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The Lancet. Psychiatry Aug 2016Drug addiction represents a dramatic dysregulation of motivational circuits that is caused by a combination of exaggerated incentive salience and habit formation, reward... (Review)
Review
Drug addiction represents a dramatic dysregulation of motivational circuits that is caused by a combination of exaggerated incentive salience and habit formation, reward deficits and stress surfeits, and compromised executive function in three stages. The rewarding effects of drugs of abuse, development of incentive salience, and development of drug-seeking habits in the binge/intoxication stage involve changes in dopamine and opioid peptides in the basal ganglia. The increases in negative emotional states and dysphoric and stress-like responses in the withdrawal/negative affect stage involve decreases in the function of the dopamine component of the reward system and recruitment of brain stress neurotransmitters, such as corticotropin-releasing factor and dynorphin, in the neurocircuitry of the extended amygdala. The craving and deficits in executive function in the so-called preoccupation/anticipation stage involve the dysregulation of key afferent projections from the prefrontal cortex and insula, including glutamate, to the basal ganglia and extended amygdala. Molecular genetic studies have identified transduction and transcription factors that act in neurocircuitry associated with the development and maintenance of addiction that might mediate initial vulnerability, maintenance, and relapse associated with addiction.
Topics: Brain; Humans; Neural Pathways; Neurobiology; Substance-Related Disorders
PubMed: 27475769
DOI: 10.1016/S2215-0366(16)00104-8 -
Cold Spring Harbor Perspectives in... Apr 2021Drug addiction is a chronic relapsing disorder, and a significant amount of research has been devoted to understand the factors that contribute to the development, loss... (Review)
Review
Drug addiction is a chronic relapsing disorder, and a significant amount of research has been devoted to understand the factors that contribute to the development, loss of control, and persistence of compulsive addictive behaviors. In this review, we provide an overview of various theories of addiction to drugs of abuse and the neurobiology involved in elements of the addiction cycle. Specific focus is devoted to the role of the mesolimbic pathway in acute drug reinforcement and occasional drug use, the role of the mesocortical pathway and associated areas (e.g., the dorsal striatum) in escalation/dependence, and the contribution of these pathways and associated circuits to conditioned responses, drug craving, and loss of behavioral control that may underlie drug relapse. By enhancing the understanding of the neurobiological factors that mediate drug addiction, continued preclinical and clinical research will aid in the development of novel therapeutic interventions that can serve as effective long-term treatment strategies for drug-dependent individuals.
Topics: Behavior, Addictive; Disease Progression; Humans; Neurobiology; Recurrence; Substance-Related Disorders
PubMed: 32205414
DOI: 10.1101/cshperspect.a039628 -
Neuron Mar 2002Current treatments for depression are inadequate for many individuals, and progress in understanding the neurobiology of depression is slow. Several promising hypotheses... (Review)
Review
Current treatments for depression are inadequate for many individuals, and progress in understanding the neurobiology of depression is slow. Several promising hypotheses of depression and antidepressant action have been formulated recently. These hypotheses are based largely on dysregulation of the hypothalamic-pituitary-adrenal axis and hippocampus and implicate corticotropin-releasing factor, glucocorticoids, brain-derived neurotrophic factor, and CREB. Recent work has looked beyond hippocampus to other brain areas that are also likely involved. For example, nucleus accumbens, amygdala, and certain hypothalamic nuclei are critical in regulating motivation, eating, sleeping, energy level, circadian rhythm, and responses to rewarding and aversive stimuli, which are all abnormal in depressed patients. A neurobiologic understanding of depression also requires identification of the genes that make individuals vulnerable or resistant to the syndrome. These advances will fundamentally improve the treatment and prevention of depression.
Topics: Animals; Depression; Disease Models, Animal; Humans; Neurobiology
PubMed: 11931738
DOI: 10.1016/s0896-6273(02)00653-0 -
Learning & Memory (Cold Spring Harbor,... Sep 2017Fear, which can be expressed innately or after conditioning, is triggered when a danger or a stimulus predicting immediate danger is perceived. Its role is to prepare... (Review)
Review
Fear, which can be expressed innately or after conditioning, is triggered when a danger or a stimulus predicting immediate danger is perceived. Its role is to prepare the body to face this danger. However, dysfunction in fear processing can lead to psychiatric disorders in which fear outweighs the danger or possibility of harm. Although recognized as highly debilitating, pathological fear remains insufficiently treated, indicating the importance of research on fear processing. The neurobiological basis of normal and pathological fear reactions is reviewed in this article. Innate and learned fear mechanisms, particularly those involving the amygdala, are considered. These fear mechanisms are also distinguished in specific phobias, which can indeed be nonexperiential (implicating innate, learning-independent mechanisms) or experiential (implicating learning-dependent mechanisms). Poor habituation and poor extinction are presented as dysfunctional mechanisms contributing to persistence of nonexperiential and experiential phobias, respectively.
Topics: Animals; Brain; Fear; Humans; Instinct; Neurobiology; Phobic Disorders
PubMed: 28814472
DOI: 10.1101/lm.044115.116 -
FEBS Letters Jun 2007Romantic and maternal love are highly rewarding experiences. Both are linked to the perpetuation of the species and therefore have a closely linked biological function... (Review)
Review
Romantic and maternal love are highly rewarding experiences. Both are linked to the perpetuation of the species and therefore have a closely linked biological function of crucial evolutionary importance. The newly developed ability to study the neural correlates of subjective mental states with brain imaging techniques has allowed neurobiologists to learn something about the neural bases of both romantic and maternal love. Both types of attachment activate regions specific to each, as well as overlapping regions in the brain's reward system that coincide with areas rich in oxytocin and vasopressin receptors. Both deactivate a common set of regions associated with negative emotions, social judgment and 'mentalizing' that is, the assessment of other people's intentions and emotions. Human attachment seems therefore to employ a push-pull mechanism that overcomes social distance by deactivating networks used for critical social assessment and negative emotions, while it bonds individuals through the involvement of the reward circuitry, explaining the power of love to motivate and exhilarate. Yet the biological study of love, and especially romantic love, must go beyond and look for biological insights that can be derived from studying the world literature of love, and thus bring the output of the humanities into its orbit.
Topics: Beauty; Brain; Brain Chemistry; Humans; Love; Neurobiology
PubMed: 17531984
DOI: 10.1016/j.febslet.2007.03.094 -
Journal of Visualized Experiments : JoVE Feb 2016Having appropriate in vivo and in vitro systems that provide translational models for human disease is an integral aspect of research in neurobiology and the...
Having appropriate in vivo and in vitro systems that provide translational models for human disease is an integral aspect of research in neurobiology and the neurosciences. Traditional in vitro experimental models used in neurobiology include primary neuronal cultures from rats and mice, neuroblastoma cell lines including rat B35 and mouse Neuro-2A cells, rat PC12 cells, and short-term slice cultures. While many researchers rely on these models, they lack a human component and observed experimental effects could be exclusive to the respective species and may not occur identically in humans. Additionally, although these cells are neurons, they may have unstable karyotypes, making their use problematic for studies of gene expression and reproducible studies of cell signaling. It is therefore important to develop more consistent models of human neurological disease. The following procedure describes an easy-to-follow, reproducible method to obtain homogenous and viable human neuronal cultures, by differentiating the chromosomally stable human neuroblastoma cell line, SH-SY5Y. This method integrates several previously described methods(1-4) and is based on sequential removal of serum from media. The timeline includes gradual serum-starvation, with introduction of extracellular matrix proteins and neurotrophic factors. This allows neurons to differentiate, while epithelial cells are selected against, resulting in a homogeneous neuronal culture. Representative results demonstrate the successful differentiation of SH-SY5Y neuroblastoma cells from an initial epithelial-like cell phenotype into a more expansive and branched neuronal phenotype. This protocol offers a reliable way to generate homogeneous populations of neuronal cultures that can be used for subsequent biochemical and molecular analyses, which provides researchers with a more accurate translational model of human infection and disease.
Topics: Cell Count; Cell Culture Techniques; Cell Differentiation; Cell Line, Tumor; Humans; Neurobiology; Neuroblastoma; Neurons
PubMed: 26967710
DOI: 10.3791/53193 -
The Journal of Neuroscience : the... Sep 2021Throughout the body, lymphatic fluid movement supports critical functions including clearance of excess fluid and metabolic waste. The glymphatic system is the analog of... (Review)
Review
Throughout the body, lymphatic fluid movement supports critical functions including clearance of excess fluid and metabolic waste. The glymphatic system is the analog of the lymphatic system in the CNS. As such, the glymphatic system plays a key role in regulating directional interstitial fluid movement, waste clearance, and, potentially, brain immunity. The glymphatic system enables bulk movement of CSF from the subarachnoid space along periarterial spaces, where it mixes with interstitial fluid within the parenchyma before ultimately exiting from the parenchyma via perivenous spaces. This review focuses on important questions about the structure of this system, why the brain needs a fluid transport system, and unexplored aspects of brain fluid transport. We provide evidence that astrocytes and blood vessels determine the shape of the perivascular space, ultimately controlling the movement of perivascular fluid. Glymphatic fluid movement has the potential to alter local as well as global transport of signaling molecules and metabolites. We also highlight the evidence for cross talk among the glymphatic system, cardiovascular system, gastrointestinal tract, and lymphatic system. Much remains to be studied, but we propose that the glymphatic/lymphatic system acts as a cornerstone in signaling between the brain and body.
Topics: Animals; Astrocytes; Brain; Choroid Plexus; Glymphatic System; Humans; Neurobiology
PubMed: 34526407
DOI: 10.1523/JNEUROSCI.0619-21.2021 -
Nature Neuroscience Oct 2019Memory retrieval involves the interaction between external sensory or internally generated cues and stored memory traces (or engrams) in a process termed 'ecphory'.... (Review)
Review
Memory retrieval involves the interaction between external sensory or internally generated cues and stored memory traces (or engrams) in a process termed 'ecphory'. While ecphory has been examined in human cognitive neuroscience research, its neurobiological foundation is less understood. To the extent that ecphory involves 'reawakening' of engrams, leveraging recently developed technologies that can identify and manipulate engrams in rodents provides a fertile avenue for examining retrieval at the level of neuronal ensembles. Here we evaluate emerging neuroscientific research of this type, using cognitive theory as a guiding principle to organize and interpret initial findings. Our Review highlights the critical interaction between engrams and retrieval cues (environmental or artificial) for memory accessibility and retrieval success. These findings also highlight the intimate relationship between the mechanisms important in forming engrams and those important in their recovery, as captured in the cognitive notion of 'encoding specificity'. Finally, we identify several questions that currently remain unanswered.
Topics: Animals; Cognitive Science; Humans; Memory; Mental Recall; Neurobiology
PubMed: 31551594
DOI: 10.1038/s41593-019-0493-1 -
The European Journal of Neuroscience Jan 2021Major depressive disorder (MDD) is a chronic and recurrent psychiatric condition characterized by depressed mood, social isolation and anhedonia. It will affect 20% of... (Review)
Review
Major depressive disorder (MDD) is a chronic and recurrent psychiatric condition characterized by depressed mood, social isolation and anhedonia. It will affect 20% of individuals with considerable economic impacts. Unfortunately, 30-50% of depressed individuals are resistant to current antidepressant treatments. MDD is twice as prevalent in women and associated symptoms are different. Depression's main environmental risk factor is chronic stress, and women report higher levels of stress in daily life. However, not every stressed individual becomes depressed, highlighting the need to identify biological determinants of stress vulnerability but also resilience. Based on a reverse translational approach, rodent models of depression were developed to study the mechanisms underlying susceptibility vs resilience. Indeed, a subpopulation of animals can display coping mechanisms and a set of biological alterations leading to stress resilience. The aetiology of MDD is multifactorial and involves several physiological systems. Exacerbation of endocrine and immune responses from both innate and adaptive systems are observed in depressed individuals and mice exhibiting depression-like behaviours. Increasing attention has been given to neurovascular health since higher prevalence of cardiovascular diseases is found in MDD patients and inflammatory conditions are associated with depression, treatment resistance and relapse. Here, we provide an overview of endocrine, immune and vascular changes associated with stress vulnerability vs. resilience in rodents and when available, in humans. Lack of treatment efficacy suggests that neuron-centric treatments do not address important causal biological factors and better understanding of stress-induced adaptations, including sex differences, could contribute to develop novel therapeutic strategies including personalized medicine approaches.
Topics: Adaptation, Psychological; Animals; Antidepressive Agents; Depression; Depressive Disorder, Major; Female; Humans; Male; Mice; Neurobiology; Stress, Psychological
PubMed: 31421056
DOI: 10.1111/ejn.14547 -
Mayo Clinic Proceedings Mar 2021Physician burnout and other forms of occupational distress are a significant problem in modern medicine, especially during the coronavirus disease pandemic, yet few... (Review)
Review
Physician burnout and other forms of occupational distress are a significant problem in modern medicine, especially during the coronavirus disease pandemic, yet few doctors are familiar with the neurobiology that contributes to these problems. Burnout has been linked to changes that reduce a physician's sense of control over their own practice, undermine connections with patients and colleagues, interfere with work-life integration, and result in uncontrolled stress. Brain research has revealed that uncontrollable stress, but not controllable stress, impairs the functioning of the prefrontal cortex, a recently evolved brain region that provides top-down regulation over thought, action, and emotion. The prefrontal cortex governs many cognitive operations essential to physicians, including abstract reasoning, higher-order decision making, insight, and the ability to persevere through challenges. However, the prefrontal cortex is remarkably reliant on arousal state and is impaired under conditions of fatigue and/or uncontrollable stress when there are inadequate or excessive levels of the arousal modulators (eg, norepinephrine, dopamine, acetylcholine). With chronic stress exposure, prefrontal gray matter connections are lost, but they can be restored by stress relief. Reduced prefrontal cortex self-regulation may explain several challenges associated with burnout in physicians, including reduced motivation, unprofessional behavior, and suboptimal communication with patients. Understanding this neurobiology may help physicians have a more informed perspective to help relieve or prevent symptoms of burnout and may help administrative leaders to optimize the work environment to create more effective organizations. Efforts to restore a sense of control to physicians may be particularly helpful.
Topics: Burnout, Professional; COVID-19; Humans; Neurobiology; Pandemics; Physicians; Workplace
PubMed: 33673923
DOI: 10.1016/j.mayocp.2020.12.027