Moods as ups and downs of the motivation pendulum: revisiting reinforcement sensitivity theory (RST) in bipolar disorder

A Virtual In Vivo Dissection and Analysis of Socioaffective Symptoms Related to Cerebellum-Midbrain Reward Circuitry in Humans

Emerging research in nonhuman animals implicates cerebellar projections to the ventral tegmental area (VTA) in appetitive behaviors, but these circuits have not been characterized in humans. Here, we mapped cerebello-VTA white matter connectivity in a cohort of men and women using probabilistic tractography on diffusion imaging data from the Human Connectome Project. We uncovered the topographical organization of these connections by separately tracking from parcels of cerebellar lobule VI, crus I/II, vermis, paravermis, and cerebrocerebellum. Results revealed that connections between the cerebellum and VTA predominantly originate in the right cerebellar hemisphere, interposed nucleus, and paravermal cortex and terminate mostly ipsilaterally. Paravermal crus I sends the most connections to the VTA compared with other lobules. We discovered a mediolateral gradient of connectivity, such that the medial cerebellum has the highest connectivity with the VTA. Individual differences in microstructure were associated with measures of negative affect and social functioning. By splitting the tracts into quarters, we found that the socioaffective effects were driven by the third quarter of the tract, corresponding to the point at which the fibers leave the deep nuclei. Taken together, we produced detailed maps of cerebello-VTA structural connectivity for the first time in humans and established their relevance for trait differences in socioaffective regulation.

An in vivo Dissection, and Analysis of Socio-Affective Symptoms related to Cerebellum-Midbrain Reward Circuitry in Humans

Emerging research in non-human animals implicates cerebellar projections to the ventral tegmental area (VTA) in appetitive behaviors, but these circuits have not been characterized in humans. Here, we mapped cerebello-VTA white-matter connectivity in humans using probabilistic tractography on diffusion imaging data from the Human Connectome Project. We uncovered the topographical organization of these connections by separately tracking from parcels of cerebellar lobule VI, crus I/II, vermis, paravermis, and cerebrocerebellum. Results revealed that connections from the cerebellum to the VTA predominantly originate in the right hemisphere, interposed nucleus, and paravermal cortex, and terminate mostly ipsilaterally. Paravermal crus I sends the most connections to the VTA compared to other lobules. We discovered a medial-to-lateral gradient of connectivity, such that the medial cerebellum has the highest connectivity with the VTA. Individual differences in microstructure were associated with measures of negative affect and social functioning. By splitting the tracts into quarters, we found that the socio-affective effects were driven by the third quarter of the tract, corresponding to the point at which the fibers leave the deep nuclei. Taken together, we produced detailed maps of cerebello-VTA structural connectivity for the first time in humans and established their relevance for trait differences in socio-affective regulation.

Increased behavioral inhibition trait and negative stress coping in non-rapid eye movement parasomnias

STUDY OBJECTIVES

Reduced gray matter volume in the posterior cingulate cortex (PCC) has recently been found in patients with non-rapid eye movement (NREM) parasomnia, providing a neuroanatomical substrate for the arousal state dissociation. It remains unclear whether PCC changes in NREM parasomnias might also play a role in cognitive or affective dysfunction in these patients. The aim of this exploratory study was to investigate neurobehavioral correlates of PCC abnormalities in patients with NREM parasomnia.

METHODS

The Reinforcement Sensitivity Theory of Personality Questionnaire and the Stress Coping Questionnaire were used to assess personality and stress coping in 15 patients with NREM parasomnia and 15 age- and sex-matched healthy controls. Patients' left PCC gray matter volume was quantified with voxel-based morphometry on 3 Tesla T1-weighted magnetic resonance imaging data.

RESULTS

In the Reinforcement Sensitivity Theory of Personality Questionnaire, increased trait reactivity of the behavioral inhibition system and goal-drive persistence contributed most to the discrimination of patients and controls. In the Stress Coping Questionnaire, patients showed an increased negative coping trait (ie, anxious rumination) related to an increase in adjusted left PCC volume.

CONCLUSIONS

The results suggest subclinical behavioral abnormalities in patients with NREM parasomnias. Such traits might trigger maladaptive emotion regulation processes related to a relative PCC volume increase. The findings encourage further longitudinal studies on this topic, which can provide insights into the causal relations underlying the PCC volume-behavior correlation. Such future studies will have a more direct implication for the clinical management of patients with NREM parasomnias.

Effects of valence and arousal on implicit approach/ avoidance tendencies: A fMRI study

To date, it is still a matter of debate, whether valence or valence and arousal interactively foster implicit approach and avoidance tendencies, and which neural circuitries underlie these effects. To address these questions, we investigated the effects of valence and arousal on implicit approach/avoidance tendencies during fMRI in healthy volunteers (N=46). The implicit approach of positive social scenes was associated with shorter response preparation times and increased activation of the lingual, parahippocampal and fusiform gyri. Valence and arousal did not influence reaction times interactively, but we observed increased activation of prefrontal, motor, temporal, middle cingulate and parietal cortex during the approach of positive highly arousing and negative mildly arousing pictures, and the avoidance of positively mildly arousing and negative highly arousing pictures. These findings confirm the facilitation of implicit approach by positive scenes and advance our understanding regarding the neurobiological correlates of implicit approach-/avoidance biases.

Human mesostriatal response tracks motivational tendencies under naturalistic goal conflict

Goal conflict situations, involving the simultaneous presence of reward and punishment, occur commonly in real life, and reflect well-known individual differences in the behavioral tendency to approach or avoid. However, despite accumulating neural depiction of motivational processing, the investigation of naturalistic approach behavior and its interplay with individual tendencies is remarkably lacking. We developed a novel ecological interactive scenario which triggers motivational behavior under high or low goal conflict conditions. Fifty-five healthy subjects played the game during a functional magnetic resonance imaging scan. A machine-learning approach was applied to classify approach/avoidance behaviors during the game. To achieve an independent measure of individual tendencies, an integrative profile was composed from three established theoretical models. Results demonstrated that approach under high relative to low conflict involved increased activity in the ventral tegmental area (VTA), peri-aquaductal gray, ventral striatum (VS) and precuneus. Notably, only VS and VTA activations during high conflict discriminated between approach/avoidance personality profiles, suggesting that the relationship between individual personality and naturalistic motivational tendencies is uniquely associated with the mesostriatal pathway. VTA-VS further demonstrated stronger coupling during high vs low conflict. These findings are the first to unravel the multilevel relationship among personality profile, approach tendencies in naturalistic set-up and their underlying neural manifestation, thus enabling new avenues for investigating approach-related psychopathologies.