The article concerns the problem of mechanisms of memory formation. The study was conducted on polyclonal antibodies to serotonin-modulating anticonsolidation protein (SMAP) that is in linear relationship with serotonin. Intra-cerebral administration of polyclonal anti-SMAP antibodies significantly enhanced elaboration and strengthened memory formation in two complex behavioral conditioned models. At the same time, intra-cerebral administration of these antibodies brought to upregulation of nerve growth factor (NGF) in the hippocampus (p<0.001). Intra-cerebral administration of antibodies to dihydropyrimidinase-related protein 2 (active component of SMAP, two other component proteins – tubulin and actin – are structural proteins lacking any regulatory activity) brought to downregulation of beta III tubulin (marker of differentiated neurons) in the hippocampus (p<0.001) and in the left parietal cortex (p<0.01). The obtained results indicate to the process of back remodeling of mature nerve cells of adult organisms occurring under the effects of anti-SMAP and anti-DRP2 antibodies. Conclusion is made that back remodeling (dedifferentiation) of mature nerve cells, apparently, is engaged in memory formation.