How brains organize behavior based on internal needs on the one hand and changing environmental information on the other is one of the key questions in neuroscience. Learning is defined as a process leading to a lasting alteration in behavior due to experience. Even animals as simple as the Drosophila larva are able to form and recall an association of a particular odor with a rewarding stimulus. In the last years it turned out that - similar to the adult fly - the larval mushroom bodies (MB) are required for diverse behavioral functions, including odor learning and memory. The larval MB consists of about 2000 embryonic and larval born Kenyon cells. The seemingly unlimited genetic toolbox in Drosophila, which allows one to visualize, silence or activate defined neurons, combined with the simplicity in terms of cell numbers, the larva offers a useful system to study the neuronal correlates underlying learning and memory processes. In previous work we could demonstrate that only around 100 embryonic born Kenyon cells are required for associative odor-sugar learning. Furthermore, optogenetic activation of dopaminergic/octopaminergic neurons is sufficient to substitute the unconditional stimulus (US) during conditioning, while optogenetic activation of specific olfactory neurons is sufficient to substitute the conditional stimulus (CS). However, to our knowledge it is still elusive whether the conditional activation of Kenyon cells is sufficient to form memory traces. Thus, I am interested in whether a conditional optogenetic activation of Kenyon cells is, dependent on the set of Kenyon cells included in the Gal4 line, sufficient to induce an appetitive or aversive memory.