Prefrontal Cortical Areas Research Articles

Event-related prefrontal activations during online video game playing are modulated by game mechanics, physiological arousal and the amount of daily playing

There is a trend to study human brain functions in ecological contexts and in relation to human factors. In this study, functional near-infrared spectroscopy (fNIRS) was used to record real-time prefrontal activities in 42 male university student habitual video game players when they played a round of multiplayer online battle arena game, League of Legends. A content-based event coding approach was used to analyze regional activations in relation to event type, physiological arousal indexed by heart rate (HR) change, and individual characteristics of the player. Game events Slay and Slain were found to be associated with similar HR and prefrontal responses before the event onset, but differential responses after the event onset. Ventrolateral prefrontal cortex (VLPFC) activation preceding the Slay onset correlated positively with HR change, whereas activations in dorsolateral prefrontal cortex (DLPFC) and rostral frontal pole area (FPAr) preceding the Slain onset were predicted by self-reported hours of weekly playing (HoWP). Together, these results provide empirical evidence to support the notion that event-related regional prefrontal activations during online video game playing are shaped by game mechanics, in-game dynamics of physiological arousal and individual characteristics the players.

Altered effective connectivity among face-processing systems in major depressive disorder.

Neuroimaging studies have revealed abnormal functional interaction during the processing of emotional faces in patients with major depressive disorder (MDD), thereby enhancing our comprehension of the pathophysiology of MDD. However, it is unclear whether there is abnormal directional interaction among face-processing systems in patients with MDD. A group of patients with MDD and a healthy control group underwent a face-matching task during functional magnetic resonance imaging. Dynamic causal modelling (DCM) analysis was used to investigate effective connectivity between 7 regions in the face-processing systems. We used a Parametric Empirical Bayes model to compare effective connectivity between patients with MDD and controls. We included 48 patients and 44 healthy controls in our analyses. Both groups showed higher accuracy and faster reaction time in the shape-matching condition than in the face-matching condition. However, no significant behavioural or brain activation differences were found between the groups. Using DCM, we found that, compared with controls, patients with MDD showed decreased self-connection in the right dorsolateral prefrontal cortex (DLPFC), amygdala, and fusiform face area (FFA) across task conditions; increased intrinsic connectivity from the right amygdala to the bilateral DLPFC, right FFA, and left amygdala, suggesting an increased intrinsic connectivity centred in the amygdala in the right side of the face-processing systems; both increased and decreased positive intrinsic connectivity in the left side of the face-processing systems; and comparable task modulation effect on connectivity. Our study did not include longitudinal neuroimaging data, and there was limited region of interest selection in the DCM analysis. Our findings provide evidence for a complex pattern of alterations in the face-processing systems in patients with MDD, potentially involving the right amygdala to a greater extent. The results confirm some previous findings and highlight the crucial role of the regions on both sides of face-processing systems in the pathophysiology of MDD.

Prefrontal cortex activity and functional organisation in dual-task ocular pursuit is affected by concurrent upper limb movement.

Tracking a moving object with the eyes seems like a simple task but involves areas of prefrontal cortex (PFC) associated with attention, working memory and prediction. Increasing the demand on these processes with secondary tasks can affect eye movements and/or perceptual judgments. This is particularly evident in chronic or acute neurological conditions such as Alzheimer's disease or mild traumatic brain injury. Here, we combined near infrared spectroscopy and video-oculography to examine the effects of concurrent upper limb movement, which provides additional afference and efference that facilitates tracking of a moving object, in a novel dual-task pursuit protocol. We confirmed the expected effects on judgement accuracy in the primary and secondary tasks, as well as a reduction in eye velocity when the moving object was occluded. Although there was limited evidence of oculo-manual facilitation on behavioural measures, performing concurrent upper limb movement did result in lower activity in left medial PFC, as well as a change in PFC network organisation, which was shown by Graph analysis to be locally and globally more efficient. These findings extend upon previous work by showing how PFC is functionally organised to support eye-hand coordination when task demands more closely replicate daily activities.

Alterations in adolescent brain serotonin (5HT)1A, 5HT2A, and dopamine (D)2 receptor systems in a nonhuman primate model of early life adversity.

Stress affects brain serotonin (5HT) and dopamine (DA) function, and the effectiveness of 5HT and DA to regulate stress and emotional responses. However, our understanding of the long-term impact of early life adversity (ELA) on primate brain monoaminergic systems during adolescence is scarce and inconsistent. Filling this gap in the literature is critical, given that the emergence of psychopathology during adolescence has been related to deficits in these systems. Here, we use a translational nonhuman primate (NHP) model of ELA (infant maltreatment by the mother) to examine the long-term impact of ELA on adolescent 5HT1A, 5HT2A and D2 receptor systems. These receptor systems were chosen based on their involvement in stress/emotional control, as well as reward and reinforcement. Rates of maternal abuse, rejection, and infant's vocalizations were obtained during the first three postnatal months, and hair cortisol concentrations obtained at 6 months postnatal were examined as early predictors of binding potential (BP) values obtained during adolescence using positron emission tomography (PET) imaging. Maltreated animals demonstrated significantly lower 5HT1A receptor BP in prefrontal cortical areas as well as the amygdala and hippocampus, and lower 5HT2A receptor BP in striatal and prefrontal cortical areas. Maltreated animals also demonstrated significantly lower D2 BP in the amygdala. None of the behavioral and neuroendocrine measurements obtained early in life predicted any changes in BP data. Our findings suggest that early caregiving experiences regulate the development of brain 5HT and DA systems in primates, resulting in long-term effects evident during adolescence.

Effects of repeated alcohol abstinence on within-subject prefrontal cortical gene expression in rhesus macaques.

Male rhesus monkeys (n = 24) had a biopsy of prefrontal cortical area 46 prior to chronic ethanol self-administration (n = 17) or caloric control (n = 7). Fourteen months of daily self-administration (water vs. 4% alcohol, 22h access/day termed "open-access") was followed by two cycles of prolonged abstinence (5weeks) each followed by 3months of open-access alcohol and a final abstinence followed by necropsy. At necropsy, a biopsy of Area 46, contralateral to the original biopsy, was obtained. Gene expression data (RNA-Seq) were collected comparing biopsy/necropsy samples. Monkeys were categorized by drinking status during the final post-abstinent drinking phase as light (LD), binge (BD), heavy (HD) and very heavy (VHD drinkers). Comparing pre-ethanol to post-abstinent biopsies, four animals that converted from HD to VHD status had significant ontology enrichments in downregulated genes (necropsy minus biopsy n = 286) that included immune response (FDR < 9 × 10-7) and plasma membrane changes (FDR < 1 × 10-7). Genes in the immune response category included IL16 and 18, CCR1, B2M, TLR3, 6 and 7, SP2 and CX3CR1. Upregulated genes (N = 388) were particularly enriched in genes associated with the negative regulation of MAP kinase activity (FDR < 3 × 10-5), including DUSP 1, 4, 5, 6 and 18, SPRY 2, 3, and 4, SPRED2, BMP4 and RGS2. Overall, these data illustrate the power of the NHP model and the within-subject design of genomic changes due to alcohol and suggest new targets for treating severe escalated drinking following repeated alcohol abstinence attempts.

Activation of trace amine-associated receptor 1 ameliorates PTSD-like symptoms

Trace amine-associated receptor 1 (TAAR1) negatively modulates monoaminergic transmission in the mammalian brain and participates in many psychiatric disorders. Preclinical evidence indicate that selective TAAR1 agonists have anxiolytic effects and anti-stress properties. Post-traumatic stress disorder (PTSD) is an anxiety disorder triggered by experiencing or witnessing traumatic stressors. However, it remains unknown whether TAAR1 is involved in PTSD. Here, we investigated the role of TAAR1 in two PTSD animal models, including single prolonged stress (SPS)-induced impairment of fear extinction and stress-enhanced fear learning (SEFL). SPS decreased TAAR1 mRNA levels in the prefrontal cortex and ventral tegmental area. Acute treatment of the TAAR1 partial agonist RO5263397 attenuated SPS-induced anxiety-like behavior evaluated by the elevated-plus maze test. Compared to non-stressed animals, rats that experienced SPS showed higher freezing levels in the extinction retention test, indicating an impairment of fear extinction retention after SPS exposure. Acute and chronic treatment of RO5263397 ameliorated SPS-induced impairment of fear extinction retention. In the SEFL model, compared to the No-shock group, rats that experienced severe foot shock before fear conditioning showed higher freezing levels during the tests, indicating enhanced fear learning after stress exposure. Chronic treatment of RO5263397 partially attenuated the SEFL. Moreover, chronic treatment with the selective TAAR1 full agonist RO5166017 completely prevented the SEFL. Taken together, these data showed that pharmacological activation of TAAR1 could ameliorate PTSD-like symptoms. The present study thus provides the first evidence that TAAR1 might participate in the development of PTSD, and TAAR1 agonists could be potential pharmacological treatments for this disorder.

Analogical Visuospatial Matrix Reasoning, Verbal Relational Reasoning, Verbal IQ and Memory Relationships With Maths and Science: A Behavioural and fMRI Study

There is no research that combines behavioural and functional magnetic resonance imaging (fMRI) research approaches to investigate the relationships between analogical reasoning and the mediating and moderating effects of working memory, verbal IQ, visuospatial and verbal reasoning on students’ performance of maths and science. This paper investigates all these multiple relationships between working memory (WM), verbal IQ, visuospatial and verbal reasoning with performance in maths and science accuracy. The multimethod research consists of a behavioural survey and a fMRI neuroscience investigating the interactive and multiple relationships of all cognitive independent variables (IVs) with the dependent variables (DVs) of maths and science performance. Using structural Equation Modelling (SEM) and Warp Partial Least Squares (Warp PLS) analytical approach, the research discusses the findings of both, the behavioural and fMRI data. The adolescent sample (N=34) for the behavioural and fMRI study, was recruited from consenting schools in London, UK, and consisted of equal numbers of girls and boys between 11-15 years old. The hypothesised behavioural SEM model predicted positive relationships between all the independent variables (IV) of visuospatial matrix reasoning (VSMatAR), verbal analogical reasoning (VerbAR), verbal working memory (VWM), visuospatial working memory (VSWM) and verbal IQ, with performance in maths and science accuracy. The findings support all hypotheses except two and identifies verbal IQ, Verbal WM and VerbAR as the three strongest predictors of maths and science accuracy. The hypothesised fMRI SEM, produced mixed results, which supported some of the hypothesised relationships between the IVs of verbal AR and VSMatrix AR associations and four brain regions, namely, the bilateral dorso lateral prefrontal cortex (DLPFC), Parietal, Temporal and pre-supplementary motor area (PSMA). The paper makes two original contributions, firstly, by testing the hypothesis that Verbal WM mediates the independent variables’ effects on maths and science outcomes. And secondly, by using Warp PLS to test the SEM (behavioural and fMRI) models’ multiple non-linear interactions simultaneously between the IVs with the DVs of maths and science accuracy. The research produced some interesting new insights relevant for educational practitioners regarding the strong relationships between Verbal analogical reasoning and maths and science performance for adolescent students.

Neural Mechanisms of Nonauditory Effects of Noise Exposure on Special Populations.

Due to the abnormal structure and function of brain neural networks in special populations, such as children, elderly individuals, and individuals with mental disorders, noise exposure is more likely to have negative psychological and cognitive nonauditory effects on these individuals. There are unique and complex neural mechanisms underlying this phenomenon. For individuals with mental disorders, there are anomalies such as structural atrophy and decreased functional activation in brain regions involved in emotion and cognitive processing, such as the prefrontal cortex (PFC). Noise exposure can worsen these abnormalities in relevant brain regions, further damaging neural plasticity and disrupting normal connections and the transmission of information between the PFC and other brain areas by causing neurotransmitter imbalances. In the case of children, in a noisy environment, brain regions such as the left inferior frontal gyrus and PFC, which are involved in growth and development, are more susceptible to structural and functional changes, leading to neurodegenerative alterations. Furthermore, noise exposure can interrupt auditory processing neural pathways or impair inhibitory functions, thus hindering children's ability to map sound to meaning in neural processes. For elderly people, age-related shrinkage of brain regions such as the PFC, as well as deficiencies in hormone, neurotransmitter, and nutrient levels, weakens their ability to cope with noise. Currently, it is feasible to propose and apply coping strategies to improve the nonauditory effects of noise exposure on special populations based on the plasticity of the human brain.

Effect of South Sulawesi Propolis in Sevoflurane Anesthesia-Induced Rat Model During Weaning Period: Study Levels of IL-6, TNF⍺, IL-10, and PSD95 in the Prefrontal Cortex

Background: A recent study discovered that exposure to the anesthetic gas sevoflurane in the early years of life can impact cognitive function. Objectives: This study aims to investigate the effects of prolonged and repeated exposure to sevoflurane during the weaning period and whether the administration of propolis, a well-known herbal substance with anti-inflammatory properties, has a beneficial effect on inflammation and synaptic markers in the prefrontal cortex area, as well as its effect on spatial working memory function. Methods: We utilized Sprague Dawley rats aged 21 days (P21), divided into three groups: Control, sevoflurane, and sevoflurane with propolis. The exposure to sevoflurane (3%) was conducted three times for 2 hours each at P21, P23, and P25. Propolis treatments were administered orally for four weeks, starting from the first day of exposure to sevoflurane. Analyses of IL-6, TNF-alpha, and IL-10 levels were performed using ELISA at P25 and P51, while spatial working memory was measured using the spontaneous Y-maze. Results: Exposure to sevoflurane during the weaning period had no effect on IL-6, TNF-alpha, IL-10, and PSD95 levels in the prefrontal cortex, nor on working memory function. Similarly, the administration of propolis did not have any beneficial effect on these parameters. Conclusions: Prolonged and repeated exposure to sevoflurane during the weaning period did not induce neuroinflammation conditions that would affect synaptic markers and working memory function. Further studies are required to identify a dose of sevoflurane that causes detrimental effects on memory function and to explore the beneficial effects of propolis on this condition.

Chronometric TMS-fMRI of personalized left dorsolateral prefrontal target reveals state-dependency of subgenual anterior cingulate cortex effects

Transcranial magnetic stimulation (TMS) applied to a left dorsolateral prefrontal cortex (DLPFC) area with a specific connectivity profile to the subgenual anterior cingulate cortex (sgACC) has emerged as a highly effective non-invasive treatment option for depression. However, antidepressant outcomes demonstrate significant variability among therapy plans and individuals. One overlooked contributing factor is the individual brain state at the time of treatment. In this study we used interleaved TMS-fMRI to investigate the influence of brain state on acute TMS effects, both locally and remotely. TMS was performed during rest and during different phases of cognitive task processing. Twenty healthy participants were included in this study. In the first session, imaging data for TMS targeting were acquired, allowing for identification of individualized targets in the left DLPFC based on highest anti-correlation with the sgACC. The second session involved chronometric interleaved TMS-fMRI measurements, with 10 Hz triplets of TMS administered during rest and at distinct timings during an N-back task. Consistent with prior findings, interleaved TMS-fMRI revealed significant BOLD activation changes in the targeted network. The precise timing of TMS relative to the cognitive states during the task demonstrated distinct BOLD response in clinically relevant brain regions, including the sgACC. Employing a standardized timing approach for TMS using a task revealed more consistent modulation of the sgACC at the group level compared to stimulation during rest. In conclusion, our findings strongly suggest that acute local and remote effects of TMS are influenced by brain state during stimulation. This study establishes a basis for considering brain state as a significant factor in designing treatment protocols, possibly improving TMS treatment outcomes.

Increased gene dosage of RFWD2 causes autistic-like behaviors and aberrant synaptic formation and function in mice

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interactions, communication deficits and repetitive behaviors. A study of autistic human subjects has identified RFWD2 as a susceptibility gene for autism, and autistic patients have 3 copies of the RFWD2 gene. The role of RFWD2 as an E3 ligase in neuronal functions, and its contribution to the pathophysiology of ASD, remain unknown. We generated RFWD2 knockin mice to model the human autistic condition of high gene dosage of RFWD2. We found that heterozygous knockin (Rfwd2+/−) male mice exhibited the core symptoms of autism. Rfwd2+/− male mice showed deficits in social interaction and communication, increased repetitive and anxiety-like behavior, and spatial memory deficits, whereas Rfwd2+/− female mice showed subtle deficits in social communication and spatial memory but were normal in anxiety-like, repetitive, and social behaviors. These autistic-like behaviors in males were accompanied by a reduction in dendritic spine density and abnormal synaptic function on layer II/III pyramidal neurons in the prelimbic area of the medial prefrontal cortex (mPFC), as well as decreased expression of synaptic proteins. Impaired social behaviors in Rfwd2+/− male mice were rescued by the expression of ETV5, one of the major substrates of RFWD2, in the mPFC. These findings indicate an important role of RFWD2 in the pathogenesis of autism.

Cognitive, Emotional, and Daily Functioning Domains Involved in Decision-Making among Patients with Mild Cognitive Impairment: A Systematic Review.

Mild cognitive impairment (MCI) is a transitional or prodromal stage of dementia in which autonomies are largely preserved (autonomies are not particularly affected). However, this condition may entail a depletion of decision-making (DM) abilities likely due to a gradual deterioration of the prefrontal cortex and subcortical brain areas underlying cognitive-emotional processing. Given the clinical implications of a decline in self-determination observed in some MCI sufferers, the present systematic review was aimed at investigating the literature addressing DM processes in patients with MCI, consistent with PRISMA guidelines. The six online databases inquired yielded 1689 research articles that were screened and then assessed based on eligibility and quality criteria. As a result, 41 studies were included and classified following the PICOS framework. Overall, patients with MCI who underwent neuropsychological assessment were found to be slightly or moderately impaired in DM abilities related to financial management, medical adherence, specific cognitive performances, risky conditions, and especially uncertain life circumstances. Comparative cross-sectional studies indicated not only mid-stage cognitive functioning in MCI but also borderline or deficit DM patterns evaluated through different tasks and procedures. Further research addressing MCI profiles suggested an association between explicit memory, executive functions, and DM performance. These findings highlight the diversity of MCI manifestations, in addition to the critical importance of DM features and correlates in patients' daily functioning. Due to a lack of consensus on both MCI and DM, this review paper sought to shed light on assessment and intervention strategies accounting for the interplay between emotion, motivation, and learning to foster DM in cognitively impaired individuals.

Instrumental successive negative contrast in rats: Trial distribution, reward magnitude, and prefrontal cortex activation

Successive negative contrast (SNC) has been used to study reward relativity, reward loss, and frustration for decades. In instrumental SNC (iSNC), the anticipatory performance of animals downshifted from a large reward to a small reward is compared to that of animals always reinforced with the small reward. iSNC involves a transient deterioration of anticipatory behavior in downshifted animals compared to unshifted controls. There is scattered information on the optimal parameters to produce this effect and even less information about its neural basis. Five experiments with rats trained in a runway to collect food pellets explored the effects of trial distribution (massed or spaced), amount of preshift training, reward disparity, and reward magnitude on the development of an iSNC effect. Start, run, and goal latencies were measured. Using spaced trials (one trial per day), evidence of the iSNC effect was observed with 24 preshift trials and a 32-to-4 pellet disparity. With massed trials (4 trials per session separated by 30-s intertrial intervals), evidence of iSNC was found with 12 preshift sessions (a total of 48 trials) and a 16-to-2 pellet disparity. The massed-training procedure was then used to assess neural activity in three prefrontal cortex areas using c-Fos expression in animals perfused after the first downshift session. There was evidence of increased activation in the anterior cingulate cortex and a trend toward increased activation in the infralimbic and prelimbic cortices. These procedures open a venue for studying the neural basis of the instrumental behavior of animals that experience reward loss.

Increased NLRP1 mRNA and Protein Expression Suggests Inflammasome Activation in the Dorsolateral Prefrontal and Medial Orbitofrontal Cortex in Schizophrenia.

Schizophrenia is a complex mental condition, with key symptoms marked for diagnosis including delusions, hallucinations, disorganized thinking, reduced emotional expression, and social dysfunction. In the context of major developmental hypotheses of schizophrenia, notably those concerning maternal immune activation and neuroinflammation, we studied NLRP1 expression and content in the postmortem brain tissue of 10 schizophrenia and 10 control subjects. In the medial orbitofrontal cortex (Brodmann's area 11/12) and dorsolateral prefrontal cortex (area 46) from both hemispheres of six schizophrenia subjects, the NLRP1 mRNA expression was significantly higher than in six control brains (p < 0.05). As the expression difference was highest for the medial orbitofrontal cortex in the right hemisphere, we assessed NLRP1-immunoreactive pyramidal neurons in layers III, V, and VI in the medial orbitofrontal cortex in the right hemisphere of seven schizophrenia and five control brains. Compared to controls, we quantified a significantly higher number of NLRP1-positive pyramidal neurons in the schizophrenia brains (p < 0.01), suggesting NLRP1 inflammasome activation in schizophrenia subjects. Layer III pyramidal neuron dysfunction aligns with working memory deficits, while impairments of pyramidal neurons in layers V and VI likely disrupt predictive processing. We propose NLRP1 inflammasome as a potential biomarker and therapeutic target in schizophrenia.

Influencing Factors of Prepulse Inhibition Deficit in Patients with Schizophrenia and Observations on the Efficacy of Traditional Chinese Medicine

This study aims to analyze the abnormal expression of lncRNAs in peripheral blood mononuclear cells (PBMCs) of patients with schizophrenia, investigate the influencing factors of prepulse inhibition deficit in patients and observe the efficacy of traditional Chinese medicine. A total of 106 patients with schizophrenia who underwent treatment at our hospital from January 2020 to December 2022 were included, along with 45 healthy individuals who received routine check-ups as control subjects. The significantly expressed lncRNAs were validated and analyzed using ROC curve analysis, and logistic regression analysis was used to identify the factors influencing prepulse inhibition deficit. Find 125 lncRNAs were found to be differentially expressed lncRNAs in the PBMCs of patients with schizophrenia, including 62 upregulated and 63 downregulated lncRNAs. And smoking amount, and relapse frequency were influencing factors for prepulse inhibition deficit in patients with schizophrenia. Animal experiments were conducted using hematoxylin eosin staining to observe the number and morphology of neurons in the hippocampal CA3 area and prefrontal cortex of rats, and the effects of natural Chinese medicine Poria cocos on the nervous system were analyzed. Find the acidic polysaccharides from Poria cocos, a natural traditional Chinese medicine, can promote the regeneration of neuronal cells, reduce excessive autophagy of neurons in the CA3 area of the hippocampus and prefrontal cortex of rats, promote neuronal cell proliferation, and improve neuronal cell morphology. Traditional Chinese medicine has good effects in psychopathology, positive and negative symptoms, and PANSS total score. Disruption of lncRNA expression may be one of the biological factors contributing to the pathogenesis of schizophrenia and is closely related to its mechanism. Prepulse inhibition, reflecting sensory gating function, is an important factor affecting perceptual and cognitive functions in patients with schizophrenia. Gender, smoking amount, and relapse frequency may influence prepulse inhibition deficit in these patients. Traditional Chinese medicine shows potential in improving prepulse inhibition deficit. The acidic polysaccharides from Poria cocos, a natural traditional Chinese medicine, can promote the regeneration of neuronal cells, effectively improve the damage to the structure and function of neurons in the hippocampal CA3 area and prefrontal cortex. When used in combination with other traditional Chinese medicines, it could offer new approaches for treating schizophrenia.

New organizational principles and 3D cytoarchitectonic maps of the dorsolateral prefrontal cortex in the human brain.

Areas of the dorsolateral prefrontal cortex (DLPFC) are part of the frontoparietal control, default mode, salience, and ventral attention networks. The DLPFC is involved in executive functions, like working memory, value encoding, attention, decision-making, and behavioral control. This functional heterogeneity is not reflected in existing neuroanatomical maps. For example, previous cytoarchitectonic studies have divided the DLPFC into two or four areas. Macroanatomical parcellations of this region rely on gyri and sulci, which are not congruent with cytoarchitectonic parcellations. Therefore, this study aimed to provide a microstructural analysis of the human DLPFC and 3D maps of cytoarchitectonic areas to help address the observed functional variability in studies of the DLPFC. We analyzed ten human post-mortem brains in serial cell-body stained brain sections and mapped areal boundaries using a statistical image analysis approach. Five new areas (i.e., SFG2, SFG3, SFG4, MFG4, and MFG5) were identified on the superior and middle frontal gyrus, i.e., regions corresponding to parts of Brodmann areas 9 and 46. Gray level index profiles were used to determine interregional cytoarchitectural differences. The five new areas were reconstructed in 3D, and probability maps were generated in commonly used reference spaces, considering the variability of areas in stereotaxic space. Hierarchical cluster analysis revealed a high degree of similarity within the identified DLPFC areas while neighboring areas (frontal pole, Broca's region, area 8, and motoric areas) were separable. Comparisons with functional imaging studies revealed specific functional profiles of the DLPFC areas. Our results indicate that the new areas do not follow a simple organizational gradient assumption in the DLPFC. Instead, they are more similar to those of the ventrolateral prefrontal cortex (Broca's areas 44, 45) and frontopolar areas (Fp1, Fp2) than to the more posterior areas. Within the DLPFC, the cytoarchitectonic similarities between areas do not seem to follow a simple anterior-to-posterior gradient either, but cluster along other principles. The new maps are part of the publicly available Julich Brain Atlas and provide a microstructural reference for existing and future imaging studies. Thus, our study represents a further step toward deciphering the structural-functional organization of the human prefrontal cortex.

Increased brain fractional perfusion in obesity using intravoxel incoherent motion (IVIM) MRI metrics.

This research seeks to shed light on the associations between brain perfusion, cognitive function, and mental health in individuals with and without obesity. In this study, we employed the noninvasive intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) technique to examine brain fractional perfusion (FP) in two groups: individuals with obesity (N = 72) and healthy controls (N = 66). Additionally, we investigated potential associations between FP, cognitive function, and depressive symptoms in the participants with and without obesity. Finally, artificial intelligence algorithms (Boruta analysis) were also used. Participants with obesity exhibited increased FP within dopaminergic brain circuits, particularly involving prefrontal cortex areas, anterior and posterior sections of the cingulate cortex, the right striatum, and the midbrain. Additionally, these individuals demonstratedlower working memory and higher depressive symptoms compared to the control group. Notably, higher FP in the inferior temporal and occipital cortices correlated with greater depressive symptoms, whereas increased FP in the right ventral caudate and the midbrain was associated with better working memory performance. A link between inflammatory and metabolic variables, with a particular emphasis on monocytes, and FP in obesity was also evidenced by Boruta analysis. Increased brain perfusion in individuals with obesity is associated with cognitive function and mental health through interaction with metabolic and inflammatory factors.

Brief exposure to enriched environment rapidly shapes the glutamate synapses in the rat brain: A metaplastic fingerprint.

Environmental enrichment (EE) has been shown to produce beneficial effects in addiction disorders; however, due to its configurational complexity, the underlying mechanisms are not yet fully elucidated. Recent evidence suggests that EE, acting as a metaplastic agent, may affect glutamatergic mechanisms underlying appetitive memory and, in turn, modulate reward-seeking behaviours: here, we have investigated such a possibility following a brief EE exposure. Adult male Sprague-Dawley rats were exposed to EE for 22 h and the expression of critical elements of the glutamate synapse was measured 2h after the end of EE in the medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and hippocampus (Hipp) brain areas, which are critical for reward and memory. We focused our investigation on the expression of NMDA and AMPA receptor subunits, their scaffolding proteins SAP102 and SAP97, vesicular and membrane glutamate transporters vGluT1 and GLT-1, and critical structural components such as proteins involved in morphology and function of glutamatergic synapses, PSD95 and Arc/Arg3.1. Our findings demonstrate that a brief EE exposure induces metaplastic changes in glutamatergic mPFC, NAc and Hipp. Such changes are area-specific and involve postsynaptic NMDA/AMPA receptor subunit composition, as well as changes in the expression of their main scaffolding proteins, thus influencing the retention of such receptors at synaptic sites. Our data indicate that brief EE exposure is sufficient to dynamically modulate the glutamatergic synapses in mPFC-NAc-Hipp circuits, which may modulate rewarding and memory processes.

Neural mechanisms of odour imagery induced by non-figurative visual cues

Odour imagery, the ability to experience smell when an appropriate stimulus is absent, has widely been documented as being particularly difficult. However, previous studies have shown the beneficial effect of visual cues (e.g., pictures or words) to facilitate performance in numerous tasks of olfactory nature. Therefore, the use of visual cues to evoke odours seems relevant. In this study, our interest is directed towards non-figurative coloured arrangements, which result from a patented technology and aim at chromatically representing any smell from its chemical composition and sensory description. The aim of this study was to characterise the neural mechanisms of odour imagery facilitated by these non-figurative coloured arrangements. Using functional magnetic resonance imaging, we recorded and compared hemodynamic responses during odour imagery facilitated by non-figurative coloured arrangements and pictures. Our findings reveal that the use of non-figurative coloured arrangements during odour imagery solicits olfactory and non-olfactory brain regions (orbitofrontal cortex, insula, hippocampus, thalamus, dorsolateral prefrontal cortex and supplementary motor area), which are mainly involved in olfactory processing and multimodal integration. Moreover, very similar cortical activity was found between the use of non-figurative coloured arrangements and pictures during odour imagery, with increased activity in the supplementary motor area during the use of coloured arrangements only. Overall, non-figurative coloured arrangements could become a robust tool to visually evoke odours without requiring prior familiarity with the depicted odour. Future studies should use psychometric measures to determine the relationships between brain activation, odour imagery ability and vividness of the generated odour images.

Transcranial Magnetic Stimulation of Dorsolateral Prefrontal Cortex in Treatment-Resistant Obsessive Compulsive Disorder: A Mini-Review

Introduction: Approximately two-thirds of patients with Obsessive-Compulsive Disorder (OCD) exhibit inadequate responses to current standard therapies. A previous meta-analysis has shown the potential benefit of repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (dlPFC) area in patients with OCD. However, the analysis also included patients who had not previously failed first-line treatments. This mini-review aims to explore the therapeutic effects of rTMS applied to the dlPFC area in patients with treatment-resistant OCD. Methods: We conducted a comprehensive search for randomized controlled trials (RCTs) and observational studies across various databases (PubMed, EMBASE, Ebsco, Web of Science, and Cochrane Central). Eligible studies encompassed rTMS administered to the dlPFC area in cases of treatment-resistant OCD. Studies that did not focus on using the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) to assess the efficacy of rTMS were excluded. Quality assessments were conducted based on the Cochrane risk-of-bias tool. Results: Our review identified five RCTs involving 132 patients that met the established criteria. The application of high-frequency (HF) and low-frequency (LF) rTMS to the dlPFC region yielded controversial post-treatment Y-BOCS findings due to factors such as small sample sizes, short-term study durations, variations in rTMS protocols, and four studies exhibiting a high risk of bias. Discussion: The available data is constrained by a scarcity of high-quality, large-scale trials with extended follow-up periods and optimized protocols. Further research is warranted to establish the efficacy of rTMS administered to the dlPFC in this patient population.