Throughout the scientific literature, it is well established that dopamine is heavily involved in the reward system of the brain. In the very first studies from our group, we examined the effects of dopamine in the brain. We also examined reward learning in the brain, where participants were scanned twice on both an active and a passive version of the Iowa Gambling Task, a widely used decision making task. Instructing both groups of participants to complete this task showed that there were significantly larger changes in available dopamine in the participants with gambling issues. Furthermore, the gamblers who played with great risk (and lost money) had great amounts of dopamine released, whereas the participants who gambled with low risk (and won money) had a decreased availability of dopamine - in other words, the predictability of the associated outcome bored and tired the gamblers, in spite of the fact that they won. In non-gamblers, there was shown no significant effect of this.

Other studies from our group have found an association between the dopaminergic system in the brain and 1) skin conductance responses (SCR), and 2) different forms of gambling strategy. In a separate study, we found an association between personality (sensation-seeking personality traits) and the percentage of available dopamine receptors in the brain. On the day of publication, this was presented on Danish national television news (DR1).

In line with this, our group also examined the risk of parkinsonian patients treated with dopamine agonists to develop gambling addiction or other impulse control-related issues. These side-effects have proven detrimental to the everyday lives of parkinsonian patients. In line with this clinical issue and lack of treatment hereof, our group has looked at the association between gambling issues and depression. Here, participants with gambling issues were allowed only to participate if not receiving anti-depressant treatment during the study and if not diagnosed with clinical depression. After neuropsychological testing had been conducted, we showed that approximately 50 percent of participants showed depressive symptoms. And that this subgroup showed greater gambling problems with regards to both time and money spent gambling. This pointed towards the idea of gambling behaviour representing a form of self-medication and an addiction-reinforcing mean.

Based on these studies, our group attempted to create a gambling-reducing slot-machine, in which participants with gambling issues were exposed to different types of slot-machines (e.g. in which the time delay before a new game could be started was manipulated). Here, non-gamblers did not identify a difference across these different manipulations, whereas gamblers elicited increased stress responses as a consequence of changes in delay periods prior to a novel gamble situation.

Apart from our group’s research within dopamine, we have conducted studies within serotonin, another neurotransmitter in the brain involved in gambling and depression. In a study on the brain’s serotonergic system, we tested a group of participants, who were given medicine manipulating the serotonergic system. This manipulation affected participants to become more risk-willing in their behaviours when gambling. Yet another contribution to the literature on gambling issues.

Furthermore, our group has been the first to assess magnetoencephalogram (MEG) brain correlates in a gambling study, where participants were scanned on the first MEG-scanner in Scandinavia. Here we demonstrated that a control and inhibitory-oriented region of the brain, the right orbitofrontal cortex, was significantly different in its neural patterns across gamblers and non-gambling participants.

A third neurotransmitter involved in reward processing is GABA, an inhibitory neurotransmitter to neural activation. Here, we have conducted a study, where participants were tested twice on different medications; one, were we induced increased dopamine availability in the brain, and one which functioned as a placebo. The results revealed that dopamine-induced GABA release was significantly increased in non-gamblers (the fictitious handbrake), whereas in participants with gambling issues, the results were much more ambiguous and varying in comparison with the group of non-gamblers, illustrating clear GABA changes in gambling participants.

1) Investigating the clinical implications of olfaction in pathological gambling

Changes in olfaction related to a range of neurological and neuropsychological disorders has been reported in the literature. Olfaction have yet to be systematically investigated in pathological gambling. Nevertheless, as the neurotransmitter dopamine is central both in olfaction and in pathological gambling we aim to study both the diagnostic properties of olfaction and whether olfaction can predict who is prone to develop a gambling disorder.

The research group consists of Jakob Eriksen, Caroline Martens, Arne Møller, Alexander Fjældstad, and Thomas Alrik Sørensen, who collaborate between ”Center for Ludomani”, Aalborg University and Aarhus University. The testing began in November 2016.

2) The experience of action in pathological gamblers

The project will investigate the experience of actions of pathological gamblers and how we experience our actions and their effects on the world gives us a feeling of control. The aim of this project is to investigate if people with pathological gambling feel a different kind of control in gambling situations. If so, this might be a key to understand the subjective experience of gambling and hopefully a possible tool that can be used for therapeutic aid.

The research group consists of Mads Jensen, Morten Storm Overgaard and Arne Møller, who collaborate between ”Center for Ludomani”, CFIN, CNRU, and the PET-Centre at Aarhus University Hospital. The expected beginning of testing is early 2017.

3) Impulsivity and compulsivity: the roles of dopamine and serotonin in rewards

This PhD project seeks to delineate the relationship between the roles of dopamine and serotonin in rewards, and between dopaminergic and serotonergic roles in the neuropsychological measurements of impulsivity and compulsivity. If possible to further delineate, this potential of increasing dopamine and decreasing serotonin separately and in combination should yield intriguing results in demarcating the biological markers of impulsivity and compulsivity, thus highlighting necessary assessment and treatment potentials.

The research group consists of Casper Schmidt, Valerie Voon, and Arne Møller, who collaborate between ”Center for Ludomani”, the University of Cambridge, Aarhus University and Aarhus University Hospital. The expected beginning of testing is May 2017.

Severity of gambling is Associated with severity of depressive symptoms in pathological gamblers. / Rømer Thomsen, Kristine; Callesen, Mette Buhl; Linnet, Jakob; Kringelbach, Morten L.; Møller, Arne. I: Behavioural Pharmacology, Vol. 20, Nr. 5-6, 2009, s. 527-36.

Parkinsons sygdom og ludomani. / Callesen, Mette Buhl; Møller, Arne.I: Parkinson Nyt, Vol. 29, Nr. 1, 2009, s. 10-11.

Pathological gambling: Relation of skin conductance response to dopaminergic neurotransmission and sensation-seeking. / Peterson, Ericka; Møller, Arne; Doudet, Doris; Bailey, Christopher; Hansen, Kim Vang; Rodell, Anders; Linnet, Jakob; Gjedde, Albert. I: European Neuropsychopharmacology, Vol. 20, 2010, s. 766–775.

Inverted-U-shaped correlation between dopamine receptor availability in striatum and sensation seeking. / Gjedde, Albert; Kumakura, Yoshitaka; Cumming, Paul; Linnet, Jakob; Møller, Arne. I: National Academy of Sciences. Proceedings, 2010.

Event frequency, excitement and desire to gamble, among pathological gamblers. / Linnet, Jakob; Rømer Thomsen, Kristine; Møller, Arne; Callesen, Mette Buhl. I: International Gambling Studies, Vol. 10, Nr. 2, 2010.

Event frequency, excitement, and desire to gamble among pathological gamblers. / Linnet, Jakob; Rømer Thomsen, Kristine; Møller, Arne; Callesen, Mette Buhl I: International Gambling Studies, Vol. 10, Nr. 2, 2010, s. 177-188.

Experienced Poker Players Differ in Estimation Bias and Decision Bias from Inexperienced Poker Players. / Linnet, Jakob; Josefsen, Line Gebauer; Mouridsen, Kim; Shaffer, Howard J.; Møller, Arne. I: Journal of Gambling Issues, Nr. 24, 07.2010, s. 86-100.

Dopamine release in ventral striatum of pathological gamblers losing money. / Linnet, Jakob; Peterson, Ericka; Doudet, Doris; Gjedde, Albert; Møller, Arne. I: Acta Psychiatrica Scandinavica, Vol. 122, Nr. 4, 10.2010.

Inverse association between dopaminergic neurotransmission and Iowa Gambling Task performance in pathological gamblers and healthy controls. / Linnet, Jakob; Møller, Arne; Peterson, Ericka; Gjedde, Albert; Doudet, Doris. I: Scandinavian Journal of Psychology, Vol. 52, Nr. 1, 02.2011.

Dopamine release in ventral striatum during Iowa Gambling Task performance is associated with increased excitement levels in pathological gambling. /Linnet, Jakob; Møller, Arne; Peterson, Ericka; Gjedde, Albert; Doudet, Doris. I: Addiction, Vol. 106, Nr. 2, 11.02.2011, s. 383-390.

Striatal dopamine release codes uncertainty in pathological gambling. / Linnet, Jakob; Mouridsen, Kim; Peterson, Ericka; Møller, Arne; Doudet, Doris; Gjedde, Albert. I: Psychiatry Research: Neuroimaging, 2012, s. 55.

Modulation of Social Influence by Methylphenidate. / Campbell-Meiklejohn, Daniel; Simonsen, Arndis; Jensen, Mads; Wohlert, Victoria; Gjerløff, Trine; Scheel-Kruger, Jørgen; Møller, Arne; Frith, Chris D; Roepstorff, Andreas. I: Neuropsychopharmacology, 2012.

In for a penny, in for a pound : methylphenidate reduces the inhibiting effect of high stakes on persistent risky decisions in healthy adults. / Campbell-Meiklejohn, Daniel; Simonsen, Arndis; Scheel-Krüger, Jørgen; Wohlert, Victoria; Gjerløff, Trine; Frith, Chris D; Roepstorff, Andreas; Rogers, Robert; Møller, Arne. I: Journal of Neuroscience, Vol. 32, Nr. 38, 19.09.2012, s. 13032.

Slot Machine Response Frequency Predicts Pathological Gambling. / Linnet, Jakob; Rømer Thomsen, Kristine; Møller, Arne; Callesen, Mette Buhl. I: International Journal of Psychological Studies, Vol. 5, Nr. 1, 2013.

Prevalence of impulse control disorders in Danish patients with Parkinson's disease. / Callesen, Mette Buhl; Weintraub, Daniel ; Damholdt, Malene Flensborg; Møller, Arne. I: Movement Disorders, Vol. 28, Nr. Suppl 1, 2013, s. 347.

A Systematic Review of Impulse Control Disorders in Parkinson's Disease. / Callesen, Mette Buhl; Scheel-Krüger, Jørgen; Kringelbach, Morten L.; Møller, Arne. I: Journal of Parkinson's Disease, Vol. 3, Nr. 2, 2013, s. 105-138.

Dopaminergic and clinical correlates of pathological gambling in Parkinson's disease : A case report. / Callesen, Mette Buhl; Hansen, Kim Vang; Gjedde, Albert; Linnet, Jakob; Møller, Arne. I: Frontiers in Behavioral Neuroscience, Vol. 7, Nr. 95, 29.07.2013, s. 1-8.

Impulsive and compulsive behaviors among Danish patients with Parkinson’s diseass : Prevalence, depression, and personality. / Callesen, Mette Buhl; Weintraub, Daniel ; Damholdt, Malene Flensborg; Møller, Arne. I: Parkinsonism & Related Disorders, Vol. 20, Nr. 1, 2014, s. 22-26.

Serotoninergic effects on judgments and social learning of trustworthiness. / Simonsen, Arndis; Scheel-Krüger, Jørgen; Jensen, Mads; Roepstorff, Andreas; Møller, Arne; Frith, Chris D; Campbell-Meiklejohn, Daniel. I: Psychopharmacology, 25.01.2014.

Applying incentive sensitization models to behavioral addiction. / Rømer Thomsen, Kristine; Fjorback, Lone ; Møller, Arne

; Lou, Hans C. I: Neuroscience & Biobehavioral Reviews, Vol. 45, Nr. 2014, dx.doi.org/10.1016/j.neubiorev.2014.07.009, 15.07.2014, s. 343.