects global properties of the street entered. When forced detours require re-planning of the route to the goal, bilateral inferior lateral prefrontal activity scales with the planning demands of a breadth-first search of future paths. These results help shape models of how hippocampal and prefrontal regions support navigation, planning and future simulation.

Age-Related Changes in the Neurophysiology of Language in Adults: Relationship to Regional Cortical Thinning and White Matter Microstructure

Although reading skill remains relatively stable with advancing age in humans, neurophysiological measures suggest potential reductions in efficiency of lexical information processing. It is unclear whether these age-related changes are secondary to decreases in regional cortical thickness and/or microstructure of fiber tracts essential to language. Magnetoencephalography, volumetric MRI, and diffusion tensor imaging were performed in 10 young (18-33 years) and 10 middle-aged (42-64 years) human individuals to evaluate the spatiotemporal dynamics and structural correlates of age-related changes in lexical-semantic processing. Increasing age was associated with reduced activity in left temporal lobe regions from 250 to 350 ms and in left inferior prefrontal cortex from 350 to 450 ms (i.e., N400). Hierarchical regression indicated that age no longer predicted left inferior prefrontal activity after cortical thickness and fractional anisotropy (FA) of the uncinate fasciculus (UF) were considered. Interestingly, FA of the UF was a stronger predictor of the N400 response than cortical thickness. Age-related reductions in left-lateralization of language responses were observed between 250 and 350 ms, and were associated with left temporal thinning and frontotemporal FA reductions. N400 reductions were not associated with poorer task performance. Rather, increasing age was associated with reduction in the left prefrontal N400, which in turn was also associated with slower response time. These results reveal that changes in the neurophysiology of language occur by middle age and appear to be partially mediated by structural brain loss. These neurophysiological changes may reflect an adaptive process that ensues as communication between left perisylvian regions declines.

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.

Sex differences and autism: brain function during verbal fluency and mental rotation.

Autism spectrum conditions (ASC) affect more males than females. This suggests that the neurobiology of autism: 1) may overlap with mechanisms underlying typical sex-differentiation or 2) alternately reflect sex-specificity in how autism is expressed in males and females. Here we used functional magnetic resonance imaging (fMRI) to test these alternate hypotheses. Fifteen men and fourteen women with Asperger syndrome (AS), and sixteen typically developing men and sixteen typically developing women underwent fMRI during performance of mental rotation and verbal fluency tasks. All groups performed the tasks equally well. On the verbal fluency task, despite equivalent task-performance, both males and females with AS showed enhanced activation of left occipitoparietal and inferior prefrontal activity compared to controls. During mental rotation, there was a significant diagnosis-by-sex interaction across occipital, temporal, parietal, middle frontal regions, with greater activation in AS males and typical females compared to AS females and typical males. These findings suggest a complex relationship between autism and sex that is differentially expressed in verbal and visuospatial domains.

The Relationship between Brain Oscillations and BOLD Signal during Memory Formation: A Combined EEG–fMRI Study

Previous studies demonstrated that increases in the theta frequency band with concomitant decreases in the alpha/beta frequency band indicate successful memory formation. However, little is known about the brain regions and the cognitive processes that underlie these encoding-related oscillatory memory effects. We investigated this relationship using simultaneous EEG-fMRI recordings in humans during long-term memory encoding. In line with prior studies, we demonstrate that a decrease in beta power and an increase in theta power positively predict subsequent recall. In fMRI, stronger activity in the left inferior prefrontal cortex and the right parahippocampal gyrus correlated with successful memory formation. EEG source localization revealed that the subsequent memory effect in the beta band was localized in the left inferior prefrontal cortex, whereas the effect in the theta band was localized in medial temporal lobe regions. Trial-by-trial correlations between EEG and BOLD activity showed that beta power correlated negatively with left inferior prefrontal cortex activity. This correlation was more pronounced for items that could later be successfully recalled compared to items later forgotten. Based on these findings, we suggest that beta oscillations in the left inferior prefrontal cortex indicate semantic encoding processes, whereas theta oscillations in the medial temporal lobe reflect the binding of an item to its spatiotemporal context.

Longitudinal development of prefrontal function during early childhood

This is a longitudinal study on development of prefrontal function in young children. Prefrontal areas have been observed to develop dramatically during early childhood. To elucidate this development, we gave children cognitive shifting tasks related to prefrontal function at 3 years of age (Time 1) and 4 years of age (Time 2). We then monitored developmental changes in behavioral performance and examined prefrontal activation using near infrared spectroscopy. We found that children showed better behavioral performance and significantly stronger inferior prefrontal activation at Time 2 than they did at Time 1. Moreover, we demonstrated individual differences in prefrontal activation for the same behavioral tasks. Children who performed better in tasks at Time 1 showed significant activation of the right inferior prefrontal regions at Time 1 and significant activation of the bilateral inferior prefrontal regions at Time 2. Children who showed poorer performance at Time 1 exhibited no significant inferior prefrontal activation at Time 1 but significant left inferior prefrontal activation at Time 2. These results indicate the importance of the longitudinal method to address the link between cognitive and neural development.

On the neural basis of emotional word processing. A combined EEG-MEG study with individual head models

Event Abstract Back to Event On the neural basis of emotional word processing. A combined EEG-MEG study with individual head models Marisa Nordt1*, Kati Keuper1, Peter Zwanzger2 and Christian Dobel1 1 Institute for Biomagnetism and Biosignalanalysis, Germany 2 Department of Psychiatry, University of Münster, Germany Emotional stimuli effectively capture attention and therefore obtain prioritized processing. Kissler et al. (2007) demonstrated in an EEG study that this also holds for emotional words. They reported enhanced amplitudes of the ‘early posterior negativity’ (EPN; 200-300 ms) for emotional compared to neutral nouns in left occipito-temporal brain areas. The present study aimed at further investigating the neural mechanisms of early emotional word processing by means of simultaneous EEG-MEG measurements. Participants silently read continuously presented streams of neutral, positive and negative nouns. Data were analyzed using L2 minimum norm solutions based on individual head models and cortical constraints. For the time window of 200-300msec we found enhanced activation for emotional compared to neutral words in left occipito-temporal regions and the Brodmann areas 30 and 40. Findings in left occipito-temporal regions are in line with the results of Kissler et al. (2007). The enhanced activation in Brodmann area 30 comprising the cingulate cortex is consistent with fMRI studies on emotional word processing (Maddock et al., 2003), but has not been found in electrophysiological studies before. Additionally, we found differences between positive and negative words, with more right dorsolateral prefrontal activity for negative words and more left inferior prefrontal activity for positive words. This supports early hemispheric specialization for symbolic emotional stimuli (e.g. Davidson, 2001). Methodologically, this study emphasizes the benefit of combined neurophysiological measures. Funding: Supported by IZKF (Do3/021/10). Keywords: EEG, Language Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Emotion, Motivation and the Social Brain Citation: Nordt M, Keuper K, Zwanzger P and Dobel C (2011). On the neural basis of emotional word processing. A combined EEG-MEG study with individual head models. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00502 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 22 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Ms. Marisa Nordt, Institute for Biomagnetism and Biosignalanalysis, Münster, Germany, marisa.nordt@uni-muenster.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marisa Nordt Kati Keuper Peter Zwanzger Christian Dobel Google Marisa Nordt Kati Keuper Peter Zwanzger Christian Dobel Google Scholar Marisa Nordt Kati Keuper Peter Zwanzger Christian Dobel PubMed Marisa Nordt Kati Keuper Peter Zwanzger Christian Dobel Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Functional Reorganization Associated with Semantic Language Processing in Temporal Lobe Epilepsy Patients after Anterior Temporal Lobectomy : A Longitudinal Functional Magnetic Resonance Image Study

The focus of this study is brain plasticity associated with semantic aspects of language function in patients with medial temporal lobe epilepsy (mTLE). Using longitudinal functional magnetic resonance imaging (fMRI), patterns of brain activation were observed in twelve left and seven right unilateral mTLE patients during a word-generation task relative to a pseudo-word reading task before and after anterior temporal section surgery. No differences were observed in precentral activations in patients relative to normal controls (n = 12), and surgery did not alter the phonological-associated activations. The two mTLE patient groups showed left inferior prefrontal activations associated with semantic processing (word-generation > pseudo-word reading), as did control subjects. The amount of semantic-associated activation in the left inferior prefrontal region was negatively correlated with epilepsy duration in both patient groups. Following temporal resection, semantic-specific activations in inferior prefrontal region became more bilateral in left mTLE patients, but more left-lateralized in right mTLE patients. The longer the duration of epilepsy in the patients, the larger the increase in the left inferior prefrontal semantic-associated activation after surgery in both patient groups. Semantic activation of the intact hippocampus, which had been negatively correlated with seizure frequency, normalized after the epileptic side was removed. These results indicate alternation of semantic language network related to recruitment of left inferior prefrontal cortex and functional recovery of the hippocampus contralateral to the epileptogenic side, suggesting an intra- and inter-hemispheric reorganization following surgery.

Preparing hearts and minds: Cardiac slowing and a cortical inhibitory network

Preparing for a cued, speeded response induces a set of physiological changes. A review of the psychophysiology of preparation suggested that inhibition of action was an important process among the constellation of changes constituting attentive preparation. The current experiment combined event-related functional magnetic resonance imaging and cardiac inter-beat interval measures in an experiment that compared preparing for a response, watching stimuli without responding, and responding in the absence of preparation. Ten college-aged participants were tested in an initial psychophysiological experiment followed by two scanning sessions during which reverse spiral imaging was performed concurrent with inter-beat interval measurement. Two analytic approaches were used to confirm blood oxygenation level dependent responses during preparation, and these converged to show inferior prefrontal and related subthalamic nuclei activity in the context of other known changes related to brain attentional networks. Subthalamic nuclei changes were related to the depth of preparatory cardiac deceleration. This pattern of findings suggests that preparation involves the activation of a complex inhibitory neural network implicating brain and autonomic nervous systems.

Sex-dependent age modulation of frontostriatal and temporo-parietal activation during cognitive control

Developmental functional imaging studies of cognitive control show progressive age-related increase in task-relevant fronto-striatal activation in male development from childhood to adulthood. Little is known, however, about how gender affects this functional development. In this study, we used event related functional magnetic resonance imaging to examine effects of sex, age, and their interaction on brain activation during attentional switching and interference inhibition, in 63 male and female adolescents and adults, aged 13 to 38. Linear age correlations were observed across all subjects in task-specific frontal, striatal and temporo-parietal activation. Gender analysis revealed increased activation in females relative to males in fronto-striatal areas during the Switch task, and laterality effects in the Simon task, with females showing increased left inferior prefrontal and temporal activation, and males showing increased right inferior prefrontal and parietal activation. Increased prefrontal activation clusters in females and increased parietal activation clusters in males furthermore overlapped with clusters that were age-correlated across the whole group, potentially reflecting more mature prefrontal brain activation patterns for females, and more mature parietal activation patterns for males. Gender by age interactions further supported this dissociation, revealing exclusive female-specific age correlations in inferior and medial prefrontal brain regions during both tasks, and exclusive male-specific age correlations in superior parietal (Switch task) and temporal regions (Simon task). These findings show increased recruitment of age-correlated prefrontal activation in females, and of age-correlated parietal activation in males, during tasks of cognitive control. Gender differences in frontal and parietal recruitment may thus be related to gender differences in the neurofunctional maturation of these brain regions.

Left inferior prefrontal activation associated with inhibition of irrelevant temporal-order information during recency judgments

Left inferior prefrontal activation associated with inhibition of irrelevant temporal-order information during recency judgments

Neural origin of cognitive shifting in young children

Cognitive shifting is the ability to adapt to changes in the environment. Extensive research has revealed that the prefrontal cortex plays an important role in cognitive shifting. Adult neuroimaging studies have shown that the inferior prefrontal cortex is activated during cognitive shifting tasks. Developmental studies have shown that cognitive shifting changes significantly during preschool years. It is known that 3-year-old children often perseverate to previous mental sets, whereas 5-year-old children do not. Developmental psychologists assume that maturation of the prefrontal cortex plays an essential role in the development of shifting; however, direct supporting evidence is lacking. We used near-infrared spectroscopy and showed that inferior prefrontal activation is associated with successful shifting in young children. We also showed that even preschool children display adult-like inferior prefrontal activation during a simple cognitive shifting task. This report demonstrates the neural origins of cognitive shifting in young children. These results have the potential to contribute to our understanding of cognitive and brain development in both typically and atypically developed children.

Dissecting medial temporal lobe contributions to item and associative memory formation

A fundamental and intensively discussed question is whether medial temporal lobe (MTL) processes that lead to non-associative item memories differ in their anatomical substrate from processes underlying associative memory formation. Using event-related functional magnetic resonance imaging, we implemented a novel design to dissociate brain activity related to item and associative memory formation not only by subsequent memory performance and anatomy but also in time, because the two constituents of each pair to be memorized were presented sequentially with an intra-pair delay of several seconds. Furthermore, the design enabled us to reduce potential differences in memory strength between item and associative memory by increasing task difficulty in the item recognition memory test. Confidence ratings for correct item recognition for both constituents did not differ between trials in which only item memory was correct and trials in which item and associative memory were correct. Specific subsequent memory analyses for item and associative memory formation revealed brain activity that appears selectively related to item memory formation in the posterior inferior temporal, posterior parahippocampal, and perirhinal cortices. In contrast, hippocampal and inferior prefrontal activity predicted successful retrieval of newly formed inter-item associations. Our findings therefore suggest that different MTL subregions indeed play distinct roles in the formation of item memory and inter-item associative memory as expected by several dual process models of the MTL memory system.

The Influence of Multiple Primes on Bottom-Up and Top-Down Regulation during Meaning Retrieval: Evidence for 2 Distinct Neural Networks

Meaning retrieval of a word can proceed fast and effortlessly or can be characterized by a controlled search for candidate lexical items and a subsequent selection process. In the current study, we facilitated meaning retrieval by increasing the number of words that were related to the final target word in a triplet (e.g., lion-stripes-tiger). To induce higher search and selection demands, we presented ambiguous words as targets (i.e., homonyms like ball) in half of the trials. Hereby, the dominant (game), low-frequent (dance), or both meanings of the homonym were primed. Participants performed a relatedness judgment during functional magnetic resonance imaging. Activation in a bilateral network (angular gyrus, rostromedial prefrontal cortex) increased linearly with multiple related primes, whereas the posterior left inferior prefrontal cortex (pLIPC) showed the reverse activation pattern for unambiguous trials. When homonyms served as targets, pLIPC responded strongest when both meanings or low-frequent concepts were addressed. Additional anterior left inferior prefrontal cortex activation was observed for the latter trials only. The data support an interaction between 2 distinct cerebral networks that can be linked to automatic bottom-up support and top-down control during meaning retrieval. They further imply a functional specialization of the LIPC along an anterior-posterior dimension.

On Verbal/Nonverbal Modality Dependence of Left and Right Inferior Prefrontal Activation during Performance of Flanker Interference Task

One of the most prevailing views on the functional localization of human cognition is the hemispheric specialization, wherein the left and right hemispheres are implicated primarily in verbal and nonverbal functions, respectively. Cognitive control is known to involve the lateral prefrontal cortex. However, it remains unclear whether the hemispheric specialization in the lateral prefrontal cortex can be observed in cognitive control per se, independent of sensory aspects of stimulus materials. In this functional magnetic resonance imaging study, we tested whether the verbal/nonverbal hemispheric specialization applies to the lateral prefrontal activation by investigating interference suppression, the ability to filter out irrelevant information in the environment. The flanker task was employed using a compound stimulus that contained a target and a flanker. The flanked stimulus was either a color word flanked by a colored patch or a colored patch flanked by a color word, which allowed us to manipulate the modality of the presented flanker stimulus from which interference originates, keeping the total stimulus modality balanced. The inferior frontal gyrus (IFG) showed prominent Modality-by-Hemisphere interaction in interference suppression, the left IFG being activated when a word flanker (plus a patch target) was presented and the right IFG being activated when a patch flanker (plus a word target) was presented. These results suggest that the verbal/nonverbal hemispheric specialization in the IFG can be explained by cognitive control processes per se, independent of sensory aspects of presented materials.

Differential superior prefrontal activity on initial versus subsequent shifts in naive subjects

Flexible adaptation to changing environments requires shifting of a cognitive set, one basic function of the prefrontal cortex. Set shifting, as instantiated in the Wisconsin Card Sorting Task (WCST) administered in a neuropsychological testing room, is typically achieved when subjects have no prior experiences of updating one WCST behavior to another. By contrast, earlier neuroimaging studies typically involved examination of repeated transitions between particular behaviors, to which situation subjects are far from naive. Naive subjects with no prior knowledge of the WCST were recruited in the present functional magnetic resonance imaging study to test set shifting under unknown situations that they experienced for the first time. Prominent activation was revealed in the left superior prefrontal cortex selectively on the initial shifts. On the other hand, the inferior prefrontal cortex was significantly activated on both the initial and subsequent shifts. The superior prefrontal activation distinguishable from the conventional inferior prefrontal activation suggests a selective role of this region in performance of the WCST in naive subjects.

Perirhinal Contributions to Human Visual Perception

SummaryMedial temporal lobe (MTL) structures including the hippocampus, entorhinal cortex, and perirhinal cortex are thought to be part of a unitary system dedicated to memory [1, 2], although recent studies suggest that at least one component—perirhinal cortex—might also contribute to perceptual processing [3–6]. To date, the strongest evidence for this comes from animal lesion studies [7–14]. In contrast, the findings from human patients with naturally occurring MTL lesions are less clear and suggest a possible functional difference between species [15–20]. Here, both these issues were addressed with functional neuroimaging in healthy volunteers performing a perceptual discrimination task originally developed for monkeys [7]. This revealed perirhinal activation when the task required the integration of visual features into a view-invariant representation but not when it could be accomplished on the basis of simple features (e.g., color and shape). This activation pattern matched lateral inferotemporal regions classically associated with visual processing but differed from entorhinal cortex associated with memory encoding. The results demonstrate a specific role for the perirhinal cortex in visual perception and establish a functional homology for perirhinal cortex between species, although we propose that in humans, the region contributes to a wider behavioral repertoire including mnemonic, perceptual, and linguistic processes.

Prefrontal‐hippocampal‐fusiform activity during encoding predicts intraindividual differences in free recall ability: An event‐related functional‐anatomic MRI study

The ability to spontaneously recall recently learned information is a fundamental mnemonic activity of daily life, but has received little study using functional neuroimaging. We developed a functional MRI (fMRI) paradigm to study regional brain activity during encoding that predicts free recall. In this event-related fMRI study, ten lists of fourteen pictures of common objects were shown to healthy young individuals and regional brain activity during encoding was analyzed based on subsequent free recall performance. Free recall of items was predicted by activity during encoding in hippocampal, fusiform, and inferior prefrontal cortical regions. Within-subject variance in free recall performance for the ten lists was predicted by a linear combination of condition-specific inferior prefrontal, hippocampal, and fusiform activity. Recall performance was better for lists in which prefrontal activity was greater for all items of the list and hippocampal and fusiform activity were greater specifically for items that were recalled from the list. Thus, the activity of medial temporal, fusiform, and prefrontal brain regions during the learning of new information is important for the subsequent free recall of this information. These fronto-temporal brain regions act together as a large-scale memory-related network, the components of which make distinct yet interacting contributions during encoding that predict subsequent successful free recall performance.

Left inferior prefrontal cortex activation during a semantic decision-making task predicts the degree of semantic organization

Semantic organization, an aspect of semantic processing, requires a pre-existing network of semantic knowledge that relies on a widely distributed neural network. The inferior prefrontal cortex (IPFC) has been identified as a vital structure for processing competing semantic information when making a decision about the meaning of a stimulus. However, the precise role of the IPFC in maintaining or creating a consistent semantic organizational structure is unclear. In this study, a semantic triadic decision-making task (Tallent, K.A., Weinberger, D.R., and Goldberg, T.E. 2001. Associating semantic space abnormalities with formal thought disorder in schizophrenia: use of triadic comparisons. J. Clin. Exp. Neuropsychol. 285–296) was used during functional magnetic resonance imaging to test the hypothesis that the degree of activation in the IPFC correlates with the consistency of semantic organization in healthy subjects. In this sample, subjects who had greater activation in the IPFC also demonstrated smaller stress coefficients in a two-dimensional “semantic space”, indicating a greater organization of words along semantic dimensions. This finding is consistent with the role of the IPFC in establishing self-generated semantic relationships between stimuli.

Dissociation of inhibition from error processing using a parametric inhibitory task during functional magnetic resonance imaging

Inhibition, the process that overrides and reverses the execution of a thought, action, or emotion, is important in daily life. Sixteen healthy volunteers performed a parametrically modulated motor inhibition task during functional magnetic resonance imaging. Two results were observed: (1) increased error-related anterior cingulate cortex activation and, (2) increased inferior frontal gyrus and medial prefrontal cortex activation during inhibition, irrespective of errors. Thus, the parametric nature of the task elucidated a functional dissociation of brain structures involved in motor inhibition from those involved in error processing. Additionally, this task allowed the identification of unique areas of increased activation within specific subregions of the anterior cingulate cortex related to errors made during trials with a high (dorsal anterior cingulate cortex) and low (ventral anterior cingulate cortex) inhibitory load.