Temperament and arousal systems: A new synthesis of differential psychology and functional neurochemistry.

This paper critically reviews the unidimensional construct of General Arousal as utilised by models of temperament in differential psychology for example, to underlie 'Extraversion'. Evidence suggests that specialization within monoamine neurotransmitter systems contrasts with the attribution of a "general arousal" of the Ascending Reticular Activating System. Experimental findings show specialized roles of noradrenaline, dopamine, and serotonin systems in hypothetically mediating three complementary forms of arousal that are similar to three functional blocks described in classical models of behaviour within kinesiology, clinical neuropsychology, psychophysiology and temperament research. In spite of functional diversity of monoamine receptors, we suggest that their functionality can be classified using three universal aspects of actions related to expansion, to selection-integration and to maintenance of chosen behavioural alternatives. Monoamine systems also differentially regulate analytic vs. routine aspects of activities at cortical and striatal neural levels. A convergence between main temperament models in terms of traits related to described functional aspects of behavioural arousal also supports the idea of differentiation between these aspects analysed here in a functional perspective

Reply to: Systematic Overestimation of Reflection Impulsivity in the Information Sampling Task

To the Editor: Impulsivity, a psychological construct comprising both motor and cognitive factors, is thought to underlie important interindividual differences in health and disease (1). In particular, reflection impulsivity, which refers to the tendency to gather and evaluate information before decision making (2), has been implicated in many psychiatric and neurological disorders (3, 4, 5). One of the standard tasks for measuring reflection impulsivity in healthy and clinical populations is the Information Sampling Task (IST), designed by Clark et al. (3) and included in the widely used Cambridge Neuropsychological Test Automated Battery (CANTAB) (6). In this CANTAB version of the IST, participants sample a variable amount of information about an uncertain outcome before making a decision. The amount of information sampled before the decision gives a measure of participants’ reflection impulsivity. In this correspondence, we show that the calculation of the IST’s main outcome measure, P(correct), is based on incorrect statistical inference, resulting in systematic overestimation of participants’ reflection impulsivity and potentially inflated type II error rates. This might affect the results of numerous recent psychopharmacological, neuropsychological, and psychiatric publications that have used the IST (4, 5, 7).This work was supported by a Strategic Research Initiative Grant (to CM) from the University of Melbourne, Australia, and the National Health and Medical Research Council of Australia (Grant No. APP1021973 to MY

IS THERE POTENTIAL FOR REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION (rTMS) AS A TREATMENT OF OCD?

Obsessive-Compulsive Disorder (OCD) is a common and highly debilitating psychiatric disorder. Amongst OCD sufferers are a significant number (40-60%) of so-called non-responders who do not fully respond to commonly available treatments, which include medications (Selective Serotonin Reuptake Inhibitors-SSRIs) and cognitive behavior therapy (CBT). Modern \u27neuromodulatory\u27 techniques such as Deep Brain Stimulation (DBS), repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS) potentially offer alternative forms of treatment for OCD patients who either do not respond to, or are unable or unwilling to take SSRIs and undergo CBT. Although shown to be effective in treatment resistant OCD, DBS requires invasive neurosurgical procedures with associated risks. On the other hand, rTMS and tDCS are non-invasive forms of treatment, which are largely risk free, but the evidence of their efficacy so far is somewhat limited, with only small number of published studies. In this brief survey we will address the potential of rTMS as a therapeutic tool for OCD and review the published literature on the cortical targets for rTMS used so far. We will also discuss some of the newer variants of rTMS techniques only a few of which have been employed so far, and speculate whether there might be a place for rTMS as a standard treatment in OCD, along side CBT, SSRIs and DBS

IS THERE POTENTIAL FOR REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION (rTMS) AS A TREATMENT OF OCD?

Obsessive-Compulsive Disorder (OCD) is a common and highly debilitating psychiatric disorder. Amongst OCD sufferers are a significant number (40-60%) of so-called non-responders who do not fully respond to commonly available treatments, which include medications (Selective Serotonin Reuptake Inhibitors-SSRIs) and cognitive behavior therapy (CBT). Modern \u27neuromodulatory\u27 techniques such as Deep Brain Stimulation (DBS), repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS) potentially offer alternative forms of treatment for OCD patients who either do not respond to, or are unable or unwilling to take SSRIs and undergo CBT. Although shown to be effective in treatment resistant OCD, DBS requires invasive neurosurgical procedures with associated risks. On the other hand, rTMS and tDCS are non-invasive forms of treatment, which are largely risk free, but the evidence of their efficacy so far is somewhat limited, with only small number of published studies. In this brief survey we will address the potential of rTMS as a therapeutic tool for OCD and review the published literature on the cortical targets for rTMS used so far. We will also discuss some of the newer variants of rTMS techniques only a few of which have been employed so far, and speculate whether there might be a place for rTMS as a standard treatment in OCD, along side CBT, SSRIs and DBS

From the ventral to the dorsal striatum: Devolving views of their roles in drug addiction

AbstractWe revisit our hypothesis that drug addiction can be viewed as the endpoint of a series of transitions from initial voluntarily drug use to habitual, and ultimately compulsive drug use. We especially focus on the transitions in striatal control over drug seeking behaviour that underlie these transitions since functional heterogeneity of the striatum was a key area of Ann Kelley's research interests and one in which she made enormous contributions. We also discuss the hypothesis in light of recent data that the emergence of a compulsive drug seeking habit both reflects a shift to dorsal striatal control over behaviour and impaired prefontal cortical inhibitory control mechanisms. We further discuss aspects of the vulnerability to compulsive drug use and in particular the impact of impulsivity. In writing this review we acknowledge the untimely death of an outstanding scientist and a dear personal friend

Fronto-striatal circuits in response-inhibition: Relevance to addiction.

Disruptions to inhibitory control are believed to contribute to multiple aspects of drug abuse, from preexisting vulnerability in at-risk individuals, through escalation to dependence, to promotion of relapse in chronic users. Paradigms investigating the suppression of actions have been investigated in animal and human research on drug addiction. Rodent research has focused largely on impulsive behaviors, often gauged by premature responding, as a viable model highlighting the relevant role of dopamine and other neurotransmitters primarily in the striatum. Human research on action inhibition in stimulant dependence has highlighted impaired performance and largely prefrontal cortical abnormalities as part of a broader pattern of cognitive abnormalities. Animal and human research implicate inhibitory difficulties mediated by fronto-striatal circuitry both preceding and as a result of excessive stimulus use. In this regard, response-inhibition has proven a useful cognitive function to gauge the integrity of fronto-striatal systems and their role in contributing to impulsive and compulsive features of drug dependence.This is the final version. It was first published by Elsevier at http://dx.doi.org/10.1016/j.brainres.2014.09.01

Value generalization in human avoidance learning.

Generalization during aversive decision-making allows us to avoid a broad range of potential threats following experience with a limited set of exemplars. However, over-generalization, resulting in excessive and inappropriate avoidance, has been implicated in a variety of psychological disorders. Here, we use reinforcement learning modelling to dissect out different contributions to the generalization of instrumental avoidance in two groups of human volunteers (N = 26, N = 482). We found that generalization of avoidance could be parsed into perceptual and value-based processes, and further, that value-based generalization could be subdivided into that relating to aversive and neutral feedback - with corresponding circuits including primary sensory cortex, anterior insula, amygdala and ventromedial prefrontal cortex. Further, generalization from aversive, but not neutral, feedback was associated with self-reported anxiety and intrusive thoughts. These results reveal a set of distinct mechanisms that mediate generalization in avoidance learning, and show how specific individual differences within them can yield anxiety.Wellcome, Arthritis Research U

Pharmacological treatment of cognitive deficits in nondementing mental health disorders .

Evidence for pharmacological remediation of cognitive deficits in three major psychiatric disorders-attention deficit- hyperactivity disorder (ADHD), schizophrenia, and depression-is reviewed. ADHD is effectively treated with the stimulant medications methylphenidate and d-amphetamine, as well as nonstimulants such as atomoxetine, implicating cognitive enhancing effects mediated by noradrenaline and dopamine. However, the precise mechanisms underlying these effects remains unclear. Cognitive deficits in schizophrenia are less effectively treated, but attempts via a variety of neurotransmitter strategies are surveyed. The possibility of treating cognitive deficits in depression via antidepressant medication (eg, selective serotonin reuptake inhibitors) and by adjunctive drug treatment has only recently received attention because of confounding, or possibly interactive, effects on mood. Prospects for future advances in this important area may need to take into account transdiagnostic perspectives on cognition (including neurodegenerative diseases) as well as improvements in neuropsychological, neurobiological, and clinical trial design approaches to cognitive enhancement.


What are the Odds? The Neural Correlates of Active Choice during Gambling

Gambling is a widespread recreational activity and requires pitting the values of potential wins and losses against their probability of occurrence. Neuropsychological research showed that betting behavior on laboratory gambling tasks is highly sensitive to focal lesions to the ventromedial prefrontal cortex (vmPFC) and insula. In the current study, we assessed the neural basis of betting choices in healthy participants, using functional magnetic resonance imaging of the Roulette Betting Task. In half of the trials, participants actively chose their bets; in the other half, the computer dictated the bet size. Our results highlight the impact of volitional choice upon gambling-related brain activity: Neural activity in a distributed network – including key structures of the reward circuitry (midbrain, striatum) – was higher during active compared to computer-dictated bet selection. In line with neuropsychological data, the anterior insula and vmPFC were more activated during self-directed bet selection, and responses in these areas were differentially modulated by the odds of winning in the two choice conditions. In addition, responses in the vmPFC and ventral striatum were modulated by the bet size. Convergent with electrophysiological research in macaques, our results further implicate the inferior parietal cortex (IPC) in the processing of the likelihood of potential outcomes: Neural responses in the IPC bilaterally reflected the probability of winning during bet selection. Moreover, the IPC was particularly sensitive to the odds of winning in the active-choice condition, when the processing of this information was required to guide bet selection. Our results indicate an important role of the IPC in human decision-making under risk and help to integrate neuropsychological data of risk-taking following vmPFC and insula damage with models of choice derived from human neuroimaging and monkey electrophysiology

Cognitive Inflexibility Predicts Extremist Attitudes.

Research into the roots of ideological extremism has traditionally focused on the social, economic, and demographic factors that make people vulnerable to adopting hostile attitudes toward outgroups. However, there is insufficient empirical work on individual differences in implicit cognition and information processing styles that amplify an individual's susceptibility to endorsing violence to protect an ideological cause or group. Here we present original evidence that objectively assessed cognitive inflexibility predicts extremist attitudes, including a willingness to harm others, and sacrifice one's life for the group. Across two samples (N = 1,047) from the United Kingdom and United States, structural equation models demonstrated that cognitive inflexibility predicted endorsement of violence to protect the national ingroup, which in turn predicted a willingness to die for the group. These statistical models accounted for an average of 31.4% of the variance in willingness to die for the group, after accounting for demographic variables. Furthermore, cognitive inflexibility was related to greater confidence in the decision to sacrifice one's life in an ingroup trolley problem scenario. Analysis of participants' performance on the cognitive tasks revealed that cognitive rigidity - distinctly from other aspects of cognition - was specifically implicated as a cognitive antecedent of extremist attitudes. Implications for the study of radicalization and identity fusion through a neurocognitive lens are discussed