Why we abruptly forget a person's name Here we showed that lapses in memory coincide with periods when consolidation of memory is susceptible to disturbances from outside the memory network. Changes in the molecular pathways underlying consolidation are responsible for these periods of vulnerability. In their study, the researchers introduced snails to an unfamiliar substance during feeding so that the animals would learn to recognise it as food. When they were fed later, scientists found the snails responded to the stimulus, with memory lapses after 30 minutes and two hours, before the memory became consolidated at about four hours. But if the snail received another different stimulus during the memory-lapse periods, the memory consolidation became disrupted, it was discovered. Dr Kemenes added: "Memory formation is an energy-consuming process. The brain would need to decide if it was worth expending energy for the consolidation of that particular memory. The brain has a restricted capacity to learn things and preventing some memory formation would be a way to avoid overload. The next stage of the study, titled Susceptibility of memory consolidation during lapse in recall, will investigate what happens to the brain during the memory disruption.