196 • CHAPTER 7 Long-Term Memory: Encoding and Retrieval
In Condition 2, the rat receives the pairing of the tone and shock on Day 1, but the
drug is injected right away, before consolidation has occurred (Figure 7.23b). The fact
that the drug has blocked consolidation is confi rmed when the rat does not freeze to the
tone on Day 3. The rat behaves as if it never received the tone-shock pairing, because
the possibility of forming a stable memory was wiped out by the drug.
Condition 3 is the crucial condition (Figure 7.23c). The procedure on Day 1 is
the same as in Condition 1—the rat receives a pairing of tone and shock. On Day 2,
the tone is presented again, and the rat freezes because of the conditioning on Day 1.
This response to the tone is reactivation—eliciting a memory after the initial event.
Immediately after the reactivation, the drug is injected. When the rat is tested on Day 3
by presenting the tone again, the rat doesn’t freeze. By reactivating the memory on
Day 2, Nader set up a situation in which the memory became vulnerable to disruption,
and injecting the drug eliminated the memory for the tone-shock pairing.
The result in Condition 3 shows that when a memory is reactivated, it becomes
fragile, just as it was immediately after it was fi rst formed. Nader and other researchers● FIGURE 7.23 The Nader et al. (2000a) experiment on the eff ect on fear conditioning of
injecting anisomycin.Day 1 Day 2 Day 3Day 1 Day 2 Day 3Day 1 Day 2 Day 3Inject anisomycinInject anisomycinTone
+
ShockTone
+
ShockTone
onlyTone
onlyTone
onlyRat does not freezeRat does not freeze(b) Condition 2: Inject before consolidation(a) Condition 1: Inject after consolidation(c) Condition 3: Inject during reactivationRat learns
to fear toneTone
+
ShockRat learns
to fear toneTone
onlyRat freezes
in response to toneCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.