Intense emotional experiences and enhanced training prevent memory loss induced by post-training amnesic treatments administered to the striatum, amygdala, hippocampus or substantia nigra

Abstract

Most of the work related to the neurobiological basis of memory has been guided by the memory consolidation theory, which was derived from the seminal work of Miiller and Pilzecker that was published over a century ago. This theory proposes that the transfer from short- to long-term memory is mediated by a process called consolidation,and while consolidation is taking place, the information to be stored is in a labile state. A great deal of experimentation has given strong support to this proposal,as it has been found repeatedly that interference with neural activity shortly after a learning experience impedes durable retention of that experience. A growing body of evidence, however, indicates that intense emotional experiences prevent memory loss induced by amnesic treatments,even when these treatments are administered intracerebrally shortly after the learning experience. This evidence implies that the memory consolidation theory cannot account for long-term memory formation when neural activity is disrupted while consolidation should be taking place, and it calls for new hypotheses to account for these findings.

Protein synthesis is not required for acquisition, consolidation, and extinction of high foot-shock active avoidance training

“…There are instances, however, in which PSIs do not disturb consolidation, for example, when mice are given relatively high numbers of trials of active avoidance training [7]. This result is consistent with those showing that interference with brain activity, produced by a variety of treatments, hinders memory consolidation, but they become ineffective when animals are subjected to enhanced training in diverse learning tasks (for a review see [8]). …”

“…Even though we are far from understanding the mechanisms underlying the protective effect of enhanced training against typical amnestic agents, seen in a wide variety of behavioral tasks [8], a growing body of literature supports the idea that amnestic agents exert their disruptive effects when new information is being updated [47][48][49]; thus, initial extinction trials serve as a novel piece of information for an organism that has received relatively consistent reinforcement. When CHX was administered prior to the first set of extinction trials, it produced an amnesic effect when low intensity was used for training (i.e., when the previous shock reinforcement memory was being updated to an extinction memory).…”

Histamine in the basolateral amygdala promotes inhibitory avoidance learning independently of hippocampus

“…Therefore, it is plausible that IA memory is spared after inactivation of the histaminergic system in the hippocampus because BLA histaminergic system takes over the process of consolidation, for example, enabling the storage of such information in other brain systems such as the entorhinal cortex or parietal cortex. Many reports have shown that IA training with high-intensity foot shocks reduced the memory impairment caused by hippocampal inactivation (38)(39)(40), thus suggesting that consolidation of intense emotional experiences do not require a functioning hippocampus. However, this fear memory is acquired slowly and forgotten when remote memory is tested (41).…”

Mushroom spine dynamics in medium spiny neurons of dorsal striatum associated with memory of moderate and intense training

“…A growing body of evidence indicates that treatments that commonly produce amnesia become ineffective when animals are given enhanced training (i.e., a high number of training sessions or relatively high levels of aversive stimulation). This protective effect against amnesia induced by interference with normal activity of brain nuclei has been found in a wide variety of learning tasks (1). Extensive evidence indicates that the dorsal striatum is intimately involved in the acquisition, consolidation, and retrieval memory for many kinds of training experiences (2)(3)(4)(5).…”