The γ MB neuron LTM trace is detectable between 18 and 48 hr after spaced conditioning. Thus, the γ MB neuron LTM trace covers a later window of time after conditioning and is thus referred to as a late-phase,

LTM selleck compound trace. One additional form of molecular plasticity has been reported that may be associated with long-term behavioral memory. Ashraf et al. (2006) constructed a reporter transgene encoding YFP but carrying the sequences from the CaMKII gene in the 3′UTR that confer dendritic localization on the mRNA. Animals carrying this transgene were subjected to spaced conditioning and 1 day later the amount of reporter gene product in glomeruli of the AL was quantified relative to untrained animals. An odorant-specific, training-dependent increase in synaptic protein synthesis was observed. When Oct was used as the CS+, an increase in synaptic protein synthesis was observed in glomeruli D

and DL3. When Mch was used as the CS+, an increase in synaptic protein synthesis was observed in DA1 and VA1. Remarkably, the increased synaptic CX-5461 order protein synthesis occurred in essentially the same glomeruli that are recruited into odorant representation immediately after training (Yu et al., 2004; see above). Thus, the early events within PNs that cause their recruitment into the representation of the learned odor may lead to later molecular processes that increase synaptic localization of specific mRNAs and synaptic protein synthesis. A unique and important feature of olfactory classical conditioning using Drosophila is that the ongoing learning is relatively simple compared to other popular learning models, such as spatial learning or contextual learning in rodents and insects, or novel object recognition in rodents or humans. In these and many other popular learning models, the information learned is complex and relational or occurs through many sensory systems that are difficult to separate. This all complexity creates significant

difficulty in mapping the functions that underlie memory formation—such as acquisition, consolidation, retrieval, or the various temporal forms of memory—to discrete regions of the brain. Mapping these and other learning functions to the neuroanatomy is necessary for understanding the logic behind the organization of the learning network and for effectively probing and understanding the meaning of the many molecular and cellular changes that occur within nodes of the network. Olfactory classical conditioning in flies provides learning about a single association, the smell of an odor and a mild electric shock, and affords the possibility of mapping memory traces with functional optical imaging to specific nodes of the olfactory nervous system.