Beyond visual associative memory, the MB was shown to be important in various vision-guided behavioral tasks ( Liu et al., 1999 Brembs, 2009 Zhang et al., 2007). Studies of the neuronal circuits underlying olfactory learning have benefitted from well-characterized neuronal pathways conveying olfactory information to the MB ( Turner et al., 2008 Butcher et al., 2012). However, the required subsets of MB Kenyon cells (KCs) are not the same ( Aso et al., 2014a Vogt et al., 2014), raising the possibility that memory-relevant visual and olfactory information may be represented by different KC subsets in the MB. The role of MB output during memory acquisition and testing is similar in visual and olfactory memories ( Vogt et al., 2014). In the fruit fly, the MB receives distinct dopaminergic inputs that signal reward and punishment, and this valence circuit in the MB is shared for associative memories of different modalities: olfaction, gustation, and vision ( Masek et al., 2015 Aso et al., 2012 Liu et al., 2012 Perisse et al., 2013). In insects, such associative modulation takes place in the mushroom body (MB) ( Heisenberg, 2003). Rewarding or punitive stimuli modulate behavioral responses to sensory stimuli.
