Disentangling pain and fatigue in chronic fatigue syndrome: a resting state connectivity study before and after cognitive behavioral therapy.

Background: Fatigue is a central feature of myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), but many ME/CFS patients also report comorbid pain symptoms. It remains unclear whether these symptoms are related to similar or dissociable brain networks. This study used resting-state fMRI to disentangle networks associated with fatigue and pain symptoms in ME/CFS patients, and to link changes in those networks to clinical improvements following cognitive behavioral therapy (CBT).

Acquisition learning is stronger for aversive than appetitive events.

Appetitive and aversive learning are both key building blocks of adaptive behavior, yet knowledge regarding their differences is sparse. Using a capsaicin heat pain model in 36 healthy participants, this study directly compared the acquisition and extinction of conditioned stimuli (CS) predicting pain exacerbation and relief. Valence ratings show stronger acquisition during aversive compared to appetitive learning, but no differences in extinction.

Catecholaminergic modulation of trust decisions.

Rationale: Trust is a key component of social interactions. In order to assess the trustworthiness of others, people rely on both information learned from previous encounters, as well as on implicit biases associated with specific facial features.

Objective: Here, we investigated the role of catecholamine (dopamine and noradrenaline) transmission on trust decisions as a function of both experienced behavior and facial features.

Hair and salivary cortisol in a cohort of women with chronic fatigue syndrome.

Hypocortisolism has been found in CFS patients in blood, urine, and saliva. It is unclear if hypocortisolism can also be demonstrated using long-term cortisol measurements, such as cortisol in hair. In addition, the interaction between the HPA axis and the immune system, both expected to play an important role in CFS, is unclear.

Fatigue Is Associated With Altered Monitoring and Preparation of Physical Effort in Patients With Chronic Fatigue Syndrome.

Background: Chronic fatigue syndrome (CFS) is characterized by disabling fatigue, which is suggested to be maintained by dysfunctional beliefs. Fatigue and its maintenance are recently conceptualized as arising from abnormally precise expectations about bodily inputs and from beliefs of diminished control over bodily states, respectively. This study used functional neuroimaging to identify the neural correlates of fatigue and its maintenance by beliefs during a physical effort task.

Effort but not Reward Sensitivity is Altered by Acute Sickness Induced by Experimental Endotoxemia in Humans.

Sickness behavior in humans is characterized by low mood and fatigue, which have been suggested to reflect changes in motivation involving reorganization of priorities. However, it is unclear which specific processes underlying motivation are altered. We tested whether bacterial endotoxin E.

Interleukin-1 as a mediator of fatigue in disease: a narrative review.

Fatigue is commonly reported in a variety of illnesses, and it has major impact on quality of life. Previously, it was thought that fatigue originates in the skeletal muscles, leading to cessation of activity. However, more recently, it has become clear that the brain is the central regulator of fatigue perception.

Prefrontal Structure Varies as a Function of Pain Symptoms in Chronic Fatigue Syndrome.

Background: Chronic fatigue syndrome (CFS) is characterized by severe fatigue persisting for ≥6 months and leading to considerable impairment in daily functioning. Neuroimaging studies of patients with CFS have revealed alterations in prefrontal brain morphology. However, it remains to be determined whether these alterations are specific for fatigue or whether they relate to other common CFS symptoms (e.

The Neurocognitive Cost of Enhancing Cognition with Methylphenidate: Improved Distractor Resistance but Impaired Updating.

A balance has to be struck between supporting distractor-resistant representations in working memory and allowing those representations to be updated. Catecholamine, particularly dopamine, transmission has been proposed to modulate the balance between the stability and flexibility of working memory representations. However, it is unclear whether drugs that increase catecholamine transmission, such as methylphenidate, optimize this balance in a task-dependent manner or bias the system toward stability at the expense of flexibility (or vice versa).

Acute effects of cocaine and cannabis on reversal learning as a function of COMT and DRD2 genotype.

Rationale: Long-term cannabis and cocaine use has been associated with impairments in reversal learning. However, how acute cannabis and cocaine administration affect reversal learning in humans is not known.

Objective: In this study, we aimed to establish the acute effects of administration of cannabis and cocaine on valence-dependent reversal learning as a function of DRD2 Taq1A (rs1800497) and COMT Val108/158Met (rs4680) genotype.

Dopaminergic Modulation of the Functional Ventrodorsal Architecture of the Human Striatum.

Interactions between motivational, cognitive, and motor regions of the striatum are crucial for implementing behavioral control. Work with experimental animals indicates that such interactions are sensitive to modulation by dopamine. Using systematic pharmacological manipulation of dopamine D2-receptors and resting-state functional imaging, we defined the functional architecture of the human striatum and quantified the effects of dopaminergic drugs on intrinsic effective connectivity between striatal subregions.

Investigating neural mechanisms of change of cognitive behavioural therapy for chronic fatigue syndrome: a randomized controlled trial.

Background: Chronic fatigue syndrome (CFS) is characterized by profound and disabling fatigue with no known somatic explanation. Cognitive behavioral therapy (CBT) has proven to be a successful intervention leading to a reduction in fatigue and disability. Based on previous neuroimaging findings, it has been suggested that central neural mechanisms may underlie CFS symptoms and play a role in the change brought on by CBT.

Dopaminergic drug effects during reversal learning depend on anatomical connections between the orbitofrontal cortex and the amygdala.

Dopamine in the striatum is known to be important for reversal learning. However, the striatum does not act in isolation and reversal learning is also well-accepted to depend on the orbitofrontal cortex (OFC) and the amygdala. Here we assessed whether dopaminergic drug effects on human striatal BOLD signaling during reversal learning is associated with anatomical connectivity in an orbitofrontal-limbic-striatal network, as measured with diffusion tensor imaging (DTI).

Working memory capacity predicts effects of methylphenidate on reversal learning.

Increased use of stimulant medication, such as methylphenidate, by healthy college students has raised questions about its cognitive-enhancing effects. Methylphenidate acts by increasing extracellular catecholamine levels and is generally accepted to remediate cognitive and reward deficits in patients with attention deficit hyperactivity disorder. However, the cognitive-enhancing effects of such 'smart drugs' in the healthy population are still unclear.

Anatomical connection strength predicts dopaminergic drug effects on fronto-striatal function.

Rationale: The neurotransmitter dopamine plays a key role in cognitive functions that are associated with fronto-striatal circuitry and has been implicated in many neuropsychiatric disorders. However, there is a large variability in the direction and extent of dopaminergic drug effects across individuals.

Objectives: We investigated whether individual differences in dopaminergic drug effects on human fronto-striatal functioning are associated with individual differences in white matter tracts.

Establishing the dopamine dependency of human striatal signals during reward and punishment reversal learning.

Drugs that alter dopamine transmission have opposite effects on reward and punishment learning. These opposite effects have been suggested to depend on dopamine in the striatum. Here, we establish for the first time the neurochemical specificity of such drug effects, during reward and punishment learning in humans, by adopting a coadministration design.

Bromocriptine does not alter speed-accuracy tradeoff.

Being quick often comes at the expense of being accurate. This speed-accuracy tradeoff is a central feature of many types of decision making. It has been proposed that dopamine plays an important role in adjusting responses between fast and accurate behavior.

Distinct linear and non-linear trajectories of reward and punishment reversal learning during development: relevance for dopamine's role in adolescent decision making.

Abnormalities in value-based decision making during adolescence have often been attributed to non-linear, inverted-U shaped development of reward-related processes. This hypothesis is strengthened by functional imaging work revealing an inverted-U shaped relationship between age and reward-related activity in the striatum. However, behavioural studies have mostly reported linear rather than non-linear increases in reward-related performance.

Human cognitive flexibility depends on dopamine D2 receptor signaling.

Rationale: Accumulating evidence indicates that the cognitive effects of dopamine depend on the subtype of dopamine receptor that is activated. In particular, recent work with animals as well as current theorizing has suggested that cognitive flexibility depends on dopamine D2 receptor signaling. However, there is no evidence for similar mechanisms in humans.