If true, then an artificial way of producing this effect would be needed to show that the memory trace drives behavior. Little is currently known about the mechanisms http://www.selleckchem.com/products/ch5424802.html by which these the various traces are generated. This is clearly a prime area of exploration for the future. Another open question is whether the memory traces are generated in parallel and independently of one another or whether they are generated in serial with later forming traces being dependent

on the formation of early traces. Only one observation has been made relative to this issue: the DPM neuron memory trace fails to form in the amn mutant, and the LTM trace of the α/β MBNs fails to form in this mutant. This observation is consistent with the possibility that the formation of the α/β MBN LTM trace is dependent on the earlier formation of the DPM neuron memory. However, too little evidence is currently available to make a convincing argument for either serial or parallel modes of formation. Although the bias in the field is to emphasize serial formation, it should be noted that there exists significant evidence

for parallel processing ( McGaugh, 2000). Prior studies using invertebrate and vertebrate systems have revealed that late forms of synaptic plasticity and memory can form in the absence of earlier forms ( Emptage and Carew, 1993, Mauelshagen et al., 1996, Grünbaum and Müller, 1998, Sherff and Carew, 2004 and Sossin, 2008). Thymidine kinase For instance, serotonin application selleck compound that is restricted only to the cell bodies of sensory neurons generates long-term facilitation in the absence of short- and intermediate-term facilitation. Ho et al. (2007) reported that LTM of olfactory learning forms in the absence of STM in flies expressing the GAP-related domain of neurofibromin, whereas

the C-terminal domain of neurofibromin is required for STM. It is important to note that the cellular memory traces described above must be a small subset of the changes that occur due to learning. At present, the most reliable and thoroughly characterized optical reporters for monitoring changes due to learning detect changes in calcium influx (e.g., G-CaMP) or synaptic release (synapto-pHluorin). It could be that calcium influx is well downstream in the series of physiological changes that occur due to learning and may even prove to be the optimal surrogate for evaluating where changes in activity occur, but it could also be that plasticity of calcium influx is not a currency valued highly within the memory trace market, making any model emphasizing calcium-based traces as much too simplistic.