[Reversible and irreversible stages of amnesia development after disruption of associative memory reactivation in snail].

We found previously that the inhibition of NMDA glutamate receptors during food aversion conditioning reactivation initiated disruption of long-term memory. In this work the dynamics of amnesia development was investigated. MK-801 (NMDA receptor antagonist) was injected into snail body cavity 24 hours after food aversion conditioning and conditioned food was presented (reminding procedure).Testing on the first and third days after the MK-801 injection/reminding procedure revealed a gradual decrease in the number of conditioned food aversions. Repeated the-same-food aversion conditioning recovered the initial memory in these periods of time. The number of food aversions was minimal 10 days after the MK-810 injection/reminding. Repeated food aversion conditioning was ineffective and did not result in the formation of food aversion conditioning at that time. So we were the first who found that the long-term memory reactivation disruption induced two stages of amnesia development. The first stage of amnesia development (up to 10 days) is reversible: the recovery of the long-term memory is possible after repeated the-same-food aversion conditioning. The second stage of amnesia development is irreversible: the recovery of the long-term memory is disrupted (revealed by the repeated the-same-food aversion conditioning). The findings may be of value for understanding the mechanisms of acute amnesia after some neurological diseases or injuries.