Harnessing motivation to alleviate neglect

This article is made available through the Brunel Open Access Publishing Fund. Copyright: © 2013 Russell, Li and Malhotra. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.The syndrome of spatial neglect results from the combination of a number of deficits in attention, with patients demonstrating both spatially lateralized and non-lateralized impairments. Previous reports have hinted that there may be a motivational component to neglect and that modulating this might alleviate some of the debilitating symptoms. Additionally, recent work on the effects of reward on attention in healthy participants has revealed improvements across a number of paradigms. As the primary deficit in neglect has been associated with attention, this evidence for reward's effects is potentially important. However, until very recently there have been few empirical studies addressing this potential therapeutic avenue. Here we review the growing body of evidence that attentional impairments in neglect can be reduced by motivation, for example in the form of preferred music or anticipated monetary reward, and discuss the implications of this for treatments for these patients. Crucially these effects of positive motivation are not observed in all patients with neglect, suggesting that the consequences of motivation may relate to individual lesion anatomy. Given the key role of dopaminergic systems in motivational processes, we suggest that motivational stimulation might act as a surrogate for dopaminergic stimulation. In addition, we consider the relationship between clinical post stroke apathy and lack of response to motivation

Missing motoric manipulations: rethinking the imaging of the ventral striatum and dopamine in human reward

Human neuroimaging studies of natural rewards and drugs of abuse frequently assay the brain’s response to stimuli that, through Pavlovian learning, have come to be associated with a drug’s rewarding properties. This might be characterized as a ‘sensorial’ view of the brain’s reward system, insofar as the paradigms are designed to elicit responses to a reward’s (drug’s) sight, aroma, or flavor. A different field of research nevertheless suggests that the mesolimbic dopamine system may also be critically involved in the motor behaviors provoked by such stimuli. This brief review and commentary surveys some of the preclinical data supporting this more “efferent” (motoric) view of the brain’s reward system, and discusses what such findings might mean for how human brain imaging studies of natural rewards and drugs of abuse are designed

How accurate appraisal of behavioral costs and benefits guides adaptive pain coping

Coping with pain is a complex phenomenon encompassing a variety of behavioral responses and a large network of underlying neural circuits. Whether pain coping is adaptive or maladaptive depends on the type of pain (e.g., escapable or inescapable), personal factors (e.g., individual experiences with coping strategies in the past), and situational circumstances. Keeping these factors in mind, costs and benefits of different strategies have to be appraised and will guide behavioral decisions in the face of pain. In this review we present pain coping as an unconscious decision-making process during which accurately evaluated costs and benefits lead to adaptive pain coping behavior. We emphasize the importance of passive coping as an adaptive strategy when dealing with ongoing pain and thus go beyond the common view of passivity as a default state of helplessness. In combination with passive pain coping, we highlight the role of the reward system in reestablishing affective homeostasis and discuss existing evidence on a behavioral and neural level. We further present neural circuits involved in the decision-making process of pain coping when circumstances are ambiguous and, therefore, costs and benefits are difficult to anticipate. Finally, we address the wider implications of this topic by discussing its relevance for chronic pain patients

Lost in Translation? On the Need for Convergence in Animal and Human Studies on the Role of Dopamine in Diet-Induced Obesity

Purpose of Review: Animal and human studies suggest that diet-induced obesity and plasticity in the central dopaminergic system are linked. However, it is unclear whether observed changes depend on diet or obesity, and whether they are specific to brain regions and cognitive functions. Here, we focus on neural and cognitive changes in frontostriatal circuits. Recent Findings: Both diet and obesity affect dopaminergic transmission. However, site and direction of effects are inconsistent across species and studies. Non-specific changes are observed spanning all frontostriatal loops, from sensory input to motivated behaviour. Given the impact of peripheral signals on central dopaminergic signalling and the interaction between the frontostriatal loops, modulation of dopamine likely propagates through all loops and, thus, affects behaviour on various levels of complexity. Summary: To improve convergence between animal and human studies on diet-induced obesity, animal studies should include sophisticated cognitive measures and diets resembling human obesogenic diets, and human studies should adopt diet interventions and longitudinal designs.Peer reviewe

Reduced reward-related probability learning in schizophrenia patients

Although it is known that individuals with schizophrenia demonstrate marked impairment in reinforcement learning, the details of this impairment are not known. The aim of this study was to test the hypothesis that reward-related probability learning is altered in schizophrenia patients. Twenty-five clinically stable schizophrenia patients and 25 age- and gender-matched controls participated in the study. A simple gambling paradigm was used in which five different cues were associated with different reward probabilities (50%, 67%, and 100%). Participants were asked to make their best guess about the reward probability of each cue. Compared with controls, patients had significant impairment in learning contingencies on the basis of reward-related feedback. The correlation analyses revealed that the impairment of patients partially correlated with the severity of negative symptoms as measured on the Positive and Negative Syndrome Scale but that it was not related to antipsychotic dose. In conclusion, the present study showed that the schizophrenia patients had impaired reward-based learning and that this was independent from their medication status

Dopamine-Dependent Task Performance over the Menstrual Cycle

Estradiol (E2) has been found to influence dopamine (DA) activity in the nonhuman animal brain. While there has been very little research performed looking at E2’s effects on DA-related cognitive function in humans, recent research found that women tested during high E2 phases of the menstrual cycle had significantly better performance on a DA-dependent spatial working memory task, than women tested during the lowest E2 phase. The current study utilized the natural hormone fluctuations that occur over the menstrual cycle to determine if E2 is associated with DA-dependent task performance. Using a repeated measures design, 47 women completed a battery of tasks, including 3 that are known to depend heavily on DA. The results showed that DA-dependent task performance was significantly associated with menstrual cycle phase. These findings provide preliminary evidence that variations in E2 over the menstrual cycle can affect central DA function in humans

Psychobiological mechanisms of endogenous pain modulation by pain relief as reward

Pain is much more than a sensory experience. Pain has strong emotional and motivational components that fulfill crucial functions for survival and well-being, because they drive behavior to avoid and escape from pain. This motivation is also reflected in the opposite and rewarding nature of the pleasure of pain relief. Both endogenous modulation of the perception of pain and pain relief are thought to promote the motivational drive and with that behavior that serves homeostatic needs. In contrast to pain and despite this crucial role of pain relief as reward, the psychobiological mechanisms underlying pain relief perception as well as related learning remain poorly understood. The aim of this dissertation was to deepen our understanding of psychological and neurobiological mechanisms of pain relief in healthy humans and possible alterations of these mechanisms in patients suffering from chronic pain. In a first experimental study, the role of the neurotransmitters dopamine and endogenous opioids in pain modulation and reinforcement learning were investigated using a probabilistic relief seeking task in healthy volunteers. The results showed that the informational value of pain and pain relief was endogenously enhanced in states of active decision making compared to passive states. This endogenous pain modulation scaled with perceived uncertainty of expected outcomes. Dopamine increased endogenous pain and pain relief modulation, while no evidence for the involvement of endogenous opioids was found. Successful reinforcement learning as found in the placebo condition was impaired by dopamine and endogenous opioids. The same probabilistic relief seeking task was used in a second study to investigate neural correlates of learning driven by pain and pain relief using functional magnetic resonance imaging in patients with chronic pain and healthy controls. This study replicated the effects of endogenous pain modulation by its informational value, while no alterations in patients with chronic pain were found compared to healthy controls. This result suggests that motivationally driven enhancement of pain relief perception is a robust phenomenon that appears to be spared by maladaptive changes during pain chronification. However, compared to healthy controls patients with fibromyalgia showed a stronger bias towards relief related cues during learning, but a weaker association of activation in the pregenual anterior cingulate cortex with relief prediction errors. These findings suggest that although the informational content of pain relief seems to be preserved in patients with chronic pain, subtle differences in the underlying mechanisms may reflect altered reward processing in chronic pain, which have been discussed before. In sum, the results highlight the important role of motivation and prospective control of behavior for endogenous modulation of pain and pain relief and provide insights in underlying psychobiological mechanisms in healthy states and in chronic pain

Decision-making during gambling: an integration of cognitive and psychobiological approaches

Gambling is a widespread form of entertainment that may afford unique insights into the interaction between cognition and emotion in human decision-making. It is also a behaviour that can become harmful, and potentially addictive, in a minority of individuals. This article considers the status of two dominant approaches to gambling behaviour. The cognitive approach has identified a number of erroneous beliefs held by gamblers, which cause them to over-estimate their chances of winning. The psychobiological approach has examined case-control differences between groups of pathological gamblers and healthy controls, and has identified dysregulation of brain areas linked to reward and emotion, including the ventromedial prefrontal cortex (vmPFC) and striatum, as well as alterations in dopamine neurotransmission. In integrating these two approaches, recent data are discussed that reveal anomalous recruitment of the brain reward system (including the vmPFC and ventral striatum) during two common cognitive distortions in gambling games: the near-miss effect and the effect of personal control. In games of chance, near-misses and the presence of control have no objective influence on the likelihood of winning. These manipulations appear to harness a reward system that evolved to learn skill-oriented behaviours, and by modulating activity in this system, these cognitive distortions may promote continued, and potentially excessive, gambling