Negative value can be conveyed by the MB-MP1 and MB-MV1 DA neurons in the protocerebral posterior lateral (PPL) 1 cluster and by the MB-M3 neurons in the PAM cluster (Aso et al., 2012). MB-MV1 only innervates the proximal α′ region and γ lobe, MB-MP1 the heel of γ, and base of the peduncle (Figure 6E), and Nutlin-3a mw MB-M3 ramifies in the tip of the β lobe (Figure 6F). In contrast to the positively reinforcing MB-M8 neurons, cross-sections through the relevant parts of the MB revealed that the aversive reinforcing MB-M3 and MB-MP1 DA neurons preferentially arborize in the

αβs layer and exhibit no or much weaker innervation of αβc. Differential innervation of the αβ neuron subsets is also evident with behaviorally relevant MB efferent neurons. Two independent recent studies have

determined that MB-V3 neurons that innervate the tip of the α lobe are required for either appetitive (P.Y. Plaçais and T. Preat, personal communication) or aversive memory (Pai et al., 2013). A cross-section view through the tip of the α lobe reveals MB-V3 arbors throughout the βs and βc regions (Figure 6G). In contrast, dendrites of the aversive memory-specific MB-V2α output neurons (Séjourné et al., 2011) are most pronounced in the αs (Figure 6H). Therefore, the fine anatomy of reinforcing DA neurons and output neurons supports our observed Ibrutinib research buy functional difference between αβs and αβc MB neurons. Furthermore, their architecture indicates that the stratified functional asymmetry in the αβ ensemble may be established by reinforcement during training,

whereas differential pooling of outputs is critical for the expression of conditioned avoidance Mannose-binding protein-associated serine protease or approach. When faced with a choice, animals must select the appropriate behavioral response. Learning provides animals the predictive benefit of prior experience and allows researchers to influence behavioral outcomes. After olfactory learning, fruit flies are provided with a simple binary choice in the T-maze. Aversively trained flies preferentially avoid the conditioned odor, whereas appetitively conditioned flies approach it. A major goal of the field is to understand the neural mechanisms through which the fly selects the appropriate direction. In mammals, mitral cells take olfactory information direct from the olfactory bulb to the amygdala and the perirhinal, entorhinal, and piriform cortices (Davis, 2004 and Wilson and Mainen, 2006). In doing so, odor information is segregated into different streams, allowing it to be associated with other modalities and emotionally salient events. In contrast, most olfactory projection neurons in the fly innervate the MB calyx and lateral horn or only the lateral horn (Wong et al., 2002 and Jefferis et al., 2007).