Neuroinflammation in post-acute sequelae of COVID-19 (PASC) as assessed by [11C]PBR28 PET correlates with vascular disease measures.

The COVID-19 pandemic caused by SARS-CoV-2 has triggered a consequential public health crisis of post-acute sequelae of COVID-19 (PASC), sometimes referred to as long COVID. The mechanisms of the heterogeneous persistent symptoms and signs that comprise PASC are under investigation, and several studies have pointed to the central nervous and vascular systems as being potential sites of dysfunction. In the current study, we recruited individuals with PASC with diverse symptoms, and examined the relationship between neuroinflammation and circulating markers of vascular dysfunction. We used [11C]PBR28 PET neuroimaging, a marker of neuroinflammation, to compare 12 PASC individuals versus 43 normative healthy controls. We found significantly increased neuroinflammation in PASC versus controls across a wide swath of brain regions including midcingulate and anterior cingulate cortex, corpus callosum, thalamus, basal ganglia, and at the boundaries of ventricles. We also collected and analyzed peripheral blood plasma from the PASC individuals and found significant positive correlations between neuroinflammation and several circulating analytes related to vascular dysfunction. These results suggest that an interaction between neuroinflammation and vascular health may contribute to common symptoms of PASC.

Cognition and Ventral Attention Network Connectivity: Associations With Treatment Response in Posttraumatic Stress Disorder.

OBJECTIVE: Posttraumatic stress disorder (PTSD) is a highly heterogeneous disorder, which makes it difficult to link clinical phenotypes with biomarkers to improve treatment outcomes. Findings from previous studies suggest that cognitive measures such as verbal memory or attention paired with within-ventral attention network (VAN) or salience network resting-state functional connectivity may predict treatment response among individuals with PTSD. METHODS: In a sample comprising 20 individuals with PTSD and 10 healthy control group individuals, the investigators subtyped individuals by using both discriminant function analysis and standardized norms for a single measure of memory and neuropsychological batteries of memory, attention, and executive functioning; attempted to replicate previous findings of lower within-VAN connectivity among individuals with cognitive impairment; and explored whether within-VAN connectivity paired with cognitive impairment predicted treatment outcomes. RESULTS: PTSD patients with cognitive impairment (defined by using a discriminant function analysis with verbal memory performance) had greater within-VAN resting-state functional connectivity compared with control group individuals and cognitively intact PTSD patients at a level that fell short of statistical significance (F=3.41; df=2, 21; ηp2=0.237). The interaction between verbal memory performance and within-VAN connectivity also predicted treatment-related change in PTSD symptoms at a level that also fell short of statistical significance (ß=-0.442). CONCLUSIONS: These findings somewhat support the clinical utility of identifying cognitive phenotypes within PTSD (by using discriminant function analysis and verbal memory performance) to predict treatment outcomes.

Manipulating placebo analgesia and nocebo hyperalgesia by changing brain excitability.

Harnessing placebo and nocebo effects has significant implications for research and medical practice. Placebo analgesia and nocebo hyperalgesia, the most well-studied placebo and nocebo effects, are thought to initiate from the dorsal lateral prefrontal cortex (DLPFC) and then trigger the brain's descending pain modulatory system and other pain regulation pathways. Combining repeated transcranial direct current stimulation (tDCS), an expectancy manipulation model, and functional MRI, we investigated the modulatory effects of anodal and cathodal tDCS at the right DLPFC on placebo analgesia and nocebo hyperalgesia using a randomized, double-blind and sham-controlled design. We found that compared with sham tDCS, active tDCS could 1) boost placebo and blunt nocebo effects and 2) modulate brain activity and connectivity associated with placebo analgesia and nocebo hyperalgesia. These results provide a basis for mechanistic manipulation of placebo and nocebo effects and may lead to improved clinical outcomes in medical practice.

A Low-Intensity Transcranial Focused Ultrasound Parameter Exploration Study of the Ventral Capsule/Ventral Striatum.

OBJECTIVES: Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) is effective for treatment-resistant obsessive-compulsive disorder (OCD); however, DBS is associated with neurosurgical risks. Transcranial focused ultrasound (tFUS) is a newer form of noninvasive (ie, nonsurgical) stimulation that can modulate deeper regions, such as the VC/VS. tFUS parameters have just begun to be studied and have often not been compared in the same participants. We explored the effects of three VC/VS tFUS protocols and an entorhinal cortex (ErC) tFUS session on the VC/VS and cortico-striato-thalamo-cortical circuit (CSTC) in healthy individuals for later application to patients with OCD. MATERIALS AND METHODS: Twelve individuals participated in a total of 48 sessions of tFUS in this exploratory multisite, within-subject parameter study. We collected resting-state, reward task, and arterial spin-labeled (ASL) magnetic resonance imaging scans before and after ErC tFUS and three VC/VS tFUS sessions with different pulse repetition frequencies (PRFs), pulse widths (PWs), and duty cycles (DCs). RESULTS: VC/VS protocol A (PRF = 10 Hz, PW = 5 ms, 5% DC) was associated with increased putamen activation during a reward task (p = 0.003), and increased VC/VS resting-state functional connectivity (rsFC) with the anterior cingulate cortex (p = 0.022) and orbitofrontal cortex (p = 0.004). VC/VS protocol C (PRF = 125 Hz, PW = 4 ms, 50% DC) was associated with decreased VC/VS rsFC with the putamen (p = 0.017), and increased VC/VS rsFC with the globus pallidus (p = 0.008). VC/VS protocol B (PRF = 125 Hz, PW = 0.4 ms, 5% DC) was not associated with changes in task-related CSTC activation or rsFC. None of the protocols affected CSTC ASL perfusion. CONCLUSIONS: This study began to explore the multidimensional parameter space of an emerging form of noninvasive brain stimulation, tFUS. Our preliminary findings in a small sample suggest that VC/VS tFUS should continue to be investigated for future noninvasive treatment of OCD.

Rumination in bipolar disorder associated with brain network and behavioural measures of inhibitory executive control.

OBJECTIVE: Rumination is a passive form of negative self-focused cognition that predicts depressive episodes for individuals with bipolar disorder (BD). Individuals with BD also have impaired inhibitory executive control; rumination in BD may therefore reflect executive dysfunction. We investigated the relationship between a neural measure of executive functioning (functional connectivity between the frontoparietal control network [FPCN] and the default mode network [DMN] during an effortful task), behavioural measures of executive functioning (the Behavior Rating Inventory of Executive Function) and rumination (the Ruminative Responses Scale). METHODS: Fifteen individuals with BD and fifteen healthy controls underwent MRI scans during mental distraction. Using CONN toolbox, between-network FPCN-DMN connectivity values were calculated. We conducted Pearson's r bivariate correlations between connectivity values, BRIEF and RRS scores. RESULTS: RRS scores were positively correlated with BRIEF Behavioral Regulation Index (BRI) scores. In individuals with BD, there was a positive correlation between FPCN-DMN functional connectivity during distraction and BRIEF BRI scores. FPCN-DMN functional connectivity was also positively correlated with RRS ruminative brooding scores. Healthy controls did not show significant correlations between these behavioural and neural measures of executive functioning and rumination. CONCLUSION: For individuals with BD, the greater the tendency to ruminate and the higher the executive dysfunction, the stronger the connectivity between an executive control network and a network involved in rumination during an unrelated cognitive task. This could reflect continual attempts to inhibit ruminative thinking and shift back to the distraction task. Therefore, engagement in rumination may reflect failed inhibitory executive control.

Neurobiology of subtypes of trichotillomania and skin picking disorder.

BACKGROUND: Trichotillomania (TTM) and skin picking disorder (SPD) are common and often debilitating mental health conditions, grouped under the umbrella term of body-focused repetitive behaviors (BFRBs). Recent clinical subtyping found that there were three distinct subtypes of TTM and two of SPD. Whether these clinical subtypes map on to any unique neurobiological underpinnings, however, remains unknown. METHODS: Two hundred and fifty one adults [193 with a BFRB (85.5% [n = 165] female) and 58 healthy controls (77.6% [n = 45] female)] were recruited from the community for a multicenter between-group comparison using structural neuroimaging. Differences in whole brain structure were compared across the subtypes of BFRBs, controlling for age, sex, scanning site, and intracranial volume. RESULTS: When the subtypes of TTM were compared, low awareness hair pullers demonstrated increased cortical volume in the lateral occipital lobe relative to controls and sensory sensitive pullers. In addition, impulsive/perfectionist hair pullers showed relative decreased volume near the lingual gyrus of the inferior occipital-parietal lobe compared with controls. CONCLUSIONS: These data indicate that the anatomical substrates of particular forms of BFRBs are dissociable, which may have implications for understanding clinical presentations and treatment response.

Measuring Consciousness in the Intensive Care Unit.

Early reemergence of consciousness predicts long-term functional recovery for patients with severe brain injury. However, tools to reliably detect consciousness in the intensive care unit are lacking. Transcranial magnetic stimulation electroencephalography has the potential to detect consciousness in the intensive care unit, predict recovery, and prevent premature withdrawal of life-sustaining therapy.

Neural correlates of learning accommodation and consolidation in generalised anxiety disorder.

OBJECTIVE.: Anxiety can interfere with attention and working memory, which are components that affect learning. Statistical models have been designed to study learning, such as the Bayesian Learning Model, which takes into account prior possibilities and behaviours to determine how much of a new behaviour is determined by learning instead of chance. However, the neurobiological basis underlying how anxiety interferes with learning is not yet known. Accordingly, we aimed to use neuroimaging techniques and apply a Bayesian Learning Model to study learning in individuals with generalised anxiety disorder (GAD). METHODS.: Participants were 25 controls and 14 individuals with GAD and comorbid disorders. During fMRI, participants completed a shape-button association learning and reversal task. Using a flexible factorial analysis in SPM, activation in the dorsolateral prefrontal cortex, basal ganglia, and hippocampus was compared between groups during first reversal. Beta values from the peak of these regions were extracted for all learning conditions and submitted to repeated measures analyses in SPSS. RESULTS.: Individuals with GAD showed less activation in the basal ganglia and the hippocampus only in the first reversal compared with controls. This difference was not present in the initial learning and second reversal. CONCLUSION.: Given that the basal ganglia is associated with initial learning, and the hippocampus with transfer of knowledge from short- to long-term memory, our results suggest that GAD may engage these regions to a lesser extent during early accommodation or consolidation of learning, but have no longer term effects in brain activation patterns during subsequent learning.

Pain perception and physiological correlates in body-focused repetitive behavior disorders.

BACKGROUND: Behaviors typical of body-focused repetitive behavior disorders such as trichotillomania (TTM) and skin-picking disorder (SPD) are often associated with pleasure or relief, and with little or no physical pain, suggesting aberrant pain perception. Conclusive evidence about pain perception and correlates in these conditions is, however, lacking. METHODS: A multisite international study examined pain perception and its physiological correlates in adults with TTM (n = 31), SPD (n = 24), and healthy controls (HCs; n = 26). The cold pressor test was administered, and measurements of pain perception and cardiovascular parameters were taken every 15 seconds. Pain perception, latency to pain tolerance, cardiovascular parameters and associations with illness severity, and comorbid depression, as well as interaction effects (group × time interval), were investigated across groups. RESULTS: There were no group differences in pain ratings over time (P = .8) or latency to pain tolerance (P = .8). Illness severity was not associated with pain ratings (all P > .05). In terms of diastolic blood pressure (DBP), the main effect of group was statistically significant (P = .01), with post hoc analyses indicating higher mean DBP in TTM (95% confidence intervals [CI], 84.0-93.5) compared to SPD (95% CI, 73.5-84.2; P = .01), and HCs (95% CI, 75.6-86.0; P = .03). Pain perception did not differ between those with and those without depression (TTM: P = .2, SPD: P = .4). CONCLUSION: The study findings were mostly negative suggesting that general pain perception aberration is not involved in TTM and SPD. Other underlying drivers of hair-pulling and skin-picking behavior (eg, abnormal reward processing) should be investigated.

Clinical Characteristics of Youth with Trichotillomania (Hair-Pulling Disorder) and Excoriation (Skin-Picking) Disorder.

Body-focused repetitive disorders (BFRBDs) are understudied in youth and understanding of their underlying mechanisms is limited. This study evaluated BFRBD clinical characteristics, and two factors commonly implicated in their maintenance - emotion regulation and impulsivity - in 53 youth aged 11 to 17 years: 33 with BFRBDs and 20 controls. Evaluators administered psychiatric diagnostic interviews. Participants rated BFRBD severity, negative affect, quality of life, family functioning, emotion regulation, distress tolerance, and impulsivity. Youth with BFRBDs showed poorer distress tolerance and quality of life, and higher impulsivity and negative affect than controls, with no differences in family impairment. BFRBD distress/impairment, but not BFRBD severity, correlated with anxiety and depression, and poorer distress tolerance. Findings suggest youth with BFRBDs show clinical patterns aligning with prior research; highlight the role of distress tolerance in child BFRBDs; and suggest the utility of acceptance and mindfulness-based therapies for unpleasant emotions in BFRBDs. Continued research should evaluate factors underlying BFRBDs in youth.

Perturbing fMRI brain dynamics using transcranial direct current stimulation.

The dynamic nature of resting-state functional magnetic resonance imaging (fMRI) brain activity and connectivity has drawn great interest in the past decade. Specific temporal properties of fMRI brain dynamics, including metrics such as occurrence rate and transitions, have been associated with cognition and behaviors, indicating the existence of mechanism distruption in neuropsychiatric disorders. The development of new methods to manipulate fMRI brain dynamics will advance our understanding of these pathophysiological mechanisms from native observation to experimental mechanistic manipulation. In the present study, we applied repeated transcranial direct current stimulation (tDCS) to the right dorsolateral prefrontal cortex (rDLPFC) and the left orbitofrontal cortex (lOFC), during multiple simultaneous tDCS-fMRI sessions from 81 healthy participants to assess the modulatory effects of stimulating target brain regions on fMRI brain dynamics. Using the rDLPFC and the lOFC as seeds, respectively, we first identified two reoccurring co-activation patterns (CAPs) and calculated their temporal properties (e.g., occurrence rate and transitions) before administering tDCS. The spatial maps of CAPs were associated with different cognitive and disease domains using meta-analytical decoding analysis. We then investigated how active tDCS compared to sham tDCS in the modulation of the occurrence rates of these different CAPs and perturbations of transitions between CAPs. We found that by enhancing neuronal excitability of the rDLPFC and the lOFC, the occurrence rate of one CAP was significantly decreased while that of another CAP was significantly increased during the first 6 min of stimulation. Furthermore, these tDCS-associated changes persisted over subsequent testing sessions (both during and before/after tDCS) across three consecutive days. Active tDCS could perturb transitions between CAPs and a non-CAP state (when the rDLPFC and the lOFC were not activated), but not the transitions within CAPs. These results demonstrate the feasibility of modulating fMRI brain dynamics, and open new possibilities for discovering stimulation targets and dynamic connectivity patterns that can ensure the propagation of tDCS-induced neuronal excitability, which may facilitate the development of new treatments for disorders with altered dynamics.

Mapping the subcortical connectivity of the human default mode network.

The default mode network (DMN) mediates self-awareness and introspection, core components of human consciousness. Therapies to restore consciousness in patients with severe brain injuries have historically targeted subcortical sites in the brainstem, thalamus, hypothalamus, basal forebrain, and basal ganglia, with the goal of reactivating cortical DMN nodes. However, the subcortical connectivity of the DMN has not been fully mapped, and optimal subcortical targets for therapeutic neuromodulation of consciousness have not been identified. In this work, we created a comprehensive map of DMN subcortical connectivity by combining high-resolution functional and structural datasets with advanced signal processing methods. We analyzed 7 Tesla resting-state functional MRI (rs-fMRI) data from 168 healthy volunteers acquired in the Human Connectome Project. The rs-fMRI blood-oxygen-level-dependent (BOLD) data were temporally synchronized across subjects using the BrainSync algorithm. Cortical and subcortical DMN nodes were jointly analyzed and identified at the group level by applying a novel Nadam-Accelerated SCAlable and Robust (NASCAR) tensor decomposition method to the synchronized dataset. The subcortical connectivity map was then overlaid on a 7 Tesla 100 µm ex vivo MRI dataset for neuroanatomic analysis using automated segmentation of nuclei within the brainstem, thalamus, hypothalamus, basal forebrain, and basal ganglia. We further compared the NASCAR subcortical connectivity map with its counterpart generated from canonical seed-based correlation analyses. The NASCAR method revealed that BOLD signal in the central lateral nucleus of the thalamus and ventral tegmental area of the midbrain is strongly correlated with that of the DMN. In an exploratory analysis, additional subcortical sites in the median and dorsal raphe, lateral hypothalamus, and caudate nuclei were correlated with the cortical DMN. We also found that the putamen and globus pallidus are negatively correlated (i.e., anti-correlated) with the DMN, providing rs-fMRI evidence for the mesocircuit hypothesis of human consciousness, whereby a striatopallidal feedback system modulates anterior forebrain function via disinhibition of the central thalamus. Seed-based analyses yielded similar subcortical DMN connectivity, but the NASCAR result showed stronger contrast and better spatial alignment with dopamine immunostaining data. The DMN subcortical connectivity map identified here advances understanding of the subcortical regions that contribute to human consciousness and can be used to inform the selection of therapeutic targets in clinical trials for patients with disorders of consciousness.

Local and distant responses to single pulse electrical stimulation reflect different forms of connectivity.

Measuring connectivity in the human brain involves innumerable approaches using both noninvasive (fMRI, EEG) and invasive (intracranial EEG or iEEG) recording modalities, including the use of external probing stimuli, such as direct electrical stimulation. To examine how different measures of connectivity correlate with one another, we compared 'passive' measures of connectivity during resting state conditions to the more 'active' probing measures of connectivity with single pulse electrical stimulation (SPES). We measured the network engagement and spread of the cortico-cortico evoked potential (CCEP) induced by SPES at 53 out of 104 total sites across the brain, including cortical and subcortical regions, in patients with intractable epilepsy (N=11) who were undergoing intracranial recordings as a part of their clinical care for identifying seizure onset zones. We compared the CCEP network to functional, effective, and structural measures of connectivity during a resting state in each patient. Functional and effective connectivity measures included correlation or Granger causality measures applied to stereoEEG (sEEGs) recordings. Structural connectivity was derived from diffusion tensor imaging (DTI) acquired before intracranial electrode implant and monitoring (N=8). The CCEP network was most similar to the resting state voltage correlation network in channels near to the stimulation location. In contrast, the distant CCEP network was most similar to the DTI network. Other connectivity measures were not as similar to the CCEP network. These results demonstrate that different connectivity measures, including those derived from active stimulation-based probing, measure different, complementary aspects of regional interrelationships in the brain.

CLoSES: A platform for closed-loop intracranial stimulation in humans.

Targeted interrogation of brain networks through invasive brain stimulation has become an increasingly important research tool as well as therapeutic modality. The majority of work with this emerging capability has been focused on open-loop approaches. Closed-loop techniques, however, could improve neuromodulatory therapies and research investigations by optimizing stimulation approaches using neurally informed, personalized targets. Implementing closed-loop systems is challenging particularly with regard to applying consistent strategies considering inter-individual variability. In particular, during intracranial epilepsy monitoring, where much of this research is currently progressing, electrodes are implanted exclusively for clinical reasons. Thus, detection and stimulation sites must be participant- and task-specific. The system must run in parallel with clinical systems, integrate seamlessly with existing setups, and ensure safety features are in place. In other words, a robust, yet flexible platform is required to perform different tests with a single participant and to comply with clinical requirements. In order to investigate closed-loop stimulation for research and therapeutic use, we developed a Closed-Loop System for Electrical Stimulation (CLoSES) that computes neural features which are then used in a decision algorithm to trigger stimulation in near real-time. To summarize CLoSES, intracranial electroencephalography (iEEG) signals are acquired, band-pass filtered, and local and network features are continuously computed. If target features are detected (e.g. above a preset threshold for a certain duration), stimulation is triggered. Not only could the system trigger stimulation while detecting real-time neural features, but we incorporated a pipeline wherein we used an encoder/decoder model to estimate a hidden cognitive state from the neural features. CLoSES provides a flexible platform to implement a variety of closed-loop experimental paradigms in humans. CLoSES has been successfully used with twelve patients implanted with depth electrodes in the epilepsy monitoring unit. During cognitive tasks (N=5), stimulation in closed loop modified a cognitive hidden state on a trial by trial basis. Sleep spindle oscillations (N=6) and sharp transient epileptic activity (N=9) were detected in near real-time, and stimulation was applied during the event or at specified delays (N=3). In addition, we measured the capabilities of the CLoSES system. Total latency was related to the characteristics of the event being detected, with tens of milliseconds for epileptic activity and hundreds of milliseconds for spindle detection. Stepwise latency, the actual duration of each continuous step, was within the specified fixed-step duration and increased linearly with the number of channels and features. We anticipate that probing neural dynamics and interaction between brain states and stimulation responses with CLoSES will lead to novel insights into the mechanism of normal and pathological brain activity, the discovery and evaluation of potential electrographic biomarkers of neurological and psychiatric disorders, and the development and testing of patient-specific stimulation targets and control signals before implanting a therapeutic device.

Parallel transmission to reduce absorbed power around deep brain stimulation devices in MRI: Impact of number and arrangement of transmit channels.

PURPOSE: To assess the mean and variance performance of parallel transmission (pTx) coils for reduction of the absorbed power around electrodes (APAE) in patients implanted with deep brain stimulation (DBS) devices. METHODS: We simulated 4 pTx coils (8 and 16 channels, head and body coils) and a birdcage body coil. We characterized the RF safety risk using the APAE, which is the integral of the deposited power (in Watts) in a small cylindrical volume of brain tissue surrounding the electrode tips. We assessed the APAE mean and variance by simulation of 5 realistic DBS patient models that include the full DBS implant length, extracranial loops, and implanted pulse generator. RESULTS: PTx coils with 8 (16) channels were able to reduce the APAE by >18× (>169×) compared to the birdcage coil in average for all patient models, at no cost in term of flip angle uniformity or global specific absorption rate (SAR). Moreover, local pTx coils performed significantly better than body arrays. CONCLUSION: PTx is a possible solution to the problem of RF heating of DBS patients when performing MRI, but the large interpatient variability of the APAE indicates that patient-specific safety monitoring may be needed.

A transdiagnostic perspective of constructs underlying obsessive-compulsive and related disorders: An international Delphi consensus study.

BACKGROUND: The Research Domain Criteria seeks to bridge knowledge from neuroscience with clinical practice by promoting research into valid neurocognitive phenotypes and dimensions, irrespective of symptoms and diagnoses as currently conceptualized. While the Research Domain Criteria offers a vision of future research and practice, its 39 functional constructs need refinement to better target new phenotyping efforts. This study aimed to determine which Research Domain Criteria constructs are most relevant to understanding obsessive-compulsive and related disorders, based on a consensus between experts in the field of obsessive-compulsive and related disorders. METHODS: Based on a modified Delphi method, 46 experts were recruited from Australia, Africa, Asia, Europe and the Americas. Over three rounds, experts had the opportunity to review their opinion in light of feedback from the previous round, which included how their response compared to other experts and a summary of comments given. RESULTS: Thirty-four experts completed round one, of whom 28 (82%) completed round two and 24 (71%) completed round three. At the final round, four constructs were endorsed by ⩾75% of experts as 'primary constructs' and therefore central to understanding obsessive-compulsive and related disorders. Of these constructs, one came from the Positive Valence System (Habit), two from the Cognitive Control System (Response Selection/Inhibition and Performance Monitoring) and the final construct was an additional item suggested by experts (Compulsivity). CONCLUSION: This study identified four Research Domain Criteria constructs that, according to experts, cut across different obsessive-compulsive and related disorders. These constructs represent key areas for future investigation, and may have potential implications for clinical practice in terms of diagnostic processes and therapeutic management of obsessive-compulsive and related disorders.

Decoding Hidden Cognitive States From Behavior and Physiology Using a Bayesian Approach.

Cognitive processes, such as learning and cognitive flexibility, are both difficult to measure and to sample continuously using objective tools because cognitive processes arise from distributed, high-dimensional neural activity. For both research and clinical applications, that dimensionality must be reduced. To reduce dimensionality and measure underlying cognitive processes, we propose a modeling framework in which a cognitive process is defined as a low-dimensional dynamical latent variable-called a cognitive state, which links high-dimensional neural recordings and multidimensional behavioral readouts. This framework allows us to decompose the hard problem of modeling the relationship between neural and behavioral data into separable encoding-decoding approaches. We first use a state-space modeling framework, the behavioral decoder, to articulate the relationship between an objective behavioral readout (e.g., response times) and cognitive state. The second step, the neural encoder, involves using a generalized linear model (GLM) to identify the relationship between the cognitive state and neural signals, such as local field potential (LFP). We then use the neural encoder model and a Bayesian filter to estimate cognitive state using neural data (LFP power) to generate the neural decoder. We provide goodness-of-fit analysis and model selection criteria in support of the encoding-decoding result. We apply this framework to estimate an underlying cognitive state from neural data in human participants (N=8) performing a cognitive conflict task. We successfully estimated the cognitive state within the 95% confidence intervals of that estimated using behavior readout for an average of 90% of task trials across participants. In contrast to previous encoder-decoder models, our proposed modeling framework incorporates LFP spectral power to encode and decode a cognitive state. The framework allowed us to capture the temporal evolution of the underlying cognitive processes, which could be key to the development of closed-loop experiments and treatments.

Deficits in frontoparietal activation and anterior insula functional connectivity during regulation of cognitive-affective interference in bipolar disorder.

OBJECTIVES: Bipolar disorders (BD) are characterized by emotion and cognitive dysregulation. Mapping deficits in the neurocircuitry of cognitive-affective regulation allows for potential identification of intervention targets. This study used functional MRI data in BD patients and healthy controls during performance on a task requiring cognitive and inhibitory control superimposed on affective images, assessing cognitive and affective interference. METHODS: Functional MRI data were collected from 39 BD patients and 36 healthy controls during performance on the Multi-Source Interference Task overlaid on images from the International Affective Picture System (MSIT-IAPS). Analyses examined patterns of activation in a priori regions implicated in cognitive and emotional processing. Functional connectivity to the anterior insula during task performance was also examined, given this region's role in emotion-cognition integration. RESULTS: BD patients showed significantly less activation during cognitive interference trials in inferior parietal lobule, dorsomedial prefrontal cortex, anterior insula, mid-cingulate, and ventrolateral prefrontal cortex regardless of affective valence. BD patients showed deviations in functional connectivity with anterior insula in regions of the default mode and frontoparietal control networks during negatively valenced cognitive interference trials. CONCLUSIONS: Our findings show disruptions in cognitive regulation and inhibitory control in BD patients in the presence of irrelevant affective distractors. Results of this study suggest one pathway to dysregulation in BD is through inefficient integration of affective and cognitive information, and highlight the importance of developing interventions that target emotion-cognition integration in BD.

Human dorsal anterior cingulate cortex neurons mediate ongoing behavioural adaptation.

The ability to optimize behavioural performance when confronted with continuously evolving environmental demands is a key element of human cognition. The dorsal anterior cingulate cortex (dACC), which lies on the medial surface of the frontal lobes, is important in regulating cognitive control. Hypotheses about its function include guiding reward-based decision making, monitoring for conflict between competing responses and predicting task difficulty. Precise mechanisms of dACC function remain unknown, however, because of the limited number of human neurophysiological studies. Here we use functional imaging and human single-neuron recordings to show that the firing of individual dACC neurons encodes current and recent cognitive load. We demonstrate that the modulation of current dACC activity by previous activity produces a behavioural adaptation that accelerates reactions to cues of similar difficulty to previous ones, and retards reactions to cues of different difficulty. Furthermore, this conflict adaptation, or Gratton effect, is abolished after surgically targeted ablation of the dACC. Our results demonstrate that the dACC provides a continuously updated prediction of expected cognitive demand to optimize future behavioural responses. In situations with stable cognitive demands, this signal promotes efficiency by hastening responses, but in situations with changing demands it engenders accuracy by delaying responses.

The impact of substance use disorders on recovery from bipolar depression: Results from the Systematic Treatment Enhancement Program for Bipolar Disorder psychosocial treatment trial.

OBJECTIVE: Up to 60% of patients with bipolar disorder develop a substance use disorder during their lifetime. The purpose of this paper was to assess the impact of substance use disorders on depression recovery among bipolar patients randomly assigned to different psychotropic medications and psychosocial interventions. We hypothesized that patients with a comorbid substance use disorder would benefit less from psychotherapy regardless of treatment intensity/length compared to patients without a comorbid substance use disorder. METHOD: We conducted post hoc analyses among bipolar disorder patients ( n = 270) with and without comorbid substance use disorders enrolled in the Systematic Treatment Enhancement Program for Bipolar Disorder randomized psychosocial intervention trial. All patients entered during or shortly after the onset of a bipolar depressive episode. Logistic regression and Cox proportional hazard models were used to assess whether current or past substance use disorders moderated the response of patients to intensive psychosocial intervention or brief psychoeducation with collaborative care, operationalized as full recovery from an episode of bipolar depression. RESULTS: Current comorbid substance use disorders significantly predicted likelihood of recovery (odds ratio = 2.25, p = 0.025) and time to recovery (odds ratio = 1.71, p = 0.006) from bipolar depression. We found that 74.5% of patients with a current substance use disorder, compared to 56.5% without a current substance use disorder, recovered from bipolar depression. Past substance use disorders did not predict likelihood of recovery or time to recovery. Current substance use disorders did not significantly moderate response to intensive psychotherapy versus collaborative care. CONCLUSION: Contrary to our hypotheses, bipolar disorder participants with a current comorbid substance use disorder were more likely to recover from psychosocial treatment for bipolar depression than patients without a current comorbid substance use disorder. If this finding is replicated, it has implications for the ordering of treatment for patients with comorbid bipolar disorder and substance use disorders.