Long-term memory consolidation or reconsolidation impairment induces amnesia with key characteristics that are similar to key learning characteristics

• Published in: Neuroscience and biobehavioral reviews Vol. 108; pp. 542 - 558
• Main Authors: Nikitin, V.P., Solntseva, S.V., Kozyrev, S.A., Nikitin, P.V.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.01.2020
• Subjects: Amnesia; Amnesia - metabolism; Amnesia - physiopathology; Animals; Avoidance Learning - physiology; Memory consolidation; Memory Consolidation - physiology; Memory reconsolidation; Memory, Long-Term - physiology; Practice, Psychological; Memory consolidation; Memory reconsolidation; Amnesia
• ISSN: 0149-7634; 1873-7528
• DOI: 10.1016/j.neubiorev.2019.12.005

•Protein and RNA syntheses are necessary for amnesia induction.•The sensitivity of amnesia to retraining and reminders is reorganized over time.•Amnesia can be reactivated by a reminder presentation.•Late-stage amnesia that is resistant to retraining can be defined as specific anterograde amnesia.•The key characteristics of amnesia and memory formation are similar. According to a common perspective, amnesia is a passive consequence of memory consolidation or reconsolidation impairment. The results of our own study, as well as literature data, allowed us to offer an interpretation of amnesia. Amnesia is an active process whose key characteristics are similar to those of other long-term plastic rearrangements of the brain, including learning processes. In accordance with this hypothesis, the review considers the data we obtained on the mechanisms of amnesia induction and development caused by impairment of conditioned food aversion memory consolidation or reconsolidation. In particular, experimental data indicating the dependence of amnesia induction on protein and RNA syntheses are described. After amnesia induction, a time-dependent reorganization of its processes is shown to occur. In early amnesia stages (< 10 days), a gradual decrease in the possibility of memory formation during a second training was observed. In late stages of amnesia (10 days or more), an unusual physiological phenomenon was revealed—the second training did not lead to the formation of long-term memory. This effect was specific, as memory for a new type of food could possibly be formed in these animals. The described properties of amnesia facilitate its characterization as specific anterograde amnesia. In addition, at an early but not late amnesia stages, reminder presentation caused amnesia reactivation, impairment of which by DNA methyltransferase inhibitors caused memory recovery. The results obtained allow us to characterize amnesia as a specific, time-dependent, separate process. In conclusion, the potential biological significance of the described type of amnesia is considered, and we discuss the possible molecular mechanisms underlying it.