Insights into human behavior from lesions to the prefrontal cortex

Screening tools for subjective cognitive decline and mild cognitive impairment based on task-state prefrontal functional connectivity: a functional near-infrared spectroscopy study

BACKGROUND

Subjective cognitive decline (SCD) and mild cognitive impairment (MCI) carry the risk of progression to dementia, and accurate screening methods for these conditions are urgently needed. Studies have suggested the potential ability of functional near-infrared spectroscopy (fNIRS) to identify MCI and SCD. The present fNIRS study aimed to develop an early screening method for SCD and MCI based on activated prefrontal functional connectivity (FC) during the performance of cognitive scales and subject-wise cross-validation via machine learning.

METHODS

Activated prefrontal FC data measured by fNIRS were collected from 55 normal controls, 80 SCD patients, and 111 MCI patients. Differences in FC were analyzed among the groups, and FC strength and cognitive scale performance were extracted as features to build classification and predictive models through machine learning. Model performance was assessed based on accuracy, specificity, sensitivity, and area under the curve (AUC) with 95 % confidence interval (CI) values.

RESULTS

Statistical analysis revealed a trend toward more impaired prefrontal FC with declining cognitive function. Prediction models were built by combining features of prefrontal FC and cognitive scale performance and applying machine learning models, The models showed generally satisfactory abilities to differentiate among the three groups, especially those employing linear discriminant analysis, logistic regression, and support vector machine. Accuracies of 92.0 % for MCI vs. NC, 80.0 % for MCI vs. SCD, and 76.1 % for SCD vs. NC were achieved, and the highest AUC values were 97.0 % (95 % CI: 94.6 %-99.3 %) for MCI vs. NC, 87.0 % (95 % CI: 81.5 %-92.5 %) for MCI vs. SCD, and 79.2 % (95 % CI: 71.0 %-87.3 %) for SCD vs. NC.

CONCLUSION

The developed screening method based on fNIRS and machine learning has the potential to predict early-stage cognitive impairment based on prefrontal FC data collected during cognitive scale-induced activation.

Functional connectivity of default mode network in non-hospitalized patients with post-COVID cognitive complaints

Introduction

Neurologic impairment is common in patients with acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. While patients with severe COVID have a higher prevalence of neurologic symptoms, as many as one in five patients with mild COVID may also be affected, exhibiting impaired memory as well as other cognitive dysfunctions.

Methods

To characterize the effect of COVID on the brain, the current study recruited a group of adults with post-COVID cognitive complaints but with mild, non-hospitalized cases. They were then evaluated through formal neuropsychological testing and underwent functional MRI of the brain. The participants in our study performed nearly as expected for cognitively intact individuals. Additionally, we characterized the functional connectivity of the default mode network (DMN), which is known for cognitive functions including memory as well as the attention functions involved in normal aging and degenerative diseases.

Results

Along with the retention of functional connectivity in the DMN, our results found the DMN to be associated with neurocognitive performance through region-of-interest and whole-brain analyses. The connectivity between key nodes of the DMN was positively correlated with cognitive scores (r = 0.51, p = 0.02), with higher performers exhibiting higher DMN connectivity.

Discussion

Our findings provide neuroimaging evidence of the functional connectivity of brain networks among individuals experiencing cognitive deficits beyond the recovery of mild COVID. These imaging outcomes indicate expected functional trends in the brain, furthering understanding and guidance of the DMN and neurocognitive deficits in patients recovering from COVID.

Neural activity is modulated by spontaneous and volitionally controlled breathing

Recent studies have provided evidence regarding respiration-brain coupling, but our understanding of how continuously varying dynamics of breathing modulate neural activity remains incomplete. We examined whether the neural state differs between spontaneous and volitionally controlled breathing and across the phases of breathing, inspiration and expiration. Magnetoencephalography (MEG) with a respiratory belt was used to record cortical oscillatory activity during spontaneous, deep, and square breathing (n = 33). Additionally, self-report measures of mood and arousal were applied to assess changes in the psychological state during the breathing techniques. Alpha power was suppressed during inspiration and increased during expiration (p < .01) indicating dynamically fluctuating neural states across the respiratory cycle. This effect was observed in the sensorimotor areas during both spontaneous and volitionally controlled deep breathing. Compared to spontaneous and volitionally controlled square breathing, alpha power increased during deep breathing (p < .01) within a cortical network extending to frontal and temporal areas. We also observed a steeper aperiodic slope and a broadband shift in the power spectrum in the left superior frontal gyrus during square breathing in comparison with spontaneous breathing suggesting that not only oscillatory activity but also the more general spectral characteristics of ongoing neural activity are modulated by the rate, depth, and pattern of breathing. Self-reported mood and arousal did not differ across the breathing techniques. Altogether, we demonstrate that neural activity is modulated by the phases of breathing and can also be volitionally influenced by varying the rate, depth, and pattern of breathing.

Stress in utero: prenatal dexamethasone exposure causes greater structural gliovascular alterations in female offspring than in males

From early in life, experiences like prenatal stress profoundly affect long-term health and behavior. Fetal exposure to increased levels of glucocorticoids (GC), via maternal stress or through antenatal corticosteroid therapy (commonly used in women at risk of preterm birth), can disrupt brain development and raise the susceptibility to psychiatric disorders. Previous studies on prenatal exposure to synthetic GCs, such as dexamethasone (DEX), revealed impairments in neurogenesis and dendritic spine development. However, the impact of prenatal stress, specifically antenatal DEX exposure, on the gliovascular interface remains unclear. This interface, involving the relationship between astrocytes and blood vessels, is essential for healthy brain development. Astrocytic endfeet coverage and organization are crucial features of the gliovascular interface, and in this study, we evaluated these aspects through aquaporin-4 (AQ4) expression and organization along the lectin labelled-vasculature. At Postnatal Day 14, no differences in AQ4 expression were observed between males and females. However, prenatal stress induced by DEX exposure (50 μg/kg was administered subcutaneously to pregnant mice through gestational days 16, 17 and 18) significantly impacted this structure in females but not in males. Specifically, in female offspring prenatally exposed to DEX, AQ4 expression was significantly upregulated in the hippocampus, and its rearrangement was observed in the prefrontal cortex. A comparison of vascular density between male and female brains showed no significant sex differences in any analyzed regions, though male cerebellar vessel segments were shorter. Interestingly, prenatal stress caused morphological alterations in female brains, including increased vessel tortuosity, while no such changes were seen in males. In the hippocampus, prenatal DEX exposure reduced vessel segment length in males but did not affect females. In the cerebellum, DEX exposure increased vessel segment length in females. This study highlights sex-specific differences in the impact of prenatal stress on the gliovascular structure across various brain regions, suggesting AQ4 as a potential molecular target relevant to depressive-like behaviors in female offspring. Future studies are needed to correlate the gliovascular structural alterations found with functional disturbances and sex-specific mental health issues.

Dose-dependent developmental fluoride exposure leads to neurotoxicity and impairs excitatory synapse development

Developmental fluoride exposure has been implicated in cognitive deficits and neurotoxicity, yet the mechanisms underlying these effects remain unclear. Here, we investigated the dose- and time-dependent impacts of sodium fluoride (NaF) on neuronal morphology, viability, oxidative stress, and synaptic function using both in vitro and in vivo mouse models. Cultured primary embryonic mouse cortical neurons were exposed to varying concentrations of NaF (0-200 μg/ml). Acute exposure led to neuronal swelling at higher concentrations (≥ 50 μg/ml), while prolonged exposure reduced neuronal viability. Notably, NaF dose-dependently elevated reactive oxygen species (ROS) production, implicating oxidative stress as a key mechanism of fluoride-induced neurotoxicity. Synaptic development was also impaired, as evidenced by reduced density and co-localization of excitatory synapse markers with prolonged 2 μg/ml NaF exposure. To extend these in vitro findings, pregnant mice were exposed to 50 mg/L NaF in drinking water, and offspring brain functions were evaluated postnatally. Whole-cell patch-clamp recordings in layer V pyramidal neurons in the prefrontal cortex revealed reduced frequency and amplitude of miniature excitatory post-synaptic currents (mEPSCs), indicating impaired synaptic function. Morphological analysis showed decreased dendritic spine density and head diameter. These findings suggest that fluoride exposure during critical period of brain development disrupts synaptic integrity and function through excitatory synapse impairments.

Molecular Characterization and Expression of Lactoferrin Receptor (LfR) in Different Regions of the Brain Responding to Lactoferrin Intervention

Lactoferrin (LF), an iron-binding glycoprotein rich in human milk, promotes neurodevelopment and cognition, but whether it acts through the LF receptor (LfR) and its expression profile in the brain remains unknown. We characterized 972 bp of piglet brain LfR cDNA and found LfR mRNA was expressed all brain regions being highest in the frontal lobe, followed by parietal lobe, brainstem, occipital lobe, cingulate gyrus, subventricular zone, olfactory bulb, hippocampus, amygdala, cerebellum, and thalamus. LfR mRNA and protein in different regions of the brain responded to low (155 mg/kg/day) and high (285 mg/kg/day) LF supplementation of piglets from postnatal days 3 to 38. By postnatal day 39, the low LF diet significantly increased LfR protein expression in the occipital lobe compared to controls, but not the high LF diet. LfR protein in the subventricular zone of the high LF group was 42% and 38% higher than that of the low LF group and controls, respectively. There was a trend for a dose-response relationship between LF intervention and LfR protein expression only in the prefrontal and parietal lobes. LF supplementation significantly improved piglet working memory for a difficult task, which was positively correlated with LfR protein in the prefrontal, parietal, and occipital lobes, but no dose response. Brain LfR responds to dietary LF supplementation, a mechanism by which LF can promote learning and working memory through its receptor. LfR is expressed in the whole brain, and its expression level is anatomic region specific.

How Age and Culture Influence Cognition: A Lifespan Developmental Perspective

It has long been assumed that cognitive aging is a universal phenomenon. However, increasing evidence substantiates the importance of individual differences in cognitive aging. How do experiential factors related to culture shape developmental trajectories of cognition? We propose a new model examining how age and culture influence cognitive processes, building on past models and expanding upon them to incorporate a lifespan developmental perspective. The current model posits that how age and culture interact to influence cognition depends on (a) the extent to which the cognitive task relies on top-down or bottom-up processes, and (b) for more top-down processes, the level of cognitive resources required to perform the task. To assess the validity of the model, we review literature not only from adulthood but also childhood, making this the first model to adopt a lifespan perspective in the study of culture and cognition. The current work advances understanding of cognitive aging by delineating the combined effects of biological aging processes, assumed to apply across cultures, and culture-dependent experiential aging processes, which reflect unique cultural experiences throughout one's lifespan. This approach enables understanding of comprehensive potential mechanisms that underlie the influence of culture on cognitive development across life stages.

The medial prefrontal cortex as a proposed regulatory structure in the relationship between anxiety and perceived social support: a review

Perceived social support is recognized as a critical protective factor against the development of mental health disorders. Anxiety disorders are the most common group of mental health disorders and have a substantial impact on individuals' well-being. Despite extensive research on anxiety and perceived social support, a significant gap exists in our understanding of the neural mechanisms linking these two phenomena. While several brain regions, including the amygdala, hippocampus, and insula, have been implicated in anxiety regulation and social support processing, the medial prefrontal cortex (mPFC) emerges as a particularly intriguing structure due to its central role in emotional regulation and social processing.Here, we hypothesize that the mPFC serves as a potential neural substrate mediating the relationship between anxiety and perceived social support. To support our hypothesis, we conducted a literature search in the PubMed database using a systematic Boolean search strategy. In total, 43 articles met our inclusion criteria. The reviewed studies suggest that the mPFC may play an essential role in regulating the effect of perceived social support on anxiety levels. The evidence indicates that individuals with higher levels of perceived social support may exhibit enhanced regulatory control over anxiety-related processes, with the mPFC mediating this effect.Understanding the neural mechanisms that underpin the relationship between anxiety and social support is crucial for devising targeted interventions. Further investigation into mPFC's role as a candidate structure in this domain could provide invaluable insights and aid in the development of new therapeutic strategies for the management of anxiety.

Relationship between overall right pre-frontal cortex activity and learning and retention of a visuomotor adaptation task: A continuous analysis

Learning a visuomotor adaptation task (VMA) is typically assessed by describing the behavioral changes during adaption (early-fast and late-slow phases) and retention (consolidation) tests. Few studies have concurrently examined behavioral and brain activity during this type of learning and therefore their time-dependent dynamics is unknown. It has been proposed that two distinct strategies can be used during such learning: a model-free and a model-based, which distinctively involved explicit and implicit learning strategies. It has also been proposed that prefrontal cortex (PFC) is more implicated when explicit processes are more relevant as it was observed in the early adaptation (Taylor & Ivry, 2014; Wolpe et al., 2020). Additionally, an explicit model-based strategy has been inferred when prefrontal (PFC) activity increases. Therefore, the study's aims were: (1) to examine the continuous temporal dynamics of behavior and right PFC activity during adaptation and retention of a VMA, and (2) to infer the implication of explicit processes during the learning of a VMA derived from right PFC activity. Eighteen young adults (24.22 ± 3.12 years) took part in this study. Continuous measures of the performance (the initial directional error, IDE, and the root mean square error, RMSE) of a rotational visuomotor adaptation task during an adaptation (AD) and two retention sets at 1 h (RT1) and 24 h (RT24) were collected. Concurrently, measures of the right PFC activity (relative changes of the oxyhemoglobin concentration, [ΔO2Hb]) were registered via a three-channel functional near-infrared spectroscopy device. General linear mixed models were run to explore differences across adaptation and retentions. Also, cross-correlations between performance (IDE and RMSE) and PFC activity were conducted to observe their relation during sets. The main results indicated that (1) initial fast behavioral improvement (decrease of IDE and RMSE) did not occur simultaneously with the largest increase of the [ΔO2Hb] in the PFC during the AD, and (2) there was similar performance in the RT1 and RT24 but possibly involving the PFC differently. While in both retentions the errors improved after the first trials, in RT1, the [ΔO2Hb] decreased from the very beginning, whereas the PFC activity initially increased in RT24. Our observations would suggest that various cooperating learning strategies, including model-free (i.e., exploratory) and model-based explicit (i.e., strategy) and implicit (i.e., sensory prediction errors), are coordinated in different timings to cooperate during the sensorimotor adaptation and consolidation processes. Furthermore, the involvement of these strategies during the retention may depend on the time elapsed from the end of the adaptation to the re-introduction of the task.

Stress and Inflammation Target Dorsolateral Prefrontal Cortex Function: Neural Mechanisms Underlying Weakened Cognitive Control

Most mental disorders involve dysfunction of the dorsolateral prefrontal cortex (dlPFC), a recently evolved brain region that subserves working memory, abstraction, and the thoughtful regulation of attention, action, and emotion. For example, schizophrenia, depression, long COVID, and Alzheimer's disease are all associated with dlPFC dysfunction, with neuropathology often being focused in layer III. The dlPFC has extensive top-down projections, e.g., to the posterior association cortices to regulate attention and to the subgenual cingulate cortex via the rostral and medial PFC to regulate emotional responses. However, the dlPFC is particularly dependent on arousal state and is very vulnerable to stress and inflammation, which are etiological and/or exacerbating factors for most mental disorders. The cellular mechanisms by which stress and inflammation impact the dlPFC are a topic of current research and are summarized in this review. For example, the layer III dlPFC circuits that generate working memory-related neuronal firing have unusual neurotransmission, depending on NMDA receptor and nicotinic α7 receptor actions that are blocked under inflammatory conditions by kynurenic acid. These circuits also have unusual neuromodulation, with the molecular machinery to magnify calcium signaling in spines needed to support persistent firing, which must be tightly regulated to prevent toxic calcium actions. Stress rapidly weakens layer III connectivity by driving feedforward calcium-cAMP (cyclic adenosine monophosphate) opening of potassium channels on spines. This is regulated by postsynaptic noradrenergic α2A adrenergic receptor and mGluR3 (metabotropic glutamate receptor 3) signaling but dysregulated by inflammation and/or chronic stress exposure, which contribute to spine loss. Treatments that strengthen the dlPFC via pharmacological (the α2A adrenergic receptor agonist, guanfacine) or repetitive transcranial magnetic stimulation manipulation provide a rational basis for therapy.

Correspondence between thalamic injury-induced changes in resting-state fMRI of monkeys and their sensorimotor behaviors and neural activities

Resting state functional MRI (rsfMRI) exploits variations in blood-oxygenation-level-dependent (BOLD) signals to infer resting state functional connectivity (FC) within and between brain networks. However, there have been few reports quantifying and validating the results of rsfMRI analyses with other metrics of brain circuits. We measured longitudinal changes in FC both within and between brain networks in three squirrel monkeys after focal lesions of the thalamic ventroposterior lateral nucleus (VPL) that were intended to disrupt the input to somatosensory cortex and impair manual dexterity. Local field potential signals were recorded to assess electrophysiological changes during each animal's recovery, and behavioral performances were measured longitudinally using a sugar-pellet grasping task. Finally, end-point histological evaluations were performed on brain tissue slices to quantify the VPL damage. The rsfMRI data analysis showed significant decrease in FC measures both within and between networks immediately post-injury, which started to recover at different time-points for each animal. The trajectories of FC recovery for each animal mirrored their individual behavioral recovery time-courses. Electrophysiological measurements of inter-electrode coherences and end-point histological measures also aligned well with the graded injury effects measured using rsfMRI-based FC. A simple algorithm employing FC measures from the somatosensory network could accurately predict each monkeys' behavioral recovery timeframe after four weeks post-injury. Whole brain between-network FC measures further revealed that the injury effects were not limited to thalamocortical connections but were rather more widespread. Overall, this study provides evidence of the validity of rsfMRI based FC measures as indicators of the functional integrity and behavioral relevance following an injury to a specific brain circuit.

Differential Abnormality in Regional Brain Spontaneous Activity and Functional Connectivity in Patients of Non-Acute Subcortical Stroke With Versus Without Global Cognitive Functional Impairment

INTRODUCTION

Cognitive impairment after a stroke significantly affects patients' quality of life, yet not all strokes lead to such impairment, and the underlying reasons remain unclear. This study employs resting-state functional magnetic resonance imaging (rs-fMRI) to compare subcortical stroke patients with and without cognitive impairment. Our goal is to identify distinct abnormalities in regional brain spontaneous activity and functional connectivity (FC) to better understand the neural basis of post-stroke cognitive outcomes.

METHODS

A total of 62 first-ever non-acute subcortical stroke patients were classified into post-stroke with abnormal cognition (PSAC) and with normal cognition (PSNC) groups. Rs-MRI was utilized to assess regional homogeneity (ReHo) in 32 PSAC, 30 PSNC, and 62 age- and sex-matched healthy controls (HC). Then we performed the seed-based whole-brain FC analysis based on the ReHo results. A partial correlation analysis examined the relationship between altered ReHo or FC and Montreal Cognitive Assessment (MoCA) scores.

RESULTS

It showed varied activity in cognitive-related brain regions in both stroke groups compared to HC, such as the right superior frontal gyrus, the right middle temporal gyrus, the right postcentral gyrus, and the left cerebellar lobules. The PSAC group had increased activity in the bilateral inferior temporal gyrus as well. Significant differences in activity were also found between PSAC and PSNC groups, with the PSAC group showing decreased activity in the left gyrus rectus (REC) and increased activity in cerebellar lobules. FC analysis revealed decreased connections in the PSAC group, particularly involving the left REC. Activity and FC in left REC and cerebellum also significantly correlated with MoCA scores.

CONCLUSIONS

These findings suggest unique patterns of brain activity and connectivity in non-acute subcortical stroke patients with cognitive impairment, shedding light on potential neural mechanisms underlying post-stroke cognitive impairment. While the left REC may be a potential neural regulatory stimulus target in clinical applications.

An exploration of distinguishing subjective cognitive decline and mild cognitive impairment based on resting-state prefrontal functional connectivity assessed by functional near-infrared spectroscopy

Purpose

Functional near-infrared spectroscopy (fNIRS) has shown feasibility in evaluating cognitive function and brain functional connectivity (FC). Therefore, this fNIRS study aimed to develop a screening method for subjective cognitive decline (SCD) and mild cognitive impairment (MCI) based on resting-state prefrontal FC and neuropsychological tests via machine learning.

Methods

Functional connectivity data measured by fNIRS were collected from 55 normal controls (NCs), 80 SCD individuals, and 111 MCI individuals. Differences in FC were analyzed among the groups. FC strength and neuropsychological test scores were extracted as features to build classification and predictive models through machine learning. Model performance was assessed based on accuracy, specificity, sensitivity, and area under the curve (AUC) with 95% confidence interval (CI) values.

Results

Statistical analysis revealed a trend toward compensatory enhanced prefrontal FC in SCD and MCI individuals. The models showed a satisfactory ability to differentiate among the three groups, especially those employing linear discriminant analysis, logistic regression, and support vector machine. Accuracies of 94.9% for MCI vs. NC, 79.4% for MCI vs. SCD, and 77.0% for SCD vs. NC were achieved, and the highest AUC values were 97.5% (95% CI: 95.0%-100.0%) for MCI vs. NC, 83.7% (95% CI: 77.5%-89.8%) for MCI vs. SCD, and 80.6% (95% CI: 72.7%-88.4%) for SCD vs. NC.

Conclusion

The developed screening method based on resting-state prefrontal FC measured by fNIRS and machine learning may help predict early-stage cognitive impairment.

A language model of problem solving in humans and macaque monkeys

Human intelligence is characterized by the remarkable ability to solve complex problems by planning a sequence of actions that takes us from an initial state to a desired goal state. Quantifying and comparing problem-solving capabilities across species and finding their evolutionary roots are critical for understanding how the brain carries out this intricate process. We introduce the Language of Problem Solving (LoPS) model as a novel quantitative framework that investigates the structure of problem-solving behavior through a language model. We applied the model to an adapted classic Pac-Man game as a cross-species behavioral paradigm to test both humans and macaque monkeys. The LoPS model extracted the latent structure, or grammar, embedded in the agents' gameplay, revealing the non-Markovian temporal dependency structure of their problem-solving behavior and the hierarchical structures of problem solving in both species. The complexity of LoPS grammar correlated with individuals' game performance and reflected the difference in problem-solving capacity between humans and monkeys. Both species evolved their LoPS grammars during learning, progressing from simpler to more complex ones, suggesting that the structure of problem solving is not fixed but evolves to support more sophisticated and efficient problem solving. Our study provides insights into how humans and monkeys break down problem solving into compositional units and navigate complex tasks, deepening our understanding of human intelligence and its evolution and establishing a foundation for future investigations of the neural mechanisms of problem solving.

The role of the prefrontal cortex in modulating aggression in humans and rodents

Accumulating evidence suggests that the prefrontal cortex (PFC) plays an important role in aggression. However, the findings regarding the key neural mechanisms and molecular pathways underlying the modulation of aggression by the PFC are relatively scattered, with many inconsistencies and areas that would benefit from exploration. Here, we highlight the relationship between the PFC and aggression in humans and rodents and describe the anatomy and function of the human PFC, along with homologous regions in rodents. At the molecular level, we detail how the major neuromodulators of the PFC impact aggression. At the circuit level, this review provides an overview of known and potential subcortical projections that regulate aggression in rodents. Finally, at the disease level, we review the correlation between PFC alterations and heightened aggression in specific human psychiatric disorders. Our review provides a framework for PFC modulation of aggression, resolves several intriguing paradoxes from previous studies, and illuminates new avenues for further study.

Targeting of retrovirus-derived Rtl8a/8b causes late-onset obesity, reduced social response and increased apathy-like behaviour

Retrotransposon Gag-like (RTL) 8A, 8B and 8C are eutherian-specific genes derived from a certain retrovirus. They cluster as a triplet of genes on the X chromosome, but their function remains unknown. Here, we demonstrate that Rtl8a and Rtl8b play important roles in the brain: their double knockout (DKO) mice not only exhibit reduced social responses and increased apathy-like behaviour, but also become obese from young adulthood, similar to patients with late Prader-Willi syndrome (PWS), a neurodevelopmental genomic imprinting disorder. Mouse RTL8A/8B proteins are expressed in the prefrontal cortex and hypothalamus and localize to both the nucleus and cytoplasm of neurons, presumably due to the N-terminal nuclear localization signal-like sequence at the N-terminus. An RNAseq study in the cerebral cortex revealed reduced expression of several GABA type A receptor subunit genes in DKO, in particular Gabrb2, which encodes its β2 subunit. We confirmed the reduction of GABRB2 protein in the DKO cerebral cortex by western blotting. As GABRB2 has been implicated in the aetiology of several neurodevelopmental and neuropsychiatric disorders, it is likely that the reduction of GABRB2 is one of the major causes of the neuropsychiatric defects in the DKO mice.

Emotional pictures in the brain and their interaction with the task: A fine-grained fMRI coordinate-based meta-analysis study

The impacting research on emotions of the last decades was carried out with different methods. The most popular was based on the use of a validated sample of slides, the International Affective Pictures System (IAPS), divided mainly into pleasant, neutral and unpleasant categories, and on fMRI as a measure of brain activation induced by these stimuli. With the present coordinate-based meta-analysis (CBMA) based on ALE approach, we aimed to unmask the main brain networks involved in the contrast of pleasant vs. neutral and unpleasant vs. neutral IAPS slide categories. Furthermore, we included studies employing both IAPS and non-IAPS (but analogously validated) pictures, a condition termed as IAPS EXTENDED. After selecting 97 papers published in the 2000-2023 interval, the planned contrasts were analyzed by also considering their interaction with the Load factor of the concomitant task, which comprised the conditions: No Load (passive viewing), Low-Load tasks and High-Load tasks. We analyzed a total of 152 experiments (106 focusing on the negative vs. neutral contrast; 46 reporting positive vs. neutral contrasts). We additionally performed conjunction and contrast analyses. Results confirmed outcomes of past meta-analyses on the involvement of a number of cortical and subcortical paralimbic and limbic regions during unpleasant picture processing, but the increase of the pubblications on this topic in last years, together with a more fine-grained analysis, allowed us to find also the involvement of additional areas, such as the right middle frontal gyrus, left inferior frontal gyrus (BA 9), posterior cingulate, and left inferior parietal lobule. Concerning passive viewing and low-load tasks, a clear frontal asymmetry emerged with greater right prefrontal activation (BA9) to unpleasant vs. pleasant pictures, whereas, during No Load tasks only, left frontal dominance to pleasant vs. unpleasant stimuli was found (BA13). The unpleasant vs. neutral comparison on High-Load tasks (the pleasant condition had an insufficient sample size) revealed a specific lateralization of several areas of the right hemisphere (STG-BA 38, MFG-BA 46, FG-BA 37), whereas, in the other load conditions, the inferior frontal gyrus was right lateralized, but the main activated regions were bilateral or left lateralized. Results are discussed considering the effects of both valence and task/load variables, and the involvement of hippocampus/amygdala, hemispheric asymmetries of emotions, the occipito-temporal areas, several sub-regions of the prefrontal/orbitofrontal cortex, and an extended motor network.

The effect of sensory manipulation on the static balance control and prefrontal cortex activation in older adults with mild cognitive impairment: a functional near-infrared spectroscopy (fNIRS) study

BACKGROUND

This study aimed to investigate the modulatory role of prefrontal cortex (PFC) activity in older adults with mild cognitive impairment (MCI) when sensory cues were removed or presented inaccurately (i.e., increased sensory complexity) during sensory manipulation of a balance task. The research sheds light on the neural regulatory mechanisms of the brain related to balance control in individuals with MCI.

METHODS

21 older adults with MCI (male/female: 9/12, age: 71.19 ± 3.36 years) were recruited as the experimental group and 19 healthy older adults (male/female: 10/9, age: 70.16 ± 4.54 years) as the control group. Participants were required to perform balance tests under four standing conditions: standing on a solid surface with eyes open, standing on a foam surface with eyes open, standing on a solid surface with eyes closed, and standing on a foam surface with eyes closed. Functional Near-Infrared Spectroscopy (fNIRS) and force measuring platform are used to collect hemodynamic signals of the PFC and center of pressure (COP) data during the balance task, respectively.

RESULTS

Under the eyes open condition, significant Group*Surface interaction effects were found in the mean velocity of the COP (MVELO), the mean velocity in the medial-lateral (ML) direction (MVELOml) and the 95% confidence ellipse area of the COP (95%AREA-CE). Additionally, significant Group*Surface interaction effect was found in the left orbitofrontal cortex (L-OFC). The significant group effects were detected for three ROI regions, namely the left ventrolateral prefrontal cortex (L-VLPFC), the left dorsolateral prefrontal cortex (L-DLPFC), the right dorsolateral prefrontal cortex (R-DLPFC). Under the eyes closed condition, the significant Group*Surface interaction effects were found in root mean square (RMS), the RMS in the ML direction (RMSml) and the 95%AREA-CE. Additionally, significant group effects were detected for five ROI regions, namely R-VLPFC, the left frontopolar cortex (L-FPC), L-DLPFC, R-DLPFC and R-OFC.

CONCLUSION

Our study emphasizes the role of the PFC in maintaining standing balance control among older adults with MCI, particularly during complex sensory conditions, and provides direct evidence for the role of the PFC during balance control of a clinically relevant measure of balance.

TRIAL REGISTRATION

ChiCTR2100044221, 12/03/2021.

Neuroanatomical substrates of depression in dementia with Lewy bodies and Alzheimer's disease

Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are often associated with depressive symptoms from the prodromal stage. The aim of the present study was to investigate the neuroanatomical correlates of depression in prodromal to mild DLB patients compared with AD patients. Eighty-three DLB patients, 37 AD patients, and 18 healthy volunteers were enrolled in this study. Depression was evaluated with the Mini International Neuropsychiatric Interview (MINI), French version 5.0.0. T1-weighted three-dimensional anatomical images were acquired for all participants. Regression and comparison analyses were conducted using a whole-brain voxel-based morphometry (VBM) approach on the grey matter volume (GMV). DLB patients presented a significantly higher mean MINI score than AD patients (p = 0.004), 30.1% of DLB patients had clinical depression, and 56.6% had a history of depression, while 0% of AD patients had clinical depression and 29.7% had a history of depression. VBM regression analyses revealed negative correlations between the MINI score and the GMV of right prefrontal regions in DLB patients (p < 0.001, uncorrected). Comparison analyses between DLB patients taking and those not taking an antidepressant mainly highlighted a decreased GMV in the bilateral middle/inferior temporal gyrus (p < 0.001, uncorrected) in treated DLB patients. In line with the literature, our behavioral analyses revealed higher depression scores in DLB patients than in AD patients. We also showed that depressive symptoms in DLB are associated with decreased GMV in right prefrontal regions. Treated DLB patients with long-standing depression would be more likely to experience GMV loss in the bilateral middle/inferior temporal cortex. These findings should be taken into account when managing DLB patients.

Alcohol, flexible behavior, and the prefrontal cortex: Functional changes underlying impaired cognitive flexibility

Cognitive flexibility enables individuals to alter their behavior in response to changing environmental demands, facilitating optimal behavior in a dynamic world. The inability to do this, called behavioral inflexibility, is a pervasive behavioral phenotype in alcohol use disorder (AUD), driven by disruptions in cognitive flexibility. Research has repeatedly shown that behavioral inflexibility not only results from alcohol exposure across species but can itself be predictive of future drinking. Like many high-level executive functions, flexible behavior requires healthy functioning of the prefrontal cortex (PFC). The scope of this review addresses two primary themes: first, we outline tasks that have been used to investigate flexibility in the context of AUD or AUD models. We characterize these based on the task features and underlying cognitive processes that differentiate them from one another. We highlight the neural basis of flexibility measures, focusing on the PFC, and how acute or chronic alcohol in humans and non-human animal models impacts flexibility. Second, we consolidate findings on the molecular, physiological and functional changes in the PFC elicited by alcohol, that may contribute to cognitive flexibility deficits seen in AUD. Collectively, this approach identifies several key avenues for future research that will facilitate effective treatments to promote flexible behavior in the context of AUD, to reduce the risk of alcohol related harm, and to improve outcomes following AUD. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".

Attenuated processing of task-irrelevant speech and other auditory stimuli: fMRI evidence from arithmetic tasks

When performing cognitive tasks in noisy conditions, the brain needs to maintain task performance while additionally controlling the processing of task-irrelevant and potentially distracting auditory stimuli. Previous research indicates that a fundamental mechanism by which this control is achieved is the attenuation of task-irrelevant processing, especially in conditions with high task demands. However, it remains unclear whether the processing of complex naturalistic sounds can be modulated as easily as that of simpler ones. To address this issue, the present fMRI study examined whether activity related to task-irrelevant meaningful speech is attenuated similarly as that related to meaningless control sounds (nonsense speech and noise-vocoded, unintelligible sounds). The sounds were presented concurrently with three numerical tasks varying in difficulty: an easy control task requiring no calculation, a 'routine' arithmetic calculation task and a more demanding 'creative' arithmetic task, where solutions are generated to reach a given answer. Consistent with their differing difficulty, the tasks activated fronto-parieto-temporal regions parametrically (creative > routine > control). In bilateral auditory regions, activity related to the speech stimuli decreased as task demands increased. Importantly, however, the attenuation was more pronounced for meaningful than nonsense speech, demonstrating that distractor type can strongly modulate the extent of the attenuation. This also suggests that semantic processing may be especially susceptible to attenuation under conditions with increased task demands. Finally, as this is the first study to utilize the 'creative' arithmetic task, we conducted exploratory analyses to examine its potential in assessing neural processes involved in mathematical problem-solving beyond routine arithmetic.

Static and temporal dynamic changes of intrinsic brain activity in early-onset and adult-onset schizophrenia: a fMRI study of interaction effects

Background

Schizophrenia is characterized by altered static and dynamic spontaneous brain activity. However, the conclusions regarding this are inconsistent. Evidence has revealed that this inconsistency could be due to mixed effects of age of onset.

Methods

We enrolled 66/84 drug-naïve first-episode patients with early-onset/adult-onset schizophrenia (EOS/AOS) and matched normal controls (NCs) (46 adolescents, 73 adults), undergoing resting-state functional magnetic resonance imaging. Two-way ANOVA was used to determine the amplitude of low-frequency fluctuation (ALFF) and dynamic ALFF (dALFF) among the four groups.

Result

Compared to NCs, EOS had a higher ALFF in inferior frontal gyrus bilateral triangular part (IFG-tri), left opercular part (IFG-oper), left orbital part (IFG-orb), and left middle frontal gyrus (MFG). The AOS had a lower ALFF in left IFG-tri, IFG-oper, and lower dALFF in left IFG-tri. Compared to AOS, EOS had a higher ALFF in the left IFG-orb, and MFG, and higher dALFF in IFG-tri. Adult NCs had higher ALFF and dALFF in the prefrontal cortex (PFC) than adolescent NCs. The main effects of diagnosis were found in the PFC, medial temporal structures, cerebrum, visual and sensorimotor networks, the main effects of age were found in the visual and motor networks of ALFF and PFC of dALFF.

Conclusion

Our findings unveil the static and dynamic neural activity mechanisms involved in the interaction between disorder and age in schizophrenia. Our results underscore age-related abnormalities in the neural activity of the PFC, shedding new light on the neurobiological mechanisms underlying the development of schizophrenia. This insight may offer valuable perspectives for the specific treatment of EOS in clinical settings.

Maintenance of Bodily Expressions Modulates Functional Connectivity Between Prefrontal Cortex and Extrastriate Body Area During Working Memory Processing

Background/Objectives: As a form of visual input, bodily expressions can be maintained and manipulated in visual working memory (VWM) over a short period of time. While the prefrontal cortex (PFC) plays an indispensable role in top-down control, it remains largely unclear whether this region also modulates the VWM storage of bodily expressions during a delay period. Therefore, the two primary goals of this study were to examine whether the emotional bodies would elicit heightened brain activity among areas such as the PFC and extrastriate body area (EBA) and whether the emotional effects subsequently modulate the functional connectivity patterns for active maintenance during delay periods. Methods: During functional magnetic resonance imaging (fMRI) scanning, participants performed a delayed-response task in which they were instructed to view and maintain a body stimulus in working memory before emotion categorization (happiness, anger, and neutral). If processing happy and angry bodies consume increased cognitive demands, stronger PFC activation and its functional connectivity with perceptual areas would be observed. Results: Results based on univariate and multivariate analyses conducted on the data collected during stimulus presentation revealed an enhanced processing of the left PFC and left EBA. Importantly, subsequent functional connectivity analyses performed on delayed-period data using a psychophysiological interaction model indicated that functional connectivity between the PFC and EBA increases for happy and angry bodies compared to neutral bodies. Conclusions: The emotion-modulated coupling between the PFC and EBA during maintenance deepens our understanding of the functional organization underlying the VWM processing of bodily information.

Cortical and subcortical substrates of working memory in the right hemisphere: A connectome-based lesion-symptom mapping study

Working Memory (WM) is a cognitive system whose crucial role is to temporarily hold and manipulate information. Early studies suggest that verbal WM is typically associated with left hemisphere (LH) brain regions, while the processing of visuospatial information in WM more specifically depends on the right hemisphere (RH). However, recent evidence suggests a more complex network involving both hemispheres' prefrontal and posterior parietal cortices in these processes. Unfortunately, previous lesion studies often examined only one modality (either verbal, or visuospatial) or one hemisphere, which limits the possible conclusions regarding non-lateralized hemispheric involvement. Using connectome-based lesion-symptom mapping on a large sample of patients with left (LBD) and right (RBD) focal brain damage, we examined whether gray matter damage and white matter disconnections predict deficits of WM updating in an N-back task. Patients were examined with two WM tasks that differed regarding modality (verbal, spatial) and cognitive load (1-back, 2-back). Behavioral outcomes indicated that RBD patients showed significant deficits in WM updating, regardless of task modality or load. This observation was supported by whole-brain voxel-based analysis, revealing associations between WM deficits and gray matter clusters in the RH. Specifically, damage to the right lateral frontal cortex including the brain region homologous to Broca's area was associated with verbal WM deficits, while damage to the right inferior parietal lobe and posterior temporal cortex predicted spatial WM deficits. Additionally, white matter analyses identified severely impacted tracts in the RH, predicting deficits in both verbal and spatial WM. Our findings suggest that the mental manipulation of both verbal and visuospatial information in WM updating relies on the integrity of the RH, irrespective of the specific type of information held in mind.

Procognitive Effects of Adjunctive D-Cycloserine to Intermittent Theta-Burst Stimulation in Major Depressive Disorder: Effets procognitifs de la D-cyclosérine en traitement complémentaire par la stimulation thêta-burst intermittente dans le trouble dépressif caractérisé

OBJECTIVE

Major depressive disorder (MDD) is associated with cognitive impairments that persist despite successful treatment. Transcranial magnetic stimulation is a noninvasive treatment for MDD that is associated with small procognitive effects on working memory and executive function. We hypothesized that pairing stimulation with N-methyl-D-aspartate (NMDA) receptor agonism would enhance the effects of stimulation and its procognitive effects.

METHOD

The effect of NMDA receptor agonism (D-cycloserine, 100 mg) on cognitive performance was tested in two randomized double-blind placebo-controlled trials: (1) acute effects of in the absence of stimulation (n = 20 healthy participants) and (2) a treatment study of individuals with MDD (n = 50) randomized to daily intermittent theta-burst stimulation (iTBS) with placebo or D-cycloserine for 2 weeks. Cognitive function was measured using the THINC-it battery, comprised of the Perceived Deficits Questionnaire, the Choice Reaction Time, the Trail Making Test, the Digit Symbol Substitution Test, and the 1-Back tests.

RESULTS

D-cycloserine had no acute effect on cognition compared to placebo. iTBS + D-cycloserine was associated with significant improvements in subjective cognitive function and correct responses on the 1-Back when compared to iTBS + placebo. Improvements in subjective cognition paralleled depressive symptoms improvement, however 1-Back improvements were not attributable to improvement in depression.

CONCLUSIONS

An intersectional strategy pairing iTBS with NMDA receptor agonism may restore cognitive function in MDD.

Translation and validation of the abbreviated Prefrontal Symptoms Inventory (PSI-20): A tool for assessing prefrontal symptoms in English-speaking populations

This study introduces the translation and validation of the Prefrontal Symptoms Inventory (PSI) into English, aiming to provide an ecologically valid tool for assessing prefrontal symptoms in English-speaking populations in the United States. The prefrontal cortex (PFC) plays a crucial role in executive functions and other higher-order cognitive processes, with dysfunctions in this area associated with various cognitive, emotional and behavioural changes. Despite the existence of established tools like the Dysexecutive Questionnaire (DEX), the PSI addresses limitations found in the literature, presenting a novel ecologically valid tool for assessing prefrontal symptoms. The current study, involving 226 English-speaking participants, lays a foundational step for validating the PSI for use in a new population. Semi-confirmatory factorial analysis revealed a unidimensional structure, mirroring the Spanish version with robust fit indicators. Additionally, in assessing convergent validity, the abbreviated version (PSI-20) exhibited high correlations with DEX scores and moderate correlations with Psychological Stress Scale and General Health Questionnaire-12 scores. These findings align with previous reports, supporting the PSI-20's measurement of similar constructs related to prefrontal cortex activity and mental health components. The results of this study overall highlight the PSI's potential contribution to advancing prefrontal symptom evaluation in clinical and non-clinical settings.

The visual cortex in the blind but not the auditory cortex in the deaf becomes multiple-demand regions

The fate of deprived sensory cortices (visual regions in the blind and auditory regions in the deaf) exemplifies the extent to which experience can change brain regions. These regions are frequently seen to activate during tasks involving other sensory modalities, leading many authors to infer that these regions have started to process sensory information of other modalities. However, such observations can also imply that these regions are now activating in response to any task event, regardless of the sensory modality. Activating in response to task events, irrespective of the sensory modality involved, is a feature of the multiple-demands (MD) network. This is a set of regions within the frontal and parietal cortices that activate in response to any kind of control demand. Thus, demands as diverse as attention, perceptual difficulty, rule-switching, updating working memory, inhibiting responses, decision-making and difficult arithmetic all activate the same set of regions that are thought to instantiate domain-general cognitive control and underpin fluid intelligence. We investigated whether deprived sensory cortices, or foci within them, become part of the MD network. We tested whether the same foci within the visual regions of the blind and auditory regions of the deaf activated in response to different control demands. We found that control demands related to updating auditory working memory, difficult tactile decisions, time-duration judgments and sensorimotor speed all activated the entire bilateral occipital regions in the blind but not in the sighted. These occipital regions in the blind were the only regions outside the canonical frontoparietal MD regions to show such activation in response to multiple control demands. Furthermore, compared with the sighted, these occipital regions in the blind had higher functional connectivity with frontoparietal MD regions. Early deaf, in contrast, did not activate their auditory regions in response to different control demands, showing that auditory regions do not become MD regions in the deaf. We suggest that visual regions in the blind do not take a new sensory role but become part of the MD network, and this is not a response of all deprived sensory cortices but a feature unique to the visual regions.

Timescales of learning in prefrontal cortex

The lateral prefrontal cortex (PFC) in humans and other primates is critical for immediate, goal-directed behaviour and working memory, which are classically considered distinct from the cognitive and neural circuits that support long-term learning and memory. Over the past few years, a reconsideration of this textbook perspective has emerged, in that different timescales of memory-guided behaviour are in constant interaction during the pursuit of immediate goals. Here, we will first detail how neural activity related to the shortest timescales of goal-directed behaviour (which requires maintenance of current states and goals in working memory) is sculpted by long-term knowledge and learning - that is, how the past informs present behaviour. Then, we will outline how learning across different timescales (from seconds to years) drives plasticity in the primate lateral PFC, from single neuron firing rates to mesoscale neuroimaging activity patterns. Finally, we will review how, over days and months of learning, dense local and long-range connectivity patterns in PFC facilitate longer-lasting changes in population activity by changing synaptic weights and recruiting additional neural resources to inform future behaviour. Our Review sheds light on how the machinery of plasticity in PFC circuits facilitates the integration of learned experiences across time to best guide adaptive behaviour.

Key Roles of CACNA1C/Cav1.2 and CALB1/Calbindin in Prefrontal Neurons Altered in Cognitive Disorders

Importance

The risk of mental disorders is consistently associated with variants in CACNA1C (L-type calcium channel Cav1.2) but it is not known why these channels are critical to cognition, and whether they affect the layer III pyramidal cells in the dorsolateral prefrontal cortex that are especially vulnerable in cognitive disorders.

Objective

To examine the molecular mechanisms expressed in layer III pyramidal cells in primate dorsolateral prefrontal cortices.

Design, Setting, and Participants

The design included transcriptomic analyses from human and macaque dorsolateral prefrontal cortex, and connectivity, protein expression, physiology, and cognitive behavior in macaques. The research was performed in academic laboratories at Yale, Harvard, Princeton, and the University of Pittsburgh. As dorsolateral prefrontal cortex only exists in primates, the work evaluated humans and macaques.

Main Outcomes and Measures

Outcome measures included transcriptomic signatures of human and macaque pyramidal cells, protein expression and interactions in layer III macaque pyramidal cells using light and electron microscopy, changes in neuronal firing during spatial working memory, and working memory performance following pharmacological treatments.

Results

Layer III pyramidal cells in dorsolateral prefrontal cortex coexpress a constellation of calcium-related proteins, delineated by CALB1 (calbindin), and high levels of CACNA1C (Cav1.2), GRIN2B (NMDA receptor GluN2B), and KCNN3 (SK3 potassium channel), concentrated in dendritic spines near the calcium-storing smooth endoplasmic reticulum. L-type calcium channels influenced neuronal firing needed for working memory, where either blockade or increased drive by β1-adrenoceptors, reduced neuronal firing by a mean (SD) 37.3% (5.5%) or 40% (6.3%), respectively, the latter via SK potassium channel opening. An L-type calcium channel blocker or β1-adrenoceptor antagonist protected working memory from stress.

Conclusions and Relevance

The layer III pyramidal cells in the dorsolateral prefrontal cortex especially vulnerable in cognitive disorders differentially express calbindin and a constellation of calcium-related proteins including L-type calcium channels Cav1.2 (CACNA1C), GluN2B-NMDA receptors (GRIN2B), and SK3 potassium channels (KCNN3), which influence memory-related neuronal firing. The finding that either inadequate or excessive L-type calcium channel activation reduced neuronal firing explains why either loss- or gain-of-function variants in CACNA1C were associated with increased risk of cognitive disorders. The selective expression of calbindin in these pyramidal cells highlights the importance of regulatory mechanisms in neurons with high calcium signaling, consistent with Alzheimer tau pathology emerging when calbindin is lost with age and/or inflammation.

Age-related changes in the architecture and biochemical markers levels in motor-related cortical areas of SHR rats-an ADHD animal model

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder whose exact pathophysiology has not been fully understood yet. Numerous studies have suggested disruptions in the cellular architecture and neuronal activity within brain structures of individuals with ADHD, accompanied by imbalances in the immune system, oxidative stress, and metabolism.

Methods

This study aims to assess two functionally and histologically distinct brain areas involved in motor control and coordination: the motor cortex (MC) and prefrontal cortex (PFC). Namely, the morphometric analysis of the MC throughout the developmental stages of Spontaneously Hypertensive Rats (SHRs) and Wistar Kyoto Rats (WKYs). Additionally, the study aimed to investigate the levels and activities of specific immune, oxidative stress, and metabolic markers in the PFC of juvenile and maturing SHRs in comparison to WKYs.

Results

The most significant MC volume reductions occurred in juvenile SHRs, accompanied by alterations in neuronal density in these brain areas compared to WKYs. Furthermore, juvenile SHRs exhibit heightened levels and activity of various markers, including interleukin-1α (IL-1α), IL-6, serine/threonine-protein mammalian target of rapamycin, RAC-alpha serine/threonine-protein kinase, glucocorticoid receptor β, malondialdehyde, sulfhydryl groups, superoxide dismutase, peroxidase, glutathione reductase, glutathione S-transferase, glucose, fructosamine, iron, lactic acid, alanine, aspartate transaminase, and lactate dehydrogenase.

Discussion

Significant changes in the MC morphometry and elevated levels of inflammatory, oxidative, and metabolic markers in PFC might be associated with disrupted brain development and maturation in ADHD.

Intracranial Directed Connectivity Links Subregions of the Prefrontal Cortex to Major Depression

Understanding the neural basis of major depressive disorder (MDD) is vital to guiding neuromodulatory treatments. The available evidence supports the hypothesis that MDD is fundamentally a disease of cortical disinhibition, where breakdowns of inhibitory neural systems lead to diminished emotion regulation and intrusive ruminations. Recent research also points towards network changes in the brain, especially within the prefrontal cortex (PFC), as primary sources of MDD etiology. However, due to limitations in spatiotemporal resolution and clinical opportunities for intracranial recordings, this hypothesis has not been directly tested. We recorded intracranial EEG from the dorsolateral (dlPFC), orbitofrontal (OFC), and anterior cingulate cortices (ACC) in neurosurgical patients with MDD. We measured daily fluctuations in self-reported depression severity alongside directed connectivity between these PFC subregions. We focused primarily on delta oscillations (1-3 Hz), which have been linked to GABAergic inhibitory control and intracortical communication. Depression symptoms worsened when connectivity within the left vs. right PFC became imbalanced. In the left hemisphere, all directed connectivity towards the ACC, from the dlPFC and OFC, was positively correlated with depression severity. In the right hemisphere, directed connectivity between the OFC and dlPFC increased with depression severity as well. This is the first evidence that delta oscillations flowing between prefrontal subregions transiently increase intensity when people are experiencing more negative mood. These findings support the overarching hypothesis that MDD worsens with prefrontal disinhibition.

Late recovery from acquired sociopathy in a boy with a left frontopolar injury

The long-term outcome of acquired sociopathy with preservation of cognition is still unknown. Here, we present the long-term outcome of a severe antisocial change in personality that followed a traumatic left frontopolar injury in a previously gentle, loving, and introverted adolescent. Nine years after the accident, antisocial behaviors gradually became sporadic, while, at the same time, the patient's sense of responsibility and care for his family increased. He became more extroverted and assertive, yet flexible enough to deal with the hardships of his poor socioeconomic background. His "new personality" was, in fact, more adjusted than ever. We argue that his late recovery reflected a conjunction of factors, especially (i) his early age, (ii) the static nature of the injury, (iii) the preservation of the ventromedial frontal cortices and related basal forebrain regions, and (iv) an unusual asymmetric representation of social cognition in the cerebral hemispheres. Our case and the case of Franz Binz indicate that social recovery is possible after gross prefrontal injuries, even when they are no longer expected to occur. It also emphasizes the importance of reporting on the long-term follow-up of brain-injured patients.

Metacognition as a window into subjective affective experience

When patients seek professional help for mental disorders, they often do so because of troubling subjective affective experiences. While these subjective states are at the center of the patient's symptomatology, scientific tools for studying them and their cognitive antecedents are limited. Here, we explore the use of concepts and analytic tools from the science of consciousness, a field of research that has faced similar challenges in having to develop robust empirical methods for addressing a phenomenon that has been considered difficult to pin down experimentally. One important strand is the operationalization of some relevant processes in terms of metacognition and confidence ratings, which can be rigorously studied in both humans and animals. By assessing subjective experience with similar approaches, we hope to develop new scientific approaches for studying affective processes and promoting psychological resilience in the face of debilitating emotional experiences.

Connectomic insights into the impact of 1p/19q co-deletion in dominant hemisphere insular glioma patients

Objectives

This study aimed to elucidate the influences of 1p/19q co-deletion on structural connectivity alterations in patients with dominant hemisphere insular diffuse gliomas.

Methods

We incorporated 32 cases of left insular gliomas and 20 healthy controls for this study. Using diffusion MRI, we applied correlational tractography, differential tractography, and graph theoretical analysis to explore the potential connectivity associated with 1p/19q co-deletion.

Results

The study revealed that the quantitative anisotropy (QA) of key deep medial fiber tracts, including the anterior thalamic radiation, superior thalamic radiation, fornix, and cingulum, had significant negative associations with 1p/19q co-deletion (FDR = 4.72 × 10-5). These tracts are crucial in maintaining the integrity of brain networks. Differential analysis further supported these findings (FWER-corrected p < 0.05). The 1p/19q non-co-deletion group exhibited significantly higher clustering coefficients (FDR-corrected p < 0.05) and reduced betweenness centrality (FDR-corrected p < 0.05) in regions around the tumor compared to HC group. Graph theoretical analysis indicated that non-co-deletion patients had increased local clustering and decreased betweenness centrality in peritumoral brain regions compared to co-deletion patients and healthy controls (FDR-corrected p < 0.05). Additionally, despite not being significant through correction, patients with 1p/19q co-deletion exhibited lower trends in weighted average clustering coefficient, transitivity, small worldness, and global efficiency, while showing higher tendencies in weighted path length compared to patients without the co-deletion.

Conclusion

The findings of this study underline the significant role of 1p/19q co-deletion in altering structural connectivity in insular glioma patients. These alterations in brain networks could have profound implications for the neural functionality in patients with dominant hemisphere insular gliomas.

Neural dynamics underlying minute-timescale persistent behavior in the human brain

The ability to pursue long-term goals relies on a representations of task context that can both be maintained over long periods of time and switched flexibly when goals change. Little is known about the neural substrate for such minute-scale maintenance of task sets. Utilizing recordings in neurosurgical patients, we examined how groups of neurons in the human medial frontal cortex and hippocampus represent task contexts. When cued explicitly, task context was encoded in both brain areas and changed rapidly at task boundaries. Hippocampus exhibited a temporally dynamic code with fast decorrelation over time, preventing cross-temporal generalization. Medial frontal cortex exhibited a static code that decorrelated slowly, allowing generalization across minutes of time. When task context needed to be inferred as a latent variable, hippocampus encoded task context with a static code. These findings reveal two possible regimes for encoding minute-scale task-context representations that were engaged differently based on task demands.

Superagers Resist Typical Age-Related White Matter Structural Changes

Superagers are elderly individuals with the memory ability of people 30 years younger and provide evidence that age-related cognitive decline is not inevitable. In a sample of 64 superagers (mean age, 81.9; 59% women) and 55 typical older adults (mean age, 82.4; 64% women) from the Vallecas Project, we studied, cross-sectionally and longitudinally over 5 years with yearly follow-ups, the global cerebral white matter status as well as region-specific white matter microstructure assessment derived from diffusivity measures. Superagers and typical older adults showed no difference in global white matter health (total white matter volume, Fazekas score, and lesions volume) cross-sectionally or longitudinally. However, analyses of diffusion parameters revealed the better white matter microstructure in superagers than in typical older adults. Cross-sectional differences showed higher fractional anisotropy (FA) in superagers mostly in frontal fibers and lower mean diffusivity (MD) in most white matter tracts, expressed as an anteroposterior gradient with greater group differences in anterior tracts. FA decrease over time is slower in superagers than in typical older adults in all white matter tracts assessed, which is mirrored by MD increases over time being slower in superagers than in typical older adults in all white matter tracts except for the corticospinal tract, the uncinate fasciculus, and the forceps minor. The better preservation of white matter microstructure in superagers relative to typical older adults supports resistance to age-related brain structural changes as a mechanism underpinning the remarkable memory capacity of superagers, while their regional aging pattern is in line with the last-in-first-out hypothesis.

Kynurenic acid inflammatory signaling expands in primates and impairs prefrontal cortical cognition

Cognitive deficits from dorsolateral prefrontal cortex (dlPFC) dysfunction are common in neuroinflammatory disorders, including long-COVID, schizophrenia and Alzheimer's disease, and have been correlated with kynurenine inflammatory signaling. Kynurenine is further metabolized to kynurenic acid (KYNA) in brain, where it blocks NMDA and α7-nicotinic receptors (nic-α7Rs). These receptors are essential for neurotransmission in dlPFC, suggesting that KYNA may cause higher cognitive deficits in these disorders. The current study found that KYNA and its synthetic enzyme, KAT II, have greatly expanded expression in primate dlPFC in both glia and neurons. Local application of KYNA onto dlPFC neurons markedly reduced the delay-related firing needed for working memory via actions at NMDA and nic-α7Rs, while inhibition of KAT II enhanced neuronal firing in aged macaques. Systemic administration of agents that reduce KYNA production similarly improved cognitive performance in aged monkeys, suggesting a therapeutic avenue for the treatment of cognitive deficits in neuroinflammatory disorders.

A genome-wide association study reveals a polygenic architecture of speech-in-noise deficits in individuals with self-reported normal hearing

Speech-in-noise (SIN) perception is a primary complaint of individuals with audiometric hearing loss. SIN performance varies drastically, even among individuals with normal hearing. The present genome-wide association study (GWAS) investigated the genetic basis of SIN deficits in individuals with self-reported normal hearing in quiet situations. GWAS was performed on 279,911 individuals from the UB Biobank cohort, with 58,847 reporting SIN deficits despite reporting normal hearing in quiet. GWAS identified 996 single nucleotide polymorphisms (SNPs), achieving significance (p < 5*10-8) across four genomic loci. 720 SNPs across 21 loci achieved suggestive significance (p < 10-6). GWAS signals were enriched in brain tissues, such as the anterior cingulate cortex, dorsolateral prefrontal cortex, entorhinal cortex, frontal cortex, hippocampus, and inferior temporal cortex. Cochlear cell types revealed no significant association with SIN deficits. SIN deficits were associated with various health traits, including neuropsychiatric, sensory, cognitive, metabolic, cardiovascular, and inflammatory conditions. A replication analysis was conducted on 242 healthy young adults. Self-reported speech perception, hearing thresholds (0.25-16 kHz), and distortion product otoacoustic emissions (1-16 kHz) were utilized for the replication analysis. 73 SNPs were replicated with a self-reported speech perception measure. 211 SNPs were replicated with at least one and 66 with at least two audiological measures. 12 SNPs near or within MAPT, GRM3, and HLA-DQA1 were replicated for all audiological measures. The present study highlighted a polygenic architecture underlying SIN deficits in individuals with self-reported normal hearing.

Same, Same but Different? A Multi-Method Review of the Processes Underlying Executive Control

Attention, working memory, and executive control are commonly considered distinct cognitive functions with important reciprocal interactions. Yet, longstanding evidence from lesion studies has demonstrated both overlap and dissociation in their behavioural expression and anatomical underpinnings, suggesting that a lower dimensional framework could be employed to further identify processes supporting goal-directed behaviour. Here, we describe the anatomical and functional correspondence between attention, working memory, and executive control by providing an overview of cognitive models, as well as recent data from lesion studies, invasive and non-invasive multimodal neuroimaging and brain stimulation. We emphasize the benefits of considering converging evidence from multiple methodologies centred on the identification of brain mechanisms supporting goal-driven behaviour. We propose that expanding on this approach should enable the construction of a comprehensive anatomo-functional framework with testable new hypotheses, and aid clinical neuroscience to intervene on impairments of executive functions.

Prefrontal activity during IOWA Gambling Task in young adult women

This study aims to investigate the relationships between personality traits of impulsivity, using the UPPS-P Impulsive Behaviour Scales shortened version, and prefrontal cortex (PFC) activity during the IOWA Gambling Task (IGT) in young adult women. The study included a sample of 83 young, healthy females (19.8 ± 1.4 years), who voluntarily took part in the study. Repeated measures analysis during the IGT revealed a significant increase in HbO (all p <.001; ηp2 >.31) and a decrease in Hbr (all p <.003; ηp2 >.08) in all prefrontal quadrants. This increase in oxygenation occurs primarily during the choice period under ambiguity (r =.23; p =.039). Additionally, there was a significant linear decrease in selecting the decks associated with a high frequency of losses (p <.001), while the favorable deck with low losses showed a linear increase (F = 12.96; p <.001). Notably, discrepancies were found between UPPS-P and IGT impulsivity ratings. The Lack of Perseverance and Lack of Premeditation scales from the UPPS-P were identified as significant predictors of HbO levels, mainly in the two quadrants of the left hemisphere's, lateral (adjusted R2 =.23; p <.001; f2 =.34) and rostral (adjusted R2 =.13; p <.002; f2 =.17). These findings suggest that young adult women predominantly adopt a punishment-avoidance strategy during IGT, exhibiting increased activation in the left hemisphere, especially during the task's initial phase characterized by ambiguity.

Physical activity and self-efficacy in college students: the mediating role of grit and the moderating role of gender

Background

There is a paucity of knowledge concerning the psychological variables that serve to facilitate the connection between physical activity and self-efficacy, and the factors capable of moderating these pathways. This study aimed to examine the relationship between physical activity and self-efficacy among college students, with a focus on the mediating effect of grit and the moderating effect of gender.

Methods

This study recruited 3,228 undergraduate students from a university in Shanghai, China. They completed the General Self-Efficacy Scale, the Short Grit Scale, and the International Physical Activity Questionnaire. Statistical analysis was conducted using SPSS 26.0 and the Process v4.0 plugin.

Results

Physical activity had both a direct effect on self-efficacy (β = 0.07, 95% CI [0.04-0.11]) and an indirect effect through the two dimensions of grit: perseverance of effort (β = 0.06, 95% CI [0.04-0.07]) and consistency of interest (β = 0.03, 95% CI [0.02-0.04]). The mediating effect explained 53.27% of the total effect. Furthermore, gender moderated the relationship between perseverance of effort and self-efficacy, with a stronger effect observed in males (β = 0.08, t = 3.27, p < 0.01).

Conclusion

The results revealed that grit is an underlying psychological mechanism that links physical activity and self-efficacy. Moreover, gender moderates the effect of perseverance of effort on self-efficacy, with a stronger effect observed in males. These findings have practical implications for educators to design tailored physical activity interventions that foster grit and self-efficacy among college students.

Neurocysticercosis: Isolated Lesion in the Left Middle Frontal Gyrus

OBJECTIVE

Neurocysticercosis (NCC) is one of the most common parasitic infections of the central nervous system. We present a case study of a 21-year-old African man with an isolated NCC lesion to the left middle frontal gyrus, which is also known as the dorsolateral prefrontal cortex (dlPFC).

METHOD

A neuropsychological evaluation was requested by the patient's inpatient psychiatry team regarding worsening attention and depressive symptoms approximately 6 months after NCC diagnosis and treatment.

RESULTS

Neuropsychological findings revealed deficits in the aspects of executive functioning, attention, working memory, and significant depressive symptoms.

CONCLUSION

To our knowledge, this is the first case study of its kind demonstrating deficits in cognitive functioning consistent with the dlPFC lesion location. Sociocultural and linguistic considerations, clinical findings, and limitations are discussed.

Interruption Value Type and Source Matter in Different Phases of an Interruption Process: Emotional/Cognitive Impact and Neural Evidence

OBJECTIVE

To examine the effect of interruption value type (utilitarian, hedonic) and source (external, internal) in different phases of an interruption process.

BACKGROUND

Prior studies on interruption mostly focused on the cognitive outcomes of utilitarian interruptions. Hedonic interruptions are common in life; however, they are not sufficiently explored through research. Hedonic value is closely associated with emotional experiences, and, in turn, influences behaviors. Moreover, the way the effect of values is moderated by interruptions initiated by intrinsic motives is worth exploring.

METHOD

A 2 × 2 mixed design experiment was conducted with 48 participants who were asked to respond to instant messages during the writing task. The interruption value was induced by work or non-work tasks. The interruption source was manipulated by providing an alert. Functional near-infrared spectroscopy, behavioral data, and subjective measurements were collected and analyzed.

RESULTS

Hedonic interruptions increased emotional valence, while utilitarian interruptions decreased it. These effects were strengthened by internal interruptions. The effect of interruption value type on work exhaustion was also moderated by the source. Interruption value type and source influenced the attention allocation before an interruption occurred. Hedonic interruptions led to longer resumption lags, whereas utilitarian interruptions required longer interruption durations. Internal interruptions led to improved performance in the resumed task.

CONCLUSION

Interruption source modulate the effect of interruption value type, especially on emotional experience and attention allocation before an interruption occurs.

APPLICATION

Self-initiated hedonic interruptions have emotional benefits, while alerts for utilitarian interruptions will improve attention on the main task before interruptions.

Multiplexed Levels of Cognitive Control through Delta and Theta Neural Oscillations

Cognitive control allows behavior to be guided according to environmental contexts and internal goals. During cognitive control tasks, fMRI analyses typically reveal increased activation in frontal and parietal networks, and EEG analyses reveal increased amplitude of neural oscillations in the delta/theta band (2-3, 4-7 Hz) in frontal electrodes. Previous studies proposed that theta-band activity reflects the maintenance of rules associating stimuli to appropriate actions (i.e., the rule set), whereas delta synchrony is specifically associated with the control over the context for when to apply a set of rules (i.e., the rule abstraction). We tested these predictions using EEG and fMRI data collected during the performance of a hierarchical cognitive control task that manipulated the level of abstraction of task rules and their set-size. Our results show a clear separation of delta and theta oscillations in the control of rule abstraction and of stimulus-action associations, respectively, in distinct frontoparietal association networks. These findings support a model by which frontoparietal networks operate through dynamic, multiplexed neural processes.

β1-adrenoceptor expression on GABAergic interneurons in primate dorsolateral prefrontal cortex: potential role in stress-induced cognitive dysfunction

Uncontrollable stress exposure impairs working memory and reduces the firing of dorsolateral prefrontal cortex (dlPFC) "Delay cells", involving high levels of norepinephrine and dopamine release. Previous work has focused on catecholamine actions on dlPFC pyramidal cells, but inhibitory interneurons may contribute as well. The current study combined immunohistochemistry and multi-scale microscopy with iontophoretic physiology and behavioral analyses to examine the effects of beta1-noradrenergic receptors (β1-ARs) on inhibitory neurons in layer III dlPFC. We found β1-AR robustly expressed on different classes of inhibitory neurons labeled by the calcium-binding proteins calbindin (CB), calretinin (CR), and parvalbumin (PV). Immunoelectron microscopy confirmed β1-AR expression on the plasma membrane of PV-expressing dendrites. PV interneurons can be identified as fast-spiking (FS) in physiological recordings, and thus were studied in macaques performing a working memory task. Iontophoresis of a β1-AR agonist had a mixed effect, increasing the firing of a subset and decreasing the firing of others, likely reflecting loss of firing of the entire microcircuit. This loss of overall firing likely contributes to impaired working memory during stress, as pretreatment with the selective β1-AR antagonist, nebivolol, prevented stress-induced working memory deficits. Thus, selective β1-AR antagonists may be helpful in treating stress-related disorders.

Mood moderates the effects of prefrontal tDCS on executive functions: A meta-analysis testing the affective state-dependency hypothesis

BACKGROUND

In recent decades, numerous studies have investigated the effects of transcranial direct current stimulation (tDCS) on cognitive functioning. However, results of these studies frequently display inconsistency and pose challenges regarding replicability. The present work aimed at testing the hypothesis of mood as potential moderator of prefrontal tDCS effects on executive functions (EF). This hypothesis refers to the relationship between mood and EF, as well as to the association of mood with the dorsolateral prefrontal cortex (dlPFC) activity.

METHODS

We conducted a meta-analysis of 11 articles where the dlPFC was stimulated with anodal tDCS, EF were measured, and mood was assessed prior to the stimulation. We then conducted a meta-regression to examine whether mood moderated the tDCS effects on EF.

RESULTS

While no significant effect of tDCS on EF emerged from the meta-analysis, the meta-regression indicated that mood plays a significant role as moderator, with greater tDCS effects on EF in individuals with higher depressive symptoms.

LIMITATIONS

The limited number of studies included, the heterogeneous samples considered, and the limited generalizability to other non-invasive brain stimulation techniques and affective states.

CONCLUSIONS

Findings suggest that evaluating mood prior to stimulation could increase the sensitivity and specificity of tDCS application, and provide the first meta-analytic evidence in favor of the affective state-dependency hypothesis.

Why did humans surpass all other primates? Are our brains so different? Part 2

The second part of this review is an attempt to explain why only Homo sapiens developed language. It should be remarked that this review is based on the opinion of a clinical neurologist and does not intend to go beyond an overview of this complex topic. The progressive development of language was probably due to the expansion of the prefrontal cortex (PFC) and its networks. PFC is the largest area of the human cerebral cortex and is much more expanded in humans than in other primates. To achieve language, several other functions should have been attained, including abstraction, reasoning, expanded working memory, and executive functions. All these functions are strongly related to PFC and language had a profound retroactive impact on them all. Language and culture produce anatomic and physiological modifications in the brain. Learning to read is presented as an example of how culture modifies the brain.

Cognitive function and work resilience of healthcare professionals: A comparative cross-sectional study

BACKGROUND

Healthcare professionals (HCPs) face a variety of work-related stressors that have impact on their mental health and cognitive performance. Work resilience is a psychological resource that helps workers cope with stress and prevents unfavorable psychological impact. The aim of this study was to assess the associations between working as HCPs and cognitive function as well as work resilience.

MATERIALS AND METHODS

This was a comparative cross-sectional study conducted among HCPs at Suez Canal University Hospital in Ismailia Governorate, Egypt, during April 2023 to August 2023. Two hundred and thirty-five HCPs and 107 administrative employees (Admins) were invited to participate in this study. A self-administered questionnaire was used to obtain sociodemographic and other relavent data. Cognitive function was assessed with the Mini-Mental State Examination test; work resilience was assessed with the Brief Resilience Scale; and psychological distress was measured with the Depression, Anxiety, and Stress Scale - 21-items (DASS-21) scale. Statistical significance was determined by Mann Whitney U-test for continuous variables, and Chi-square test or Fisher's exact, as appropriate, for categorical variables. Multiple logistic regression models were employed to determine associations between the main outcomes (cognitive impairment and low resilience) and the main covariate (working as HCPs vs. Admins), adjusting for all potential confounders.

RESULTS

HCPs showed a significantly greater cognitive impairment, less resilience, and DASS-21 than the Admins. The odds of impaired cognitive function in HCPs were significantly higher than the Admins (odds ratio [OR]: 4.45, 95% confidence interval [CI]: 1.27-15.67, P = 0.020), adjusted for all potential covariates. Similarly, the odds of low resilience in HCPs were significantly higher than Admins (OR: 5.81, 95% CI: 2.72-12.44, P < 0.001), adjusted for all potential covariates. However, the adjusted association between impaired cognitive function and low resilience was not statistically significant (OR: 0.55, 95% CI: 0.23-1.33, P = 0.185).

CONCLUSION

HCPs had significantly impaired cognitive function and low work resilience. Workplace policies and interventions to control depression, stress, and anxiety are required as it is the encouragement of physical activity. Programs that combine positive coping skills training (e.g., relaxation training, positive thinking, and problem solving) with resilience-building interventions (e.g., taking a proactive approach to solving problems, being flexible and adaptive) should be developed, with special attention to HCPs who have a higher sense of self-efficacy.

Spillover and spillback: Linking daily job insecurity to next-day counterproductive work behavior

Spillover effect theory posits that work stressors can have spillover effects into workers' home lives. Although job insecurity spillover into the home domain has been explored extensively, potential spillback effects into the work domain have not. We posit that daily job insecurity represents a negative subjective perception that can spillover into the home domain and lead to insomnia, which will damage the recovery of self-regulatory resources and make employees unable to regulate their own behavior, ultimately resulting in next-day counterproductive work behavior. We hypothesized that self-compassion, as an individual trait, weakens the spillover effect of job insecurity and moderates the indirect effect of job insecurity on next-day counterproductive work behavior via insomnia. Our analyses of data collected from 132 full-time employees across 10 consecutive working days showed that insomnia mediates the relationship between daily job insecurity and next-day counterproductive work behavior, and further showed that this relationship was moderated by self-compassion. Overall, our research captures the cascading effects of daily job insecurity and contributes to a more complete understanding of the spillover effect of job insecurity.

Efficacy of transcranial direct current stimulation for treating anhedonia in patients with depression: A randomized, double-blind, sham-controlled clinical trial

BACKGROUND

Anhedonia, the core symptom of major depressive disorder (MDD), is highly prevalent in patients with depression. Anhedonia is associated with low efficacy of drug treatment, high suicide rates, and poor social function. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technology that uses constant, low-intensity direct current to treat MDD by regulating cortical activity and neuronal excitability. However, little is known about the efficacy of tDCS for treating anhedonia in patients with depression, and even the existing results of clinical trials are conflicting. In addition, there is no consensus on what brain regions should be targeted by tDCS during the treatment of anhedonia in patients with depression.

OBJECTIVE

This study aimed to evaluate the efficacy and safety of tDCS over the left dorsolateral prefrontal cortex (DLPFC) and right orbitofrontal cortex (OFC) in the improvement of anhedonia in patients with depression and finally identified suitable brain regions to be stimulated during treatment.

METHODS

This randomized, double-blind, sham-controlled clinical trial recruited 70 patients with anhedonia and depressive episodes. Patients were randomly assigned to three groups according to the stimulation site: right orbitofrontal cortex (OFC), left dorsolateral prefrontal cortex (DLPFC), and sham stimulation. Each group received twelve 20-min interventions (ten as primary treatment and two for consolidation). The primary outcome was a decrease in Snaith-Hamilton Pleasure Scale (SHAPS) scores after primary treatment. Evaluations were performed at baseline, post-treatment, and 8-week follow-up.

RESULTS

The depression mood of the three groups of patients at each time point was better than the baseline, but there was no significant difference in the efficacy between the groups (p>0.05). On the basis of the improvement of depression, this study found that tDCS of the DLPFC significantly improved anhedonia (p = 0.028) after primary treatment (2 weeks), and tDCS of the DLPFC and OFC significantly improved social functioning (p = 0.005) at 8-week follow-up.

LIMITATIONS

The sample size of this study was small, with only about 23/24 patients in each group completing the intervention assessments; due to the impact of the COVID-19 epidemic, data analysis was limited by the lack of patients during the follow-up period.

CONCLUSIONS

tDCS of the DLPFC significantly improves anhedonia in depressed patients and is thus a potential adjuvant therapy for anhedonia in these patients.