Elliot A. Stein - US grants

One of the main causes for repeated addict relapse is thought to be the direct conditioning of morphine responses in the central nervous system. The role of morphine as a hedonic agent will be investigated by comparing single unit responses in various subcortical loci to the effects of other less pathological rewards (food and intracranial self-stimulation). One goal will be to determine if morphine uses the same reward sites as these other agents and the correlation between them. In addition to these direct tests to compare a natural reward, brain stimulation and morphine, tests will be made to condition the morphine-induced neuronal responses to previously neutral stimuli to determine if and where responses can be conditioned. The basis for this is the hypothesis that morphine causes a relatively long-lasting hedonic response under some conditions which may be manifest within this system. Electrodes will be placed in known food reward sites (medial and lateral hypothalamus), sites which support ICSS (locus coeruleus, hypothalamus and other catecholamine centers), medial thalamus and other sites previously implicated to be involved in various aspects of morphine's action. The significance of this study should lie in a better understanding of the mechanisms involved in craving and how morphine "borrows" these systems from natural rewards. It will also provide a picture of what parts of the brain's response to morphine are amenable to conditioning and how these may be applied to behavioral therapy for post-addicts.

1. Short-term meditation induces white matter changes in the anterior cingulate: We previously showed that 3 h of mental training (integrative bodymind training, IBMT), increases ACC activity and improves self-regulation. However, it is not known whether changes in white matter connectivity can result from small amounts of mental training. We here report that 11 h of IBMT increases fractional anisotropy (FA), an index indicating the integrity and efficiency of white matter in the corona radiata, an important white-matter tract connecting the ACC to other structures. We suggest that IBMT could provide a means for improving self-regulation and perhaps reducing or preventing various mental disorders, including smoking dependence. 2. Local and circuit resting-state activity predicts brain activation and behavioral performance during working memory (WM): Resting-state neuronal activity corresponds with task-induced activations. Our goal was to determine if both local and circuit activity in the absence of task performance can predict task activations and whether the rest-task relationship is dependent on task load. Used as an index of local resting-state activity, we found that fractional amplitude of low frequency fluctuations (fALFF) in the middle frontal gyrus and inferior/superior parietal lobule were positively correlated with WM task induced activation, while fALFF in the superior frontal gyrus was negatively correlated with WM task induced deactivation. Resting-state functional connectivity (rsFC) used as an index of circuit activity, showed that the rsFC between frontal and parietal cortices were significantly correlated with WM task activation. The rsFC between task activated and deactivated regions were significantly correlated with both WM task activation and deactivation, while rsFC between task deactivated midline and posterior temporal regions significantly correlated with WM task deactivation. Further, the relationship between the resting-state activity and task-evoked activation in these lateral/superior frontal, inferior/superior parietal, posterior temporal and midline regions was stronger at higher task loads. Additionally, both resting-state activity and task-induced activation in a lateral fronto-parietal circuit were significantly correlated with WM behavioral performance. These findings suggest that intrinsic resting-state activity serves to facilitate brain circuits engaged when performing a cognitive task, and that resting activity can predict task-induced brain responses and behavioral performance. 3. Neural Correlates of Distress Intolerance (DI): This project aims to determine the neurobiological mechanisms that underlie distress tolerance between drug users and controls. Individuals who report high levels of chronic psychosocial stress display greater acute stress-induced activation in corticolimbic regions including the vmPFC, amygdala, insula, and ACC, suggesting that high levels of chronic stress may result in more reactive responses in the face of acute stress, and may require recruitment of more input from prefrontal regulatory regions to cope. Greater distress-induced activation in the bilateral dorsal ACC and the right anterior insula was associated with higher scores on the Barrett Impulsivity Scale (BIS)-Motor subscale, suggesting that impulsive individuals may need more regulatory input from this region to inhibit their actions. The distress phase of the PASAT-M induced greater activation in the insula and ventral ACC relative to the neutral phase of the task. Decreased activation in the prefrontal cortex and parahippocampal gyrus was also observed in the distress phase relative to the neutral. Individuals with low distress tolerance evidenced reduced activation in the subgenual ACC and greater activation in the ventral and dorsal ACC relative to individuals with high DT. Additionally, subjects who reported higher levels of childhood emotional abuse had significantly lower activation in the right vmPFC and the right sACC during a stressful task. Those who reported higher levels of childhood physical abuse had significantly lower activation in the right vmPFC, left vmPFC, and the right sACC, and significantly higher activation in the left OFC. These findings are in line with evidence suggesting that exposure to childhood abuse may lead to hyperactivity of corticotrophin-releasing factor systems that subsequently disrupt development of the cortico-limbic system. 4. Stress induction modulation by a CRHR1 antagonist: We are developing an imaging version of the Trier Social Stress Task to be used first in healthy controls and subsequently in smokers, heavy drinkers and over-eaters. Preliminary results indicate a mild subjective stress response in the absence of stress-induced craving. The task induced robust activation in insula, ACC and right inferior frontal gyrus. We next will be examining if the task increases smoking behavior and then the effects of a pharmacological intervention to reduce the stress/craving response and neuronal activation. 5. Effects of childhood trauma x genotype on brain morphology: In 120 healthy controls, we found that the BDNF Val66Met SNP and early childhood stress interact to alter volume of the superior temporal cortex. The interaction was driven by Met allele carriers with a history of early childhood trauma having smaller volume in this region. There was a negative correlation between total CTQ score and volume for Met allele carriers only, consistent with other reports of Met allele carriers of the BDNF gene being sensitive to early stress. Met allele carriers with high early trauma showed an increase in externally oriented thinking. Resting-state connectivity analyses revealed an interaction between BDNF Val66Met genotype and early childhood trauma between right amygdala and left insula. Additional connectivity analyses are underway using the interaction area found in the volumetric. These data may help our understanding of stress-induced brain plasticity that contributes to drug use vulnerability. 6. Functional polymorphism of the mu-opioid receptor gene (OPRM1) influences reinforcement: Previous reports on the functional effects and phenotypic outcomes of a commonly occurring functional SNP of the mu-opioid receptor (OPRM1 A118G) have been inconsistent. Here we examine its effect on implicit reward learning. We used a probabilistic signal detection task to determine whether this polymorphism impacts response bias to monetary reward in 63 healthy subjects: 51 AA homozygotes and 12 G allele carriers. OPRM1 AA homozygotes exhibited typical responding to the rewarded response (their bias to the rewarded stimulus increased over time). However, OPRM1 G allele carriers exhibited a decline in response compared to the AA homozygotes. These results extend previous reports on the heritability of performance on this task by implicating a specific polymorphism. This may suggest that the polymorphism may confer reduced response to natural reward through a dopamine-mediated decrease during positive reinforcement learning.

Using data acquired from adolescents enrolled in this study, we evaluated the inter-rater reliability, internal consistency and/or temporal reliability of a number of the test instruments. We assessed the internal consistency and temporal stability of Conner's Continuous Performance Test (CCPT) as a clinical tool for the assessment of attention-deficit/hyperactivity disorder (ADHD) the CCPT in a sample of 51 adolescents, (19 with ADHD, 8 with ADHD and another disorder, and 24 controls). The CCPT has adequate split-half reliability, and performance was found to be moderately correlated over the span of 1.3 years. ADHD participants tended to perform worse than controls during the first, but not second, CCPT administration. The CCPT was found to be an insensitive indicator of diagnostic status and, while several CCPT performance measures correlated with parent ratings of ADHD symptomatology, the pattern of these correlations was largely independent of the interpretive guidelines provided in the test manual. We conclude that the poor diagnostic validity and the unclear functional relevance of CCPT scores might confound clinical interpretation of the CCPT. We assessed the inter-rater agreement and internal consistency of the Rey Complex Figure Test (RCFT) in a sample of adolescents enrolled in this study. We found each of the RCFT outcome measures to be associated with clinically acceptable inter-rater reliability estimates. Additionally, we found the copy and recall accuracy scores to be associated with clinically acceptable internal consistency. The organizational scoring method we evaluated, while associated with internal consistency that is acceptable for research purposes, was found to be somewhat below estimates associated with clinical acceptability. We assessed the short- and long-term stability of the Stroop Color and Word Test, a commercially-available version of Stroop s original task in 87 adolescents. Participants were tested an average of one month apart at baseline and twice more at approximately 15 month intervals. We found that all of the commonly used performance indices are associated with practice effects and that the three primary scores, but not the formula-derived interference score, were associated with acceptable reliability. [unreadable] Baseline data from participants in this longitudinal study were combined with data from other studies performed at NIMH on adolescents to examine whether face-emotion labeling deficits are illness-specific or an epiphenomenon of generalized impairment in pediatric psychiatric disorders involving mood and behavioral dysregulation. In total, data from two hundred fifty-two youths (718 years old) who had completed child and adult facial expression recognition subtests from the Diagnostic Analysis of Nonverbal Accuracy instrument were used. Forty-two participants had bipolar disorder, 39 had severe mood dysregulation (i.e., chronic irritability, hyperarousal without manic episodes), 44 had anxiety and/or major depressive disorders, 35 had attention-deficit/hyperactivity and/or conduct disorder, and 92 were controls. Dependent measures were number of errors labeling happy, angry, sad, or fearful emotions. We found that children with bipolar disorder and those with severe mood dysregulation made more errors than those presenting with anxiety and/or major depressive disorders, attention-deficit/hyperactivity and/or conduct disorder, or controls when labeling adult or child emotional expressions. Children with bipolar disorder and those with severe mood dysregulation did not differ in their emotion- labeling deficits. Therefore, we concluded that the face-emotion labeling deficits differentiate children with bipolar disorder and those with severe mood dysregulation from controls and those with anxiety and/or major depressive disorders or those with attention-deficit/hyperactivity and/or conduct disorder. The extent to which such deficits cause versus result from emotional dysregulation requires further study.

Part of this project determined if differences in nAChR density between smokers and non-smokers could be shown in vivo with PET and to determine the neuroanatomical extent of the difference. We used dynamic PET imaging with 2F-18F-A-85380 (2FA) to measure total volume of distribution (VT) in non-smokers and heavy smokers. Values for VT obtained by several modeling methods using a metabolite-corrected arterial input function for 2FA yielded similar results. The thalamus (TH), midbrain (MB), pons (P), cerebellum (CB), frontal cortex (FC), putamen (PUT) and corpus callosum (CC) were sampled. VT was significantly higher in smokers than in nonsmokers in CB, FC, MB, P and PUT. PET imaging of nAChRs suggests that it can be used to study the role of nicotine-induced upregulation of nAChRs in smoking behaviors and in smoking cessation. Quantifying nAChRs in this study required arterial blood sampling and dynamic scanning as the 2FA was administered as a bolus injection. A second part of this project evaluated the less invasive bolus plus constant infusion (B/I) paradigm for quantifying nAChRs. Volunteers underwent a bolus injection study and a study in which the 2FA was administered by B/I to evaluate the feasibility of using shorter scan times and data from venous blood. VT values from the B/I studies were very similar to those calculated from bolus studies. Test/retest showed a high reproducibility of VT measurements. We conclude that B/I methodology will be useful for clinical and research studies of human brain nAChRs. We developed a one-step solid-phase extraction (SPE) method for measuring the concentration of unmetabolized 2FA, which allowed many samples to be processed in a short period of time. SPE effectively separated 2FA from radioactive metabolites typically observed in blood plasma after 2FA administration to humans, yielding nearly identical values to those obtained with HPLC, and showed good reproducibility within and between runs. These results suggest that SPE is the method of choice for the determination of the plasma 2FA concentration when measurement of individual metabolites is not required.[unreadable] Male squirrel monkeys underwent quantitative studies of nAChRs with 2FA. Non-displaceable volumes of distribution (VDnd) were determined following blockade of 2FA specific binding by nicotine infusion. Binding potential (BP*) values, estimated using Cb and muscle as reference regions, were compared for reproducibility of measurements. Administration of 2 mg/kg/day nicotine via osmotic pump nearly completely saturated specific binding to nAChRs and led to a very small changes in VT in CB and muscle (-9 4% and 0 6%, respectively), suggesting limited specific binding of 2FA in these areas. VT measured in muscle in 15 monkeys was reasonably constant but VDnd in studied brain regions exceeded VT in muscles by a factor of 1.3. Applying this factor and using muscle as a reference region, BP* values calculated for studied brain regions were in a good agreement with those obtained using CB as a reference region, suggesting that nAChRs can be accurately quantified using 2FA and muscle as a reference region. [unreadable] To expand the capability of microPET to quantify nAChRs in the rat brain, we measured BP* in anesthetized rats that were imaged repeatedly over six months Using a B/I paradigm, 2FA was administered intravenously over 8 to 9 h. Steady state conditions developed within 5 h. A 2-h nicotine infusion initiated 2 h before the end of scanning displaced specifically bound 2FA. BP* averages for TH, forebrain, and CB were consistent with nAChR distribution in rat brain measured in vitro. Studies of nAChR occupancy determined that 0.29 nmol/kg/h nicotine occupied 50% of the nAChRs. [unreadable] A novel radioligand F-18 NIDA131 for imaging extrathalamic nAChRs was characterized in vitro and in vivo. The Kd and T1/2 of dissociation of NIDA522131 measured in vitro were 4.9 pM and 81 min, respectively. The in vivo patterns of radioactivity distribution for F-18NIDA522131 and 2FA were similar and matched the distribution of nAChRs. F-18NIDA522131 exhibited better in vivo binding properties than 2FA, and accumulated in monkey brain to a substantially greater extent. VT and VDnd were substantially greater than those of 2FA. The toxicity of NIDA522131 in mice was comparable to 2FA and was consistent with a 2300 fold higher affinity for alpha4beta2* nAChRs than for alpha3beta4* nAChRs. These results suggest that F-18 NIDA131 is promising for studying extrathalamic nAChR in humans.[unreadable] Nicotine may function as a gateway drug to illicit drug use. Nicotine produces cross sensitization to opioids in rats in a conditioned place preference (CPP) paradigm. We utilized CPP to test the hypothesis that nicotine produces behavioral cross sensitization to stimulants and demonstrated that nicotine pretreatment enhances the rewarding effects of amphetamine for at least 3 to 5 days following the cessation of nicotine, with this effect dissipating within 19 days. The underlying mechanism involves alpha4beta2 nAChRs as a competitive alpha4beta2 antagonist effectively blocks development of nicotine-induced cross sensitization. An alpha7 nicotinic antagonist also blocked cross-sensitization at doses that do not block nicotine self-administration in rats. This study clearly demonstrated that nicotine produces cross-sensitization to the rewarding effects of both psychostimulants measured with CPP. [unreadable] We compared D2 dopamine receptor (D2DR) occupancy by dopamine (DA) in the MPTP-unilaterally lesioned (a model of Parkinson's disease) and contralateral PUT of four pig-tailed macaques. PET and in vitro binding techniques were used to measure BP* and D2DR density (Bmax), respectively. There were relatively higher values of BP* and Bmax and less amphetamine-induced decreases in C-11raclopride binding in the lesioned compared with the contralateral PUT in each animal. The percent differences between the measurements were similar for BP* and Bmax values. As BP* is a measure of unoccupied D2DRs, these findings suggest that endogenous DA occupies a similar fraction of receptors in the lesioned PUT and contralateral PUT. Therefore, the DA occupies a greater number of D2DRs in the lesioned than in the contralateral PUT, possibly because despite a loss in available DA, there is an increase in the ratio of D2DR in the low-affinity to those in the high affinity state on the lesioned side.[unreadable] Childhood trauma is associated with increased risk for developing depression, anxiety, posttraumatic stress and substance abuse disorders. Rearing infant macaques with same-aged peers in the absence of adults, an established model of early adversity, induces high levels of anxiety-like behavior in monkeys. Chronic early life stress affects expression and function of 5-HT1A receptors (5HTR), which may increase vulnerability to mood and anxiety disorders. In addition, human data shows sex differences in 5HTR. Based on the hypothesis that peer-reared (PR) macaques would exhibit differences in 5HTR density (measured with 18FFPWAY and PET) relative to those raised by their mothers (MR), we evaluated these effects in male MR, female MR, male PR and female PR rhesus monkeys, at 24-29 months (corresponding to 6-7 human years). The distribution of 18FFPWAY was consistent with the known pattern of 5HTR density (highest accumulation in hippocampus and cingulate cortex, intermediate in the prefrontal cortex and the lowest in the CB) and showed a significant rearing X sex interaction. In females, BP values were elevated in the dorso-medial prefrontal cortex in the PR compared to the MR group, but in males, values were lower in medial cingulate cortex in the PR group than in the MR group, suggesting that early stress affects the number of available 5HTR differently in females and males.

Methadone maintenance is the primary treatment for opiate addiction, but controversy surrounds the merits of its use in long-term treatment. Fifteen methadone-free (6-24 months) opiate abusers, twelve opiate abusers receiving methadone maintenance (stable dose over 6 months), and thirteen control subjects participated in this study. Methadone-withdrawn subjects had lower relative metabolic activity measured by F-18fluorodeoxyglucose and PET than control subjects in bilateral perigenual and the left middle cingulate gyrus. In contrast, methadone-maintained subjects exhibited lower relative activity (vs. control) in the left insula, the thalamus, and the left inferior parietal lobule; however, they exceedded control activity in the perigenual anterior cingulate gyrus and the right inferior parietal lobule. Measures of depression covaried positively with relative activity in the left perigenual and mid-cingulate gyrus in methadone-withdrawn subjects; analogous associations in control subjects covaried negatively. Methadone-maintained subjects exhibited negative covariance between state measures of depression and relative activity in the right inferior parietal lobule and the right perigenual anterior cingulate, and between trait measures of depression and relative activity in the left inferior parietal lobule. Methadone maintenance ameliorates functional abnormalities in the neural circuitry subserving negative affective states, but depresses brain function in some regions of high opiate receptor density.

Early life stress induces morphological and neurochemical changes in primate brain. Traumatic experiences in early childhood are associated with increased risk of developing stress-related disorders, which are linked to structural brain abnormalities. It is unclear whether these brain changes are present before disease onset or reflect the consequences of disease progression. Deformation-based morphometry, was applied to identify abnormalities in the whole brain development related to traumatic experience in early childhood. Rhesus monkeys were divided into a group raised with their mothers (mother reared) and a group raised with 3 age-matched monkeys (peer reared) for the first 6 months of life. Group difference maps showed enlarged dmPFC and ACC and decreased gp and vPFC in the peer reared group. Further, compared with controls, serotonin1A receptor availability was elevated in peer-reared females in the dmPFC, and decreased in peer-reared males in the ACC. These changes were mainly driven by decreased serotonin levels rather than changes in receptor density. These data suggest that early life stress induces morphological abnormalities and may be a structural phenotype for increased risk of stress-related neuropsychiatric disorders in human beings. Neuropharmacological consequences of chronic cocaine self-administration. A systems-level investigation of neuroadaptations in rats previously exposed to chronic cocaine self-administration revealed a decreased regional CBV, an index of neuronal activity, in ACC and OFC as compared to sucrose and control groups. Such hypoactivity is consistent with human imaging pointing to a role of the ACC and OFC in cocaine dependence. These data set the stage to provide comparative data for evaluation of this animal model of drug addiction. Functional MRI with Repeated Administration of Nicotine in Drug Nave Rats. Rapid tolerance develops to many of the behavioral and autonomic effects of nicotine. However, the central sites of nicotine tolerance are less well studied. Dose-related effects of nicotine on rCBV were observed throughout the brains of nave animals, but there was regional specificity as certain areas manifested inverted U-shaped dose-response curves while others exhibited monotonic curves. Acute tolerance developed in many neocortical and limbic-related cortical areas in both groups, but little tolerance developed in subcortical limbic structures. Nicotine methiodide, which does not enter the brain, yet increases blood pressure like nicotine, did not elicit changes in rCBV, thus demonstrating that the actions of nicotine occurred directly in the brain and not as a result of blood pressure changes. Functional MRI with Repeated Administration of Nicotine in Nicotine-Abstinent Rats. Rats received nicotine chronically for 12 days using osmotic pumps. Sensitized responses to the first nicotine dose developed, relative to nave rats, along with tolerance to the second dose. These data reveal another facet of the evolving plasticity in response to nicotine-induced changes within specific brain regions during tachyphylaxis in abstinent rats. Local field potential changes associated with the self-administration of cocaine in the rat orbitofrontal cortex. Local Field Potentials (LFP) from 16 electrode micro-arrays were recorded from the OFC of rats before, during, and after a cocaine SA session. Significantly more LFP spectral power was observed post compared to pre baseline in frequency bands greater than 20 Hz. A significant increase in LFP spectral power in 8-12 Hz band was observed in the 2 second epoch before the lever press. While increased spiking is thought to indicate output from the OFC, increased LFP activity reflects increased dendritic activity or input to the OFC. Thus, OFC appears to integrate afferent neural activity in preparation for the operant response for cocaine self-administration. Methamphetamine neurotoxicity. We found that single high doses of METH in rats dose-dependently increase cocaine SA. The increased SA appeared to be a compensatory response to reduced cocaine reward after METH. Further, METH produced large DA release followed by a significant reduction in striatal DA and DOPAC content, but without significant changes in striatal DA transporter levels. These findings suggest that METH caused striatal DA depletion or hypofunction without severe damage in DA terminals, which may contribute to the increased cocaine-taking behavior observed. Nicotine receptors and nicotine self-administration in squirrel monkeys. Factors underlying inter-individual differences in vulnerability to nicotine dependence are not well understood. Baseline levels of alpha4beta2* nAChRs were measured using PET in squirrel monkeys. Greater motivation to self-administer nicotine was associated with lower levels of midbrain nAChRs, suggesting that level of expression of nAChRs is a contributing factor in the development of nicotine dependence. Nicotine receptors in human smokers. We used PET measure total volumes of distribution in nonsmokers and heavy smokers. V(T)/f(P) was significantly higher in smokers than in nonsmokers in frontal cortex, midbrain, putamen, pons, cerebellum, and corpus callosum (but not thalamus). Nicotine receptor quantification in human brain. We conclude that B/I methodology will be useful for clinical and research studies of brain nAChRs. Nicotinic receptor PET ligand. A novel radioligand, 6-chloro-3-((2-(S)-azetidinyl)methoxy)-5-(2-fluoropyridin-4-yl)pyridine (NIDA522131), for imaging extrathalamic nicotinic acetylcholine receptors (nAChRs) was characterized in vitro and in vivo using PET.

Using a rsFC analysis, we placed seed in the cingulate gyrus (3 ant, 3 post, 1 middle division) in a group of smokers. Acute nicotine, compared to placebo, increased 7 specific cingulate-cortical circuits consistent with behavioral characteristics of smoking. The connectivity strength of a circuit from the dACC to the ventral striatum (VS) was inversely correlated with addiction severity (FTND), but not altered by acute nicotine, suggesting in this double dissociation the existence of brain circuits that indexed cognition vs. addiction. The nAChR α5 subunit gene functional variant rs16969968 associated with a virtually identical dACC-VS/EA rsFC, such that the risk allele leads to reduced rsFC in the circuit;rsFC strength was reduced in smokers compared to nonsmokers;reduction of rsFC predicts more severe nicotine addiction. Multiple brain regions were identified with reduced white matter integrity (fractional anisotropy, FA) in schizophrenia and in smoking independently. The only overlapping FA reduction between the two conditions was in the left anterior thalamic radiation/anterior limb of the internal capsule, a fiber track that connects frontal cortex (including dACC) to striatum. Reduced rsFC strength in the same circuit was found in patients with psychiatric conditions that was independently and additively present with the nAChR α5 genetic effect. These resting state and DTI data provide converging evidence that this circuit may be related to high risk of smoking in psychiatric conditions. The above findings do not speak to the behavioral significance of anatomical and rsFC abnormalities. Striatal-cingulate regions identified are implicated in response inhibition (RI)/impulsivity processing. A GO/NOGO task indicated striatum and dACC activation and a significant group effect iin dACC. The striatal RI response is positively associated with FTND and negatively associated with rsFC strength between dACC-VS, indicating that rsFC may be indexing a RI function such that a reduced rsFC in the circuit is related to less controlled striatal activity during inhibitory functioning;the striatal response itself appears linked to nicotine addiction severity. This multi-modal imaging approach implicates a dACC-VS/EA circuit in smoking, and that this circuit can tie together aspects of the genetic, behavioral, comorbidity and cognitive correlates of smoking to provide a particularly salient biomarker for guiding and testing new treatment development. Anatomical differences and network characteristics underlying smoking cue reactivity. A distributed network of brain regions is linked to drug-related cue responding. However, the relationships between smoking cue-induced phasic activity and possible underlying differences in brain structure, tonic neuronal activity and connectivity between these brain areas are as yet unclear. Six brain areas, dorsal lateral prefrontal cortex (dlPFC), dorsal medial prefrontal cortex (dmPFC), dACC, rACC, occipital cortex, and insula/operculum, showed smoking cue-elicited activity in smokers compared with controls. Secondary analysis showed that rsFC strength between rACC and dlPFC was positively correlated with cue-elicited activity in dlPFC;rsFC strength between dlPFC and dmPFC was positively correlated with the cue-elicited activity in dmPFC;rsFC between dmPFC and insula/operculum was negatively correlated with the cue-elicited activity in both dmPFC and insula/operculum, suggesting these brain circuits may facilitate the response to salient smoking cues. The gray matter density in dlPFC was decreased in smokers and correlated with cue-elicited activity in the same brain area, suggesting a neurobiological mechanism for the impaired cognitive control associated with drug use. These results begin to address the underlying neurobiology of smoking cue salience, and may speak to novel treatment strategies and targets for therapeutic interventions. Factors underlying prefrontal and insula structural alterations in smokers. In a large, well-matched sample of smokers and non-smokers gray matter density was lower in PFC in high pack-years smokers and inversely related to pack-years. Insular cortex gray matter density was higher in smokers and associated with TAS total score and with difficulty-identifying-feelings factor. The most highly dependent smokers show lower PFC FA, which was negatively correlated with FTND. These data suggest chronic tobacco use is correlated with PFC gray matter damage, while differences in insula gray matter and PFC white matter appear to reflect stable and heritable differences between smokers and non-smokers. Nicotine and working memory (WM): The cognitive-enhancing properties of nicotine on WM remain unclear. We explored the impact of transdermal nicotine on neural functioning in minimally-deprived smokers and differences between smokers and nonsmokers using a mixed block/event-related fMRI design that attempted to isolate specific central executive operations within WM function. Across both groups, task-blocks were associated with bilateral activation, notably in m/lPFC, ant insula, and parietal regions, whereas individual attentional-switch trials were associated with activation in a similar, but predominantly left-lateralized network. Within the smoker group, although nicotine increased heart rate, altered performance and mood, and reduced tobacco cravings, no acute drug (state-like) effect on brain activity was detected for either the task or switch effects. However, relative to nonsmokers, smokers showed greater tonic activation in medial superior frontal cortex, right ant insula, and bilateral anterior PFC throughout task blocks (trait-like effect), suggesting smokers require recruitment of additional WM-control and supervisory control operations during task performance. Neurocognitive effects of Varenicline and nicotine: Varenicline, is a nicotinic acetylcholine receptor partial agonist, is an efficacious pharmacotherapy for smoking cessation treatment. We are examining an array of cognitive, affective, and reward processing tasks to explore the effects of smoking abstinence, transdermal nicotine, and varenicline administration on brain function and behavioral performance. Initial results from one task suggest vareniclines efficacy as a smoking cessation aid may partly lie in its ability to decrease amygdala reactivity to emotionally evocative stimuli and amygdala-insula rsFC, which may ameliorate the negative consequences of nicotine withdrawal and thus drug seeking behavior. In the absence of nicotine, varenicline reduced amygdala reactivity. In the presence of nicotine, reactivity was also reduced, but did not differ as a function of pill. Using task-defined amygdala seed regions identify from the above analysis, indicated amygdala-insula rsFC was reduced in the nicotine, relative to placebo condition;in the absence of nicotine, such connectivity was also reduced by varenicline. Nicotine and information processing. The impact of nicotine on all aspects of information processing has not been well delineated. We sought to determine the relative behavioral and functional effects of nicotine on dissociable aspects of information processing (i.e., selective attention and motor intention). Smokers were overall more accurate than controls, while nicotine significantly increased the response to intentional primes in brain regions known to mediate response readiness, e.g., inferior parietal lobe, supramarginal gyrus, and striatum. These data suggest that the behavioral effects of nicotine in smokers are not limited to information processing input (i.e., selective attention) but are generalizable to output functions (i.e., motor intention). Nicotine's effects on intention appear to be mediated by a facilitation of function in brain regions associated with in

1. Dopamine Function and Reward Processing in Schizophrenia (SZ): We examined brain activity related to reinforcement processing in SZ and its possible relationship to clinical symptoms. Our findings indicate that SZ patients show relatively intact responses to worse-than-expected outcomes in the striatum, but a reduced ability to suppress default network activity and activate areas of frontal cortex, involved in action selection, following salient events. Our current work focuses on neural representations of the value of stimuli and actions in PFC, and their possible contributions to decision-making abnormalities in SZ. 2. Nicotine enhances but does not normalize visual sustained attention in SZ: Understanding the neural basis of how nicotine can transiently improve sustained attention in SZ patients may lead to new treatment strategies. Using the RVIP task, patients had impaired visual sustained attention accuracy and processing speed and showed significantly reduced activation in the frontal-parietal-cingulate-thalamic attention network compared with controls. Nicotine enhanced accuracy and processing speed compared with placebo, with no drug diagnosis interactions. However, patients'task performance remained impaired with nicotine patch, even when compared with controls on placebo. Nicotine exerted no significant reversal of the impaired attention network associated with SZ. Nicotine transiently enhanced sustained attention similarly in both groups. The neural mechanisms for this nicotinic effect in SZ appear similar to those for controls. However, nicotine, at least in a single sustained dose, does not normalize impaired sustained attention and its associated brain network in SZ. 3. Nicotine effects on neurophysiological functions in eye movement and attention in SZ: Behavioral performance and fMRI activation were compared in patients and healthy controls in a double blind, placebo controlled fMRI study to identify the brain regions involved in nicotine-induced change during eye tracking, anticipatory learning of eye movement, sustained attention, and resting state functional connectivity. We are currently examining whether the circuit identified last year that is related to nicotine addiction (Hong et al Arch Gen Psych 2009) can be used as a biomarker to predict changes in smoking behavior. 4. Neurobiological Phenotypes in SZ: Since individuals with SZ have a higher rate of smoking than those in the general population, we hypothesized that genes associated with smoking may be overrepresented in SZ and thus help explain their increased smoking incidence. We tested whether the functional smoking-related nicotinic acetylcholine receptor α5 subunit gene (CHRNA5) nonsynonymous single nucleotide polymorphism (SNP) rs16969968 (Asp398Asn) contributes to smoking in SZ in patients and controls. The Asp398Asn risk allele is significantly associated with smoking severity independently in SZ smokers and control smokers. Furthermore, the same risk allele is significantly associated with SZ in both Caucasian and African-American nonsmoker SZ patients compared with control nonsmokers. Intriguingly, this SNP was not significantly associated with smoking status (smokers vs. nonsmokers) in either SZ patients or controls. Therefore, our study identifies a genetic variant that is simultaneously linked to smoking and SZ in the same cohort, but whether this SNP contributes to the increased smoking prevalence in SZ patients requires additional studies. 5. Effects of smoking and SZ on white matter abnormalities: Whole brain white matter integrity (fractional anisotropy (FA)) was measured in patients and healthy control subjects. Smoking status and SZ were independently and additively associated with reduced FA in left anterior thalamic radiation/anterior limb of the internal capsule, and significant FA decreases were identified in the bilateral uncinate fasciculus/inferior fronto-occipital fasciculus in SZ and the left prefrontal area in smoking status separately. Common and distinct patterns of impaired white matter are associated with SZ and smoking. Particularly, the anatomic congruence of an additive white matter abnormality in the anterior thalamic radiation/anterior limb of the internal capsule suggests that this abnormal fiber connection between frontal cortex and striatum/thalamus may be a biomarker for the increased comorbid smoking in SZ patients. 6. Insula and Anterior Cingulate Resting State Functional Connectivity in SZ Smokers: The cause of the high rate of smoking in SZ patients remains unclear. We previously found that a dorsal anterior cingulate (dACC) striatum resting state functional connectivity (rsFC) circuit is associated with nicotine addiction in normal controls and patients. The insula is closely related to smoking and the ability to quit. Therefore, we hypothesized that SZ smokers may have more dysfunction in smoking-related insular and dACC circuits compared with control smokers, thus explaining their higher propensity to smoke. Using individually identified anterior and posterior insula, and dACC as seed regions, rsFC with the rest of the brain was determined. Significant decreases in rsFC that correlated with increased smoking severity were found in circuits between insula, dACC and striatum in both SZ and normal control smokers. These significant relationships between nicotine addiction severity and rsFC were similar between the two groups. Furthermore, subjects with SZ had additional decreases in rsFC in circuits between the dACC and insula. Reduced rsFC between the insula, dACC and striatum may underlie nicotine dependence in non-psychiatrically ill subjects as well as in SZ patients. Decreased rsFC between the dACC and insula may index an overlapping functional circuitry associated with smoking and SZ and may be a circuit biomarker for the increased smoking in SZ. 7. Effects of Prenatal Drug Exposure (PDE) on Adolescent Brain Functioning: The goal is to examine the consequences of exposure to drugs in utero in adolescents to the neurobiological mechanisms of risky decision making, working memory and functional connectivity. New findings indicate that while there is no behavioral difference between PDE and healthy adolescents on risky decision making, PDE adolescents demonstrate widespread increased activation in areas including cingulate, insula, inferior frontal gyrus, posterior temporal, parietal and occipital regions. Network circuit analysis using graph theory to examine working memory processes indicates reduced global and local efficiency in PDE adolescents. Finally, volumetric analyses indicate PDE adolescents have greater hippocampal volume that correlates negatively with measures of memory function.

Anesthesia with dexmedetomidine and low dose isoflurane increases solute transport via the glymphatic pathway in rat brain when compared to high dose isoflurane. The glymphatic pathway transports cerebrospinal fluid through the brain, thereby facilitating waste removal. A unique aspect of this pathway is that its function depends on the state of consciousness of the brain and is associated with norepinephrine activity. A current view is that all anesthetics will increase glymphatic transport by inducing unconsciousness. This view implies that the effect of anesthetics on glymphatic transport should be independent of their mechanism of action, as long as they induce unconsciousness. We tested this hypothesis by comparing the supplementary effect of dexmedetomidine, which lowers norepinephrine, with isoflurane only, which does not. Female rats were anesthetized with either isoflurane (N = 8) or dexmedetomidine plus low-dose isoflurane (N = 8). Physiologic parameters were recorded continuously. Glymphatic transport was quantified by contrast-enhanced magnetic resonance imaging. Cerebrospinal fluid and gray and white matter volumes were quantified from T1 maps, and blood vessel diameters were extracted from time-of-flight magnetic resonance angiograms. Electroencephalograms were recorded in separate groups of rats. Glymphatic transport was enhanced by 32% in rats anesthetized with dexmedetomidine plus low-dose isoflurane when compared with isoflurane. In the hippocampus, glymphatic clearance was sixfold more efficient during dexmedetomidine plus low-dose isoflurane anesthesia when compared with isoflurane. The respiratory and blood gas status was comparable in rats anesthetized with the two different anesthesia regimens. In the dexmedetomidine plus low-dose isoflurane rats, spindle oscillations (9 to 15 Hz) could be observed but not in isoflurane anesthetized rats. We propose that anesthetics affect the glymphatic pathway transport not simply by inducing unconsciousness but also by additional mechanisms, one of which is the repression of norepinephrine release. Delta rhythm orchestrates the neural activity underlying the resting state BOLD signal via phase-amplitude coupling. Spontaneous ongoing neuronal activity is a prominent feature of the mammalian brain. Temporal and spatial patterns of such ongoing activity have been exploited to examine large-scale brain network organization and function. However, the neurophysiological basis of this spontaneous brain activity as detected by resting-state functional Magnetic Resonance Imaging (fMRI) remains poorly understood. To this end, multi-site local field potentials (LFP) and blood oxygenation level-dependent (BOLD) fMRI were simultaneously recorded in the rat striatum along with local pharmacological manipulation of striatal activity. Results demonstrate that delta () band LFP power negatively, while beta () and gamma () band LFPs positively correlated with BOLD fluctuation. Furthermore, there was strong cross-frequency phase-amplitude coupling (PAC), with the phase of LFPs significantly modulating the amplitude of the high frequency signal. Enhancing dopaminergic neuronal activity significantly reduced ventral striatal functional connectivity, LFP-BOLD correlation, and the PAC effect. These data suggest that different frequency bands of the LFP contribute distinctively to BOLD spontaneous fluctuation and that PAC is the organizing mechanism through which low frequency LFPs orchestrate neural activity that underlies resting state functional connectivity.