Abstract
Drosophila melanogaster (D. melanogaster) is one of the many important model animals in neurobiology, but much remains to be understood in terms of functional connections between the various neurons associated with memory and sleep. Especially important in all phases of olfactory memory of the D. melanogaster is the mushroom body (MB). Further synaptic connections show anatomical segregations of many subsets of neurons that innervate the MB. Of particular interest from the neurons that innervate the MB is the protocerebral anterior medial (PAM) neurons, a cluster of dopaminergic neurons found to have a large role in reinforcing formation of appetitive memory and can be further segregated into LTM- and STM-PAM based on functional differences. Thermogenetic tools were employed to target the PAM neuronal subsets during consolidation after memory formation, and results demonstrated that activation of PAM-1 neurons almost abolished 24-hr memory, suggesting PAM-1 role in memory consolidation. The results complicate current learning models that pose PAM neurons as simply conveying positive valence of stimuli to the MB where information converges. Furthermore, sleep and feeding have been demonstrated to be closely linked homeostatic processes. Although a number of other structures’ roles have been considered and dopamine has been shown to have a wakefulness-promoting role by action on KC-MBON microcircuits, PAM neuronal roles in the relationship between sleep and starvation states have been less explored. PAM neurons were targeted again with thermogenetic tools, and results suggest that although PAM neurons may have wake-promoting roles in certain circumstances, PAM neuronal activity can also suppress starvation-induced sleep loss.