Authors:Suzana Herculano-Houzel Pages: 1 - 7 Abstract: Publication date: August 2017 Source:Current Opinion in Behavioral Sciences, Volume 16 Author(s): Suzana Herculano-Houzel What impact does variation in brain size have on the behavioral or cognitive capabilities of different species? Answering this seemingly simple question has been hampered by difficulties in defining and measuring the relevant variables in the brain, on the one hand, and in quantifying behavior in a way that can be compared across species, on the other. A new method of counting cells has made it easy to obtain direct estimates of the numbers of neurons that compose different brain structures. Crossing these numbers with the first large-scale quantitative studies of cognitive capabilities across species suggests that absolute numbers of neurons in the mammalian cerebral cortex, or in the bird pallium, are good correlates of cognitive diversity: the more the neurons, regardless of brain or body size, the better a species performs at a same task.
Authors:Andreas Nieder Pages: 8 - 14 Abstract: Publication date: August 2017 Source:Current Opinion in Behavioral Sciences, Volume 16 Author(s): Andreas Nieder A wealth of behavioral data show that songbirds of the corvid family are endowed with exquisite cognitive capabilities. The neurophysiological basis of this behavioral flexibility has been addressed recently by recording single-neuron activity from the associative endbrain area nidopallium caudolaterale (NCL) in behaving crows. NCL neurons encode sensory and cognitive variables during working memory, but also participate in the translation of cognitive signals to motor behaviors. These findings highlight the NCL as the corvid brain’s central executive. Intelligence in birds can be realized with an endbrain design that is radically different from the mammalian neocortex and developed independently via convergent evolution.
Authors:Andrea S Griffin; Keilah Netto; Chloe Peneaux Pages: 15 - 22 Abstract: Publication date: August 2017 Source:Current Opinion in Behavioral Sciences, Volume 16 Author(s): Andrea S Griffin, Keilah Netto, Chloe Peneaux Conversion of natural environments to cities confronts animals with abundant novel opportunities. Research on perception of threat in urban animals is fast expanding, but analyses of their capacity to exploit novel resources are scant. Experimental predictions regarding urban/non-urban behavioral differences are grounded in disparate statements regarding the ecological conditions that prevail in urban environments. We evaluate critically whether urban habitats favor high neophilia, innovation and learning in established populations. Extreme spatial complexity of urban landscapes coupled with increased resource predictability due to human routine activities should favor neophilia and learning. Cities provide exciting new opportunities to investigate empirically whether variation in these traits is related to variation in environmental complexity and predictability as forecast by a body of theoretical work.
Authors:Francesca Cirulli Pages: 65 - 71 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Francesca Cirulli The long-term consequences of psychosocial and socioeconomic challenges are hardly distinguishable from those of inappropriate nutrition, suggesting the existence of common physiological pathways funnelling the effects of early adversity. Obesity and mood disorders are highly prevalent and co-morbid in adult subjects. In order to unravel such co-morbidity, and to gain a more complete understanding of how the programming by early-life stress takes place, it is necessary to describe the common pathways, as well as the underlying molecular mechanisms. There is now robust evidence to indicate that the body reacts to stress through changes in the hypothalamic–pituitary–adrenal (HPA) axis, setting up adult responsiveness to environmental stressors and leading to individual vulnerability/resilience to stress and disease. Glucocorticoids (GCs) and neurotrophins, such as brain-derived neurotrophic factor (BDNF), play a critical role in the integration of behavioural and metabolic responses to external challenges, including nutrients availability, and have important effects on brain plasticity. In addition, very recent data indicate the existence of the gut-brain axis as another important target and mediator of the effects of early life stress and nutrition. A complete understanding of these complex regulations needs to take into account multiple intervening variables, such as sex and genetic/epigenetic landscapes, and consider the developmental/life stage in a life-long perspective. Integrative and multidisciplinary approaches will be needed in the future to advance the field and to devise early intervention strategies for a life-long mental and behavioural health.
Authors:Francesco Vailati Riboni; Catherine Belzung Pages: 72 - 77 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Francesco Vailati Riboni, Catherine Belzung Stress can occur at any time throughout the lifespan, from the prenatal period to during ageing. It has a long lasting impact on an individual’s behaviour and on the structure and functioning of the brain, particularly regarding the limbic system and the prefrontal cortex. Regarding stressors, a variety of responses have been described, with some subjects being vulnerable and others resilient. Resilience is linked to an active psychological process and to a re-organization of cerebral networks and proteins enabling the subject to cope with environmental challenges; vulnerable subjects are unable to activate these changes and consequently develop psychiatric disorders. Recently, a shift in the classification of psychiatric disorders has been proposed moving from the classical diagnostic groups (depression, anxiety disorders, schizophrenia, addiction and autism) to a more dimensional approach, the Research Domain Criteria (RdoC) project. The scope of this mini-review is to analyse how stress impacts the different constructs of the RdoC approach (valence, cognition, sociality and arousal), thus providing a new perspective on the relationship between stress and psychiatric disorders.
Authors:Adrienne Santiago; Chiye Aoki; Regina M Sullivan Pages: 78 - 85 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Adrienne Santiago, Chiye Aoki, Regina M Sullivan Young infant rat pups learn to approach cues associated with pain rather than learning amygdala-dependent fear. This approach response is considered caregiver-seeking and ecologically relevant within the context of attachment. With maturation, increases in the stress hormone corticosterone permit amygdala-dependent fear, which is crucial for survival during independent living. During the developmental transition from attachment to fear learning, maternal presence suppresses corticosterone elevation to block amygdala-dependent fear learning and re-engage the attachment circuitry. Early life trauma disrupts this developmental sequence by triggering a precocious increase of corticosterone, which permits amygdala-dependent threat responses. In this review, we explore the importance of the stress hormone corticosterone in infants’ transition from complete dependence on the caregiver to independence, with consideration for environmental influences on threat response ontogeny and mechanistic importance of social buffering of the stress response. Graphical abstract
Authors:Lauren E Chaby; Li Zhang; Israel Liberzon Pages: 86 - 93 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Lauren E Chaby, Li Zhang, Israel Liberzon Developmental windows of environmental sensitivity open and close throughout ontogeny, which can lead to vastly different effects of stress that depend upon age at exposure. It is well established that stress in adulthood can catalyze mental illness, but the effects of stress exposure during early life stages on the emergence and persistence of psychopathology remain unclear. Stress response systems undergo maturational changes that differ between early life and adolescence, and stress exposure during these two stages can have varying or even opposing consequences that persist into adulthood. In this review, we discuss clinical and rodent studies of developmental stages that seem to have distinct sensitivities to stress—early life and adolescence. We review the effects of stress during these two developmental periods on adult phenotype and risk for common stress-related disorders: depression, anxiety and posttraumatic stress disorder. We conclude by discussing challenges and recommendations for future research to investigate which features of developmental stress, or individual phenotype, may predict relative risk for common psychopathologies.
Authors:Hannah CM Niermann; Bernd Figner; Karin Roelofs Pages: 94 - 101 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Hannah CM Niermann, Bernd Figner, Karin Roelofs Alterations in primary freeze and fight-or-flight reactions in animals have been associated with increased vulnerability to develop anxious or aggressive symptomatology. Despite the potential relevance of these primary defensive responses for human stress-coping, they are still largely unexplored in humans. The present paper reviews recent evidence suggesting that individual differences in primary defensive stress responses in humans are associated with individual differences in anxiety and aggression. In addition, we discuss (neuro)endocrine systems that may underlie increased freezing and flight behavior in anxiety and increased fight tendencies in aggression-related disorders. We conclude with a research agenda for the study of human defensive stress-responses as potential behavioral markers for stress-related disorders, including anxiety and aggression.
Authors:Vitor H Pereira; Isabel Campos; Nuno Sousa Pages: 102 - 107 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Vitor H Pereira, Isabel Campos, Nuno Sousa Chronic stress increases the risk of neuropsychiatric, cardiovascular and endocrine diseases. Interestingly, the susceptibility to stress among individuals is variable and only some experience stress-related diseases. The determinants of resilience (the concept of resistance to chronic stress) are still not well understood. Their knowledge may contribute to the development of strategies to tackle stress-related disorders from a preventive perspective. Recent evidences show that the autonomic nervous system may play a role in the susceptibility to stress and may be used as a marker of resilience. Departing from that point, this short review will provide a perspective of the role of the autonomic nervous system in the susceptibility to the stress response.
Authors:Cortney A Turner; Shelly B Flagel; Peter Blandino; Stanley J Watson; Huda Akil Pages: 108 - 114 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Cortney A Turner, Shelly B Flagel, Peter Blandino, Stanley J Watson, Huda Akil Individual differences in temperament are associated with psychopathology in humans. Moreover, the relationship between temperament and anxiety-, depression-, PTSD- and addiction-related behaviors can be modeled in animals. This review will highlight these relationships with a focus on individual differences in the response to stressors, fear conditioning and drugs of abuse using animals that differ in their response to a novel environment. We will discuss behavioral and neurobiological commonalities amongst these behaviors with a focus on the hippocampus and, in particular, growth factors as promising novel targets for therapeutic intervention.
Authors:Benno Roozendaal; Erno J Hermans Pages: 115 - 122 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Benno Roozendaal, Erno J Hermans Noradrenergic activity is important for emotional enhancement of memory. Although findings from both animal and human research provide extensive support for this general conclusion, there are some important, but often ignored, differences between these research lines. Whereas animal experiments mostly employ pharmacological manipulations in the post-learning phase to investigate the effects of sustained noradrenergic activation on the consolidation of long-term memory, neuroimaging studies in humans typically focus on much more dynamic changes in noradrenergic activity during the actual encoding of information. In this paper we discuss the possibility that these two types of noradrenergic effects interact in enhancing memory for emotionally arousing experiences, and explain how elucidating this mechanism might improve synergy between animal and human research.
Authors:Jessica Deslauriers; Susan B. Powell; Victoria B Risbrough Pages: 123 - 132 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Jessica Deslauriers, Susan B. Powell, Victoria B Risbrough Mechanisms underlying posttraumatic stress disorder (PTSD) are not well understood; however, a potential role for immune signaling has recently emerged. Although PTSD is consistently associated with inflammatory markers, a causal role of immune signaling in symptom development is not clear. Here we present the most recent evidence for inflammatory dysfunction both preceding and following PTSD, and current evidence for immune-pathway contributions in animal models of PTSD. We address the role of peripheral vs. central immune signaling, single vs. chronic stress models of PTSD, and use of animal models to investigate novel anti-inflammatory treatments. Gaps in the literature including models of TBI/PTSD comorbidity, peripheral markers of inflammation, and inflammatory trajectories after severe stress are discussed.
Authors:Jessica L Bolton; Jenny Molet; Autumn Ivy; Tallie Z Baram Pages: 133 - 139 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Jessica L Bolton, Jenny Molet, Autumn Ivy, Tallie Z Baram Adverse early-life experiences, including various forms of early-life stress, have consistently been linked with vulnerability to cognitive and emotional disorders later in life. Understanding the mechanisms underlying the enduring consequences of early-life stress is an active area of research, because this knowledge is critical for developing potential interventions. Animal models of early-life stress typically rely on manipulating maternal/parental presence and care, because these are the major sources of early-life experiences in humans. Diverse models have been created, and have resulted in a wealth of behavioral outcomes. Here we focus on recent findings highlighting early-life stress-induced behavioral disturbances, ranging from hippocampus-dependent memory deficits to problems with experiencing pleasure (anhedonia). The use of naturalistic animal models of chronic early-life stress provides insight into the spectrum of cognitive and emotional outcomes and enables probing the underlying mechanisms using molecular-, cellular-, and network-level approaches.
Authors:Terence YC Pang; Annabel K Short; Timothy W Bredy; Anthony J Hannan Pages: 140 - 147 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Terence YC Pang, Annabel K Short, Timothy W Bredy, Anthony J Hannan In recent years, it has become evident that pre-conceptual exposure of males to various environmental factors induces epigenetic changes in sperm, which can mediate the transmission of acquired traits in their offspring. The most thoroughly examined paternal exposures involve stress and elevated corticosterone, which have been shown to modulate offspring phenotypes in a manner that is relevant to predisposition to brain disorders, and psychiatric illness in particular. Recent seminal studies have demonstrated that key epigenetic information transmitted via the paternal germline involves small non-coding (snc) RNA transcripts such as microRNAs. Following fertilisation, these sncRNAs appear to regulate development so as to modify the phenotype of the offspring. Understanding the mechanisms involved in such transgenerational effects may facilitate future screening of human sperm for ‘epigenetic health’ and the tailoring of therapeutic interventions according to genetic and epigenetic contributions to illness.
Authors:Gilad Ritov; Ziv Ardi; Omer Horovitz; Anne Albrecht; Gal Richter-Levin Pages: 148 - 154 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Gilad Ritov, Ziv Ardi, Omer Horovitz, Anne Albrecht, Gal Richter-Levin Only some individuals exposed to a traumatic experience eventually develop stress-related disorders such as anxiety and PTSD, indicating that the development and course of such disorders are influenced considerably by different risk factors. Understanding the way such risk factors contribute to the development of pathology is thus a key issue in understanding the neurobiology of stress-related disorders. Here we review behavioral approaches and evidence from recent studies which utilized innovative fear conditioning procedures in rats aiming to model pre- and peri-exposure risk factors, including pre-exposure to pre-pubertal adversities, and the level of controllability over the stressful experience during the exposure to the trauma. Furthermore, the importance of taking into consideration individual variability in post-exposure stress-related behaviors in order to differentiate between exposed-affected and exposed-unaffected individuals is demonstrated.
Authors:Lindsay M Squeglia; Anita Cservenka Pages: 164 - 170 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Lindsay M Squeglia, Anita Cservenka Adolescence is a period of vulnerability for developing substance use disorder. Recent neuropsychological and neuroimaging studies have elucidated underlying neural vulnerabilities that contribute to initiation of substance use during adolescence. Findings suggest poorer performance on tasks of inhibition and working memory, smaller brain volumes in reward and cognitive control regions, less brain activation during executive functioning tasks, and heightened reward responsivity are predictive of youth initiating substance use during adolescence. In youth who are family history positive (FHP) for substance use disorder, poorer executive functioning, smaller volume of limbic brain regions (e.g., amygdala), sex-specific patterns of hippocampal volume, and a positive association between nucleus accumbens volume and family history density have been reported. Further, reduced white matter integrity, altered brain response during inhibitory control, including both greater and less frontal lobe response, blunted emotional processing, and weaker neural connectivity have also been found in FHP youth. Thus, there is significant overlap among the neural precursors shown to be predictive of alcohol and substance use initiation during adolescence and those that distinguish FHP from youth without a family history of substance use disorder, suggesting common targets for prevention and intervention. Understanding these predictive factors helps identify at-risk youth for prevention efforts, as well as create interventions targeting cognitive weaknesses or brain regions involved in substance use initiation.
Authors:Sriparna Ghosal; Brendan D. Hare; Ronald S Duman Pages: 1 - 8 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Sriparna Ghosal, Brendan D. Hare, Ronald S Duman Psychiatric diseases, notably major depression, are associated with imbalance of excitatory and inhibitory neurotransmission within the prefrontal cortex (PFC) and related limbic brain circuitry. In many cases these illnesses are precipitated or exacerbated by chronic stress, which also alters excitatory and inhibitory neurotransmitter systems. Notably, exposure to repeated uncontrollable stress causes persistent changes in the synaptic integrity and function of the principal glutamatergic excitatory neurons in the PFC, characterized by neuronal atrophy and loss of synaptic connections. This can lead to dysfunction of the PFC circuitry that is necessary for execution of adaptive behavioral responses. In addition, an emerging literature shows that chronic stress causes extensive alterations of GABAergic inhibitory circuits in the PFC, leading to the hypothesis that deficits in inhibitory neurotransmission contribute to changes in PFC neuronal excitability and cognitive impairments. Here we review evidence in rodent and human, which points to the mechanisms underlying stress-induced alterations of GABA transmission in the PFC, and its relevance to circuit dysfunction in mood and stress related disorders. These findings suggest that alterations of GABA interneurons and inhibitory neurotransmission play a causal role in the development of stress-related neurobiological illness, and could identify a new line of GABA related therapeutic targets.
Authors:Anand Gururajan; Timothy G Dinan; John F Cryan Pages: 9 - 18 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Anand Gururajan, Timothy G Dinan, John F Cryan Over the last quarter of a century, research in the field of stress resilience has provided a unique perspective of how the brain responds to stress. In particular, it sheds light on the various psychosocial, biological and external factors that determines whether an individual will either be resilient or susceptible in the face of stress. MicroRNAs are small non-coding RNA sequences with a major role in regulating gene expression at the transcriptional level and a growing body of evidence suggests that they may be key molecular mediators of stress resilience. In this review we argue that an increased understanding of the functional role microRNAs have in relation to various biological determinants of resilience will enable us to develop intervention strategies which could be used to promote resilience in at-risk individuals or individuals who have experienced stress. This approach may attenuate the risk of psychiatric sequelae such as depression, anxiety and post-traumatic stress disorders which currently have a significant economic and social burden on society.
Authors:Samantha K Saland; Florian Duclot; Mohamed Kabbaj Pages: 19 - 26 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Samantha K Saland, Florian Duclot, Mohamed Kabbaj In major depressive disorder, women exhibit higher lifetime prevalence and different antidepressant response rates than men, which illustrates the importance of examining individual differences in the pathophysiology of depression and therapeutic response. In recent years, the consideration of sex in related preclinical research has thus gained interest—particularly in light of novel evidence for rapid-acting antidepressants. Notably, the literature recently revealed a higher sensitivity of females to the antidepressant effects of the N-methyl-d-aspartate receptor antagonist ketamine, in both baseline and preclinical conditions. Combined with its fast-acting and relatively sustained properties, this evidence highlights ketamine as a particularly interesting therapeutic alternative for this sensitive population, and supports the value in considering sex as a critical factor for improved individualized therapeutic strategies.
Authors:Judith R Homberg; Tamas Kozicz; Guillén Fernández Pages: 27 - 32 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Judith R Homberg, Tamas Kozicz, Guillén Fernández The stress response allows effective handling of threats, but can become maladaptive in vulnerable individuals causing anxiety. While research so far focused on individual brain regions, the field of human cognitive neuroscience emphasizes a brain organization in large-scale networks that support unique, broad cognitive domains. When threatened the balance between the salience and the executive control network is temporarily shifted towards the salience network allowing individuals to respond adequately, and re-balanced afterwards under the influence of glucocorticoids. Here we explore how risk factors like gender, early life adversity and genetics (5-HTTLPR) affect glucocorticoid release and associated network re-balancing. These risk factors set the balance towards the salience network, leading to insufficient matching to environmental demands and thereby anxiety.
Authors:Anthony J Porcelli; Mauricio R Delgado Pages: 33 - 39 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Anthony J Porcelli, Mauricio R Delgado A wide range of stressful experiences can influence human decision making in complex ways beyond the simple predictions of a fight-or-flight model. Recent advances may provide insight into this complicated interaction, potentially in directions that could result in translational applications. Early research suggests that stress exposure influences basic neural circuits involved in reward processing and learning, while also biasing decisions toward habit and modulating our propensity to engage in risk-taking. That said, a substantial array of theoretical and methodological considerations in research on the topic challenge strong cross study comparisons necessary for the field to move forward. In this review we examine the multifaceted stress construct in the context of human decision making, emphasizing stress’ effect on valuation, learning, and risk-taking.
Authors:Oliver T Wolf Pages: 40 - 46 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Oliver T Wolf Stress impairs memory retrieval. Recent findings illustrate the temporal dynamics and the underlying mechanisms of this effect. The effect appears to occur in multiple memory systems, ranging from striatal-based stimulus-response memory to prefrontal-based extinction memory. The effects of stress on memory retrieval might have long-term consequences due to their impact on re-encoding and re-consolidation. These properties could be of interest for future intervention studies.
Authors:Elizabeth V Goldfarb; Elizabeth A Phelps Pages: 47 - 53 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Elizabeth V Goldfarb, Elizabeth A Phelps Stress can strongly influence memory, in part by modulating the relative engagement of multiple memory systems. Over the last fifteen years, researchers have demonstrated that stress leads striatal, rather than hippocampal, memory to be dominant in both humans and non-human animals. This shift has been proposed to explain the etiology and maintenance of symptoms of stress-related psychopathology. However, it remains unclear how hippocampal and striatal memory are affected individually in order to facilitate this trade-off. Recent studies provide empirical support for (at least) three different pathways by which stress could modulate these memory systems. Evidence for these diverse effects of stress, and circumstances under which each might occur, are discussed.
Authors:Karl Ebner; Nicolas Singewald Pages: 54 - 64 Abstract: Publication date: April 2017 Source:Current Opinion in Behavioral Sciences, Volume 14 Author(s): Karl Ebner, Nicolas Singewald Many individuals experience stressful life events, but only a minority develops stress-related pathologies including mental disorders such as depression or anxiety disorders. Such individual differences in stress vulnerability are based on alterations in neural circuits/mechanisms designed to properly tune and terminate stress responses. Recent studies in animal models combining behavioral, molecular, functional imaging and optogenetic techniques reveal maladaptive, dysregulated gene expression and impaired stress-neurocircuit function across multiple brain regions as sources of individual stress-vulnerability. In this review, we focus on novel findings providing evidence for a critical role of stress-inhibitory neural pathways in individual stress-susceptibility. Moreover, we highlight candidate genetic, epigenetic and biochemical factors that characterize vulnerability and may drive maladaptive processes in these stress-inhibitory circuits, as well as at the level of the hypothalamic-pituitary-adrenal (HPA) axis. Finally, possible therapeutic implications of these findings are discussed, also in relation to new candidate risk factors that serve as biomarkers for the prediction of phenotypes vulnerable to develop stress-related syndromes. A better understanding of neurobiological mediators underlying individual stress-susceptibility would be a significant step forward to identify novel prevention and treatment strategies for stress-related disorders.
Authors:Shikha Prashad; Francesca M Filbey Pages: 1 - 7 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Shikha Prashad, Francesca M Filbey Cannabis use affects cortico-striatal networks that are essential for producing movement. In this review, we summarize the literature on motor system dysfunction in cannabis users and provide a rationale for why motor learning should be considered an important area in cannabis research. A majority of studies have addressed cognitive impairments in cannabis users and some have focused on driving performance, motor impulsivity, and motor inhibition. Our review of the literature has found that cannabis use is associated with motor performance impairments; however, there is a gap in the literature regarding impairments in motor learning. The involvement of the cortico-striatal network in both cannabis addiction and movement also suggests potential avenues for treatment and rehabilitation via the motor system.
Authors:Dieter J Meyerhoff Pages: 13 - 18 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Dieter J Meyerhoff The simultaneous and/or concurrent use of licit and illicit substances (polysubstance use, PSU) is most common today. Structural magnetic resonance imaging (MRI) has been applied extensively to study individuals ostensibly using a single substance. These studies have produced a picture of regional gray matter and white matter alterations with each substance or class of substances. Very few studies measured regional brain morphometry in today's polysubstance users. This limited data suggest morphometric alterations with PSU that are not simply additive but often different from those of monosubstance users. Specifically, subcortical volume enlargements are observed that may be tied to mechanisms that also oppose volume reductions in cortical brain regions, thereby underestimating actual cortical atrophy. The complex actions of polysubstance use on brain structure and function need greater scrutiny with strong methodological approaches to inform more efficient treatment of polysubstance users.
Authors:Thomas E Gladwin; Corinde E Wiers; Reinout W Wiers Pages: 19 - 24 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Thomas E Gladwin, Corinde E Wiers, Reinout W Wiers Automatic processes related to addiction can be directly targeted in novel training paradigms. First studies have demonstrated that Cognitive Bias Modification (CBM) targeting approach biases can enhance treatment outcomes when added to regular treatment. However, the overall efficacy of CBM is debated. We argue that considering the modulating role of motivation and the mediating role of actual bias change are essential to drawing valid conclusions. Findings on mediating cognitive and neural mechanisms underlying clinical effects provide further sources of evidence on CBM. Taken together the literature supports the claim that cognitive bias change can improve clinical outcome, but that there are necessary conditions that must be met. Improved theoretical understanding of changing biases and new techniques such as neuromodulation may be needed to optimally apply CBM to help patients overcome addictive behavior. Graphical abstract
Authors:Hamed Ekhtiari; Teresa A Victor; Martin P Paulus Pages: 25 - 33 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Hamed Ekhtiari, Teresa A Victor, Martin P Paulus There are a growing number of studies with different substance use populations that show evidence for aberrant decision-making, which involves but is not limited to increased temporal discounting, increased risk-taking, and inability to mediate between immediate large gains and long-term larger losses. However, the current literature is inconsistent on how these dysfunctions manifest across different substance use disorders and whether they contribute to the initiation, progression and recovery from these disorders. Moreover, there is an incomplete understanding of the neurocognitive processes that underlie these deficits, the best methods to measure them, and ways to improve dysfunction. Here, recently published literature on aberrant decision-making is reviewed to address these questions using four domains: self-report measures, behavioral tasks, computational modeling, and functional neuroimaging. In conclusion, we provide suggestions to improve the consistency, validity and applicability of these measures to the reduction of decision-making dysfunction as a core component of prevention and recovery for the future of addiction medicine. Graphical abstract
Authors:Keren Bachi; Salvador Sierra; Nora D Volkow; Rita Z Goldstein; Nelly Alia-Klein Pages: 34 - 39 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Keren Bachi, Salvador Sierra, Nora D Volkow, Rita Z Goldstein, Nelly Alia-Klein Drug-addiction may trigger early onset of age-related disease, due to drug-induced multi-system toxicity and perilous lifestyle, which remains mostly undetected and untreated. We present the literature on pathophysiological processes that may hasten aging and its relevance to addiction, including: oxidative stress and cellular aging, inflammation in periphery and brain, decline in brain volume and function, and early onset of cardiac, cerebrovascular, kidney, and liver disease. Timely detection of accelerated aging in addiction is crucial for the prevention of premature morbidity and mortality.
Authors:Victoria Manning; Antonio Verdejo-Garcia; Dan I Lubman Pages: 40 - 45 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Victoria Manning, Antonio Verdejo-Garcia, Dan I Lubman There is consistent evidence of impairments in cognitive functioning, as well as structural and neural processing abnormalities among substance-dependent populations. In this review, we summarise recent neurocognitive and neuroimaging research, particularly focussing on studies that examine the impact of faulty cognition and mechanisms on treatment outcomes, as well as the efficacy of novel neurocognitive interventions. Our review highlights growing evidence of neuroplasticity and recovery of cognitive deficits with abstinence, and the potential for targeted neurocognitive interventions to enhance clinical outcomes. Improved neurocognition appears to be a valuable therapeutic target for addiction treatment, and approaches targeting both top-down and bottom-up mechanisms have the potential to generate meaningful and sustained clinical outcomes.
Authors:Steven R Laviolette Pages: 46 - 54 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Steven R Laviolette Opiates, like many drugs of abuse, possess both rewarding and aversive stimulus properties. Nevertheless, the precise neurobiological mechanisms controlling these different motivational aspects of opiates are not well understood. The brains cannabinoid receptor system shares considerable functional and anatomical overlap with the opiate receptor system and importantly, has been shown to modulate functional inputs from neural regions controlling mesolimbic-dependent regulation of associative opiate reward memory. This review will focus on three of these regions: the basolateral amygdala (BLA), prefrontal cortex (PFC) and ventral hippocampus (vHIPP). Recent evidence demonstrates that all of these regions contain populations of output neurons that target mesolimbic areas including the dopamine (DA) containing neurons of the ventral tegmental area (VTA) and neuronal sub-populations in the nucleus accumbens (NAc). Importantly, signalling through the cannabinoid CB1 receptor (CB1R) system within these circuits has been shown to powerfully regulate the affective and memory-related processing of opiate-dependent motivational signals.
Authors:Boris B Quednow Pages: 55 - 62 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Boris B Quednow Beyond impairments in attention, memory, and executive functions, chronic users of stimulant drugs also display specific disturbances in social cognition, which are contributing to social dysfunctions in their daily life. Recent studies have shown overlapping alterations in fear recognition from faces, emotion recognition from complex visual stimuli, emotional empathy, and mental and emotional perspective-taking (Theory-of-Mind) in stimulant users. Additionally, stimulant users often have smaller social networks and show less prosocial behaviour in game-theoretical social decision-making tasks. In social interaction and social feedback tasks during functional imaging cocaine users revealed decreased activation of the medial-frontal reward system. In conclusion, training of social reward and social cognition might improve social functioning including therapeutic relationships and, thus, enhance treatment success in stimulant addiction.
Authors:Tara L. White Pages: 63 - 70 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Tara L. White Psychostimulant addiction is an important, relapsing condition for which there is no effective pharmacological treatment. Countering this problem requires an understanding of the specific risk factors that predispose individuals to initial misuse of these drugs. Healthy individuals display marked individual differences in emotional, behavioral and brain responses to low and moderate doses of stimulant drugs. These between-person differences have been most often studied using personality measures of sensation seeking. However, a growing body of work in healthy adults indicates potentially unique sources of variance in these responses that are related to four dissociable personality domains: extraversion, fearlessness, impulsivity and absorption. These four domains are empirically dissociable and can serve as endophenotypic markers of dopamine, norepinephrine and serotonin function in healthy individuals. The relationship between normal variation in these traits and the pharmacological effects of these drugs is here proposed as a framework for better understanding the specific sources of between-person variation in stimulant drug effects on mood, behavior and brain responses in healthy humans.
Authors:Celia Morgan; Amy McAndrew; Tobias Stevens; David Nutt; Will Lawn Pages: 71 - 76 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Celia Morgan, Amy McAndrew, Tobias Stevens, David Nutt, Will Lawn Psychedelic drugs have been used as treatments in indigenous cultures for thousands of years. Yet, due to their legal status, there has been limited scientific research into the therapeutic potential of these compounds for psychiatric disorders. In the absence of other effective treatments however, researchers have begun again to systematically investigate such compounds and there is now evidence pointing to the use of psychedelic drugs in the treatment of addiction. In this review we focus on human evidence for the effectiveness of preparations used by indigenous cultures in the Amazon (ayahausca) and Africa (ibogaine) and worldwide (psilocybin), and more recently synthetised drugs such as the serotonergic hallucinogen LSD and the dissociative anaesthetic ketamine. Potential mechanisms explored are anti-depressant effects, changes in neuroplasticity and existential psychological effects of these drugs.
Authors:Louk JMJ Vanderschuren; A Maryse Minnaard; Johanna AS Smeets; Heidi MB Lesscher Pages: 77 - 84 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Louk JMJ Vanderschuren, A Maryse Minnaard, Johanna AS Smeets, Heidi MB Lesscher Substance addiction is a chronic relapsing brain disorder, characterized by loss of control over substance use. In recent years, there has been a lively interest in animal models of loss of control over substance use, using punishment paradigms. We provide an overview of punishment models of addiction, that use quinine, histamine, lithium chloride and footshocks as aversive stimuli, and we discuss the merits and drawbacks of these approaches. Importantly, many studies have demonstrated that under certain conditions, animals are willing to endure punishment during the pursuit of substances of abuse, which captures an essential component of addictive behavior. We conclude that punishment models of addiction represent a valuable contribution to the study of addiction.
Authors:Brendan J Tunstall; Stephanie A Carmack; George F Koob; Leandro F Vendruscolo Pages: 85 - 90 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Brendan J Tunstall, Stephanie A Carmack, George F Koob, Leandro F Vendruscolo The transition from moderate to compulsive alcohol drinking is driven by increasingly dysfunctional reward and stress systems. We review behavioral and pharmacological studies of alcohol self-administration in rats that were mainly conducted within the framework of the alcohol vapor model of dependence. We discuss neurotransmitter systems that are implicated in alcohol drinking, with a focus on contrasting those neurotransmitter systems that drive behavior in the dependent versus nondependent states. We hypothesize that the identification of systems that become increasingly dysfunctional in alcohol dependence will reveal possible targets for successful interventions to reduce the motivation that drives compulsive alcohol drinking. In our opinion, drugs that normalize, rather than block, a hypofunctional reward system by restoring the function of hypothalamic stress systems and desensitize extrahypothalamic stress systems have the potential to selectively and effectively curb compulsive alcohol drinking. Graphical abstract
Authors:Marc L Copersino Pages: 91 - 98 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Marc L Copersino Fundamental to cognitive models of addiction is the gradual strengthening of automatic, urge-related responding that develops in tandem with the diminution of self-control-related processes aimed at inhibiting impulses. Recent conceptualizations of addiction also include a third set of cognitive processes related to self-awareness and superordinate regulation of self-control and other higher brain function. This review describes new human research evidence and theoretical developments related to the multicausal strengthening of urge-related responding and failure of self-control in addiction, and the etiology of disrupted self-awareness and rational decision-making associated with continued substance use. Recent progress in the development of therapeutic strategies targeting these mechanisms of addiction is reviewed, including cognitive bias modification, mindfulness training, and neurocognitive rehabilitation.
Authors:Michael M Barrus; Catharine A Winstanley Pages: 99 - 105 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Michael M Barrus, Catharine A Winstanley Impulsivity is thought to contribute to the development and maintenance of gambling disorder, but the mechanistic relationship between these complex and multifaceted behaviors is unclear. Animal models have been developed to examine various aspects of each, and have provided insight into the specific contributions of individual brain regions. Silencing distinct cortical and striatal regions within the affective corticostriatal loop can increase impulsivity and risky decision making, but the correspondence between various forms of both impulsivity and choice is imperfect. Instead, it appears that different facets of impulsivity and gambling-like behavior result from constellations of component processes. Such information may prove useful in understanding how risky decision making and impulsive behaviors interact in clinical conditions such as gambling disorder.
Authors:Ethan M Anderson; David W Self Pages: 117 - 123 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Ethan M Anderson, David W Self Many reports show that repeated cocaine administration increases dendritic spine density in medium spiny neurons of the nucleus accumbens, but there is less agreement regarding the persistence of these changes. In this review we examine these discrepancies by systematically categorizing papers that measured cocaine-induced changes in accumbal spine density. We compare published reports based on withdrawal time, short versus long duration of cocaine administration, environmental pairing with cocaine, and core/shell subregion specificity. Together, these studies suggest that cocaine exposure induces rapid and dose-dependent increases in spine density in accumbens neurons that may play a role in the maintenance of cocaine use and vulnerability to early relapse, but are not a factor in behavioral changes associated with longer abstinence.
Authors:Grace M Brennan; Luke W Hyde; Arielle R Baskin-Sommers Pages: 124 - 129 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Grace M Brennan, Luke W Hyde, Arielle R Baskin-Sommers The association between substance use disorders (SUDs) and crime is one of the most reliable themes in the SUDs literature. While SUDs undoubtedly contribute to crime, there is also good evidence that specific clinical syndromes place individuals at higher risk for SUDs. Of relevance, two subtypes of individuals, ‘antisocial-only’ and ‘psychopathic,’ are at elevated risk for SUDs. The former, which includes conduct disorder and antisocial personality disorder, involves a failure to regulate affective reactions, which overwhelms inhibitory controls. The latter, which includes antisocial behavior plus callous-unemotional traits and psychopathy, involves a failure of attention to adequately integrate affective experiences to guide behavioral control. We describe how these potentially divergent etiologies can inform personalized treatments.
Authors:Marco Leyton Pages: 130 - 138 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Marco Leyton Is altered dopamine transmission a pre-existing vulnerability trait for addiction? Preliminary support for this hypothesis has been provided by recent neuroimaging studies. While most effects remain to be replicated, there is now evidence that, compared to healthy controls, people at familial risk for substance use disorders exhibit both increases and decreases in striatal dopamine function. The following review assesses the strength of this evidence, considers explanations for discrepant results, and discusses potential implications for understanding pathways to addiction.
Authors:Amanda R Pahng; M Adrienne McGinn; Rod I Paulsen; Scott Edwards Pages: 139 - 143 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Amanda R Pahng, M Adrienne McGinn, Rod I Paulsen, Scott Edwards The prefrontal cortex (PFC) represents and executes the highest forms of goal-directed behavior, and has thereby attained a central neuroanatomical position in most pathophysiological conceptualizations of motivational disorders, including alcohol use disorder (AUD). Excessive, intermittent exposure to alcohol produces an allostatic dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis along with heightened forebrain glucocorticoid signaling that can damage PFC architecture and function. Negative affective states intimately associated with the transition to alcohol dependence result not only from a dysregulated HPA axis, but also from the inability of a damaged PFC to regulate subcortical stress and reinforcement centers, including the ventral striatum and amygdala. Several cognitive symptoms commonly associated with severe AUD, ranging from poor risk management to the cognitive/affective dimension of pain, are probably mediated by altered function of key anatomical elements that modulate PFC executive function, including contributions from the cingulate cortex and insula. Future therapeutic strategies for severe AUD should focus on attenuating the deleterious effects of excessive stress hormone activity on cognitive/affective and motivational behaviors gated by the PFC.
Authors:Maxime Fouyssac; Barry J Everitt; David Belin Pages: 144 - 151 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Maxime Fouyssac, Barry J Everitt, David Belin Over the course of addiction drug seeking, initially volitional, progressively becomes habitual and then compulsive. These psychological transitions in the control over behaviour are underlined by functional intrastriatal shifts from the nucleus accumbens to the dorsolateral striatum. The cellular mechanisms that contribute, in vulnerable individuals, to the aberrant recruitment and maintenance of dorsolateral striatum-dependent drug seeking habits are poorly understood. We propose a striatal endophenotype of addiction that relies on the endocannabinoid, opioid and adenosinergic systems, each of which has been implicated in the regulation of striatal plasticity and habit formation. Since these systems regulate impulsivity, a hallmark feature of addiction vulnerability and are modulated by addictive drugs they are well positioned to shape the physiology of the striatal synapse in vulnerable individuals and promote plasticity which will result in the recruitment of maladaptive drug seeking habits.
Authors:Adrianna Mendrek; Liana Fattore Pages: 152 - 157 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Adrianna Mendrek, Liana Fattore Men and women affected by schizophrenia display different age of onset, symptom profile and course of the disease. Similarly, men and women differ in the prevalence and frequency of drug use, pattern and reasons of use, and vulnerability to develop drug addiction. An understanding of the role of sex in modulating brain processes and behavior in patients with substance use disorder and/or schizophrenia-like symptoms has broad implications for gender-tailored treatment approaches. Cognizant of the considerable recent evidence for sex and gender differences in drug addiction and schizophrenia, we focused this review on the sex-dependent differences in drug-induced psychosis and on factors that may contribute to such male–female differences.
Authors:George H Vousden; Amy L Milton Pages: 158 - 163 Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): George H Vousden, Amy L Milton Memory reconsolidation—the process by which memories can become destabilised at retrieval, and be updated or modified—offers a potential therapeutic opportunity for mental health disorders based upon maladaptive emotional memories, such as drug addiction. Blocking the reconsolidation of pavlovian cue-drug memories persistently reduces subsequent relapse in rodent models and in human experimental medicine studies, but little is known about whether instrumental drug-seeking memories can be disrupted, particularly when individuals have transitioned to a compulsive drug-seeking habit. Here we discuss how studies of drug memory reconsolidation can be made more translationally relevant, with particular attention to the challenges faced by those attempting to disrupt the reconsolidation of habit memories.
Authors:Andreas Abstract: Publication date: February 2017 Source:Current Opinion in Behavioral Sciences, Volume 13 Author(s): Andreas Büttner The predominantly abused illicit substances include cannabis, opiates, cocaine, amphetamine, methamphetamine and their derivatives. Recently, the abuse of new psychoactive substances has become an increasing problem. In human drug abusers a broad spectrum of changes affecting the central nervous system are seen. The main alterations have been assumed to result from the consequences of ischemia and cerebrovascular diseases. However, detailed post-mortem investigations have shown widespread morphological alterations in the brains drug abusers. Further studies related drug abuse with the risk of accelerated brain aging and the development of neurodegenerative conditions.