Significant positive or negative experiences result in emotional memories that help us avoid future threats or seize rewards. Dysfunctions in the formation or recall of these emotional memories are linked to a variety of psychiatric conditions, from post-traumatic stress disorder to addiction. However, the underlying neuronal mechanisms for writing and discriminating such positive or negative experiences into brain networks are largely unknown.
Previous research suggests that events subjectively perceived as important - whether good or bad – increase extracellular dopamine levels, which in turn instruct a part of the limbic system called amygdala to learn. Neuroscientist Wulf Haubensak and his team hypothesise that emotional memories are reinforced by dedicated dopamine systems originating from two distinct parts of the midbrain, the dorsal tegmental area (DTA) and ventral tegmental area (VTA), which write positive or negative associations into amygdala memory, respectively. To test this hypothesis experimentally, mice will be subjected to behavioural assays in which the brain learns to associate tone cues with food reward or aversive events. Simultaneously, the IMP-researchers will perform deep brain imaging of the neuronal activities in DTA, VTA and amygdala networks to study how these elements process negative and positive experiences.
Project partners from the Lab of Volkmar Leßmann at the Institute of Physiology in Magdeburg will investigate how these experiences, together with dopamine signalling, rewire the synaptic connectivity in the amygdala that underlies memory formation. Jointly, this research will probe two alternative models of how the brain stores and discriminates opposing emotional memories in its neuronal networks. The resulting insights will help to understand how this is achieved using dopamine as a general messenger for both, negative and positive reinforcement learning. This initiative will also provide a mechanistic framework for understanding dopamine- and amygdala-circuitries in psychiatric conditions, such as post-traumatic stress, addiction and Parkinson-associated mood changes.
The project “Patterning valence specific amygdala memory by DTA and VTA” is funded jointly by the Austrian Science Fund FWF and the German Research Foundation DFG under the D-A-CH lead agency procedure. The three-year project is led jointly by Wulf Haubensak at the IMP and Volkmar Leßmann at the Otto-von-Guericke University Magdeburg, with Alipasha Vaziri at Rockefeller University, New York, as cooperation partner. The project will be supported for a period of three years, with the Austrian funds going mainly towards financing the position of senior postdoctoral researcher Florian Grössl.