Study explores a new non-dopamine reward circuitry in the brain

Perhaps the oldest and best-known reward pathway in the brain is the mesolimbic dopamine system. However, new research in Nature Neuroscience shows that other pathways may lurk beyond dopamine.

According to researchers at the University of Washington, about 30 percent of cells in the ventral tegmental area are gamma aminobutyric acid (GABA) neurons. These neurons are said to be likely implicated in reward and aversion, possibly leading to the future development of treatments for stress-linked disorders, addiction, and other mental health problems.

“The long-range GABAergic input from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) is relatively understudied, and therefore its role in reward processing has remained unknown,” the journal article explains.

“In the present study, we show, in both male and female mice, that long-range GABAergic projections from the VTA to the ventral NAc shell, but not to the dorsal NAc shell or NAc core, are engaged in reward and reinforcement behavior.”

“We show that this GABAergic projection exclusively synapses on to cholinergic interneurons (CINs) in the ventral NAc shell, thereby serving a specialized function in modulating reinforced reward behavior through the inhibition of ventral NAc shell CINs.”

Researchers uncovered GABAergic cells known to project to the nucleus accumbens. “These findings highlight the diversity in the structural and functional topography of VTA GABAergic projections, and their neuromodulatory interactions across the dorsoventral gradient of the NAc shell,” the authors also explained in their findings.