The Contribution of Thalamic Nuclei in Salience Processing

Resting state functional connectivity modifications in monoaminergic circuits underpin fatigue development in patients with multiple sclerosis

Dysregulation of monoaminergic networks might have a role in the pathogenesis of fatigue in multiple sclerosis (MS). We investigated longitudinal changes of resting state (RS) functional connectivity (FC) in monoaminergic networks and their association with the development of fatigue in MS. Eighty-nine MS patients and 49 age- and sex-matched healthy controls (HC) underwent neurological, fatigue, and RS functional MRI assessment at baseline and after a median follow-up of 1.3 years (interquartile range = 1.01-2.01 years). Monoaminergic-related RS FC was estimated with an independent component analysis constrained to PET atlases for dopamine (DA), noradrenaline (NA), and serotonin (5-HT) transporters. At baseline, 24 (27%) MS patients were fatigued (F) and 65 were not fatigued (NF). Of these, 22 (34%) developed fatigue (DEV-FAT) at follow-up and 43 remained not fatigued (NO-FAT). At baseline, F-MS patients showed increased monoaminergic-related RS FC in the caudate nucleus vs NF-MS and in the hippocampal, postcentral, temporal, and occipital cortices vs NF-MS and HC. Moreover, F-MS patients exhibited decreased RS FC in the frontal cortex vs NF-MS and HC, and in the thalamus vs NF-MS. During the follow-up, no RS FC changes were observed in HC. NO-FAT patients showed limited DA-related RS FC modifications, whereas DEV-FAT MS patients showed increased DA-related RS FC in the left hippocampus, significant at time-by-group interaction analysis. In the NA-related network, NO-FAT patients showed decreased RS FC over time in the left superior frontal gyrus. This region showed increased RS FC in both DEV-FAT and F-MS patients; this divergent behavior was significant at time-by-group interaction analysis. Finally, DEV-FAT MS patients presented increased 5-HT-related RS FC in the angular and middle occipital gyri, while this latter region showed decreased 5-HT-related RS FC during the follow-up in F-MS patients. In MS patients, distinct patterns of alterations were observed in monoaminergic networks based on their fatigue status. Fatigue was closely linked to specific changes in the basal ganglia and hippocampal, superior frontal, and middle occipital cortices.

Altered Effective Connectivity During Threat Anticipation in Individuals With Alcohol Use Disorder

BACKGROUND

A developing theory and recent research suggest that heightened reactivity to uncertain stressors or threats may be an important individual difference factor that facilitates excessive drinking as a means of avoidance-based coping and characterizes individuals with current and past alcohol use disorder (AUD). Neuroimaging studies of unpredictable threat processing have repeatedly demonstrated activation of the anterior insula, anteromedial thalamus, and dorsal anterior cingulate cortex. In the current study, we aimed to understand how these 3 regions function as a network during anticipation of unpredictable threat (and predictable threat).

METHODS

Participants were 43 adults (ages 21-30) with AUD and 26 healthy control participants. Functional magnetic resonance imaging and dynamic causal modeling were used to study interregional effective connectivities and predictable and unpredictable threat-related modulations thereof within this network. Parametric empirical Bayesian modeling was used to conduct between-group comparisons in effective connectivities.

RESULTS

During unpredictable threat trials, the increased projection from the right anteromedial thalamus to the right anterior insula was significantly present only in the AUD group. This directional influence was stronger among individuals who consumed more drinks per week on average. As expected, we found no group differences in modulatory changes to effective connectivities during predictable threat trials.

CONCLUSIONS

To our knowledge, this is the first study to examine directional interactions between key frontolimbic regions during anticipation of unpredictable and predictable threat and demonstrate the importance of bottom-up thalamic-insular projections during unpredictable threat processing in AUD. Prospective studies are warranted to determine whether this association is causal.

Assigning a social status from face adornments: an fMRI study

For at least 150,000 years, the human body has been culturally modified by the wearing of personal ornaments and probably by painting with red pigment. The present study used functional magnetic resonance imaging to explore the brain networks involved in attributing social status from face decorations. Results showed the fusiform gyrus, orbitofrontal cortex, and salience network were involved in social encoding, categorization, and evaluation. The hippocampus and parahippocampus were activated due to the memory and associative skills required for the task, while the inferior frontal gyrus likely interpreted face ornaments as symbols. Resting-state functional connectivity analysis clarified the interaction between these regions. The study highlights the importance of these neural interactions in the symbolic interpretation of social markers on the human face, which were likely active in early Homo species and intensified with Homo sapiens populations as more complex technologies were developed to culturalize the human face.

Thalamic contributions to psychosis susceptibility: Evidence from co-activation patterns accounting for intra-seed spatial variability (μCAPs)

The temporal variability of the thalamus in functional networks may provide valuable insights into the pathophysiology of schizophrenia. To address the complexity of the role of the thalamic nuclei in psychosis, we introduced micro-co-activation patterns (μCAPs) and employed this method on the human genetic model of schizophrenia 22q11.2 deletion syndrome (22q11.2DS). Participants underwent resting-state functional MRI and a data-driven iterative process resulting in the identification of six whole-brain μCAPs with specific activity patterns within the thalamus. Unlike conventional methods, μCAPs extract dynamic spatial patterns that reveal partially overlapping and non-mutually exclusive functional subparts. Thus, the μCAPs method detects finer foci of activity within the initial seed region, retaining valuable and clinically relevant temporal and spatial information. We found that a μCAP showing co-activation of the mediodorsal thalamus with brain-wide cortical regions was expressed significantly less frequently in patients with 22q11.2DS, and its occurrence negatively correlated with the severity of positive psychotic symptoms. Additionally, activity within the auditory-visual cortex and their respective geniculate nuclei was expressed in two different μCAPs. One of these auditory-visual μCAPs co-activated with salience areas, while the other co-activated with the default mode network (DMN). A significant shift of occurrence from the salience+visuo-auditory-thalamus to the DMN + visuo-auditory-thalamus μCAP was observed in patients with 22q11.2DS. Thus, our findings support existing research on the gatekeeping role of the thalamus for sensory information in the pathophysiology of psychosis and revisit the evidence of geniculate nuclei hyperconnectivity with the audio-visual cortex in 22q11.2DS in the context of dynamic functional connectivity, seen here as the specific hyper-occurrence of these circuits with the task-negative brain networks.

Sleep and the Social Profiles of Individuals With Rett Syndrome

BACKGROUND

This study investigates the distinctive social behaviors observed in individuals with Rett syndrome (RTT), characterized by the loss of spoken language, impaired eye gaze communication, gait abnormalities, and sleep issues. The research aims to identify social profiles in RTT and explore their correlation with sleep, sleep-disordered breathing (SDB), and daytime sleepiness.

METHODS

Standard overnight sleep macrostructure and respiratory parameters were assessed. Extracting 25 social-related items and one for daytime sleepiness from the Rett Syndrome Behavioral Questionnaire, factor analysis was applied to establish latent social profiles. These profiles were then correlated with sleep parameters. The nonparametric Mann-Whitney U test compared social profiles based on the presence of SDB (defined by an apnea-hypopnea index greater than one per hour) and daytime sleepiness.

RESULTS

The study involved 12 female subjects with confirmed RTT diagnoses and MECP2 mutations, aged 8.54 ± 5.30 years. The Rett Syndrome Behavioral Questionnaire revealed a total average score of 25.83 ± 12.34, indicating varying degrees of social impairments. Comprising 25 social-related items, factor analysis yielded four social profiles: "interactive motricity," "mood change," "anxiety/agitation," and "gazing." Longer sleep onset latency correlated with increased socio-behavioral impairments, particularly in interactive motricity reduction. Conversely, higher rapid eye movement sleep was associated with fewer interactive socio-motor behaviors. No significant differences in social profiles were found concerning the presence of SDB or daytime sleepiness.

CONCLUSIONS

The findings suggest four distinct social profiles in RTT individuals, hinting at shared disrupted circuits between sensorimotor functioning and sleep-related neuronal pathways. Despite the absence of differences in SDB or daytime sleepiness, the study highlights the relationship between sleep parameters, such as sleep onset latency and rapid eye movement sleep, and socio-behavioral outcomes in RTT with MECP2 mutations.

Thalamic nuclei volume differences in schizophrenia patients and healthy controls using probabilistic mapping: A comparative analysis

AIM

We aimed to investigate potential discrepancies in the volume of thalamic nuclei between individuals with schizophrenia and healthy controls.

METHODS

The imaging data for this study were obtained from the MCICShare data repository within SchizConnect. We employed probabilistic mapping technique developed by Iglesias et al. (2018). The analytical component entailed volumetric segmentation of the thalamus using the FreeSurfer image analysis suite. Our analysis focused on evaluating the differences in the volumes of various thalamic nuclei groups within the thalami, specifically the anterior, intralaminar, medial, posterior, lateral, and ventral groups in both the right and left thalami, between schizophrenia patients and healthy controls. We employed MANCOVA to analyse these dependent variables (volumes of 12 distinct thalamic nuclei groups), with diagnosis (SCZ vs. HCs) as the main explanatory variable, while controlling for covariates such as eTIV and age.

RESULTS

The assumptions of MANCOVA, including the homogeneity of covariance matrices, were met. Specific univariate tests for the right thalamus revealed significant differences in the medial (F[1, 200] = 26.360, p < 0.001), and the ventral groups (F[1, 200] = 4.793, p = 0.030). For the left thalamus, the medial (F[1, 200] = 22.527, p < 0.001); posterior (F[1, 200] = 8.227, p = 0.005), lateral (F[1, 200] = 7.004, p = 0.009), and ventral groups (F[1, 200] = 9.309, p = 0.003) showed significant differences.

CONCLUSION

These findings suggest that particular thalamic nuclei groups in both the right and left thalami may be most affected in schizophrenia, with more pronounced differences observed in the left thalamic nuclei.

FUNDINGS

The authors received no financial support for the research.

Cortical and subcortical substrates of minutes and days-long object value memory in humans

Obtaining valuable objects motivates many of our daily decisions. However, the neural underpinnings of object processing based on human value memory are not yet fully understood. Here, we used whole-brain functional magnetic resonance imaging (fMRI) to examine activations due to value memory as participants passively viewed objects before, minutes after, and 1-70 days following value training. Significant value memory for objects was evident in the behavioral performance, which nevertheless faded over the days following training. Minutes after training, the occipital, ventral temporal, interparietal, and frontal areas showed strong value discrimination. Days after training, activation in the frontal, temporal, and occipital regions decreased, whereas the parietal areas showed sustained activation. In addition, days-long value responses emerged in certain subcortical regions, including the caudate, ventral striatum, and thalamus. Resting-state analysis revealed that these subcortical areas were functionally connected. Furthermore, the activation in the striatal cluster was positively correlated with participants' performance in days-long value memory. These findings shed light on the neural basis of value memory in humans with implications for object habit formation and cross-species comparisons.

Opioid Receptors Modulate Firing and Synaptic Transmission in the Paraventricular Nucleus of the Thalamus

The paraventricular nucleus of the thalamus (PVT) is involved in drug addiction-related behaviors, and morphine is a widely used opioid for the relief of severe pain. Morphine acts via opioid receptors, but the function of opioid receptors in the PVT has not been fully elucidated. Here, we used in vitro electrophysiology to study neuronal activity and synaptic transmission in the PVT of male and female mice. Activation of opioid receptors suppresses the firing and inhibitory synaptic transmission of PVT neurons in brain slices. On the other hand, the involvement of opioid modulation is reduced after chronic morphine exposure, probably because of desensitization and internalization of opioid receptors in the PVT. Overall, the opioid system is essential for the modulation of PVT activities.SIGNIFICANCE STATEMENT Opioid receptors modulate the activities and synaptic transmission in the PVT by suppressing the firing rate and inhibitory synaptic inputs. These modulations were largely diminished after chronic morphine exposure.

Processing of sensory, painful and vestibular stimuli in the thalamus

OBJECTIVES

The thalamus plays an important role in the mediation and integration of various stimuli (e.g., somatosensory, pain, and vestibular). Whether a stimulus-specific and topographic organization of the thalamic nuclei exists is still unknown. The aim of our study was to define a functional, in vivo map of multimodal sensory processing within the human thalamus.

METHODS

Twenty healthy individuals (10 women, 21-34 years old) participated. Defined sensory stimuli were applied to both hands (innocuous touch, mechanical pain, and heat pain) and the vestibular organ (galvanic stimulation) during 3 T functional MRI.

RESULTS

Bilateral thalamic activations could be detected for touch, mechanical pain, and vestibular stimulation within the left medio-dorsal and right anterior thalamus. Heat pain did not lead to thalamic activation at all. Stimuli applied to the left body side resulted in stronger activation patterns. Comparing an early with a late stimulation interval, the mentioned activation patterns were far more pronounced within the early stimulation interval.

CONCLUSIONS

The right anterior and ventral-anterior nucleus and the left medio-dorsal nucleus appear to be important for the processing of multimodal sensory information. In addition, galvanic stimulation is processed more laterally compared to mechanical pain. The observed changes in activity within the thalamic nuclei depending on the stimulation interval suggest that the stimuli are processed in a thalamic network rather than a distinct nucleus. In particular, the vestibular network within the thalamus recruits bilateral nuclei, rendering the thalamus an important integrative structure for vestibular function.

Dynamics of personality: The Zurich model of motivation revived, extended, and applied to personality

Personality researchers are increasingly interested in the dynamics of personality, that is, the proximal causal mechanisms underlying personality and behavior. Here, we review the Zurich Model of Social Motivation concerning its potential to explain central aspects of personality. It is a cybernetic model that provides a nomothetic structure of the causal relationships among needs for security, arousal, and power, and uses them to explain an individual's approach-avoidance or "proximity-distance" behavior. We review core features of the model and extend them by adding features based on recent behavioral and neuroscientific evidence. We close by discussing the model considering contemporary issues in personality science such as the dynamics of personality, five-factor personality traits and states, and personality growth.

FKBP5 intron 7 methylation is associated with higher anxiety proneness and smaller right thalamus volume in adolescents

Dysregulation of stress response systems may mediate the detrimental effects of childhood trauma (CT) on mental health. FKBP5 regulates glucocorticoid receptor sensitivity and exerts pleiotropic effects on intracellular signaling, neurobiology and behavior. We investigated whether CT, alone and in combination with rs1360780 genotype, is associated with altered FKBP5 methylation and whether CT-associated methylation profiles are associated with anxiety proneness (AP) and structural brain volumes. Ninety-four adolescents completed the Childhood Trauma Questionnaire, and a composite AP score was generated from the Childhood Anxiety Sensitivity Index and the State-Trait Anxiety Inventory-Trait measure. Mean methylation values for 12 regulatory regions and 25 individual CpG sites were determined using high-accuracy measurement via targeted bisulfite sequencing. FKBP5 rs1360780 genotype and structural MRI data were available for a subset of participants (n = 71 and n = 75, respectively). Regression models revealed an inverse association between methylation of three intron 7 CpG sites (35558438, 35558566 and 35558710) and right thalamus volume. CpG35558438 methylation was positively associated with AP scores. Our data indicate that an intron 7 methylation profile, consistent with lower FKBP5 expression and elevated high sensitivity glucocorticoid receptor levels, is associated with higher AP and smaller right thalamus volume. Research into the mechanisms underlying the intron 7 methylation-thalamus volume relationship, and whether it confers increased risk for long-term psychopathology by altering the regulatory threshold of stress responding, is required.

Neural correlates of perceiving and interpreting engraved prehistoric patterns as human production: Effect of archaeological expertise

It has been suggested that engraved abstract patterns dating from the Middle and Lower Palaeolithic served as means of representation and communication. Identifying the brain regions involved in visual processing of these engravings can provide insights into their function. In this study, brain activity was measured during perception of the earliest known Palaeolithic engraved patterns and compared to natural patterns mimicking human-made engravings. Participants were asked to categorise marks as being intentionally made by humans or due to natural processes (e.g. erosion, root etching). To simulate the putative familiarity of our ancestors with the marks, the responses of expert archaeologists and control participants were compared, allowing characterisation of the effect of previous knowledge on both behaviour and brain activity in perception of the marks. Besides a set of regions common to both groups and involved in visual analysis and decision-making, the experts exhibited greater activity in the inferior part of the lateral occipital cortex, ventral occipitotemporal cortex, and medial thalamic regions. These results are consistent with those reported in visual expertise studies, and confirm the importance of the integrative visual areas in the perception of the earliest abstract engravings. The attribution of a natural rather than human origin to the marks elicited greater activity in the salience network in both groups, reflecting the uncertainty and ambiguity in the perception of, and decision-making for, natural patterns. The activation of the salience network might also be related to the process at work in the attribution of an intention to the marks. The primary visual area was not specifically involved in the visual processing of engravings, which argued against its central role in the emergence of engraving production.

VIP-expressing interneurons in the anterior insular cortex contribute to sensory processing to regulate adaptive behavior

Adaptive behavior critically depends on the detection of behaviorally relevant stimuli. The anterior insular cortex (aIC) has long been proposed as a key player in the representation and integration of sensory stimuli, and implicated in a wide variety of cognitive and emotional functions. However, to date, little is known about the contribution of aIC interneurons to sensory processing. By using a combination of whole-brain connectivity tracing, imaging of neural calcium dynamics, and optogenetic modulation in freely moving mice across different experimental paradigms, such as fear conditioning and social preference, we describe here a role for aIC vasoactive intestinal polypeptide-expressing (VIP+) interneurons in mediating adaptive behaviors. Our findings enlighten the contribution of aIC VIP+ interneurons to sensory processing, showing that they are anatomically connected to a wide range of sensory-related brain areas and critically respond to behaviorally relevant stimuli independent of task and modality.

Divergent time-varying connectivity of thalamic sub-regions characterizes clinical phenotypes and cognitive status in multiple sclerosis

We aimed to investigate abnormal time-varying functional connectivity (FC) for thalamic sub-regions in multiple sclerosis (MS) and their clinical, cognitive and MRI correlates. Eighty-nine MS patients (49 relapsing-remitting [RR] MS; 40 progressive [P] MS) and 53 matched healthy controls underwent neurological, neuropsychological and resting state fMRI assessment. Time-varying connectivity (TVC) was quantified using sliding-window seed-voxel correlation analysis. Standard deviation of FC across windows was taken as measure of TVC, while mean connectivity across windows expressed static FC. MS patients showed reduced TVC vs controls between most of thalamic sub-regions and fronto-temporo-occipital regions. At the same time, they showed increased static FC between all thalamic sub-regions and structurally connected cortico-subcortical regions. TVC reduction was mainly driven by RRMS; while PMS exhibited a variable pattern of TVC abnormalities, characterized by reduced TVC between frontal/motor thalamic seeds and default-mode network areas and increased TVC vs controls/RRMS between posterior thalamic sub-regions and occipito-temporo-insular cortices, associated with severity of clinical disability. Compared with controls, both cognitively preserved and impaired patients showed reduced TVC between anterior thalamic sub-regions and frontal cortex. Cognitively impaired patients also showed increased TVC of the right postcentral thalamic sub-region with the cingulate cortex and postcentral gyrus vs both controls and cognitively preserved patients. Divergent patterns of TVC thalamic abnormalities were found between RRMS and PMS patients. TVC reduction in RRMS may represent the attempt of thalamic network to keep with stable connections. Conversely, increased TVC of posterior thalamic sub-regions characterized PMS and cognitively impaired MS, possibly reflecting maladaptive mechanisms.

Hypoactive Thalamic Crh+ Cells in a Female Mouse Model of Alcohol Drinking After Social Trauma

BACKGROUND

Comorbid stress-induced mood and alcohol use disorders are increasingly prevalent among female patients. Stress exposure can disrupt salience processing and goal-directed decision making, contributing to persistent maladaptive behavioral patterns; these and other stress-sensitive cognitive and behavioral processes rely on dynamic and coordinated signaling by midline and intralaminar thalamic nuclei. Considering the role of social trauma in the trajectory of these debilitating psychopathologies, identifying vulnerable thalamic cells may provide guidance for targeting persistent stress-induced symptoms.

METHODS

A novel behavioral protocol traced the progression from social trauma to the development of social defensiveness and chronically escalated alcohol consumption in female mice. Recent cell activation-measured as cFos-was quantified in thalamic cells after safe social interactions, revealing stress-sensitive corticotropin-releasing hormone-expressing (Crh+) anterior central medial thalamic (aCMT) cells. These cells were optogenetically stimulated during stress-induced social defensiveness and abstinence-escalated binge drinking.

RESULTS

Crh+ aCMT neurons exhibited substantial activation after social interactions in stress-naïve but not in stressed female mice. Photoactivating Crh+ aCMT cells dampened stress-induced social deficits, whereas inhibiting these cells increased social defensiveness in stress-naïve mice. Optogenetically activating Crh+ aCMT cells diminished abstinence-escalated binge alcohol drinking in female mice, regardless of stress history.

CONCLUSIONS

This work uncovers a role for Crh+ aCMT neurons in maladaptive stress-induced social interactions and in binge drinking after forced abstinence in female mice. This molecularly defined thalamic cell population may serve as a critical stress-sensitive hub for social deficits caused by exposure to social trauma and for patterns of excessive alcohol drinking in female populations.

Extinction blunts paraventricular thalamic contributions to heroin relapse

Here, we use optogenetics and chemogenetics to investigate the contribution of the paraventricular thalamus (PVT) to nucleus accumbens (NAc) pathway in aversion and heroin relapse in two different heroin self-administration models in rats. In one model, rats undergo forced abstinence in the home cage prior to relapse testing, and in the other, they undergo extinction training, a procedure that is likened to cognitive behavioral therapy. We find that the PVT→NAc pathway is both sufficient and necessary to drive aversion and heroin seeking after abstinence, but not extinction. The ability of extinction to reduce this pathway's contribution to heroin relapse is accompanied by a loss of synaptic plasticity in PVT inputs onto a specific subset of NAc neurons. Thus, extinction may exert therapeutic reductions in opioid seeking by altering synaptic plasticity within the PVT→NAc pathway, resulting in reduced aversion during opioid withdrawal as well as reduced relapse propensity.

Thalamo-Nucleus Accumbens Projections in Motivated Behaviors and Addiction

The ventral striatum, also called nucleus accumbens (NAc), has long been known to integrate information from cortical, thalamic, midbrain and limbic nuclei to mediate goal-directed behaviors. Until recently thalamic afferents have been overlooked when studying the functions and connectivity of the NAc. However, findings from recent studies have shed light on the importance and roles of precise Thalamus to NAc connections in motivated behaviors and in addiction. In this review, we summarize studies using techniques such as chemo- and optogenetics, electrophysiology and in vivo calcium imaging to elucidate the complex functioning of the thalamo-NAc afferents, with a particular highlight on the projections from the Paraventricular Thalamus (PVT) to the NAc. We will focus on the recent advances in the understanding of the roles of these neuronal connections in motivated behaviors, with a special emphasis on their implications in addiction, from cue-reward association to the mechanisms driving relapse.