Self-regulation of the dopaminergic reward circuit in cocaine users with mental imagery and neurofeedback

BACKGROUND Enhanced drug-related reward sensitivity accompanied by impaired sensitivity to non-drug related rewards in the mesolimbic dopamine system are thought to underlie the broad motivational deficits and dysfunctional decision-making frequently observed in cocaine use disorder (CUD). Effective approaches to modify this imbalance and reinstate non-drug reward responsiveness are urgently needed. Here, we examined whether cocaine users (CU) can use mental imagery of non-drug rewards to self-regulate the ventral tegmental area and substantia nigra (VTA/SN). We expected that obsessive and compulsive thoughts about cocaine consumption would hamper the ability to self-regulate the VTA/SN activity and tested if real-time fMRI (rtfMRI) neurofeedback (NFB) can improve self-regulation of the VTA/SN. METHODS Twenty-two CU and 28 healthy controls (HC) were asked to voluntarily up-regulate VTA/SN activity with non-drug reward imagery alone, or combined with rtfMRI NFB. RESULTS On a group level, HC and CU were able to activate the dopaminergic midbrain and other reward regions with reward imagery. In CU, the individual ability to self-regulate the VTA/SN was reduced in those with more severe obsessive-compulsive drug use. NFB enhanced the effect of reward imagery but did not result in transfer effects at the end of the session. CONCLUSION CU can voluntary activate their reward system with non-drug reward imagery and improve this ability with rtfMRI NFB. Combining mental imagery and rtFMRI NFB has great potential for modifying the maladapted reward sensitivity and reinstating non-drug reward responsiveness. This motivates further work to examine the use of rtfMRI NFB in the treatment of CUD

First organocatalyzed asymmetric Michael addition of aldehydes to vinyl sufones

The first asymmetric direct Michael addition of aldehydes to vinyl sulfones catalyzed by N-iPr-2,2'-bipyrrolidine is described. 1,4-Adducts are obtained in good yields and enantioselectivities. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as shown previously for nitroolefins

Chiral amines as organocatalysts for asymmetric conjugate addition to nitroolefins and vinyl sulfones via enamine activation

Over the last decade the potential of organocatalysis has successfully been demonstrated. In particular, chiral amines such as pyrrolidine analogues have emerged as a broadly applicable class of organocatalyst for asymmetric conjugate addition via enamine activation. This Feature Article documents the development of these catalysts, emphasizing the design and mechanistic features that supply high selectivity in asymmetric Michael reactions

Organocatalyzed asymmetric reactions via microwave activation

Organocatalyzed asymmetric microwave-assisted reactions are described. Significant rate enhancements and a decrease of catalyst loading via microwave activation have been observed, while maintaining good to high yields and selectivities compared to literature results

First enantioselective organocatalytic conjugate addition of aldehydes to vinyl phosphonates

Chiral amines catalyze the enantioselective conjugate addition of aldehydes to vinyl phosphonates in high yields and with enantioselectivities up to 97% ee. This novel process provides synthetically useful chiral gamma-geminal phosphonate aldehydes which can be easily converted in a few steps into chiral beta-substituted vinyl phosphonates with conservation of the optical purity

The use of N-iPr-2,2'-bipyrrolidine derivatives as organocatalysts for asymmetric Michael additions

The recent rapid growth of organocatalysis has shown a new approach in organic chemistry and presents the obvious advantage in the avoidance of expensive and often toxic metals. Moreover, the organocatalysts are generally easier to make than standard catalytic reagents. Therefore, our laboratory has synthesized N-alkyl-2,2'bipyrrolidine derivatives as a new class of organocatalysts and applied them to the asymmetric Michael addition of ketones and aldehydes to nitroolefins via an enamine intermediate. We have furthermore developed the first asymmetric Michael addition of aldehydes to vinyl sulfones catalyzed with our diamines. The 1,4 adducts are obtained in good yields with enantioselectivities up to 80% ee. The determination of absolute configuration allowed us to postulate a Si,Si transition state model, as described previously for nitroolefins

Enantioselective organocatalytic conjugate addition of α-aminoketone to nitroolefins

The enantioselective organocatalytic conjugate addition of a-aminoketone to nitroolefins is reported

3,3'-Bimorpholine derivatives as a new class of organocatalysts for asymmetric michael addition

New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic synclinal model