Reconsolidation of a context long-term memory in the terrestrial snail requires protein synthesis - PubMed (original) (raw)

Reconsolidation of a context long-term memory in the terrestrial snail requires protein synthesis

Tatiana H Gainutdinova et al. Learn Mem. 2005 Nov-Dec.

Abstract

We investigated the influence of the protein synthesis blocker anisomycin on contextual memory in the terrestrial snail Helix. Prior to the training session, the behavioral responses in two contexts were similar. Two days after a session of electric shocks (5 d) in one context only, the context conditioning was observed as the significant difference of behavioral response amplitudes in two contexts. On the day following testing of context learning, a session of "reminding" was performed, immediately after which the snails were injected with anisomycin or vehicle. Testing of long-term context memory has shown that only anisomycin injections impaired the context conditioning. In control series, the snails were injected after the training session with anisomycin/saline without reminding, and no impairment of the long-term context memory was observed, while injection of anisomycin during the training session completely abolished the long-term memory. No effects of anisomycin on the short-term memory were observed. Surprisingly, injection of anisomycin after the reminding combined with reinforcing stimuli elicited no effect on the context memory. Differences between single-trial and multisession learning are discussed.

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Figures

Figure 1.

Figure 1.

(A) Protocol of context conditioning experiment with anisomycin/saline injection after testing for context conditioning, no reminding. (B) Averaged amplitudes (±SEM) of withdrawal responses in three groups of snails measured in two different contexts.

Figure 2.

Figure 2.

(A) Protocol of a context conditioning experiment with anisomycin/saline injection immediately after reminding. (B) Averaged amplitudes (±SEM) of withdrawal responses in three groups of snails measured in two different contexts.

Figure 3.

Figure 3.

(A) Protocol of a context conditioning experiment with anisomycin injection immediately after each electric shock. (B) Averaged amplitudes (±SEM) of withdrawal responses in experimental (anisomycin injection) and control (saline injection) groups of snails measured in two different contexts.

Figure 4.

Figure 4.

(A) Protocol of a context conditioning experiment with the anisomycin injection immediately after the combined reminding and sensitization stimuli. (B) Averaged amplitudes (±SEM) of withdrawal responses in three groups of snails measured in two different contexts (ANOVA, P = 0.45).

Figure 5.

Figure 5.

Averaged changes in amplitude of behavioral responses in two groups of snails (n = 6 in each group) injected 10 min prior to beginning of testing with AN or saline. After four test stimuli, one electric shock (timing is marked by an arrow) was delivered to the skin and testing continued. No significant difference in responses of snails from two groups was observed (ANOVA, P = 0.4), which suggests that AN does not influence short-term (tens of minutes) changes in excitability.

Figure 6.

Figure 6.

Specificity of the anisomycin effects for the long-term memory. Context conditioning experiment with testing of memory 4 and 24 h after the reminder + anisomycin/saline injection. (A) Protocol of the experiment. (B) Averaged amplitudes (±SEM) of withdrawal responses in four groups of snails measured in two different contexts. Significant loss of memory (ANOVA with post hoc analysis, P < 0.01) was observed only 24 h after the reminder + anisomycin injection.

References

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