Emotion, cognition, and mental state representation in amygdala and prefrontal cortex

Pharmacological restoration of anti-nociceptive functions in the prefrontal cortex relieves chronic pain

Chronic pain affects one in four adults, and effective non-sedating and non-addictive treatments are urgently needed. Chronic pain causes maladaptive changes in the cerebral cortex, which can lead to impaired endogenous nociceptive processing. However, it is not yet clear if drugs that restore endogenous cortical regulation could provide an effective therapeutic strategy for chronic pain. Here, we studied the nociceptive response of neurons in the prelimbic region of the prefrontal cortex (PL-PFC) in freely behaving rats using a spared nerve injury (SNI) model of chronic pain, and the impact of AMPAkines, a class of drugs that increase central glutamate signaling, on such response. We found that neurons in the PL-PFC increase their firing rates in response to noxious stimulations; chronic neuropathic pain, however, suppressed this important cortical pain response. Meanwhile, CX546, a well-known AMPAkine, restored the anti-nociceptive response of PL-PFC neurons in the chronic pain condition. In addition, both systemic administration and direct delivery of CX546 into the PL-PFC inhibited symptoms of chronic pain, whereas optogenetic inactivation of the PFC neurons or administration of AMPA receptor antagonists in the PL-PFC blocked the anti-nociceptive effects of CX546. These results indicate that restoration of the endogenous anti-nociceptive functions in the PL-PFC by pharmacological agents such as AMPAkines constitutes a successful strategy to treat chronic neuropathic pain.

Acupuncture for Psychological Disorders Caused by Chronic Pain: A Review and Future Directions

Accumulating evidence supports an association between chronic pain and psychological disorders, a connection that seems to be bidirectional. Treating both the pain and psychological conditions together is essential for effective treatment outcomes. Acupuncture is a somatosensory-guided mind-body therapy that can tackle the multidimensional nature of pain with fewer or no serious adverse effects. In this review, we discuss the use of acupuncture in some conditions with a high incidence of psychological disorders caused by chronic pain: headache, musculoskeletal pain, low back pain, and cancer pain, focusing on the effect and potential mechanisms of acupuncture. Overall clinical studies indicated that acupuncture might effectively contribute to management of psychological disorders caused by chronic pain. Mechanistic studies showed that acupuncture significantly alleviated such psychological disorders by regulating the activity of amygdala and insula, and regulating functional connectivity of insular and limbic regions/medial prefrontal cortex in humans and the corresponding animal models. In addition, 5-HT in the dorsal raphe nucleus, opioid receptors in the cingulate cortex, and plasma met-enkephalin are involved in acupuncture relief of pain and psychological symptoms. Substantial evidences from animal and human research support a beneficial effect of acupuncture in psychological disorders caused by chronic pain.

Dysfunction of Resting-State Functional Connectivity of Amygdala Subregions in Drug-Naïve Patients With Generalized Anxiety Disorder

Objective: Although previous studies have reported on disrupted amygdala subregional functional connectivity in generalized anxiety disorder (GAD), most of these studies were conducted in GAD patients with comorbidities or with drug treatment. Besides, whether/how the amygdala subregional functional networks were associated with state and trait anxiety is still largely unknown. Methods: Resting-state functional connectivity of amygdala subregions, including basolateral amygdala (BLA) and centromedial amygdala (CMA) as seed, were mapped and compared between 37 drug-naïve, non-comorbidity GAD patients and 31 age- and sex-matched healthy controls (HCs). Relationships between amygdala subregional network dysfunctions and state/trait anxiety were examined using partial correlation analyses. Results: Relative to HCs, GAD patients showed weaker functional connectivity of the left BLA with anterior cingulate/medial prefrontal cortices. Significantly increased functional connectivity of right BLA and CMA with superior temporal gyrus and insula were also identified in GAD patients. Furthermore, these functional connectivities showed correlations with state and trait anxiety scores. Conclusions: These findings revealed abnormal functional coupling of amygdala subregions in GAD patients with regions involved in fear processing and emotion regulation, including anterior cingulate/medial prefrontal cortex and superior temporal gyrus, which provide the unique biological markers for GAD and facilitating the future accurate clinical diagnosis and target treatment.

White Matter Connectivity in Incident Mild Cognitive Impairment: A Diffusion Spectrum Imaging Study of World Trade Center Responders at Midlife

BACKGROUND

Individuals who participated in response efforts at the World Trade Center (WTC) following 9/11/2001 are experiencing elevated incidence of mild cognitive impairment (MCI) at midlife.

OBJECTIVE

We hypothesized that white matter connectivity measured using diffusion spectrum imaging (DSI) would be restructured in WTC responders with MCI versus cognitively unimpaired responders.

METHODS

Twenty responders (mean age 56; 10 MCI/10 unimpaired) recruited from an epidemiological study were characterized using NIA-AA criteria alongside controls matched on demographics (age/sex/occupation/race/education). Axial DSI was acquired on a 3T Siemen's Biograph mMR scanner (12-channel head coil) using a multi-band diffusion sequence. Connectometry examined whole-brain tract-level differences in white matter integrity. Fractional anisotropy (FA), mean diffusivity (MD), and quantified anisotropy were extracted for region of interest (ROI) analyses using the Desikan-Killiany atlas.

RESULTS

Connectometry identified both increased and decreased connectivity within regions of the brains of responders with MCI identified in the corticothalamic pathway and cortico-striatal pathway that survived adjustment for multiple comparisons. MCI was also associated with higher FA values in five ROIs including in the rostral anterior cingulate; lower MD values in four ROIs including the left rostral anterior cingulate; and higher MD values in the right inferior circular insula. Analyses by cognitive domain revealed nominal associations in domains of response speed, verbal learning, verbal retention, and visuospatial learning.

CONCLUSIONS

WTC responders with MCI at midlife showed early signs of neurodegeneration characterized by both increased and decreased white matter diffusivity in regions commonly affected by early-onset Alzheimer's disease.

Athlete-Specific Neural Strategies under Pressure: A fNIRS Pilot Study

(1) Background: Stress and pressure during competition and training impair athletes' performance in sports. However, the influence of mental stress on the prefrontal cortex (PFC) functioning in an athlete during the visual simulation task is unknown. The purpose of this pilot study was to investigate hemodynamic responses during the visual-simulation task that induces pressure and stress using functional near-infrared spectroscopy. (2) Methods: Ten archers and ten non-athlete collegiate students performed a visual-simulation task. Participants' current stress levels were collected using a visual analog scale before and after the task. Average oxygenated hemoglobin (HbO), deoxygenated hemoglobin (HbR), and total hemoglobin (HbT) levels and their variability (standard deviation (SD) HbO, SD HbR, and SD HbT) were computed to compare the neural efficiency between athlete and non-athlete. (3) Results: In general, both groups exhibited increased stress levels after the simulation task, and there was no group difference in overall average hemodynamic response from PFC and dorsolateral prefrontal cortex (DLPFC). While the average hemodynamic response level did not differ between groups, variability in hemodynamic responses from the archer group showed a more stable pattern than the non-athlete group. (4) Conclusion: Under this experimental setting, decreasing the variability in hemodynamic responses during the visual simulation, potentially via stabilizing the fluctuation of PFC, was characterized by the stress-related compensatory neural strategy of elite archers.

Imbalance of laminar-specific excitatory and inhibitory circuits of the orbitofrontal cortex in autism

BACKGROUND

The human orbitofrontal cortex (OFC) is involved in assessing the emotional significance of events and stimuli, emotion-based learning, allocation of attentional resources, and social cognition. Little is known about the structure, connectivity and excitatory/inhibitory circuit interactions underlying these diverse functions in human OFC, as well as how the circuit is disrupted in individuals with autism spectrum disorder (ASD).

METHODS

We used post-mortem brain tissue from neurotypical adults and individuals with ASD. We examined the morphology and distribution of myelinated axons across cortical layers in OFC, at the single axon level, as a proxy of excitatory pathways. In the same regions, we also examined the laminar distribution of all neurons and neurochemically- and functionally-distinct inhibitory neurons that express the calcium-binding proteins parvalbumin (PV), calbindin (CB), and calretinin (CR).

RESULTS

We found that the density of myelinated axons increased consistently towards layer 6, while the average axon diameter did not change significantly across layers in both groups. However, both the density and diameter of myelinated axons were significantly lower in the ASD group compared with the Control group. The distribution pattern and density of the three major types of inhibitory neurons was comparable between groups, but there was a significant reduction in the density of excitatory neurons across OFC layers in ASD.

LIMITATIONS

This study is limited by the availability of human post-mortem tissue optimally processed for high-resolution microscopy and immunolabeling, especially from individuals with ASD.

CONCLUSIONS

The balance between excitation and inhibition in OFC is at the core of its function, assessing and integrating emotional and social cues with internal states and external inputs. Our preliminary results provide evidence for laminar-specific changes in the ratio of excitation/inhibition in OFC of adults with ASD, with an overall weakening and likely disorganization of excitatory signals and a relative strengthening of local inhibition. These changes likely underlie pathology of major OFC communications with limbic or other cortices and the amygdala in individuals with ASD, and may provide the anatomic basis for disrupted transmission of signals for social interactions and emotions in autism.

Turning the 'Tides on Neuropsychiatric Diseases: The Role of Peptides in the Prefrontal Cortex

Recent advancements in technology have enabled researchers to probe the brain with the greater region, cell, and receptor specificity. These developments have allowed for a more thorough understanding of how regulation of the neurophysiology within a region is essential for maintaining healthy brain function. Stress has been shown to alter the prefrontal cortex (PFC) functioning, and evidence links functional impairments in PFC brain activity with neuropsychiatric disorders. Moreover, a growing body of literature highlights the importance of neuropeptides in the PFC to modulate neural signaling and to influence behavior. The converging evidence outlined in this review indicates that neuropeptides in the PFC are specifically impacted by stress, and are found to be dysregulated in numerous stress-related neuropsychiatric disorders including substance use disorder, major depressive disorder (MDD), posttraumatic stress disorder, and schizophrenia. This review explores how neuropeptides in the PFC function to regulate the neural activity, and how genetic and environmental factors, such as stress, lead to dysregulation in neuropeptide systems, which may ultimately contribute to the pathology of neuropsychiatric diseases.

Reward-Driven Arousal Impacts Preparation to Perform a Task via Amygdala-Caudate Mechanisms

Preparing for a challenging task can increase physiological arousal, in particular when potential incentives are large (e.g., a solo musical performance in front of an audience). Here, we examine how potential reward and its influence on arousal, measured by pupil dynamics, are represented in the brain while preparing for a challenging task. We further ask how neural representations during preparation relate to actual performance. Trials resulting in performance failure were characterized by increased pupil dilation as a function of increasing reward magnitude during preparation. Such failure trials were also associated with activation of the right amygdala representing pupil dilation, and the left caudate representing reward magnitude. Notably, increases in functional connectivity between amygdala and caudate preceded performance failure. These findings highlight increased connectivity between neural regions representing reward and arousal in circumstances where reward-driven arousal impairs performance.

Effects of Amygdala Lesions on Object-Based Versus Action-Based Learning in Macaques

The neural systems that underlie reinforcement learning (RL) allow animals to adapt to changes in their environment. In the present study, we examined the hypothesis that the amygdala would have a preferential role in learning the values of visual objects. We compared a group of monkeys (Macaca mulatta) with amygdala lesions to a group of unoperated controls on a two-armed bandit reversal learning task. The task had two conditions. In the What condition, the animals had to learn to select a visual object, independent of its location. And in the Where condition, the animals had to learn to saccade to a location, independent of the object at the location. In both conditions choice-outcome mappings reversed in the middle of the block. We found that monkeys with amygdala lesions had learning deficits in both conditions. Monkeys with amygdala lesions did not have deficits in learning to reverse choice-outcome mappings. Rather, amygdala lesions caused the monkeys to become overly sensitive to negative feedback which impaired their ability to consistently select the more highly valued action or object. These results imply that the amygdala is generally necessary for RL.

EEG-Based BCI Emotion Recognition: A Survey

Affecting computing is an artificial intelligence area of study that recognizes, interprets, processes, and simulates human affects. The user's emotional states can be sensed through electroencephalography (EEG)-based Brain Computer Interfaces (BCI) devices. Research in emotion recognition using these tools is a rapidly growing field with multiple inter-disciplinary applications. This article performs a survey of the pertinent scientific literature from 2015 to 2020. It presents trends and a comparative analysis of algorithm applications in new implementations from a computer science perspective. Our survey gives an overview of datasets, emotion elicitation methods, feature extraction and selection, classification algorithms, and performance evaluation. Lastly, we provide insights for future developments.

Novel Projections to the Cerebrospinal Fluid-Contacting Nucleus From the Subcortex and Limbic System in Rat

Objective: To identify the novel projections received by the cerebrospinal fluid (CSF)-contacting nucleus from the subcortex and limbic system to understand the biological functions of the nucleus.

Methods: The cholera toxin subunit B (CB), a retrograde tracer, was injected into the CSF-contacting nucleus in Sprague–Dawley rats. After 7–10 days, the surviving rats were perfused, and the whole brain and spinal cord were sliced for CB immunofluorescence detection. The CB-positive neurons in the subcortex and limbic system were observed under a fluorescence microscope, followed by 3D reconstructed with the imaris software.

Results: CB-positive neurons were found in the basal forebrain, septum, periventricular organs, preoptic area, and amygdaloid structures. Five functional areas including 46 sub-regions sent projections to the CSF-contacting nucleus. However, the projections had different densities, ranging from sparse to moderate, to dense.

Conclusions: According to the projections from the subcortex and limbic system, we hypothesize that the CSF-contacting nucleus participates in emotion, cognition, homeostasis regulation, visceral activity, pain, and addiction. In this study, we illustrate the novel projections from the subcortex and limbic system to the CSF-contacting nucleus, which underlies the diverse and complicated circuits of the nucleus in body regulations.

Cognitive and emotional predictors of real versus sham repetitive transcranial magnetic stimulation treatment response in methamphetamine use disorder

BACKGROUND AND AIMS

Repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (DLPFC) can effectively reduce cravings in methamphetamine use disorder (MUD). However, a considerable group still fails to respond. Cognitive and emotional disturbance, as well as impulsive features, are widespread in patients with MUD and might mediate the treatment response of rTMS. The purpose of this study is to figure out whether these variables can help predicting patients' responses to rTMS treatment.

METHODS

Ninety-seven patients with severe MUD and thirty-one gender- and age-matched healthy subjects were included. Patients were randomized to receive 20 sessions of real or sham rTMS. Intermittent theta burst protocols (iTBS) or sham iTBS were applied every weekday over the DLPFC for 20 daily sessions. Both groups received regular treatment. Craving induced by drug-related cue was measured before and after stimulation. Cognition was evaluated by using the CogState Battery. Baseline characteristics were collected through the Addiction Severity Index, Patient Health Questionnaire-9, General Anxiety Disorder Scale-7, and Barrett Impulsivity Scale-11.

RESULTS

Results showed that patients with MUD have worse spatial working memory, problem-solving ability, as well as depression and anxiety symptoms compared with healthy controls. Cognition and emotion differed between responders (craving decrease ≥60%) and non-responders in real rTMS group but not in the sham group. Better cognitive and emotional functions means that patients have higher possibility for better response to real rTMS treatment.

CONCLUSIONS

This study suggests that cognitive, emotional and impulsive features could be used to predict the prospective treatment responses of rTMS in patients with MUD.

Value-Related Neuronal Responses in the Human Amygdala during Observational Learning

The amygdala plays an important role in many aspects of social cognition and reward learning. Here, we aimed to determine whether human amygdala neurons are involved in the computations necessary to implement learning through observation. We performed single-neuron recordings from the amygdalae of human neurosurgical patients (male and female) while they learned about the value of stimuli through observing the outcomes experienced by another agent interacting with those stimuli. We used a detailed computational modeling approach to describe patients' behavior in the task. We found a significant proportion of amygdala neurons whose activity correlated with both expected rewards for oneself and others, and in tracking outcome values received by oneself or other agents. Additionally, a population decoding analysis suggests the presence of information for both observed and experiential outcomes in the amygdala. Encoding and decoding analyses suggested observational value coding in amygdala neurons occurred in a different subset of neurons than experiential value coding. Collectively, these findings support a key role for the human amygdala in the computations underlying the capacity for learning through observation.SIGNIFICANCE STATEMENT Single-neuron studies of the human brain provide a unique window into the computational mechanisms of cognition. In this study, epilepsy patients implanted intracranially with hybrid depth electrodes performed an observational learning (OL) task. We measured single-neuron activity in the amygdala and found a representation for observational rewards as well as observational expected reward values. Additionally, distinct subsets of amygdala neurons represented self-experienced and observational values. This study provides a rare glimpse into the role of human amygdala neurons in social cognition.

Off-label intranasal oxytocin use in adults is associated with increased amygdala-cingulate resting-state connectivity

Intranasally administered oxytocin gained popularity as a hormone facilitating trust, cooperation, and affiliation. However, the long-term consequences of oxytocin use are not known. Given that intensive media attention and advertisements of the “love hormone” might lead to a new form of misuse, we conducted an online survey and identified 41 individuals with oxytocin misuse. Misuse will be proposed throughout the manuscript instead of the more accurate “off-label use” for reasons of simplicity. We compared the social functions of oxytocin users with that of 41 matched control volunteers. We administered the “Reading the Mind in the Eyes Test” (RMET) and the National Institute of Health (NIH) Toolbox Adult Social Relationship Scales (NIH-ASRS) to delineate affective “theory of mind” and real-life social functions, respectively. Resting-state functional brain connectivity analyses were also carried out. Results revealed no significant differences between individuals with oxytocin misuse and control participants on the RMET and NIH-ASRS. However, individuals with oxytocin misuse showed an increased connectivity between the right amygdala and dorsal anterior cingulate cortex relative to the control group. Higher estimated cumulative doses of oxytocin were associated with enhanced amygdala-cingulate connectivity. These results show that individuals who have self-selected for and pursued oxytocin use have increased amygdala-cingulate resting connectivity, compared to individuals who have not used oxytocin, despite the lack of differences in RMET and NIH-ASRS scores. Further longitudinal studies are warranted to investigate the cause-effect relationship between oxytocin use and brain connectivity.

Investigating the Use of Pretrained Convolutional Neural Network on Cross-Subject and Cross-Dataset EEG Emotion Recognition

The electroencephalogram (EEG) has great attraction in emotion recognition studies due to its resistance to deceptive actions of humans. This is one of the most significant advantages of brain signals in comparison to visual or speech signals in the emotion recognition context. A major challenge in EEG-based emotion recognition is that EEG recordings exhibit varying distributions for different people as well as for the same person at different time instances. This nonstationary nature of EEG limits the accuracy of it when subject independency is the priority. The aim of this study is to increase the subject-independent recognition accuracy by exploiting pretrained state-of-the-art Convolutional Neural Network (CNN) architectures. Unlike similar studies that extract spectral band power features from the EEG readings, raw EEG data is used in our study after applying windowing, pre-adjustments and normalization. Removing manual feature extraction from the training system overcomes the risk of eliminating hidden features in the raw data and helps leverage the deep neural network’s power in uncovering unknown features. To improve the classification accuracy further, a median filter is used to eliminate the false detections along a prediction interval of emotions. This method yields a mean cross-subject accuracy of 86.56% and 78.34% on the Shanghai Jiao Tong University Emotion EEG Dataset (SEED) for two and three emotion classes, respectively. It also yields a mean cross-subject accuracy of 72.81% on the Database for Emotion Analysis using Physiological Signals (DEAP) and 81.8% on the Loughborough University Multimodal Emotion Dataset (LUMED) for two emotion classes. Furthermore, the recognition model that has been trained using the SEED dataset was tested with the DEAP dataset, which yields a mean prediction accuracy of 58.1% across all subjects and emotion classes. Results show that in terms of classification accuracy, the proposed approach is superior to, or on par with, the reference subject-independent EEG emotion recognition studies identified in literature and has limited complexity due to the elimination of the need for feature extraction.

Cingulum and abnormal psychological stress response in schizophrenia

Stress is implicated in many aspects of schizophrenia, including heightened distress intolerance. We examined how affect and microstructure of major brain tracts involved in regulating affect may contribute to distress intolerance in schizophrenia. Patients with schizophrenia spectrum disorders (n = 78) and community controls (n = 95) completed diffusion weighted imaging and performed psychological stress tasks. Subjective affect was collected pre and post stressors. Individuals who did not persist during one or both stress tasks were considered distress intolerant (DI), and otherwise distress tolerant (DT). Fractional anisotropy (FA) of the dorsal cingulum showed a significant diagnosis x DT/DI phenotype interaction (p = 0.003). Post-hoc tests showed dorsal cingulum FA was significantly lower in DI patients compared with DI controls (p < 0.001), but not different between DT groups (p = 0.27). Regarding affect responses to stress, irritability showed the largest stress-related change (p < 0.001), but irritability changes were significantly reduced in DI patients compared to DI controls (p = 0.006). The relationship between irritability change and performance errors also differed among patients (ρ = -0.29, p = 0.011) and controls (ρ = 0.21, p = 0.042). Further modeling highlighted the explanatory power of dorsal cingulum for predicting DI even after performance and irritability were taken into account. Distress intolerance during psychological stress exposure is related to microstructural properties of the dorsal cingulum, a key structure for cognitive control and emotion regulation. In schizophrenia, the affective response to psychological stressors is abnormal, and distress intolerant patients had significantly reduced dorsal cingulum FA compared to distress intolerant controls. The findings provide new insight regarding distress intolerance in schizophrenia.

A Multifaceted Explanation of the Predisposition to Buy Organic Food

This study explores whether implicit and explicit attitudes toward organic products explain consumers’ predisposition to buy organic food, considering the hedonic and utilitarian dimensions of attitudes. The data are from an online survey, which included a section on implicit attitudes (measured using an Implicit Association Test) and a section on explicit attitudes. Two products were analyzed using 557 responses from a panel of consumers: chocolate (hedonic-oriented food) and milk (a utilitarian-oriented food). Confirmatory factor analysis and multigroup structural equations were applied to assess the proposed model. Three findings may be highlighted. First, in the model with the lowest entropy, the hedonic and utilitarian dimensions are considered to be independent. Second, different types of attitudes play different roles depending on the product. Finally, implicit attitudes influence the predisposition to buy organic food in the case of pleasure-seeking food but not utilitarian-oriented food. Thus, there is convergence between implicit and explicit attitudes for hedonic-oriented foods and divergence between such attitudes for utilitarian-oriented foods. This study’s value lies in the novel use of implicit attitudes, which have generally been neglected in attitudinal models in the organic food domain.

Transcranial magnetic stimulation demonstrates a role for the ventrolateral prefrontal cortex in emotion perception

The lateral prefrontal cortex, a region with both structural and functional connectivity to the amygdala, has been consistently implicated in the downregulation of subcortical-generated emotional responses. Although previous work has demonstrated that the ventral lateral prefrontal cortex (vlPFC) is important to emotion processing, no study has interrupted vlPFC function in order to test is role in emotion perception. In the current study, we acutely disrupted vlPFC function in twenty healthy adult participants by administering sham stimulation and transcranial magnetic stimulation (TMS), in randomized order, during performance of an emotional perception task. During sham stimulation, participants demonstrated increased perceptual sensitivity for happy faces compared to angry faces. Disruption of the vlPFC eliminated this difference: in this condition, perceptual sensitivity did not differ between happy and angry faces. Reaction times and response bias did not differ between emotions or TMS conditions. This pattern of perceptual bias is consistent with effects observed in a wide range of affective disorders, in which vlPFC dysfunction has also been reported. This study provides insight into a possible mechanism through which the vlPFC may contribute to emotion perception.

Effect of Expectation on Pain Processing: A Psychophysics and Functional MRI Analysis

Pain is a complex phenomenon that is highly modifiable by expectation. Whilst the intensity of incoming noxious information plays a key role in the intensity of perceived pain, this intensity can be profoundly shaped by an individual’s expectations. Modern brain imaging investigations have begun to detail the brain regions responsible for placebo and nocebo related changes in pain, but less is known about the neural basis of stimulus-expectancy changes in pain processing. In this functional magnetic resonance imaging study, we administered two separate protocols of the same noxious thermal stimuli to 24 healthy subjects. However, different expectations were elicited by different explanations to subjects prior to each protocol. During one protocol, pain intensities were matched to expectation and in the other protocol they were not. Pain intensity was measured continuously via a manually operated computerized visual analogue scale. When individuals expected the stimulus intensity to remain constant, but in reality it was surreptitiously increased or decreased, pain intensity ratings were significantly lower than when expectation and pain intensities were matched. When the stimulus intensities did not match expectations, various areas in the brain such as the amygdala, anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (dlPFC), and the midbrain periaqueductal gray matter (PAG) displayed significantly different patterns of activity compared to instances when stimulus intensity and pain expectations were matched. These results show that stimulus-expectancy manipulation of pain intensity alters activity in both higher brain and brainstem centers which are known to modulate pain under various conditions.

Emerging roles of the unfolded protein response (UPR) in the nervous system: A link with adaptive behavior to environmental stress?

Stressors elicit a neuroendocrine response leading to increased levels of glucocorticoids, allowing the organism to adapt to environmental changes and maintain homeostasis. Glucocorticoids have a broad effect in the body, modifying the activity of the immune system, metabolism, and behavior through the activation of receptors in the limbic system. Chronic exposition to stressors operates as a risk factor for psychiatric diseases such as depression and posttraumatic stress disorder. Among the cellular alterations observed as a consequence of environmental stress, alterations to organelle function at the level of mitochondria and endoplasmic reticulum (ER) are emerging as possible factors contributing to neuronal dysfunction. ER proteostasis alterations elicit the unfolded protein response (UPR), a conserved signaling network that re-establish protein homeostasis. In addition, in the context of brain function, the UPR has been associated to neurodevelopment, synaptic plasticity and neuronal connectivity. Recent studies suggest a role of the UPR in the adaptive behavior to stress, suggesting a mechanistic link between environmental and cellular stress. Here, we revise recent evidence supporting an evolutionary connection between the neuroendocrine system and the UPR to modulate behavioral adaptive responses.

Left Amygdala Regulates the Cerebral Reading Network During Fast Emotion Word Processing

Emotion words constitute a special class of verbal stimuli which can quickly activate the limbic system outside the left-hemisphere language network. Such fast response to emotion words may arise independently of the left occipitotemporal area involved in visual word-form analysis and rely on a distinct amygdala-dependent emotion circuit involved in fearful face processing. Using a hemifield priming paradigm with fMRI, we explored how the left and right amygdala systems interact with the reading network during emotion word processing. On each trial, participants viewed a centrally presented target which was preceded by a masked prime flashed either to the left or right visual field. Primes and targets, each denoting negative or positive nouns, could be either affectively congruent or incongruent with each other. We observed that affective congruency produced parallel changes in neural priming between the left frontal and parietotemporal regions and the bilateral amygdala. However, we also found that the left, but not right, amygdala exhibited significant change in functional connectivity with the neural components of reading as a function of affective congruency. Collectively, these results suggest that emotion words activate the bilateral amygdala during early stages of emotion word processing, whereas only the left amygdala exerts a long-distance regulatory influence over the reading network via its strong within-hemisphere connectivity.

Changes in Resting-State Cerebral Activity in Women With Polycystic Ovary Syndrome: A Functional MR Imaging Study

BACKGROUND

Previous studies have found that women with polycystic ovary syndrome (PCOS) have some degree of brain function change as well as cognitive function and emotions, such as poor executive functioning and memory, anxiety and depressive symptoms. However, the neurobiological mechanisms underlying these alterations have not yet been clarified.

METHOD

Fasting serum hormone testing, neuropsychological testing and resting-state magnetic resonance imaging (rs-fMRI) were performed in 41 women with newly diagnosed PCOS and 41 healthy controls matched by age and education during their 2-5 days of menstrual period. Analysis of the amplitude of low-frequency fluctuation (ALFF) was used to calculate the seed points. Then, the functional connectivity (FC) values between these abnormal seed points and other voxels in the whole brain were calculated. Finally, the correlations among clinical indexes, neuropsychological evaluation scores, and neuroimaging data were analyzed.

RESULTS

Compared with the control group, the PCOS group showed higher luteinizing hormone (LH) and serum insulin levels, worse sleep quality, increased depressive and anxiety state scores, and memory and executive function impairments. Pearson's correlation analysis showed that the decreased ALFF value in the left middle frontal gyrus (MFG.L), which is related to poor executive performance and depressive disorders, was negatively correlated with the plasma insulin level in subjects with insulin resistance. Furthermore, the increased FC strength between the MFG.L and left inferior frontal gyrus (IFG.L) was positively correlated with the serum testosterone level. The enhanced FC strength between the left posterior cingulate gyrus (PCG.L) and triangular part of the left inferior frontal gyrus (IFGtriang.L) was negatively correlated with the plasma LH level. When use the right middle occipital gyrus (MOG.R) as the seed point, the FC strength with the right inferior occipital gyrus (IOG.R), which is associated with impaired memory, was decreased.

CONCLUSION

The ALFF and FC results elucidated brain functional abnormalities at the regional and network levels in women with PCOS, while correlation analyses simultaneously demonstrated that these alterations were associated with serum hormones and cognitive function. These results may provide useful information regarding the potential mechanisms of cognitive impairment and emotional changes in this population.

Hippocampal subfield and amygdala nuclei volumes in schizophrenia patients with a history of violence

Schizophrenia (SCZ) is associated with an increased risk of violence compared to the general population. Previous studies have indicated smaller hippocampal and amygdala volumes in violent than non-violent psychotic patients^. However, little is known about volumetric differences at the subdivision level of these structures. In the present study, hippocampal subfields and amygdala nuclei volumes were estimated with FreeSurfer from 3 T MRI of SCZ patients with (SCZ-V, n = 24) and without (SCZ-NV, n = 51) a history of severe violence and 90 healthy controls (HC). Volumetric differences between groups were explored with a general linear model covarying for confounders, in addition to follow-up analyses in patient groups controlling for clinical characteristics such as antipsychotic medication, duration of illness and illicit substance use. SCZ-V had smaller total hippocampal volume and smaller CA1, HATA, fimbria, and molecular layer of DG volumes compared to HC. Total amygdala volume together with basal nucleus, accessory basal nucleus, CTA, and paralaminar nucleus volumes were smaller in SCZ-V compared to HC. In SCZ-NV, compared to HC, the observed smaller volumes were limited to basal and paralaminar nucleus. There were no significant differences in hippocampal subfield and amygdala nuclei volumes between SCZ-V and SCZ-NV. Follow-up analyses showed that the results in patient groups were not affected by clinical characteristics. The results suggest that smaller hippocampal subfield and amygdala nuclei volumes may be relevant to violence risk in SCZ. However, the neurobiological signature of violence in SCZ should be further investigated in larger cohorts.

The contribution of nonhuman primate research to the understanding of emotion and cognition and its clinical relevance

Psychiatric disorders are often conceptualized as arising from dysfunctional interactions between neural systems mediating cognitive and emotional processes. Mechanistic insights into these interactions have been lacking in part because most work in emotions has occurred in rodents, often without concurrent manipulations of cognitive variables. Nonhuman primate (NHP) model systems provide a powerful platform for investigating interactions between cognitive operations and emotions due to NHPs' strong homology with humans in behavioral repertoire and brain anatomy. Recent electrophysiological studies in NHPs have delineated how neural signals in the amygdala, a brain structure linked to emotion, predict impending appetitive and aversive stimuli. In addition, abstract conceptual information has also been shown to be represented in the amygdala and in interconnected brain structures such as the hippocampus and prefrontal cortex. Flexible adjustments of emotional behavior require the ability to apply conceptual knowledge and generalize to different, often novel, situations, a hallmark example of interactions between cognitive and emotional processes. Elucidating the neural mechanisms that explain how the brain processes conceptual information in relation to emotional variables promises to provide important insights into the pathophysiology accounting for symptoms in neuropsychiatric disorders.

Emergence of the Affect from the Variation in the Whole-Brain Flow of Information

Over the past few decades, the quest for discovering the brain substrates of the affect to understand the underlying neural basis of the human's emotions has resulted in substantial and yet contrasting results. Whereas some point at distinct and independent brain systems for the Positive and Negative affects, others propose the presence of flexible brain regions. In this respect, there are two factors that are common among these previous studies. First, they all focused on the change in brain activation, thereby neglecting the findings that indicate that the stimuli with equivalent sensory and behavioral processing demands may not necessarily result in differential brain activation. Second, they did not take into consideration the brain regional interactivity and the findings that identify that the signals from individual cortical neurons are shared across multiple areas and thus concurrently contribute to multiple functional pathways. To address these limitations, we performed Granger causal analysis on the electroencephalography (EEG) recordings of the human subjects who watched movie clips that elicited Negative, Neutral, and Positive affects. This allowed us to look beyond the brain regional activation in isolation to investigate whether the brain regional interactivity can provide further insights for understanding the neural substrates of the affect. Our results indicated that the differential affect states emerged from subtle variation in information flow of the brain cortical regions that were in both hemispheres. They also showed that these regions that were rather common between affect states than distinct to a specific affect were characterized with both short- as well as long-range information flow. This provided evidence for the presence of simultaneous integration and differentiation in the brain functioning that leads to the emergence of different affects. These results are in line with the findings on the presence of intrinsic large-scale interacting brain networks that underlie the production of psychological events. These findings can help advance our understanding of the neural basis of the human's emotions by identifying the signatures of differential affect in subtle variation that occurs in the whole-brain cortical flow of information.

Entropy of the Multi-Channel EEG Recordings Identifies the Distributed Signatures of Negative, Neutral and Positive Affect in Whole-Brain Variability

Individuals’ ability to express their subjective experiences in terms of such attributes as pleasant/unpleasant or positive/negative feelings forms a fundamental property of their affect and emotion. However, neuroscientific findings on the underlying neural substrates of the affect appear to be inconclusive with some reporting the presence of distinct and independent brain systems and others identifying flexible and distributed brain regions. A common theme among these studies is the focus on the change in brain activation. As a result, they do not take into account the findings that indicate the brain activation and its information content does not necessarily modulate and that the stimuli with equivalent sensory and behavioural processing demands may not necessarily result in differential brain activation. In this article, we take a different stance on the analysis of the differential effect of the negative, neutral and positive affect on the brain functioning in which we look into the whole-brain variability: that is the change in the brain information processing measured in multiple distributed regions. For this purpose, we compute the entropy of individuals’ muti-channel EEG recordings who watched movie clips with differing affect. Our results suggest that the whole-brain variability significantly differentiates between the negative, neutral and positive affect. They also indicate that although some brain regions contribute more to such differences, it is the whole-brain variational pattern that results in their significantly above chance level prediction. These results imply that although the underlying brain substrates for negative, neutral and positive affect exhibit quantitatively differing degrees of variability, their differences are rather subtly encoded in the whole-brain variational patterns that are distributed across its entire activity.

Multiple scales of valence processing in the brain

Psychological theories posit that affective experiences can be decomposed into component constituents, yet disagree on the level of representation of these components. Affective experiences have been previously described as emerging from core dimensions of valence and arousal. However, this view needs to be reconciled with accounts of valence processing in appetitive and aversive circuits from the neuroscience literature. Here we offer an account of affect that allows for both perspectives but compares across levels of analysis. At one level of analysis, valence and arousal are observed already in the properties of encountered stimuli and the appetitive and aversive neural circuits that engage accordingly. At another level of analysis, the explicit experiential aspect of affective processes are compressed and appraised in a manner that allows these experiences to be organized along valence and arousal axes. We review both the behavioral neuroscience evidence on appetitive and aversive circuits as well as the cognitive neuroscience literature on compression in information coding across multiple domains of processing. We argue that these processes are domain-general and adapt these principles to provide a perspective on how valence can be represented at multiple scales in the brain.

Genetic architecture of subcortical brain structures in 38,851 individuals

Subcortical brain structures are integral to motion, consciousness, emotions and learning. We identified common genetic variation related to the volumes of the nucleus accumbens, amygdala, brainstem, caudate nucleus, globus pallidus, putamen and thalamus, using genome-wide association analyses in almost 40,000 individuals from CHARGE, ENIGMA and UK Biobank. We show that variability in subcortical volumes is heritable, and identify 48 significantly associated loci (40 novel at the time of analysis). Annotation of these loci by utilizing gene expression, methylation and neuropathological data identified 199 genes putatively implicated in neurodevelopment, synaptic signaling, axonal transport, apoptosis, inflammation/infection and susceptibility to neurological disorders. This set of genes is significantly enriched for Drosophila orthologs associated with neurodevelopmental phenotypes, suggesting evolutionarily conserved mechanisms. Our findings uncover novel biology and potential drug targets underlying brain development and disease.

Multidimensional Neural Selectivity in the Primate Amygdala

The amygdala contributes to multiple functions including attention allocation, sensory processing, decision-making, and the elaboration of emotional behaviors. The diversity of functions attributed to the amygdala is reflected in the response selectivity of its component neurons. Previous work claimed that subsets of neurons differentiate between broad categories of stimuli (e.g., objects vs faces, rewards vs punishment), while other subsets are narrowly specialized to respond to individual faces or facial features (e.g., eyes). Here we explored the extent to which the same neurons contribute to more than one neural subpopulation in a task that activated multiple functions of the amygdala. The subjects (Macaca mulatta) watched videos depicting conspecifics or inanimate objects, and learned by trial and error to choose the individuals or objects associated with the highest rewards. We found that the same neurons responded selectively to two or more of the following task events or stimulus features: (1) alerting, task-related stimuli (fixation icon, video start, and video end); (2) reward magnitude; (3) stimulus categories (social vs nonsocial); and (4) stimulus-unique features (faces, eyes). A disproportionate number of neurons showed selectivity for all of the examined stimulus features and task events. These results suggest that neurons that appear specialized and uniquely tuned to specific stimuli (e.g., face cells, eye cells) are likely to respond to multiple other types of stimuli or behavioral events, if/when these become behaviorally relevant in the context of a complex task. This multidimensional selectivity supports a flexible, context-dependent evaluation of inputs and subsequent decision making based on the activity of the same neural ensemble.

Scaling Up Cortical Control Inhibits Pain

Acute pain evokes protective neural and behavioral responses. Chronic pain, however, disrupts normal nociceptive processing. The prefrontal cortex (PFC) is known to exert top-down regulation of sensory inputs; unfortunately, how individual PFC neurons respond to an acute pain signal is not well characterized. We found that neurons in the prelimbic region of the PFC increased firing rates of the neurons after noxious stimulations in free-moving rats. Chronic pain, however, suppressed both basal spontaneous and pain-evoked firing rates. Furthermore, we identified a linear correlation between basal and evoked firing rates of PFC neurons, whereby a decrease in basal firing leads to a nearly 2-fold reduction in pain-evoked response in chronic pain states. In contrast, enhancing basal PFC activity with low-frequency optogenetic stimulation scaled up prefrontal outputs to inhibit pain. These results demonstrate a cortical gain control system for nociceptive regulation and establish scaling up prefrontal outputs as an effective neuromodulation strategy to inhibit pain.

Ventromedial prefrontal cortex contributes to performance success by controlling reward-driven arousal representation in amygdala

When preparing for a challenging task, potential rewards can cause physiological arousal that may impair performance. In this case, it is important to control reward-driven arousal while preparing for task execution. We recently examined neural representations of physiological arousal and potential reward magnitude during preparation, and found that performance failure was explained by relatively increased reward representation in the left caudate nucleus and arousal representation in the right amygdala (Watanabe, et al., 2019). Here we examine how prefrontal cortex influences the amygdala and caudate to control reward-driven arousal. Ventromedial prefrontal cortex (VMPFC) exhibited activity that was negatively correlated with trial-wise physiological arousal change, which identified this region as a potential modulator of amygdala and caudate. Next we tested the VMPFC - amygdala - caudate effective network using dynamic causal modeling (Friston et al., 2003). Post-hoc Bayesian model selection (Friston and Penny, 2011) identified a model that best fit data, in which amygdala activation was suppressively controlled by the VMPFC only in success trials. Furthermore, fixed connectivity strength from VMPFC to amygdala explained individual task performance. These findings highlight the role of effective connectivity from VMPFC to amygdala in order to control arousal during preparation for successful performance.

Love is a physiological motivation (like hunger, thirst, sleep or sex)

The multitude of terms associated with love has given rise to a false perception of love. In this paper, only maternal and romantic love are considered. Love is usually regarded as a feeling, motivation, addiction, passion, and, above all, an emotion. This confusion has consequences in the lives of human beings, leading not only to divorces, suicides, femicides but possibly also to a number of mental illnesses and suffering. Therefore, it is crucial to first clarify what is meant by emotion, motivation and love. This work aims to finally place love within the category of physiological motivations, such as hunger, thirst, sleep, or sex, on the basis that love is also essential for human survival, especially in childhood. Love is presented from an evolutionary perspective. Some other similarities between love and other physiological motivations are pointed out, such as its importance for appropriate human development, both its ontogeny and its permanence, and the long-lasting consequences of abuse and neglect. There are summarized reasons that account for this, such as the fact that physiological motivations are essential for survival and that love is an essential motivation for the survival of human offspring. Other reasons are that minimum changes in the quantity and quality of love alters development, that there can be a variety of neurophysiological and behavioural states within a motivation, and that motivations (also love) appear and change throughout development. Also, motivations and love sometimes may lead to an addictive behaviour. Finally, it is recognized that once physiological motivations (and love) appear, they become permanent. In a third section, some potential social, cultural, clinical and scientific consequences of the proposed consideration of love as a motivation are discussed. Accordingly, love's recognition as a motivation in the clinical field would imply a better understanding of its disorders and its inclusion in classifications manuals such as The Diagnostic and Statistical Manual of Mental Disorders (DSM), or in the International Classification of Diseases (ICD). Considering love as a motivation rather than an emotion could also impact the results of scientific research (an example is included). A comprehensive understanding of these questions could potentially allow for a new therapeutic approach in the treatment of mental illness, while offering an all-inclusive evolutionary explanation of cultural phenomena such as the origin and diffusion of both language and art. Love should be understood as a physiological motivation, like hunger, sleep or sex, and not as an emotion as it is commonly considered.

Opposite environmental gating of the experienced utility ('liking') and decision utility ('wanting') of heroin versus cocaine in animals and humans: implications for computational neuroscience

BACKGROUND

In this paper, we reviewed translational studies concerned with environmental influences on the rewarding effects of heroin versus cocaine in rats and humans with substance use disorder. These studies show that both experienced utility ('liking') and decision utility ('wanting') of heroin and cocaine shift in opposite directions as a function of the setting in which these drugs were used. Briefly, rats and humans prefer using heroin at home but cocaine outside the home. These findings appear to challenge prevailing theories of drug reward, which focus on the notion of shared substrate of action for drug of abuse, and in particular on their shared ability to facilitate dopaminergic transmission.

AIMS

Thus, in the second part of the paper, we verified whether our findings could be accounted for by available computational models of reward. To account for our findings, a model must include a component that could mediate the substance-specific influence of setting on drug reward RESULTS: It appears of the extant models that none is fully compatible with the results of our studies.

CONCLUSIONS

We hope that this paper will serve as stimulus to design computational models more attuned to the complex mechanisms responsible for the rewarding effects of drugs in real-world contexts.

An amygdalar neural ensemble that encodes the unpleasantness of pain

Pain is an unpleasant experience. How the brain’s affective neural circuits attribute this aversive quality to nociceptive information remains unknown. By means of time-lapse in vivo calcium imaging and neural activity manipulation in freely behaving mice encountering noxious stimuli, we identified a distinct neural ensemble in the basolateral amygdala that encodes the negative affective valence of pain. Silencing this nociceptive ensemble alleviated pain affective-motivational behaviors without altering the detection of noxious stimuli, withdrawal reflexes, anxiety, or reward. Following peripheral nerve injury, innocuous stimuli activated this nociceptive ensemble to drive dysfunctional perceptual changes associated with neuropathic pain, including pain aversion to light touch (allodynia). These results identify the amygdalar representations of noxious stimuli that are functionally required for the negative affective qualities of acute and chronic pain perception.

Layer- and subregion-specific electrophysiological and morphological changes of the medial prefrontal cortex in a mouse model of neuropathic pain

Chronic neuropathic pain constitutes a serious public health problem, but the disease mechanisms are only partially understood. The involvement of different brain regions like the medial prefrontal cortex has already been established, but the comparison of the role of different subregions and layers is still inconclusive. In the current study, we performed patch-clamp recordings followed by anatomical reconstruction of pyramidal cells from different layers of the prelimbic and infralimbic subregions of the medial prefrontal cortex in neuropathic (spared nerve injury, SNI) and control mice. We found that in the prelimbic cortex, layer 2/3 pyramidal cells from SNI mice exhibited increased excitability compared to sham controls, whereas prelimbic layer 5 pyramidal neurons showed reduced excitability. Pyramidal cells in both layer 2/3 and layer 5 of the infralimbic subregion did not change their excitability, but layer 2/3 pyramidal cells displayed increased dendritic length and branching. Our findings support the view that chronic pain is associated with subregion- and layer-specific changes in the medial prefrontal cortex. They therefore provide new insights into the mechanisms underlying the chronification of pain.

Human Pregenual Anterior Cingulate Cortex: Structural, Functional, and Connectional Heterogeneity

The human pregenual anterior cingulate cortex (pACC) encompasses 7 distinct cyto- and receptorarchitectonic areas. We lack a detailed understanding of the functions in which they are involved, and stereotaxic maps are not available. We present an integrated structural/functional map of pACC based on probabilistic cytoarchitectonic mapping and meta-analytic connectivity modeling and quantitative functional decoding. Due to the restricted spatial resolution of functional imaging data relative to the microstructural parcellation, areas p24a of the callosal sulcus and p24b on the surface of the cingulate gyrus were merged into a "gyral component" (p24ab) of area p24, and areas pv24c, pd24cv, and pd24cd, located within the cingulate sulcus were merged into a "sulcal component" (p24c) for meta-analytic analysis. Area p24ab was specifically associated with interoception, p24c with the inhibition of action, and p32, which was also activated by emotion induction tasks pertaining negatively valenced stimuli, with the ability to experience empathy. Thus, area p32 could be classified as cingulate association cortex playing a crucial role in the cognitive regulation of emotion. By this spectrum of functions, pACC is a structurally and functionally heterogeneous region, clearly differing from other parts of the anterior and middle cingulate cortex.

Amygdala ensembles encode behavioral states

Internal states, including affective or homeostatic states, are important behavioral motivators. The amygdala regulates motivated behaviors, yet how distinct states are represented in amygdala circuits is unknown. By longitudinally imaging neural calcium dynamics in freely moving mice across different environments, we identified opponent changes in activity levels of two major, nonoverlapping populations of basal amygdala principal neurons. This population signature does not report global anxiety but predicts switches between exploratory and nonexploratory, defensive states. Moreover, the amygdala separately processes external stimuli and internal states and broadcasts state information via several output pathways to larger brain networks. Our findings extend the concept of thalamocortical "brain-state" coding to include affective and exploratory states and provide an entry point into the state dependency of brain function and behavior in defined circuits.

Amygdala Modulation During Emotion Regulation Training With fMRI-Based Neurofeedback

Available evidence suggests that individuals can enhance their ability to modulate brain activity in target regions, within the Emotion Regulation network, using fMRI-based neurofeedback. However, there is no systematic review that investigates the effectiveness of this method on amygdala modulation, a core region within this network. The major goal of this study was to systematically review and analyze the effects of real-time fMRI-Neurofeedback concerning the neuromodulation of the amygdala during Emotion Regulation training. A search was performed in PubMed, Science Direct, and Web of Science with the following key terms: ≪(“neurofeedback” or “neuro feedback” or “neuro-feedback”) and (“emotion regulation”) and (fMRI OR “functional magnetic resonance”),≫ and afterwards two additional searches were performed, replacing the term “emotion regulation” for “amygdala” and “neurofeedback” for “feedback.” Of the 531 identified articles, only 19 articles reported results of amygdala modulation during Emotional Regulation training through rtfMRI-NF, using healthy participants or patients, in original research articles. The results, systematically reviewed here, provide evidence for amygdala's modulation during rtfMRI-NF training, although studies' heterogeneity precluded a quantitative meta-analysis—the included studies relied on different outcome measures to infer the success of neurofeedback intervention. Thus, a qualitative analysis was done instead. We identified critical features influencing inference on the quality of the intervention as: the inclusion of a Practice Run, a Transfer Run and a Control Group in the protocol, and to choose adequate Emotion Regulation strategies—in particular, the effective recall of autobiographic memories. Surprisingly, the Regulated vs. Control Condition was lacking in most of the studies, precluding valid inference of amygdala neuromodulation within Session. The best controlled studies nevertheless showed positive effects. The type of stimulus/interface did not seem critical for amygdala modulation. We also identified potential effects of lateralization of amygdala responses following Up- or Down-Regulation, and the impact of fMRI parameters for data acquisition and analysis. Despite qualitative evidence for amygdala modulation during rtfMRI-NF, there are still important limitations in the design of a clear conceptual framework of NF-training research. Future studies should focus on more homogeneous guidelines concerning design, protocol structure and, particularly, harmonized outcome measures to provide quantitative estimates of neuromodulatory effects in the amygdala.

Topographic organization of connections between prefrontal cortex and mediodorsal thalamus: Evidence for a general principle of indirect thalamic pathways between directly connected cortical areas

Our ability to act flexibly, according to goals and context, is known as cognitive control. Hierarchical levels of control, reflecting different levels of abstraction, are represented across prefrontal cortex (PFC). Although the mediodorsal thalamic nucleus (MD) is extensively interconnected with PFC, the role of MD in cognitive control is unclear. Tract tracer studies in macaques, involving subsets of PFC areas, have converged on coarse MD-PFC connectivity principles; but proposed finer-grained topographic schemes, which constrain interactions between MD and PFC, disagree in many respects. To investigate a unifying topographic scheme, we performed probabilistic tractography on diffusion MRI data from eight macaque monkeys, and estimated the probable paths connecting MD with each of all 19 architectonic areas of PFC. We found a connectional topography where the orderly progression from ventromedial to anterior to posterolateral PFC was represented from anteromedial to posterolateral MD. The projection zones of posterolateral PFC areas in MD showed substantial overlap, and those of ventral and anteromedial PFC areas in MD overlapped. The exception was cingulate area 24: its projection zone overlapped with projections zones of all other PFC areas. Overall, our data suggest that nearby, functionally related, directly connected PFC areas have partially overlapping projection zones in MD, consistent with a role for MD in coordinating communication across PFC. Indeed, the organizing principle for PFC projection zones in MD appears to reflect the flow of information across the hierarchical, multi-level PFC architecture. In addition, cingulate area 24 may have privileged access to influence thalamocortical interactions involving all other PFC areas.

Brain structure links trait hostile attribution bias and attitudes toward violence

The majority of research regarding hostile attribution bias focuses on its effect on aggression. However, little is known about the brain structure associated with trait hostile attribution bias and the mediating mechanism underlying this link. The current study uses voxel-based morphometry (VBM) to identify the brain regions related to individual differences in trait hostile attribution bias, measured by a Word Sentence Association Paradigm - Hostility in a sample of 176 undergraduate students. Subsequently, two mediation models with regard to brain structure, trait hostile attribution bias, and attitudes toward violence (measured by the Attitudes toward Violence Scale) were analyzed. The results reveal that trait hostile attribution bias is positively correlated with gray matter volume (GMV) in the left orbitofrontal cortex (OFC) and negatively associated with the left lingual gyrus (LG). Furthermore, attitudes toward violence acted as a mediator underlying the association between the left OFC volume and trait hostile attribution bias. Such bias also mediated the relationship between the left OFC and attitudes toward violence. We argue that attitudes toward violence and trait hostile attribution bias seem to predict each other, and the GMV in the left OFC may involve the underlying cognitive mechanism of the bidirectional relationship between the two variables. These results and ideas may shed light on the current understanding of the relationships of the brain's anatomical features, attitudes toward violence, and trait hostile attribution bias.

An amygdalar neural ensemble that encodes the unpleasantness of pain

Pain is an unpleasant experience. How the brain's affective neural circuits attribute this aversive quality to nociceptive information remains unknown. By means of time-lapse in vivo calcium imaging and neural activity manipulation in freely behaving mice encountering noxious stimuli, we identified a distinct neural ensemble in the basolateral amygdala that encodes the negative affective valence of pain. Silencing this nociceptive ensemble alleviated pain affective-motivational behaviors without altering the detection of noxious stimuli, withdrawal reflexes, anxiety, or reward. Following peripheral nerve injury, innocuous stimuli activated this nociceptive ensemble to drive dysfunctional perceptual changes associated with neuropathic pain, including pain aversion to light touch (allodynia). These results identify the amygdalar representations of noxious stimuli that are functionally required for the negative affective qualities of acute and chronic pain perception.

A Tradeoff in the Neural Code across Regions and Species

Many evolutionary years separate humans and macaques, and although the amygdala and cingulate cortex evolved to enable emotion and cognition in both, an evident functional gap exists. Although they were traditionally attributed to differential neuroanatomy, functional differences might also arise from coding mechanisms. Here we find that human neurons better utilize information capacity (efficient coding) than macaque neurons in both regions, and that cingulate neurons are more efficient than amygdala neurons in both species. In contrast, we find more overlap in the neural vocabulary and more synchronized activity (robustness coding) in monkeys in both regions and in the amygdala of both species. Our findings demonstrate a tradeoff between robustness and efficiency across species and regions. We suggest that this tradeoff can contribute to differential cognitive functions between species and underlie the complementary roles of the amygdala and the cingulate cortex. In turn, it can contribute to fragility underlying human psychopathologies.

What we imagine is what we do? A critical overview about mental imagery as a strategy to study human defensive responses

There is not a single and perfect instinctive behavior to react to threatening situations. However, the study of particular features of these situations suggests the existence of prototypical emotional reactions and associated defensive behaviors. Since all living beings are subjected to common evolutionary pressures, such as predation and conspecific competition, it is plausible that there is conservation of some basic defensive responses in their behavioral repertoire. The choice for approaching or withdrawing from a given situation depends, among others things, on environmental features, including the threat intensity and the distance from the source of the threat. If these basic responses were conserved in humans, they should be expressed in ways similar to those observed in non-human animals. Due to ethical reasons and easy application, mental imagery has been used to test this hypothesis. The studies included in this review point to the validity of this method, with both self-report and neurophysiological findings corroborating the hypothesis under scrutiny. Despite the need for additional investigation to deal with some limitations, the information obtained with this method can help to a better understanding of the conditions that provoke specific defensive behaviors and related emotions. This knowledge may also contribute to identify vulnerability factors for fear/anxiety-related disorders.

Toward a brain theory of meditation

The rapidly progressing science of meditation has led to insights about the neural correlates of focused attention meditation (FAM), open monitoring meditation (OMM), compassion meditation (CM) and loving kindness meditation (LKM), in terms of states and traits. However, a unified theoretical understanding of the brain mechanisms involved in meditation-related functions, including mindfulness, is lacking. After reviewing the main forms of meditation and their relationships, the major brain networks and brain states, as well as influential theoretical views of consciousness, we outline a Brain Theory of Meditation (BTM). BTM takes the lead from considerations about the roles of the major brain networks, i.e., the central executive, salience and default mode networks, and their interplay, in meditation, and from an essential energetic limitation of the human brain, such that only up to 1% of the neurons in the cortex can be concurrently activated. The development of the theory is also guided by our neuroscientific studies with the outstanding participation of Theravada Buddhist monks, with other relevant findings in literature. BTM suggests mechanisms for the different forms of meditation, with the down-regulation of brain network activities in FAM, the gating and tuning of network coupling in OMM, and state-related up-regulation effects in CM and LKM. The theory also advances a leftward asymmetry in top-down regulation, and an enhanced inter-hemispheric integration, in meditation states and traits, also with implications for a theoretical understanding of conscious access. Meditation thus provides a meta-function for an efficient brain/mind regulation, and a flexible allocation of highly limited and often constrained (e.g., by negative emotion and mind wandering) brain activity resources, which can be related to mindfulness. Finally, a series of experimental predictions is derived from the theory.

A novel neuromodulation strategy to enhance the prefrontal control to treat pain

Effective pharmacological treatment options for chronic pain remain very limited, and continued reliance on opioid analgesics has contributed to an epidemic in the United States. On the other hand, nonpharmacologic neuromodulatory interventions provide a promising avenue for relief of chronic pain without the complications of dependence and addiction. An especially attractive neuromodulation strategy is to optimize endogenous pain regulatory circuits. The prefrontal cortex is known to provide top-down control of pain, and hence neuromodulation methods that selectively enhance the activities in this brain region during pain episodes have the potential to provide analgesia. In this study, we designed a low-frequency (2 Hz) electrical stimulation protocol to provide temporally and spatially specific enhancement of the prefrontal control of pain in rats. We showed that low-frequency electrical stimulation of the prelimbic region of the prefrontal cortex relieved both sensory and affective responses to acute pain in naive rats. Furthermore, we found that low-frequency electrical stimulation of the prefrontal cortex also attenuated mechanical allodynia in a rat model of chronic pain. Together, our findings demonstrated that low-frequency electrical stimulation of the prefrontal cortex represents a promising new method of neuromodulation to inhibit pain.