Part Of Medial Prefrontal Cortex Research Articles

Cortical responses to dynamic emotional facial expressions generalize across stimuli, and are sensitive to task-relevance, in adults with and without Autism

Individuals with Autism Spectrum Disorders (ASD) report difficulties extracting meaningful information from dynamic and complex social cues, like facial expressions. The nature and mechanisms of these difficulties remain unclear. Here we tested whether that difficulty can be traced to the pattern of activity in “social brain” regions, when viewing dynamic facial expressions. In two studies, adult participants (male and female) watched brief videos of a range of positive and negative facial expressions, while undergoing functional magnetic resonance imaging (Study 1: ASD n = 16, control n = 21; Study 2: ASD n = 22, control n = 30). Patterns of hemodynamic activity differentiated among facial emotional expressions in left and right superior temporal sulcus, fusiform gyrus, and parts of medial prefrontal cortex. In both control participants and high-functioning individuals with ASD, we observed (i) similar responses to emotional valence that generalized across facial expressions and animated social events; (ii) similar flexibility of responses to emotional valence, when manipulating the task-relevance of perceived emotions; and (iii) similar responses to a range of emotions within valence. Altogether, the data indicate that there was little or no group difference in cortical responses to isolated dynamic emotional facial expressions, as measured with fMRI. Difficulties with real-world social communication and social interaction in ASD may instead reflect differences in initiating and maintaining contingent interactions, or in integrating social information over time or context.

Combined Social and Spatial Coding in a Descending Projection from the Prefrontal Cortex

Social behaviors are crucial to all mammals. Although the prelimbic cortex (PL, part of medial prefrontal cortex) has been implicated in social behavior, it is not clear which neurons are relevant or how they contribute. We found that PL contains anatomically and molecularly distinct subpopulations that target three downstream regions that have been implicated in social behavior: the nucleus accumbens (NAc), amygdala, and ventral tegmental area. Activation of NAc-projecting PL neurons (PL-NAc), but not the other subpopulations, decreased the preference for a social target. To determine what information PL-NAc neurons convey, we selectively recorded from them and found that individual neurons were active during social investigation, but only in specific spatial locations. Spatially specific manipulation of these neurons bidirectionally regulated the formation of a social-spatial association. Thus, the unexpected combination of social and spatial information within the PL-NAc may contribute to social behavior by supporting social-spatial learning.

Multivariate representation of food preferences in the human brain

One major goal in decision neuroscience is to investigate the neuronal mechanisms being responsible for the computation of product preferences. The aim of the present fMRI study was to investigate whether similar patterns of brain activity, reflecting category dependent and category independent preference signals, can be observed in case of different food product categories (i.e. chocolate bars and salty snacks). To that end we used a multivariate searchlight approach in which a linear support vector machine (l-SVM) was trained to distinguish preferred from non-preferred chocolate bars and subsequently tested its predictive power in case of chocolate bars (within category prediction) and salty snacks (across category prediction). Preferences were measured by a binary forced choice decision paradigm before the fMRI task. In the scanner, subjects saw only one product per trial which they had to rate after presentation. Consistent with previous multi voxel pattern analysis (MVPA) studies, we found category dependent preference signals in the ventral parts of medial prefrontal cortex (mPFC), but also in dorsal anterior cingulate cortex (dACC) and dorsolateral prefrontal cortex (dlPFC). Category independent preference signals were observed in the dorsal parts of mPFC, dACC, and dlPFC. While the first two results have also been reported in a closely related study, the activation in dlPFC is new in this context. We propose that the dlPFC activity does not reflect the products’ value computation per se, but rather a modulatory signal which is computed in anticipation of the forthcoming product rating after stimulus presentation. Furthermore we postulate that this kind of dlPFC activation emerges only if the anticipated choices fall into the domain of primary rewards, such as foods. Thus, in contrast to previous studies which investigated preference decoding for stimuli from utterly different categories, the present study revealed some food domain specific aspects of preference processing in the human brain.

Rostro‐caudal and dorso‐ventral gradients in medial and lateral prefrontal cortex during cognitive control of affective and cognitive interference

Characterizing the anatomical substrates of major brain functions such as cognition and emotion is of utmost importance to the ongoing efforts of understanding the nature of psychiatric ailments and their potential treatment. The aim of our study was to investigate how the brain handles affective and cognitive interferences on cognitive processes. Functional magnetic resonance imaging investigation was performed on healthy individuals, comparing the brain oxygenation level dependent activation patterns during affective and cognitive counting Stroop tasks. The affective Stroop task activated rostral parts of medial prefrontal cortex (PFC) and rostral and ventral parts of lateral PFC, while cognitive Stroop activated caudal parts of medial PFC and caudal and dorsal parts of lateral PFC. Our findings suggest that the brain may handle affective and cognitive interference on cognitive processes differentially, with affective interference preferentially activating rostral and ventral PFC networks and cognitive interference activating caudal and dorsal PFC networks.

The influence of valence and decision difficulty on self-referential processing

Self-referential processing is defined as the process by which a person becomes aware that specific contents are related to his or her own self. Cortical midline structures (CMS), such as dorsal and medial prefrontal cortex, and regions such as inferior frontal cortex, insula, and temporal pole have been implicated in self-referential processing. However, the specific contribution of each of these areas is still largely unknown. More particularly, not many studies have examined the influence of valence and decision making difficulty on regions involved in self-referential processing. In this study, participants evaluated how well personality traits, differing in valence and decision difficulty, described themselves or the current US President. In line with predictions, ventral, rostral, and dorsal parts of medial prefrontal cortex showed greater activity when participants judged traits about themselves relative to judging traits about the current US President. However, none of these regions showed significant modulation by trait valence. Increasing trait decision difficulty was associated with increased activity within dorsal medial prefrontal cortex and bilateral anterior insula. However, there was very minimal overlap (6/119 voxels, i.e., 5%) of the regions of dorsal medial prefrontal cortex implicated in self-referential processing and those implicated in trait decision difficulty. The results are interpreted within current accounts of self-referential processing.

Decision making and reward in frontal cortex: Complementary evidence from neurophysiological and neuropsychological studies.

Patients with damage to the prefrontal cortex (PFC)—especially the ventral and medial parts of PFC—often show a marked inability to make choices that meet their needs and goals. These decision-making impairments often reflect both a deficit in learning concerning the consequences of a choice, as well as deficits in the ability to adapt future choices based on experienced value of the current choice. Thus, areas of PFC must support some value computations that are necessary for optimal choice. However, recent frameworks of decision making have highlighted that optimal and adaptive decision making does not simply rest on a single computation, but a number of different value computations may be necessary. Using this framework as a guide, we summarize evidence from both lesion studies and single-neuron physiology for the representation of different value computations across PFC areas.

Alterations in goal-directed behavior but not emotion after lesions of distinct subregions of macaque orbital prefrontal cortex

Event Abstract Back to Event Alterations in goal-directed behavior but not emotion after lesions of distinct subregions of macaque orbital prefrontal cortex E. A. Murray1* and P. H. Rudebeck1 1 National Institute of Mental Health, Laboratory of Neuropsychology, United States Damage to the orbital prefrontal cortex (PFo) results in marked changes in goal-directed behavior and affect. Two distinct subregions have been identified within the PFo: 1) the central part of Pfo, areas 11 and 13, and 2) the medial part of PFo, area 14. Although it has been proposed that the functions of the subregions may differ, evidence is limited. To test this possibility we compared rhesus monkeys (Macaca mulatta) with excitotoxic lesions of either areas 11/13 (n=4) or area 14 (n=4) with a group of unoperated controls (n=4). The extent of the lesions was confirmed by T2-weighted MRI. We used two tasks: reinforcer devaluation and extinction of responses to a previously rewarded object. We also evaluated emotional responses to a rubber snake. Monkeys with lesions of area 11/13 were impaired on reinforcer devaluation but not extinction. Monkeys with lesions of area 14 showed the converse result, namely, impairment in extinction but not reinforcer devaluation. All three groups behaved similarly in response the the rubber snake. These preliminary results, which show selective changes in goal directed behavior in the absence of changes in emotion, are in contrast with previous reports of macaques with more extensive PFo lesions. Conference: The 20th Annual Rotman Research Institute Conference, The frontal lobes, Toronto, Canada, 22 Mar - 26 Mar, 2010. Presentation Type: Poster Presentation Topic: Abstracts Citation: Murray EA and Rudebeck PH (2010). Alterations in goal-directed behavior but not emotion after lesions of distinct subregions of macaque orbital prefrontal cortex. Conference Abstract: The 20th Annual Rotman Research Institute Conference, The frontal lobes. doi: 10.3389/conf.fnins.2010.14.00088 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: 29 Jun 2010; Published Online: 29 Jun 2010. * Correspondence: E. A Murray, National Institute of Mental Health, Laboratory of Neuropsychology, Bethesda, United States, murraye@mail.nih.gov 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 E. A Murray P. H Rudebeck Google E. A Murray P. H Rudebeck Google Scholar E. A Murray P. H Rudebeck PubMed E. A Murray P. H Rudebeck 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.

APRAXIC AGRAPHIA FOLLOWING A RIGHT CEREBELLAR HEMORRHAGE

Apraxic agraphia follows disruption of skilled movement plans of writing and is characterized by distorted, hesitant, incomplete, and imprecise letter formation. The causative lesion is located in the superior parietal lobe (storage of graphomotor plans) or the dorsolateral and medial part of prefrontal cortex (conversion of graphomotor plans to motor commands).1 Recently, the condition was also reported after left dorsomedial thalamic infarction with reduced oxygen metabolism in left premotor areas.2 ### Case report. A 72-year-old right-handed engineer acutely developed postural instability and gait disturbances. Neurologic examination showed a pure cerebellar deficit with distinct midline cerebellar dysfunction and less pronounced right appendicular ataxia. Apart from implantation of a pacemaker for sick sinus syndrome, his medical history was unremarkable. CT scan of the brain disclosed a hemorrhagic lesion in the right cerebellar hemisphere involving cortex and the medullary core (figure 1A). No supratentorial lesions were detected by repeat CT at 3 and 6 months after onset. Figure 1 CT scan and quantified Tc-99m-ethyl cysteinate dimer SPECT studies CT scan of the brain disclosing a hemorrhage in the right cerebellar hemisphere involving cortex and the medullary core (A). Quantified Tc-99m-ethyl cysteinate dimer SPECT studies conducted …

Being with virtual others: Neural correlates of social interaction

To characterize the neural correlates of being personally involved in social interaction as opposed to being a passive observer of social interaction between others we performed an fMRI study in which participants were gazed at by virtual characters (ME) or observed them looking at someone else (OTHER). In dynamic animations virtual characters then showed socially relevant facial expressions as they would appear in greeting and approach situations (SOC) or arbitrary facial movements (ARB). Differential neural activity associated with ME > OTHER was located in anterior medial prefrontal cortex in contrast to the precuneus for OTHER > ME. Perception of socially relevant facial expressions (SOC > ARB) led to differentially increased neural activity in ventral medial prefrontal cortex. Perception of arbitrary facial movements (ARB > SOC) differentially activated the middle temporal gyrus. The results, thus, show that activation of medial prefrontal cortex underlies both the perception of social communication indicated by facial expressions and the feeling of personal involvement indicated by eye gaze. Our data also demonstrate that distinct regions of medial prefrontal cortex contribute differentially to social cognition: whereas the ventral medial prefrontal cortex is recruited during the analysis of social content as accessible in interactionally relevant mimic gestures, differential activation of a more dorsal part of medial prefrontal cortex subserves the detection of self-relevance and may thus establish an intersubjective context in which communicative signals are evaluated.

Male elderly subthreshold depression patients have smaller volume of medial part of prefrontal cortex and precentral gyrus compared with age-matched normal subjects: A voxel-based morphometry

Background The brain morphological changes in subthreshold depression (sD) have not been clarified. We examined the structural difference in regional gray matter volume between community-dwelling elderly subjects with sD and age-matched nondepressed normal subjects by voxel-based morphometry (VBM) based on magnetic resonance imaging (MRI). Methods Thirty-four community-dwelling elderly subjects with sD and 109 age-matched nondepressed normal subjects were studied by MRI. We defined subjects with sD as those who showed a Geriatric Depression Scale score of 15 or higher and a Mini Mental State Examination score of 22 or higher, and do not fulfill the criteria of major depressive disorder (MDD) in the Diagnostic and Statistical Manual for Mental Disorders IV. We collected brain magnetic resonance images of 34 subjects with sD and 109 age-matched normal subjects, and analyzed the difference in regional gray matter volume between these two groups by VBM. Results Male subjects with sD had significantly smaller volumes of the medial part of the bilateral frontal lobes and the right precentral gyrus than normal male subjects. Limitations We have not clarified the discrepancy in the results of gender difference. Conclusions Our study revealed that even community-dwelling elderly male subjects with sD show bilateral prefrontal gray matter volume reduction, which was reported to be observed in elderly patients with MDD, although there is no significant volume reduction in the hippocampus, which was also reported to be observed in MDD. Our study may contribute to clarifying the mechanism underlying brain pathological changes in sD.

Increased dopamine synthesis rate in medial prefrontal cortex and striatum in schizophrenia indicated by L-(β- 11C) DOPA and PET

Background: The aim of the present study was to investigate dopamine synthesis in the brain of drug-free schizophrenic patients, not only in the striatum but also in extrastriatal areas like the prefrontal cortex, brain areas that for a long time has been in focus of interest in the pathophysiology of schizophrenia. Methods: PET was performed in 12 drug-free (10 drug-naive) psychotic schizophrenic patients and 10 healthy volunteers matched for age and gender using 11C-labelled l-DOPA as the tracer. The time-radioactivity curve from occipital cortex (located within Brodman area 17 and 18) was used as input function to calculate l-DOPA influx rate, K i images, that were matched to a common brain atlas. A significant overall increase of the K i values was found in the schizophrenic group as compared with healthy controls. Results: In particular, significantly higher K i were found in the schizophrenic patients compared to the controls in the caudate nucleus, putamen and in parts of medial prefrontal cortex (Brod 24). The K i value reflect an increased utilization of l-DOPA, presumably due to increased activity of the amino acid decarboxylate enzyme. Conclusions: The results indicate that the synthesis of dopamine is elevated within the striatum and parts of medial prefrontal cortex in schizophrenia.