Interoception and respiratory sinus arrhythmia in gambling disorder.

Gambling has longstanding links with excitement and physiological arousal, but prior research has not considered (a) gamblers' ability to detect internal physiological signals, or (b) markers of parasympathetic functioning. The present study measured interoception in individuals with gambling disorder, using self-report measures and a heartbeat counting task administered at rest. Resting state respiratory sinus arrhythmia (RSA), an index of heart rate variability, was measured as a proxy for parasympathetic control and emotional regulation capacity. In a case-control design, 50 individuals with gambling disorder were compared against 35 controls without gambling problems. Participants completed two self-report measures of bodily awareness and a behavioral test of heartbeat counting. A resting state electrocardiogram (5 min) was used to calculate RSA. There were no significant differences on the self-report or behavioral interoception probes. The group with gambling disorder displayed significantly reduced RSA, which at face value is consistent with reduced parasympathetic control. However, the group difference in RSA did not survive controlling for age and smoking status, as established predictors of heart rate variability. Our findings do not support any changes in interoceptive processing in people with gambling disorder, at least under resting conditions. Our observation that group differences in RSA are partly explained by smoking behavior highlights the importance of controlling for nicotine use in future research characterizing physiological functioning and emotional regulation in disordered gambling.

Fronto-striatal dysregulation in drug addiction and pathological gambling: Consistent inconsistencies?

Alterations in appetitive processing are central to the major psychological theories of addiction, with differential predictions made by the reward deficiency, incentive salience, and impulsivity hypotheses. Functional MRI has become the chief means of testing these predictions, with experiments reliably highlighting disturbances at the level of the striatum, medial prefrontal cortex, and affiliated regions. However, demonstrations of hypo-reactivity and hyper-reactivity of this circuitry in drug addicted groups are reported in approximately equal measure. Similar findings are echoed in the emergent neuroimaging literature on pathological gambling, which has recently witnessed a coming of age. The first aim of this article is to consider some of the methodological aspects of these experiments that could influence the observed direction of group-level effects, including the baseline condition, trial structure and timing, and the nature of the appetitive cues (drug-related, monetary, or primary rewards). The second aim is to highlight the conceptual traction that is offered by pathological gambling, as a model of a 'toxicity free' addiction and an illness where tasks of monetary reinforcement afford a more direct mapping to the abused commodity. Our conclusion is that relatively subtle decisions in task design appear capable of driving group differences in fronto-striatal circuitry in entirely opposing directions, even with tasks and task variants that look ostensibly similar. Differentiation between the psychological theories of addiction will require a greater breadth of experimental designs, with more research needed on processing of primary appetitive cues, aversive processing, and in vulnerable/at-risk groups.

The role of the orbitofrontal cortex in human discrimination learning.

Several lines of evidence implicate the prefrontal cortex in learning but there is little evidence from studies of human lesion patients to demonstrate the critical role of this structure. To this end, we tested patients with lesions of the frontal lobe (n=36) and healthy controls (n=35) on two learning tasks: the weather prediction task (WPT), and an eight-pair concurrent visual discrimination task ('Choose'). Performance of both tasks was previously shown to be disrupted in patients with Parkinson's disease; the Choose deficit was only present when patients were medicated. Patients with damage to the orbitofrontal cortex (OFC) were significantly impaired on Choose, compared to both healthy controls and non-OFC lesion patients. The OFC lesion patients showed a mild deficit on the first 50 trials of the WPT, compared to the control subjects but not non-OFC lesion patients. The selective deficit in the OFC patients on Choose performance could not be attributed to the larger lesion size in this group, and the deficit was not correlated with the volume of damage to adjacent prefrontal subregions (e.g. anterior cingulate cortex). These data support the notion that the OFC play a role in normal discrimination learning, and suggest qualitative similarities in learning performance of patients with OFC damage and medicated PD patients.

Predictors of punding in Parkinson's disease: results from a questionnaire survey.

Dopamine replacement therapy (DRT) for Parkinson's disease (PD) has recently been linked to the development of a number of nonmotor behavioral control problems. Punding, one of these nonmotor problems, is a term used to describe complex, purposeless stereotyped behaviors such as the repetitive handling or sorting of objects. A self-report questionnaire was adapted to assess punding in the context of dysfunctional hobby-related activities. We report the results of a survey of PD outpatients from a PD research clinic (n = 141) and non-PD controls (n = 103); conducted to identify clinical and psychological factors predictive of punding behaviors. The PD group reported hobbies and activities, which scored significantly higher on the Punding Scale than controls. Higher impulsivity, poorer disease-related quality of life, younger age of disease onset, and concomitant daily medication dosage from dopamine receptor agonists were independently predictive of higher Punding Scale scores in the PD group. These findings are similar to those seen in dopamine dysregulation syndrome, and provide further evidence for the role of impulsivity and age at disease onset in DRT-related nonmotor behavioral problems in PD.