The Brain's Rules for Change - Page 2

Then, at the end of the 1990s, a major turnaround in that viewpoint began. Researchers in three different labs had resumed studying the effects of reactivating an implicit memory. Thanks to sophisticated new techniques combined with the field's advanced knowledge of exactly where in the brain certain memories form, these neuroscientists were able to determine that what makes a reactivated memory briefly dissolvable is an actual, if temporary, unlocking of synapses. In one study, researchers first trained mice to respond with fear to an auditory tone by pairing the tone with an unpleasant stimulus. Then they waited one day, enough time for full consolidation of the fear memory circuit. After reactivating the fear memory by playing the tone, the memory-bearing part of each mouse's amygdala was doused promptly with anisomycin, a chemical that precisely blocks the production of proteins necessary for consolidation of a memory circuit. When the tone was subsequently played, the mice no longer responded with fear. The implicit memory was gone. But if anisomycin was applied without first replaying the tone to reactivate the memory, the memory was left intact, and the fear response continued. The fact that a consolidation-blocking chemical could erase an already consolidated, reactivated implicit memory meant that reactivation had caused the memory to deconsolidate. This in turn implied that a reactivated deconsolidated memory undergoes a natural process of reconsolidation, which soon relocks the synapses and returns the memory to long-term durability.

This time, the neuroscience field took notice. The number of articles and conference presentations on reconsolidation and its memory-dissolving disruption has grown exponentially since then.

Further research has established that in order for synapses to unlock, the brain requires not just the experience of reactivation of the memory—it's also necessary for a second, critical experience to promptly take place while the memory reactivation experience is still occurring. That second experience consists of perceptions that sharply contradict and disconfirm the implicit expectations of the reactivited memory.

For example, suppose an animal has been trained to respond to a blue light with a fearful expectation of a harsh sound soon to follow. Subsequently, reactivating this memory by turning on the blue light will not, by itself, cause synapses to unlock. Only when the blue light is soon turned off, without any sound having occurred, do the synapses unlock, because the turning off of the light without the expected sound contradicts the implicit memory while the memory is reactivated. This need for a sharp contradiction has proven to be a key for translating these findings to psychotherapy.

These studies and others by neuroscientists at many different labs have established that the unwiring of implicit memory occurs through a type of neuroplasticity that's "experience-driven," and they've articulated the procedural, experiential steps that the brain requires for an implicit memory to be unwired:

(1) Fully reactivate the target implicit memory so that the emotional experience is occurring.

(2) While the target memory is fully reactivated and the emotional experience is occurring, promptly create an additional, concurrent experience that sharply mismatches (contradicts and disconfirms) the expectations and predictions arising from the implicit memory.

These two steps confirmed the pattern we'd clinically observed and documented. To see how this process might apply in a clinical situation, consider my client James, a mild-mannered fellow in his late thirties, who came for therapy because of intense self-doubt and anxiety at work, despite his many successes and consistently positive evaluations from supervisors and coworkers. In the first two sessions of focused, experiential retrieval work, James got more and more in touch with the implicit material underlying his difficulties on the job. We worked on putting it into words that felt emotionally accurate for him: "If I say anything with confidence that it's right, I'll be just like Dad—a know-it-all lording it over everyone. And then people will hate me for that, just the way I hate him for it. So I'd better keep myself quiet by thinking, ÔWhat do I know?' even though that makes me feel so insecure that I don't express what I do know."

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