Effects of nicotine on emotional and motivational processing

Studies in smokers indicate that nicotine exerts anxiolytic, stress-dampening and mood-enhancing effects and beneficially influences neural processing of affective information. Moreover, animal studies suggest that nicotine enhances the rewarding effects of primary and secondary reinforcers, probably due to its effects on the brain reward system. Hence, both the effects of nicotine on emotional and motivational processes might be critical for ongoing tobacco use. This functional magnetic resonance study investigates the effects of nicotine on neural emotional and motivational processing in dependent smokers and never-smokers. All participants are investigated twice. Smokers are subjected to two experimental sessions, once in a nicotine satiated state (while smoking normally) and a second time after two weeks of abstinence from smoking. Never-smokers receive nicotine (2 mg) and placebo gums in a double-blinded, randomized cross-over design. The effects of nicotine and smoking cessation on neural emotional and motivational processing are investigated with three different paradigms. An emotion processing paradigm uses pleasant, unpleasant, and neutral pictures of the International Affective Picture System to induce positive and negative affect. Furthermore, an instrumental motivation task is applied to measure brain activation in response to cues predicting the availability of different amounts of monetary reward, as well as during a subsequent instrumental response phase and during feedback of obtained reward. The instrumental response phase allows for direct assessment of the effort participants put in to receive reward. Finally, a third paradigm investigates the neural and behavioral delay discounting of a reward. Delay discounting describes the phenomenon that the value of a reward depends on the time point of its delivery. It is highest when delivered immediately and decreases when delivered with increasing delay. In this task, participants repeatedly have to choose between a smaller, immediate reward and a larger, temporally delayed reward. Behavioral studies indicate that smoking is associated with increased discounting of delayed rewards and that this effect is reversible. This study investigates the underlying neural basis of these findings.

Researchers:
Ricarda Kling
Andrea Kobiella
Hannah Scheuing
Michael N. Smolka

Collaborations:
Mira Bühler, Christian Vollmert, & Sabine Vollstädt-Klein, Department of Addictive Behaviour and Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
D. Elisabeth Ulshöfer, Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany
Christian Vollmert, Department of Addictive Behaviour and Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany
Sabine Vollstädt-Klein, Department of Addictive Behaviour and Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany

Funding:
DFG Grant # SM80/5-1