Motivational underpinnings of negative affect as revealed by emotional modulation of EEG bands

The studies reported in this thesis pertain to a project aiming at investigating the motivational underpinnings of psychopathologies characterized by negative affect, such as anxiety and depression. Unbalanced or conflicting motivational tendencies can lead to disturbances in emotional responding and ongoing affect, which are often associated with psychopathology. As it will be introduced in the first chapter, motivational drives are thought to be sustained by two main systems in the brain, namely the appetitive and the defensive motivational circuits. The appetitive system contributes to approach behaviors in response to rewarding and pleasant stimuli. On the other side, the defensive system drives withdrawal from threat and is important for triggering unpleasant emotions. Therefore, emotions can be described as action dispositions reflecting basic tendencies to both approach and withdrawal in response to emotional stimuli. Several models postulated that negative affect in psychopathology arises from an excessive activation of the defensive system, which leads to an increased and dominant tendency to actively withdrawal from potential threats in the environment. Partially contrasting with this theoretical conceptualization, the aim of this thesis was to investigate whether negative affect could also manifest in psychopathologies which are not characterized by a straightforward increase in withdrawal tendencies. In this sense, EEG correlates of motivational tendencies in response to emotional stimuli were investigated in blood phobia and in dysphoria (i.e., subclinical depression). Accordingly, blood phobia, contrary to other specific phobias, is not associated with an increase in action disposition in response to the feared stimulus. Therefore, negative affect in these individuals does not seem to arise from a pronounced tendency to actively withdrawal. Depression represents another example of condition in which it is not clear whether negative affect is subtended by a dominance of the withdrawal system or by a lack in appetitive motivation. Accordingly, it is matter of debate whether depressed mood is due to preferential processing of unpleasant stimuli or reduced sensitivity to rewards and positive emotions. In order to investigate these aspects, three studies were conducted. In study 1, it was chosen to investigate modulation of EEG bands during an emotional Go/Nogo task in blood phobia. The emotional Go/Nogo task, including phobia-related pictures, along with phobia-unrelated unpleasant, neutral and pleasant stimuli, was ideal to investigate the lack of action disposition in blood phobia. Results showed that individuals with blood phobia display a conflicting motivational pattern, characterized by co-occurring tendencies to attend and avoid the feared stimulus, in strong contrast with other phobias. In Studies 2 and 3, modulation of EEG bands during an emotional imagery task in individuals with dysphoria was investigated. The emotional imagery is an active task, in which individuals are requested to actively imagine emotional scenarios; therefore it was well suited to investigate emotional modulation of appetitive and defensive motivational tendencies. Overall, results supported the idea that depressed mood in dysphoria is due to a lack in appetitive motivation, accompanied by a reduction in processing of pleasant stimuli. Again, we found no evidences of increased defensive motivation and tendency to withdrawal in dysphoric individuals. Finally, our research focused on possible clinical implications of the abovementioned findings, concerning the application of bio-behavioral trainings for the reduction of negative affect. In line with the pertaining literature, results from of our first three studies showed that frontal alpha asymmetry is an informative index of motivational tendencies underlying affect and emotional responses. Therefore, a fourth study was conducted, aimed at evaluating the effectiveness of a frontal alpha asymmetry neurofeedback training in reducing negative affect, anxiety and depressive symptoms in healthy individuals. After five training sessions, healthy individuals succeeded in reducing right compared to left prefrontal activity, through a specific increase in right frontal alpha. In accordance with the role of the right prefrontal cortex in defensive motivation and negative affect, this increase in right frontal alpha power was associated with a significant reduction in negative affect and anxiety. In conclusion, the present thesis confirms and extends the link between motivational tendencies and negative affect, showing that negative affect is not exclusively associated with an increase in defensive motivation and in active withdrawal disposition. Accordingly, among psychopathologies characterized by negative affect, blood phobia and dysphoria do not display the typically predicted motivational pattern. A first step toward the transition from basic research to clinical application has been proposed, with the implementation of an EEG-based neurofeedback for the reduction of negative affect. Overall, the present work is of potential relevance for a better understanding of the motivational underpinnings of psychopathologies characterized by negative affect, also providing a strong rationale for the application of bio-behavioral trainings.