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Author: Betty Jo Salmeron (39)



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Jan
2018

The objective of the current study was to examine what stage of memory (encoding or retrieval) may be compromised in adolescents with a history of prenatal drug exposure (PDE) and how the effects of PDE on memory ability are substantiated at the neural level. To achieve this goal, we examined memory performance and associated brain activations in adolescents with and without a history of PDE via event-related fMRI during encoding and retrieval. Consistent with previous studies, we found that PDE subjects remembered fewer items than community comparison subjects.

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Jun
2017

Withdrawal from nicotine is an important contributor to smoking relapse. Understanding how reward-based decision making is affected by abstinence and by pharmacotherapies such as nicotine replacement therapy and varenicline tartrate may aid cessation treatment.
To independently assess the effects of nicotine dependence and stimulation of the nicotinic acetylcholine receptor on the ability to interpret valence information (reward sensitivity) and subsequently alter behavior as reward contingencies change (cognitive flexibility) in a probabilistic reversal learning task.

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May
2017

While chronic cocaine use is associated with abnormalities in both brain structure and function within and interactions between regions, previous studies have been limited to interrogating structure and function independently, and the detected neural differences have not been applied to independent samples to assess the clinical relevance of results. We investigated consequences of structural differences on resting-state functional connectivity in cocaine addiction and tested whether resting-state functional connectivity of the identified circuits predict relapse in an independent cohort. Subjects included 64 non-treatment-seeking cocaine users (NTSCUs) and 67 healthy control subjects and an independent treatment-completed cohort (n = 45) of cocaine-dependent individuals scanned at the end of a 30-day residential treatment programme.

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Aug
2017

Imaging genetics and genomics research has begun to provide insight into the molecular and genetic architecture of neural phenotypes and the neural mechanisms through which genetic risk for psychopathology may emerge. As it approaches its third decade, imaging genetics is confronted by many challenges, including the proliferation of studies using small sample sizes and diverse designs, limited replication, problems with harmonization of neural phenotypes for meta-analysis, unclear mechanisms, and evidence that effect sizes may be more modest than originally posited, with increasing evidence of polygenicity. These concerns have encouraged the field to grow in many new directions, including the development of consortia and large-scale data collection projects and the use of novel methods (e.

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Feb
2017

The relative impact of chronic vs acute cocaine on dependence-related variability in reward processing in cocaine-dependent individuals (CD) is not well understood, despite the relevance of such effects to long-term outcomes. To dissociate these effects, CD (N=15) and healthy controls (HC; N=15) underwent MRI two times while performing a monetary incentive delay task. Both scans were identical across subjects/groups, except that, in a single-blind, counterbalanced design, CD received intravenous cocaine (30 mg/70 kg) before one session (CD+cocaine) and saline in another (CD+saline).

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Dec
1969

Deficits in cognitive control processes are a primary characteristic of nicotine addiction. However, while network-based connectivity measures of dysfunction have frequently been observed, empirical evidence of task-based dysfunction in these processes has been inconsistent. Here, in a sample of smokers (n=35) and non-smokers (n=21), a previously validated parametric flanker task is employed to characterize addiction-related alterations in responses to varying (ie, high, intermediate, and low) demands for cognitive control.

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May
2015

Cocaine dependence is a complex neuropsychiatric disorder manifested as dysregulation of multiple behavioral, emotional, and cognitive constructs. Neuroimaging studies have begun to identify specific neurobiological circuit impairments in cocaine-dependent (CD) individuals that may underlie these symptoms. However, whether, where, and how the interactions within and between these circuits are disrupted remain largely unknown.

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Jun
2015

Converging evidence has long identified both impulsivity and compulsivity as key psychological constructs in drug addiction. Although dysregulated striatal-cortical network interactions have been identified in cocaine addiction, the association between these brain networks and addiction is poorly understood.
To test the hypothesis that cocaine addiction is associated with disturbances in striatal-cortical communication as captured by resting-state functional connectivity (rsFC), measured from coherent spontaneous fluctuations in the blood oxygenation level-dependent functional magnetic resonance imaging signal, and to explore the relationships between striatal rsFC, trait impulsivity, and uncontrolled drug use in cocaine addiction.

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Jul
2015

Recidivism rates for cigarette smokers following treatment often exceed 80%. Varenicline is the most efficacious pharmacotherapy currently available with cessation rates of 25-35% following a year of treatment. Although the in vivo binding properties are well known, varenicline's neurobiological mechanisms of action are still poorly understood.

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Jul
2015

The persistence of effects of prenatal drug exposure (PDE) on brain functioning during adolescence is poorly understood. We explored neural activation to a visuospatial working memory (VSWM) versus a control task using functional magnetic resonance imaging (fMRI) in adolescents with PDE and a community comparison group (CC) of non-exposed adolescents. We applied graph theory metrics to resting state data using a network of nodes derived from the VSWM task activation map to further explore connectivity underlying WM functioning.

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Sep
2014

Behavioral and neuroplastic changes occurring in the development of addiction parallel those that occur in social bonding. This has led to speculation that drugs of abuse co-opt systems that subserve social attachment to shift attachment to drugs of abuse. Oxytocin, a neuropeptide that is important in social bonding, has been shown in rodents to decrease psychostimulant self-administration, locomotor activity, and conditioned place preference, it is unclear what role it may play in human drug addiction.

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Nov
2014

This investigation examined how prospective memory (PM) relates to cognitive abilities (i.e., executive function, attention, working memory, and retrospective memory) and brain structure in adolescents who vary in prenatal drug exposure (PDE).

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Dec
1969

Addiction to cocaine is a chronic condition characterized by high rates of early relapse. This study builds on efforts to identify neural markers of relapse risk by studying resting-state functional connectivity (rsFC) in neural circuits arising from the amygdala, a brain region implicated in relapse-related processes including craving and reactivity to stress following acute and protracted withdrawal from cocaine. Whole-brain resting-state functional magnetic resonance imaging connectivity (6 min) was assessed in 45 cocaine-addicted individuals and 22 healthy controls.

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Jun
2014

Cocaine dependence impacts drug-related, dopamine-dependent reward processing, yet its influence on non-drug reward processing is unclear. Here, we investigated cocaine-mediated effects on reward learning using a natural food reinforcer. Cocaine-dependent subjects (N = 14) and healthy controls (N = 14) learned to associate a visual cue with a juice reward.

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Mar
2015

Attenuated activity in performance-monitoring brain regions following erroneous actions may contribute to the repetition of maladaptive behaviors such as continued drug use. Externalizing is a broad personality construct characterized by deficient impulse control, vulnerability to addiction and reduced neurobiological indices of error processing. The insula and dorsal anterior cingulate cortex (dACC) are regions critically linked with error processing as well as the perpetuation of cigarette smoking.

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Jan
2014

The neural correlates of response to psychosocial stress and gender differences therein are difficult to model experimentally as this type of stressor is difficult to induce in a brain imaging environment. The Trier Social Stress Test (TSST), a behavioral paradigm that reliably induces moderate levels of stress was thus modified for the MRI environment. To determine the neurobehavioral basis of gender differences in response to observing oneself under social evaluative stress, 26 subjects (14 females) performed the TSST while being videotaped.

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Oct
2013

Although the amygdala and insula are regarded as critical neural substrates perpetuating cigarette smoking, little is known about their circuit-level interactions with interconnected regions during nicotine withdrawal or following pharmacotherapy administration. To elucidate neurocircuitry associated with early smoking abstinence, we examined the impact of varenicline and nicotine, two modestly efficacious pharmacologic cessation aids, on amygdala- and insula-centered circuits using resting-state functional connectivity (rsFC).
In a functional magnetic resonance imaging study employing a two-drug, placebo-controlled design, 24 overnight-abstinent smokers and 20 nonsmokers underwent ∼17 days of varenicline and placebo pill administration and were scanned, on different days under each condition, wearing a transdermal nicotine or placebo patch.

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Jul
2013

Alexithymia is a personality trait characterized by difficulty indentifying and describing subjective emotional experiences. Decreased aptitude in the perception, evaluation, and communication of affectively laden mental states has been associated with reduced emotion regulation, more severe drug craving in addicts, and structural/functional alterations in insula and anterior cingulate cortex (ACC). The insula and ACC represent sites of convergence between the putative neural substrates of alexithymia and those perpetuating cigarette smoking.

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Apr
2013

Individuals addicted to most chemical substances present with hypoactive dopaminergic systems as well as altered prefrontal white matter structure. Prefrontal dopaminergic tone is under genetic control and is influenced by and modulates descending cortico-striatal glutamatergic pathways that in turn, regulate striatal dopamine release. The catechol-O-methyltransferase (COMT) gene contains an evolutionarily recent and common functional variant at codon 108/158 (rs4680) that plays an important role in modulating prefrontal dopaminergic tone.

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Feb
2013

Hyperactive amygdala functioning may underlie emotional dysregulation during smoking abstinence and represents one neurobiological target for pharmacological cessation aids. Available pharmacotherapies (e.g.

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Feb
2013

Dopaminergic activity plays a role in mediating the rewarding aspects of abused drugs, including nicotine. Nicotine modulates the reinforcing properties of other motivational stimuli, yet the mechanisms of this interaction are poorly understood. This study aimed to ascertain the impact of nicotine exposure on neuronal activity associated with reinforcing outcomes in dependent smokers.

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Jul
2012

The objective of the present study was to examine the influence of prenatal drug exposure (PDE) on memory performance and supporting brain structures (i.e., hippocampus) during adolescence.

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Feb
2012

The reinforcing effects of nicotine are mediated by brain regions that also support temporal difference error (TDE) processing; yet, the impact of nicotine on TDE is undetermined.
Dependent smokers (n = 21) and matched control subjects (n = 21) were trained to associate a juice reward with a visual cue in a classical conditioning paradigm. Subjects subsequently underwent functional magnetic resonance imaging sessions in which they were exposed to trials where they either received juice as temporally predicted or where the juice was withheld (negative TDE) and later received unexpectedly (positive TDE).

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Apr
2011

Real-time functional magnetic resonance imaging (rtfMRI) has been proposed as a method of providing feedback to develop a participant's ability to control his or her own neuronal activity. However, this BOLD signal is vulnerable to contamination from nonneuronal sources that can also be shaped by the feedback provided. Here we illustrate an artifact found while training participants to control signal from an ROI in the insula.

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Jan
2011

Based upon previous reports of alterations in white matter integrity and gray matter density in smokers, we examined these markers in a large, well-matched sample of smokers and non-smokers. We further investigated the effect of heavy cigarette exposure by using pack-years and the effects of two relatively stable, highly heritable traits in smokers (Fagerström Test of Nicotine Dependence (FTND), a measure of severity of nicotine dependence and Toronto Alexithymia Scale (TAS-20), a stable personality trait related to smoking). Forty-eight nicotine-dependent subjects and 48 matched controls were included in the analyses, with smokers also subdivided into high/low dependence and high/low pack-years smokers.

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Jan
2011

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. Twenty-two smokers and 22 controls viewed smoking-related and neutral pictures during a functional arterial spin labeling scanning session.

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Jul
2010

Whole-genome searches have identified nicotinic acetylcholine receptor alpha5-alpha3-beta4 subunit gene variants that are associated with smoking. How genes support this addictive and high-risk behavior through their expression in the brain remains poorly understood. Here we show that a key alpha5 gene variant Asp398Asn is associated with a dorsal anterior cingulate-ventral striatum/extended amygdala circuit, such that the "risk allele" decreases the intrinsic resting functional connectivity strength in this circuit.

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Nov
2010

Preclinical models have consistently demonstrated the importance of the mesocorticolimbic (MCL) brain reward system in drug dependence, with critical molecular and cellular neuroadaptations identified within these structures following chronic cocaine administration. Cocaine dependent individuals manifest alterations in reward functioning that may relate to changes induced by cocaine or to pre-existing differences related to vulnerability to addiction. The circuit level manifestations of these drug-induced plastic changes and predispositions to drug dependence are poorly understood in preclinical models and virtually unknown in human drug dependence.

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Dec
2009

Previous studies have shown significantly lower metabolism and functional activity in the anterior cingulate cortex (ACC) of human cocaine addicts. The present study examined whether this ACC hypoactivity is associated with altered glutamate (Glu), the primary excitatory neurotransmitter in the central nervous system (CNS), which has been recently implicated in drug addiction. Participants comprised 14 chronic cocaine addicts and 14 matched healthy volunteers who were examined using (1)H magnetic resonance spectroscopy at 3 T.

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Mar
2011

Sustained attention abnormality in schizophrenia is usually refractory to available treatment. Nicotine can transiently improve sustained attention in schizophrenia patients, although its neural mechanisms are unknown. Understanding the neural basis of this effect may lead to new treatment strategies for this cognitive deficit.

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Apr
2009

Understanding the mechanisms underlying nicotine addiction to develop more effective treatment is a public health priority. Research consistently shows that nicotine transiently improves multiple cognitive functions. However, using nicotine replacement to treat nicotine addiction yields generally inconsistent results.

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May
2009

One prevalent theory of learning states that dopamine neurons signal mismatches between expected and actual outcomes, called temporal difference errors (TDEs). Evidence indicates that dopamine system dysfunction is involved in negative symptoms of schizophrenia (SZ), including avolition and anhedonia. As such, we predicted that brain responses to TDEs in dopamine midbrain nuclei and target areas would be abnormal in SZ.

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May
2009


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Jul
2005

Modern theories of drug dependence hold the hedonic effects of drug-taking central to understanding the motivation for compulsive drug use. Previous neuroimaging studies have begun to identify brain regions associated with acute drug effects after passive delivery. In this study, a more naturalistic model of cocaine self-administration (SA) was employed in order to identify those sites associated with drug-induced high and craving as measures of reward and motivation.

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Dec
1969

Magnetic resonance imaging (MRI) techniques are capable of spatial and temporal resolution and within subject repeatability that far exceed other currently available methods of noninvasively investigating brain functioning. While functional MRI (fMRI) techniques have traditionally been used to investigate sensory, motor, and cognitive functions, they are also very attractive for investigating the effects of pharmacological agents in the brain. However, because pharmacological agents may interfere with the very mechanisms that give rise to the fMRI signal, careful attention to experimental design and data analysis issues must be exercised.

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