Expectation modulates human brain responses to acute cocaine: a functional magnetic resonance imaging study

Linking drug and food addiction: an overview of the shared neural circuits and behavioral phenotype

Despite a lack of agreement on its definition and inclusion as a specific diagnosable disturbance, the food addiction construct is supported by several neurobiological and behavioral clinical and preclinical findings. Recognizing food addiction is critical to understanding how and why it manifests. In this overview, we focused on those as follows: 1. the hyperpalatable food effects in food addiction development; 2. specific brain regions involved in both food and drug addiction; and 3. animal models highlighting commonalities between substance use disorders and food addiction. Although results collected through animal studies emerged from protocols differing in several ways, they clearly highlight commonalities in behavioral manifestations and neurobiological alterations between substance use disorders and food addiction characteristics. To develop improved food addiction models, this heterogeneity should be acknowledged and embraced so that research can systematically investigate the role of specific variables in the development of the different behavioral features of addiction-like behavior in preclinical models.

Neural underpinnings of expecting alcohol: Placebo alcohol administration alters nucleus accumbens resting state functional connectivity

BACKGROUND

Using balanced placebo designs, seminal alcohol administration research has shown individuals' beliefs about whether they have consumed alcohol, irrespective of the actual presence of alcohol, can determine level of alcohol consumption and impact social behavior. Despite the known effect of expecting alcohol on drinking behavior, few studies have used the placebo manipulation to directly investigate the neural underpinnings of the expectancy-related effects that occur following perceived alcohol consumption in humans. The present paper examined placebo responses in the laboratory to better understand the neural basis for the psychological phenomenon of expectancies.

METHODS

As part of a larger within-subjects study design, healthy young adults (N = 22, agemean+SD=23 +1) completed resting state fMRI scans and measures of subjective response before and after consuming placebo beverages. Effect of placebo beverage consumption (pre- versus post-beverage consumption) on functional connectivity within prefrontal cortical networks was examined using the CONN Toolbox. Relations between perceived subjective response to alcohol with functional connectivity response following placebo beverage consumption were examined.

RESULTS

Compared to pre-beverage scan, placebo beverage consumption was associated with increased positive functional connectivity between right nucleus accumbens - ventromedial prefrontal cortex and subcallosal cingulate cortex (pFDR<0.05). Subjective ratings of intoxication (i.e., feeling 'drunk') positively correlated with placebo beverage-related increases in nucleus accumbens - subcallosal cingulate cortex functional connectivity.

CONCLUSION

Results suggest placebo response to alcohol is associated with increased functional connectivity within a key reward network (nucleus accumbens - ventromedial prefrontal cortex and subcallosal cingulate cortex) and put forth a mechanism by which alcohol expectancies may contribute to the subjective experience of intoxication.

Acupuncture Modulation Effect on Pain Processing Patterns in Patients With Migraine Without Aura

Introduction

In this retrospective study, resting-state functional connectivity (FC) in patients with migraine was analyzed to identify potential pathological pain processing patterns and compared them to those in healthy controls (HCs). The FC patterns in patients between pre- and post-acupuncture sessions were also analyzed to determine how acupuncture affects neurological activity and pain perception during the migraine interictal period.

Methods

In total, 52 patients with migraine without aura (MwoA) and 60 HCs were recruited. Patients with migraine were given acupuncture treatment sessions for 4 weeks. As a primary observation, functional magnetic resonance images were obtained at the beginning and end of the sessions. HCs received no treatment and underwent one functional magnetic resonance imaging (fMRI) scan after enrollment. After the fMRI data were preprocessed, a region of interest (ROI)-to-ROI analysis was performed with predefined ROIs related to pain processing regions.

Results

The first analysis showed significantly different FCs between patients with MwoA and HCs [false discovery rate corrected p-value (p-FDR) < 0.05]. The FCs were found to be mainly between the cingulate gyrus (CG) and the insular gyrus, the CG and the inferior parietal lobule (IPL), the CG and the superior frontal gyrus, and the middle frontal gyrus and the IPL. The second analysis indicated that acupuncture treatment partly restored the different FCs found in the first analysis (p-FDR < 0.05). Furthermore, subgroup analysis found different brain activity patterns in headache-intensity restored condition and headache-frequency restored condition. Lastly, the correlation analysis suggested a potential correlation between FCs and clinical symptoms (p < 0.05).

Conclusion

This study suggests that pain processing is abnormal in migraine, with significantly abnormal FCs in the frontal, parietal, and limbic regions. This finding could be a typical pathological feature of migraine. Acupuncture has been identified to relieve headache symptoms in two ways: it restores the pain processing function and regulates pain perception.

Pharmacological Inactivation of Medial Prefrontal Cortex Does Not Support Dichotomous "Go/Stop" Roles for Dorsal and Ventral Subdivisions in Natural Reward Seeking in Rats

Highlighted Research Paper:Differential Effects of Dorsal and Ventral Medial Prefrontal Cortex Inactivation during Natural Reward Seeking, Extinction, and Cue-Induced Reinstatement. Jessica P. Caballero, Garrett B. Scarpa, Luke Remage-Healey, David E. Moorman.

The science of belief: A progress report

The empirical study of belief is emerging at a rapid clip, uniting work from all corners of cognitive science. Reliance on belief in understanding and predicting behavior is widespread. Examples can be found, inter alia, in the placebo, attribution theory, theory of mind, and comparative psychological literatures. Research on belief also provides evidence for robust generalizations, including about how we fix, store, and change our beliefs. Evidence supports the existence of a Spinozan system of belief fixation: one that is automatic and independent of belief rejection. Independent research supports the existence of a system of fragmented belief storage: one that relies on large numbers of causally isolated, context-sensitive stores of belief in memory. Finally, empirical and observational data support at least two systems of belief change. One system adheres, mostly, to epistemological norms of updating; the other, the psychological immune system, functions to guard our most centrally held beliefs from potential inconsistency with newly formed beliefs. Refining our understanding of these systems can shed light on pressing real-world issues, such as how fake news, propaganda, and brainwashing exploit our psychology of belief, and how best to construct our modern informational world. This article is categorized under: Psychology > Reasoning and Decision Making Philosophy > Knowledge and Belief Philosophy > Foundations of Cognitive Science.

Neuroplastic changes in resting-state functional connectivity after rTMS intervention for methamphetamine craving

Amphetamine-type stimulants are the second most commonly abused illicit drug worldwide, with no effective medical treatments currently available. Previous studies have demonstrated that high frequency repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) reduced cue-induced craving in patients with methamphetamine dependence. However, the neuroplastic mechanism underlying rTMS intervention in methamphetamine users remains to be elucidated. Sixty participants (40 males) with severe methamphetamine use disorder according to DSM-5 were randomized to receive either intermittent theta burst protocols (iTBS) (short bursts of 50 Hz rTMS repeated at a rate in the theta range (5 Hz), 2-sec on, 8-sec off for 5 min; 900 pulses) or sham rTMS over the DLPFC over four weeks (20 daily sessions). Resting state functional connectivity magnetic resonance imaging was acquired before and after rTMS intervention. Participants received drug related cue exposure and rated their craving before and after stimulation. Seed-based functional connectivity analysis was performed to probe rTMS-induced neuroplastic reorganization of brain functional networks. Results showed that twenty daily rTMS sessions decreased craving, increased functional connectivity between left DLPFC and inferior parietal lobule, and decreased functional connectivity between insula and inferior parietal lobule, medial temporal lobe and precuneus. Moreover, the increase of functional connectivity between DLPFC and inferior parietal lobule correlated with craving reduction. This study suggests that neuroplastic changes of frontoparietal functional connectivity contributes to craving reduction, shedding light on the therapeutic effect of rTMS on methamphetamine use disorder. This article is part of the special issue on Stress, Addiction and Plasticity.

Acute and Chronic Effects of Betel Quid Chewing on Brain Functional Connectivity

BACKGROUND

The active alkaloid in Betel quid is arecoline. Consumption of betel quid is associated with both acute effects and longer-term addictive effects. Despite growing evidence that betel quid use is linked with altered brain function and connectivity, the neurobiology of this psychoactive substance in initial acute chewing, and long-term dependence, is not clear.

METHODS

In this observational study, functional magnetic resonance imaging in a resting-state was performed in 24 male betel quid-dependent chewers and 28 male controls prior to and promptly after betel quid chewing. Network-based statistics were employed to determine significant differences in functional connectivity between brain networks for both acute effects and in long-term betel users versus controls. A support vector machine was employed for pattern classification analysis.

RESULTS

Before chewing betel quid, higher functional connectivity in betel quid-dependent chewers than in controls was found between the temporal, parietal and frontal brain regions (right medial orbitofrontal cortex, right lateral orbital frontal cortex, right angular gyrus, bilateral inferior temporal gyrus, superior parietal gyrus, and right medial superior frontal gyrus). In controls, the effect of betel quid chewing was significantly increased functional connectivity between the subcortical regions (caudate, putamen, pallidum, and thalamus), and the visual cortex (superior occipital gyrus and right middle occipital gyrus).

CONCLUSION

These findings show that individuals who chronically use betel quid have higher functional connectivity than controls of the orbitofrontal cortex, and inferior temporal and angular gyri. Acute effects of betel quid are to increase the functional connectivity of some visual cortical areas (which may relate to the acute symptoms) and the basal ganglia and thalamus.

The role of the orbitofrontal cortex in alcohol use, abuse, and dependence

One of the major functions of the orbitofrontal cortex (OFC) is to promote flexible motivated behavior. It is no surprise, therefore, that recent work has demonstrated a prominent impact of chronic drug use on the OFC and a potential role for OFC disruption in drug abuse and addiction. Among drugs of abuse, the use of alcohol is particularly salient with respect to OFC function. Although a number of studies in humans have implicated OFC dysregulation in alcohol use disorders, animal models investigating the association between OFC and alcohol use are only beginning to be developed, and there is still a great deal to be revealed. The goal of this review is to consider what is currently known regarding the role of the OFC in alcohol use and dependence. I will first provide a brief, general overview of current views of OFC function and its contributions to drug seeking and addiction. I will then discuss research to date related to the OFC and alcohol use, both in human clinical populations and in non-human models. Finally I will consider issues and strategies to guide future study that may identify this brain region as a key player in the transition from moderated to problematic alcohol use and dependence.

Cortico-Striatal-Thalamic Loop Circuits of the Orbitofrontal Cortex: Promising Therapeutic Targets in Psychiatric Illness

Corticostriatal circuits through the orbitofrontal cortex (OFC) play key roles in complex human behaviors such as evaluation, affect regulation and reward-based decision-making. Importantly, the medial and lateral OFC (mOFC and lOFC) circuits have functionally and anatomically distinct connectivity profiles which differentially contribute to the various aspects of goal-directed behavior. OFC corticostriatal circuits have been consistently implicated across a wide range of psychiatric disorders, including major depressive disorder (MDD), obsessive compulsive disorder (OCD), and substance use disorders (SUDs). Furthermore, psychiatric disorders related to OFC corticostriatal dysfunction can be addressed via conventional and novel neurostimulatory techniques, including deep brain stimulation (DBS), electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS). Such techniques elicit changes in OFC corticostriatal activity, resulting in changes in clinical symptomatology. Here we review the available literature regarding how disturbances in mOFC and lOFC corticostriatal functioning may lead to psychiatric symptomatology in the aforementioned disorders, and how psychiatric treatments may exert their therapeutic effect by rectifying abnormal OFC corticostriatal activity. First, we review the role of OFC corticostriatal circuits in reward-guided learning, decision-making, affect regulation and reappraisal. Second, we discuss the role of OFC corticostriatal circuit dysfunction across a wide range of psychiatric disorders. Third, we review available evidence that the therapeutic mechanisms of various neuromodulation techniques may directly involve rectifying abnormal activity in mOFC and lOFC corticostriatal circuits. Finally, we examine the potential of future applications of therapeutic brain stimulation targeted at OFC circuitry; specifically, the role of OFC brain stimulation in the growing field of individually-tailored therapies and personalized medicine in psychiatry.

Brain and Emotion

Progress in understanding the relation between brain profiles and emotions is being slowed by the belief in a collection of basic emotional states, with the names: fear, anger, joy, disgust, and sadness, that do not specify the species or age of the experiencing agent, the origin of the state, or the evidence used to infer it. This article evaluates critically the premise that decontextualized emotional words refer to natural kinds. It also suggests that investigators set aside the currently popular words and search for relations, in humans and animals, between patterns of measures to varied incentives presented in distinctive contexts.

Belief about Nicotine Modulates Subjective Craving and Insula Activity in Deprived Smokers

Little is known about the specific neural mechanisms through which cognitive factors influence craving and associated brain responses, despite the initial success of cognitive therapies in treating drug addiction. In this study, we investigated how cognitive factors such as beliefs influence subjective craving and neural activities in nicotine-addicted individuals using model-based functional magnetic resonance imaging (fMRI) and neuropharmacology. Deprived smokers (N = 24) participated in a two-by-two balanced placebo design, which crossed beliefs about nicotine (told "nicotine" vs. told "no nicotine") with the nicotine content in a cigarette (nicotine vs. placebo) which participants smoked immediately before performing a fMRI task involving reward learning. Subjects' reported craving was measured both before smoking and after the fMRI session. We found that first, in the presence of nicotine, smokers demonstrated significantly reduced craving after smoking when told "nicotine in cigarette" but showed no change in craving when told "no nicotine." Second, neural activity in the insular cortex related to craving was only significant when smokers were told "nicotine" but not when told "no nicotine." Both effects were absent in the placebo condition. Third, insula activation related to computational learning signals was modulated by belief about nicotine regardless of nicotine's presence. These results suggest that belief about nicotine has a strong impact on subjective craving and insula responses related to both craving and learning in deprived smokers, providing insights into the complex nature of belief-drug interactions.

Functional consequences of cocaine expectation: findings in a non-human primate model of cocaine self-administration

Exposure to stimuli and environments associated with drug use is considered one of the most important contributors to relapse among substance abusers. Neuroimaging studies have identified neural circuits underlying these responses in cocaine-dependent subjects. But these studies are often difficult to interpret because of the heterogeneity of the participants, substances abused, and differences in drug histories and social variables. Therefore, the goal of this study was to assess the functional effects of exposure to cocaine-associated stimuli in a non-human primate model of cocaine self-administration, providing precise control over these variables, with the 2-[(14) C]deoxyglucose method. Rhesus monkeys self-administered 0.3 mg/kg/injection cocaine (n = 4) under a fixed-interval 3-minute (FI 3-min) schedule of reinforcement (30 injections/session) for 100 sessions. Control animals (n = 4) underwent identical schedules of food reinforcement. Sessions were then discontinued for 30 days, after which time, monkeys were exposed to cocaine- or food-paired cues, and the 2-[(14) C]deoxyglucose experiment was conducted. The presentation of the cocaine-paired cues resulted in significant increases in functional activity within highly restricted circuits that included portions of the pre-commissural striatum, medial prefrontal cortex, rostral temporal cortex and limbic thalamus when compared with control animals presented with the food-paired cues. The presentation of cocaine-associated cues increased brain functional activity in contrast to the decreases observed after cocaine consumption. Furthermore, the topography of brain circuits engaged by the expectation of cocaine is similar to the distribution of effects during the earliest phases of cocaine self-administration, prior to the onset of neuroadaptations that accompany chronic cocaine exposure.

Shared neural basis of social and non-social reward deficits in chronic cocaine users

Changed reward functions have been proposed as a core feature of stimulant addiction, typically observed as reduced neural responses to non-drug-related rewards. However, it was unclear yet how specific this deficit is for different types of non-drug rewards arising from social and non-social reinforcements. We used functional neuroimaging in cocaine users to investigate explicit social reward as modeled by agreement of music preferences with music experts. In addition, we investigated non-social reward as modeled by winning desired music pieces. The study included 17 chronic cocaine users and 17 matched stimulant-naive healthy controls. Cocaine users, compared with controls, showed blunted neural responses to both social and non-social reward. Activation differences were located in the ventromedial prefrontal cortex overlapping for both reward types and, thus, suggesting a non-specific deficit in the processing of non-drug rewards. Interestingly, in the posterior lateral orbitofrontal cortex, social reward responses of cocaine users decreased with the degree to which they were influenced by social feedback from the experts, a response pattern that was opposite to that observed in healthy controls. The present results suggest that cocaine users likely suffer from a generalized impairment in value representation as well as from an aberrant processing of social feedback.

Differential roles of medial prefrontal subregions in the regulation of drug seeking

The prefrontal cortex plays an important role in shaping cognition and behavior. Many studies have shown that medial prefrontal cortex (mPFC) plays a key role in seeking, extinction, and reinstatement of cocaine seeking in rodent models of relapse. Subregions of mPFC appear to play distinct roles in these behaviors, such that the prelimbic cortex (PL) is proposed to drive cocaine seeking and the infralimbic cortex (IL) is proposed to suppress cocaine seeking after extinction. This dichotomy of mPFC function may be a general attribute, as similar dorsal-ventral distinctions exist for expression vs. extinction of fear conditioning. However, other results indicate that the role of mPFC neurons in reward processing is more complex than a simple PL-seek vs. IL-extinguish dichotomy. Both PL and IL have been shown to drive and inhibit drug seeking (and other types of behaviors) depending on a range of factors including the behavioral context, the drug-history of the animal, and the type of drug investigated. This heterogeneity of findings may reflect multiple subcircuits within each of these PFC areas supporting unique functions. It may also reflect the fact that the mPFC plays a multifaceted role in shaping cognition and behavior, including those overlapping with cocaine seeking and extinction. Here we discuss research leading to the hypothesis that dorsal and ventral mPFC differentially control drug seeking and extinction. We also present recent results calling the absolute nature of a PL vs. IL dichotomy into question. Finally, we consider alternate functions for mPFC that correspond less to response execution and inhibition and instead incorporate the complex cognitive behavior for which the mPFC is broadly appreciated.

Belief about nicotine selectively modulates value and reward prediction error signals in smokers

Little is known about how prior beliefs impact biophysically described processes in the presence of neuroactive drugs, which presents a profound challenge to the understanding of the mechanisms and treatments of addiction. We engineered smokers' prior beliefs about the presence of nicotine in a cigarette smoked before a functional magnetic resonance imaging session where subjects carried out a sequential choice task. Using a model-based approach, we show that smokers' beliefs about nicotine specifically modulated learning signals (value and reward prediction error) defined by a computational model of mesolimbic dopamine systems. Belief of "no nicotine in cigarette" (compared with "nicotine in cigarette") strongly diminished neural responses in the striatum to value and reward prediction errors and reduced the impact of both on smokers' choices. These effects of belief could not be explained by global changes in visual attention and were specific to value and reward prediction errors. Thus, by modulating the expression of computationally explicit signals important for valuation and choice, beliefs can override the physical presence of a potent neuroactive compound like nicotine. These selective effects of belief demonstrate that belief can modulate model-based parameters important for learning. The implications of these findings may be far ranging because belief-dependent effects on learning signals could impact a host of other behaviors in addiction as well as in other mental health problems.

Electrophysiological evidence of early attentional bias to drug-related pictures in chronic cannabis users

Behavioral and electrophysiological correlates of attentional bias to cannabis-related cues were investigated in a marijuana dependent group and a non-user group employing a drug Stroop task in which cannabis-related, negative and neutral images were presented. Behaviorally, cannabis users were less accurate during drug-containing blocks than non-users. Electrophysiologically, in chronic marijuana-users, an early positive ERP enhancement over left frontal scalp (EAP, 200-350ms) was present in response to drug-containing blocks relative to negative blocks. This effect was absent in the non-user group. Furthermore, drug-containing blocks gave rise to enhanced voltage of a posterior P300 (300-400ms), and a posterior sustained slow wave (LPP, 400-700ms) relative to negative blocks. However, such effects were similar between cannabis users and non-users. Brain source imaging in cannabis users revealed a generator for the EAP effect to drug stimuli in left ventromedial prefrontal cortex/medial orbitofrontal cortex, a region active in fMRI studies of drug cue-reactivity and a target of the core dopaminergic mesolimbic pathway involved in the processing of substances of abuse. This study identifies the timing and brain localization of an ERP correlate of early attentional capture to drug-related pictures in chronic marijuana users. The EAP to drug cues may identify a new electrophysiological marker with clinical implications for predicting abstinence versus relapse or to evaluate treatment interventions.

Predominance of D2 receptors in mediating dopamine's effects in brain metabolism: effects of alcoholism

Dopamine signals through D1-like and D2-like receptors, which can stimulate or inhibit, respectively, neuronal activity. Here we assessed the balance between D1 or D2 receptor signaling in the human brain and how it is affected in alcoholism. Using PET, we measured the relationship between changes in dopamine and brain glucose metabolism induced by methylphenidate in controls and alcoholics. We show that methylphenidate induced significant DA increases in striatum, amygdala, and medial orbitofrontal cortex, whereas it decreased metabolism in these brain regions. Methylphenidate-induced dopamine increases were greater in controls than in alcoholics, whereas methylphenidate-induced metabolic decreases were greater in alcoholics. For both groups, methylphenidate-induced dopamine increases were associated with decreases in regional brain metabolism, and the correlations were strongest in subthalamic nuclei, anterior cingulate, and medial orbitofrontal cortex. These correlations were more extensive and robust and the slopes steeper in alcoholics than in controls despite their attenuated dopamine responses to methylphenidate, which suggests an impaired modulation of dopamine signals in the brain of alcoholic subjects. These findings are consistent with a predominant inhibitory effect of dopamine in the human brain that is likely mediated by the prominence of dopamine D2/D3 receptors.

Nicotine related brain activity: the influence of smoking history and blood nicotine levels, an exploratory study

OBJECTIVE

In this study, we sought to explore brain activity in nicotine-dependent men in response to acute intravenous nicotine using pharmacological magnetic resonance imaging (phMRI).

METHODS

phMRI was used to evaluate brain activity in response to 1.5 mg/70 kg intravenous nicotine or saline. The nicotine and saline were administered on different visits. The time courses of individual subjects' nicotine levels were used as regressors to assess neural activity relating to the infusions. The influence of smoking history and physiological measures on the response to nicotine were also investigated.

RESULTS

Greater lifetime exposure to cigarette smoking was significantly correlated with higher peak serum nicotine levels. PhMRI analysis of the differential response of nicotine compared to the saline condition showed distinctive activation patterns when analyzed with the (a) nicotine time course, (b) nicotine time course controlling for smoking history (pack years), and (c) pack years controlling for nicotine.

CONCLUSIONS

These results suggest that smoking exposure history influences serum nicotine levels and the brain's response to nicotine. Alterations in brain activity may be a result of vascular and neuro-adaptations involved in drug exposure and addiction.

Neural coding of computational factors affecting decision making

We constantly need to make decisions that can result in rewards of different amounts with different probabilities and at different timing. To characterize the neural coding of such computational factors affecting value-based decision making, we have investigated how reward information processing is influenced by parameters such as reward magnitude, probability, delay, effort, and uncertainty using either fMRI in healthy humans or intracranial recordings in patients with epilepsy. We decomposed brain signals modulated by these computational factors, showing that prediction error (PE), salient PE, and uncertainty signals are computed in partially overlapping brain circuits and that both transient and sustained uncertainty signals coexist in the brain. When investigating the neural representation of primary and secondary rewards, we found both a common brain network, including the ventromedial prefrontal cortex and ventral striatum, and a functional organization of the orbitofrontal cortex according to reward type. Moreover, separate valuation systems were engaged for delay and effort costs when deciding between options. Finally, genetic variations in dopamine-related genes influenced the response of the reward system and may contribute to individual differences in reward-seeking behavior and in predisposition to neuropsychiatric disorders.

Dysfunction of the prefrontal cortex in addiction: neuroimaging findings and clinical implications

The loss of control over drug intake that occurs in addiction was initially believed to result from disruption of subcortical reward circuits. However, imaging studies in addictive behaviours have identified a key involvement of the prefrontal cortex (PFC) both through its regulation of limbic reward regions and its involvement in higher-order executive function (for example, self-control, salience attribution and awareness). This Review focuses on functional neuroimaging studies conducted in the past decade that have expanded our understanding of the involvement of the PFC in drug addiction. Disruption of the PFC in addiction underlies not only compulsive drug taking but also accounts for the disadvantageous behaviours that are associated with addiction and the erosion of free will.

Cocaine-induced impulsive choices are accompanied by impaired delay-dependent anticipatory activity in basolateral amygdala

Addicts and drug-experienced animals have decision-making deficits in delayed reinforcement choice task, in which they prefer small immediate rewards over large delayed rewards. Here, we show evidence that this deficit is accompanied by changed coding of delay length in the basolateral amygdala (BLA). A subset of neurons in BLA demonstrated delay-dependent anticipatory activity (either increase or decrease as a function of delay to reward) in naive rats. After 30 days of withdrawal from chronic cocaine treatment (30 mg/kg/day for 10 days ip), the proportion of delay-dependent anticipatory neurons reduced, whereas delay-dependent activity in response to elapsed delay after reward delivery increased, both in the proportion of delay-dependent neurons and in the extent of delay dependence. Cocaine exposure increased, instead of decreased, BLA neuronal expectation for different reward magnitudes. These results indicate that BLA is critical for representing and maintaining the information of delayed reward before its delivery, and cocaine exposure may affect decision-making by impairing perception of delay instead of the ability to assess the differences in reward size.

Positive emotionality is associated with baseline metabolism in orbitofrontal cortex and in regions of the default network

Positive emotionality (PEM) (personality construct of well-being, achievement/motivation, social and closeness) has been associated with striatal dopamine D2 receptor availability in healthy controls. As striatal D2 receptors modulate activity in orbitofrontal cortex (OFC) and cingulate (brain regions that process natural and drug rewards), we hypothesized that these regions underlie PEM. To test this, we assessed the correlation between baseline brain glucose metabolism (measured with positron emission tomography and [(18)F]fluoro-deoxyglucose) and scores on PEM (obtained from the multidimensional personality questionnaire or MPQ) in healthy controls (n = 47). Statistical parametric mapping (SPM) analyses revealed that PEM was positively correlated (P(c)<0.05, voxel corrected) with metabolism in various cortical regions that included orbitofrontal (Brodman area, BA 11, 47) and cingulate (BA 23, 32) and other frontal (BA 10, 9), parietal (precuneus, BA 40) and temporal (BA 20, 21) regions that overlap with the brain's default mode network (DMN). Correlations with the other two main MPQ personality dimensions (negative emotionality and constraint) were not significant (SPM P(c)<0.05). Our results corroborate an involvement of orbitofrontal and cingulate regions in PEM, which is considered a trait that protects against substance use disorders. As dysfunction of OFC and cingulate is a hallmark of addiction, these findings support a common neural basis underlying protective personality factors and brain dysfunction underlying substance use disorders. In addition, we also uncovered an association between PEM and baseline metabolism in regions from the DMN, which suggests that PEM may relate to global cortical processes that are active during resting conditions (introspection, mind wandering).

fMRI of cocaine self-administration in macaques reveals functional inhibition of basal ganglia

Disparities in cocaine-induced neurochemical and metabolic responses between human beings and rodents motivate the use of non-human primates (NHP) to model consequences of repeated cocaine exposure in human subjects. To characterize the functional response to cocaine infusion in NHP brain, we employed contrast-enhanced fMRI during both non-contingent injection of drug and self-administration of cocaine in the magnet. Cocaine robustly decreased cerebral blood volume (CBV) throughout basal ganglia and motor/pre-motor cortex and produced subtle functional inhibition of prefrontal cortex. No brain regions exhibited significant elevation of CBV in response to cocaine challenge. Theses effects in NHP brain are opposite in sign to the cocaine-induced fMRI response in rats, but consistent with previous measurements in NHP based on glucose metabolism. Because the striatal ratio of D2 to D1 receptors is larger in human beings and NHP than rats, we hypothesize that the inhibitory effects of D2 receptor binding dominate the functional response in primates, whereas excitatory D1 receptor stimulation predominates in the rat. If the NHP accurately models the human response to cocaine, downregulation of D2 receptors in human cocaine-abusing populations can be expected to blunt cocaine-induced functional responses, contributing to the weak and variable fMRI responses reported in human basal ganglia following cocaine infusion.

Development of an apparatus and methodology for conducting functional magnetic resonance imaging (fMRI) with pharmacological stimuli in conscious rhesus monkeys

Functional magnetic resonance imaging (fMRI) is a technique with significant potential to advance our understanding of multiple brain systems. However, when human subjects undergo fMRI studies they are typically conscious whereas pre-clinical fMRI studies typically utilize anesthesia, which complicates comparisons across studies. Therefore, we have developed an apparatus suitable for imaging conscious rhesus monkeys. In order to minimize subject stress and spatial motion, each subject was acclimated to the necessary procedures over several months. The effectiveness of this process was then evaluated, in fully trained subjects, by quantifying objective physiological measures. These physiological metrics were stable both within and across sessions and did not differ from when these same subjects were immobilized using standard primate handling procedures. Subject motion and blood oxygenation level dependent (BOLD) fMRI measurements were then evaluated by scanning subjects under three different conditions: the absence of stimulation, presentation of a visual stimulus, or administration of intravenous (i.v.) cocaine (0.3mg/kg). Spatial motion differed neither by condition nor along the three principal axes. In addition, maximum translational and rotational motion never exceeded one half of the voxel size (0.75 mm) or 1.5 degrees, respectively. Furthermore, the localization of changes in blood oxygenation closely matched those reported in previous studies using similar stimuli. These findings document the feasibility of fMRI data collection in conscious rhesus monkeys using these procedures and allow for the further study of the neural effects of psychoactive drugs.

Neurocircuitry of addiction

Drug addiction is a chronically relapsing disorder that has been characterized by (1) compulsion to seek and take the drug, (2) loss of control in limiting intake, and (3) emergence of a negative emotional state (eg, dysphoria, anxiety, irritability) reflecting a motivational withdrawal syndrome when access to the drug is prevented. Drug addiction has been conceptualized as a disorder that involves elements of both impulsivity and compulsivity that yield a composite addiction cycle composed of three stages: 'binge/intoxication', 'withdrawal/negative affect', and 'preoccupation/anticipation' (craving). Animal and human imaging studies have revealed discrete circuits that mediate the three stages of the addiction cycle with key elements of the ventral tegmental area and ventral striatum as a focal point for the binge/intoxication stage, a key role for the extended amygdala in the withdrawal/negative affect stage, and a key role in the preoccupation/anticipation stage for a widely distributed network involving the orbitofrontal cortex-dorsal striatum, prefrontal cortex, basolateral amygdala, hippocampus, and insula involved in craving and the cingulate gyrus, dorsolateral prefrontal, and inferior frontal cortices in disrupted inhibitory control. The transition to addiction involves neuroplasticity in all of these structures that may begin with changes in the mesolimbic dopamine system and a cascade of neuroadaptations from the ventral striatum to dorsal striatum and orbitofrontal cortex and eventually dysregulation of the prefrontal cortex, cingulate gyrus, and extended amygdala. The delineation of the neurocircuitry of the evolving stages of the addiction syndrome forms a heuristic basis for the search for the molecular, genetic, and neuropharmacological neuroadaptations that are key to vulnerability for developing and maintaining addiction.

Imaging cognitive deficits in drug abuse

The neuropsychological network is a complex structure. To identify processes location and network capacity the brain imaging techniques together and in combination with other neuropsychological techniques and the expanding of well elaborated designs provide us with a multidimensional understanding, and contributes to the understanding of each illicit drug's character, which is of importance in designing of new treatment programs and clinical practice. Cannabis, MDMA, amphetamine, cocaine, and heroin abusers display both acute effects and chronic effects, deficits in attention, memory, and executive functioning. These deficits may last beyond the period of intoxication and cumulate with years of use. Cannabis users may recruit an alternative neural network as a compensatory mechanism during performance of tasks of attention. There is some evidence indicating the detrimental effects of cannabis on the maturing adolescent brain. Stimulant dependence is characterized by a distributed alteration of functional activation. Attenuated anterior and posterior cingulate activation, reduced inferior frontal and dorsolateral prefrontal cortex activation, and altered posterior parietal activation point towards an inadequate demand-specific processing of information. On an individual level they exhibit process-related brain activation differences that are consistent with a shift from context-specific, effortful processing to more stereotyped, habitual response generation. Finally, opiate use appears to decrease the ability to shift cognitive set and inhibit inappropriate response tendencies.

c-Fos expression associated with reinstatement of cocaine-seeking behavior by response-contingent conditioned cues

The capability of cocaine cues to generate craving in cocaine-dependent humans, even after extended abstinence, is modeled in rats using cue reinstatement of extinguished cocaine-seeking behavior. We investigated neural activity associated with incentive motivational effects of cocaine cues using c-fos mRNA and Fos protein expression as markers. Unlike preceding studies, we used response-contingent presentation of discrete cues to elicit cocaine seeking. Rats were first trained to press a lever, resulting in cocaine reinforcement and light and tone cues. Rats then underwent extinction training, during which lever presses decreased. On the test day, rats either received response-contingent cocaine cues or received no cues. The cues reinstated extinguished cocaine-seeking behavior on the test day. In general, cue-elicited c-fos mRNA and protein expression were similar and both were enhanced in the prefrontal cortex, ventral tegmental area (VTA), dorsal striatum, and nucleus accumbens. Cues elicited more widespread Fos protein expression relative to our previous research in which cues were presented noncontingently without prior extinction training, including increases in the VTA, substantia nigra, ventral subiculum, and lateral entorhinal cortex. We also observed a correlation between cocaine-seeking behavior and Fos in the agranular insula (AgI) and basolateral amygdala (BLA). The findings suggest that connections between BLA and AgI play a role in cue-elicited incentive motivation for cocaine and that reinstatement of cocaine seeking by response-contingent cues activates a similar corticolimbic circuit as that observed with other modes of cue presentation; however, activation of midbrain and ventral hippocampal regions may be unique to reinstatement by response-contingent cues.

Meditators and non-meditators: EEG source imaging during resting

Many meditation exercises aim at increased awareness of ongoing experiences through sustained attention and at detachment, i.e., non-engaging observation of these ongoing experiences by the intent not to analyze, judge or expect anything. Long-term meditation practice is believed to generalize the ability of increased awareness and greater detachment into everyday life. We hypothesized that neuroplasticity effects of meditation (correlates of increased awareness and detachment) would be detectable in a no-task resting state. EEG recorded during resting was compared between Qigong meditators and controls. Using LORETA (low resolution electromagnetic tomography) to compute the intracerebral source locations, differences in brain activations between groups were found in the inhibitory delta EEG frequency band. In the meditators, appraisal systems were inhibited, while brain areas involved in the detection and integration of internal and external sensory information showed increased activation. This suggests that neuroplasticity effects of long-term meditation practice, subjectively described as increased awareness and greater detachment, are carried over into non-meditating states.

An fMRI investigation of the impact of withdrawal on regional brain activity during nicotine anticipation

Previous research indicates that drug motivational systems are instantiated in structures that process information related to incentive, motivational drive, memorial, motor/habit, craving, and cognitive control processing. The present research tests the hypothesis that activity in such systems will be powerfully affected by the combination of drug anticipation and drug withdrawal. Event-related fMRI was used to examine activation in response to a preinfusion warning cue in two experimental sessions that manipulated withdrawal status. Significant cue-induced effects were seen in the caudate, ventral anterior nucleus of the thalamus, the insula, subcallosal gyrus, nucleus accumbens, and anterior cingulate. These results suggest that withdrawal and nicotine anticipation produce (1) different motor preparatory and inhibitory response processing and (2) different craving related processing.

The salient characteristics of the central effects of acupuncture needling: limbic-paralimbic-neocortical network modulation

Human and animal studies suggest that acupuncture produces many beneficial effects through the central nervous system. However, the neural substrates of acupuncture actions are not completely clear to date. fMRI studies at Hegu (LI4) and Zusanli (ST36) indicated that the limbic system may play an important role for acupuncture effects. To test if this finding applies to other major classical acupoints, fMRI was performed on 10 healthy adults during manual acupuncture at Taichong (LV3), Xingjian (LV2), Neiting (ST44), and a sham point on the dorsum of the left foot. Although certain differences could be observed between real and sham points, the hemodynamic response (BOLD signal changes) and psychophysical response (sensory experience) to acupuncture were generally similar for all four points. Acupuncture produced extensive deactivation of the limbic-paralimbic-neocortical system. Clusters of deactivated regions were seen in the medial prefrontal cortex (frontal pole, pregenual cingulate), the temporal lobe (amygdala, hippocampus, and parahippocampus) and the posterior medial cortex (precuneus, posterior cingulate). The sensorimotor cortices (somatosensory cortices, supplementary motor cortex), thalamus and occasional paralimbic structures such as the insula and anterior middle cingulate cortex showed activation. Our results provide additional evidence in support of previous reports that acupuncture modulates the limbic-paralimbic-neocortical network. We hypothesize that acupuncture may mediate its antipain, antianxiety, and other therapeutic effects via this intrinsic neural circuit that plays a central role in the affective and cognitive dimensions of pain as well as in the regulation and integration of emotion, memory processing, autonomic, endocrine, immunological, and sensorimotor functions.

Family history of alcohol-use disorders and spatial working memory: effects on adolescent alcohol expectancies

OBJECTIVE

Family history (FH) of alcohol-use disorders (AUDs) has been associated with frontal lobe deficits, more positive expectations for alcohol effects, and increased risk of developing AUDs. We tested the hypothesis that anterior brain regions mediate the relationship between FH of AUDs and alcohol expectancies in adolescents.

METHOD

Nondrinking adolescents (N = 50) ages 12-14 completed measures of FH of AUDs, alcohol expectancies, and substance use and performed spatial working memory and vigilance tasks during functional magnetic resonance imaging.

RESULTS

Activation of the anterior cingulate significantly predicted alcohol expectancies (R(2)Delta = 9%, beta = .32, F(change) = 6.09, 1/43 df, p < .05). However, FH of AUDs was not associated with brain response or alcohol expectancies.

CONCLUSIONS

Although a mediational model was not supported, activation in the anterior cingulate was linked to alcohol expectancies, such that adolescents with less neural differentiation to task demands had more positive expectancies for alcohol's effects. These results provide a greater understanding of the interrelations among risk factors for AUD and point to individuals who might be targeted for early, cognitively based interventions.

Distinct subtypes of basolateral amygdala taste neurons reflect palatability and reward

The amygdala processes multiple, dissociable properties of sensory stimuli. Given its central location within a dense network of reciprocally connected regions, it is reasonable to expect that basolateral amygdala (BLA) neurons should produce a rich repertoire of dynamical responses to taste stimuli. Here, we examined single BLA neuron taste responses in awake rats and report the existence of two distinct subgroups of BLA taste neurons operating simultaneously during perceptual processing. One neuron type produced long, protracted responses with dynamics that were strikingly similar to those previously observed in gustatory cortex. These responses reflect cooperation between amygdala and cortex for the purposes of processing palatability. A second type of BLA taste neuron may be part of the system often described as being responsible for reward learning: these neurons produced very brief, short-latency responses to rewarding stimuli; when the rat participated in procuring the taste by pressing a lever in response to a tone, however, those phasic taste responses vanished, phasic responses to the tone appearing instead. Our data provide strong evidence that the neural handling of taste is actually a distributed set of processes and that BLA is a nexus of these multiple processes. These results offer new insights into how amygdala imbues naturalistic sensory stimuli with value.

Design and validation of an improved nonferrous smoking device for self-administration of smoked drugs with concurrent fMRI neuroimaging

Several popularly abused drugs, such as nicotine (tobacco) and THC (delta9-tetrahydrocannabinol) (marihuana) are commonly self-administered by the smoked route. Although the neuronal substrates mediating the effect of smoked drugs are of interest, studies of their acute actions in living human brain has been difficult due to the unique constraints imposed by neuroimaging equipment and scanning environments. We have previously reported a device for the self-administration of smoked drugs with concurrent blood oxygen level dependent (BOLD) fMRI imaging. Here we report improvements to the device which result in improved drug delivery to the smoker. Gas chromatography/mass spectrometry (GCMS) analysis of nicotine recovered from filter extracts revealed that the amount of nicotine delivered to subjects smoking with our original device was reduced by approximately 44% compared to nicotine delivered by cigarettes smoked normally. Improvements were made to the smoke delivery component of our apparatus in an attempt to improve drug delivery, while not interfering with collection of MRI data. Nicotine plasma levels in 9 subjects smoking both with and without the improved smoking device in the laboratory were not significantly different. Similarly, the device produced no significant difference in either ratings of the subjective effects of nicotine, or changes in cardiovascular parameters in this experiment. The improved device does not interfere with typical drug effects produced by normal smoking. Phantom scans revealed that BOLD signal was not found to be altered by the (in-bore) installation and operation of the improved device. Preliminary data analysis of smoking induced changes in the BOLD response to visual stimulation suggest that this response is not affected by the improved device, the act of smoking, air puffing, nicotine, or other components of cigarette smoke. The improved device does not interfere with the collection of MRI neuroimaging data. Use of this device will facilitate investigations of the acute neuronal effects of smoked drugs.

Separating the effects of alcohol and expectancy on brain activation: an fMRI working memory study

The aim of this study was to use BOLD fMRI to evaluate the effect of alcohol intoxication on neuronal activation, when controlling for expectancy. Behavioural studies have shown that both alcohol intoxication and expectancy affect cognition, mood and behaviour. However, previous neuroimaging studies have not separated the effects of alcohol intoxication from the possible confounding effects of expectancy. Forty-five healthy male participants participated in the study. A balanced placebo design with four groups was used together with a working memory paradigm. Half of the participants consumed a soft-drink before the MR scanning session (half of them were correctly informed about the content of their drink, and half were incorrectly informed that they consumed an alcoholic beverage), and the other half consumed an alcoholic beverage before the MR scanning session (half of them were correctly informed about the content of their drink, and half were incorrectly informed that they consumed a soft-drink). A blood alcohol concentration (BAC) of 0.08% was used as the alcohol intoxication level. The most conspicuous result was that alcohol intoxication decreased neuronal activation especially in the dorsal anterior cingulate cortex (dACC) and in prefrontal areas, while expectancy increased neuronal activation in the same areas. This study shows that alcohol intoxication and expectancy have opposite effects on neuronal activation. The present results could have implications for pharmacological imaging studies.

Neural systems and cue-induced cocaine craving

We have extended our previous work investigating the neural correlates of cue-induced cocaine craving through the use of positron emission tomography with greater spatial resolution (<4.6 mm), an evocative script, and a pixel-by-pixel analysis. Craving and cerebral glucose metabolism were measured after presentation of cocaine-related or neutral cues to 11 cocaine abusers. Cocaine cues elicited a higher degree of craving than has been previously reported and resulted in left hemispheric activation of lateral amygdala, lateral orbitofrontal cortex, and rhinal cortex and right hemispheric activation of dorsolateral prefrontal cortex and cerebellum. The intensity of activation in these areas (except cerebellum), as well as left insula, was also correlated with craving. Deactivation occurred in left ventral pole and left medial prefrontal cortex. The results suggest that induction of drug craving involves a neural network that assigns incentive motivational value to environmental stimuli through the coactivation of brain regions that process information about memories and emotions.