Merel Kindt and her team demonstrated that fear memory can be deleted in humans (Kindt et al. 2009). This was achieved by the oral administration of β-adrenergic receptor antagonist propranolol before the reactivation of memory. They propose that their strategy of disrupting the (re-) stabilization of a memory after retrieval (reconsolidation) could pave the way for a long term cure for patients with emotional disorders. In such a treatment it would be important to have content limited memory deletion. Therefore it is straight forward that Marieke Soeter and Merel Kindt here investigate how aspects of fear generalization are affected by their pharmacological approach of memory erasure. They show that the fear potentiated startle response to the trained and reactivated stimulus is deleted by the administration of propranolol before the reactivation. In contrast the response to a parallel trained but not reactivated stimulus is not affected. Further they demonstrate that category related generalization normally occurs. Nevertheless they show that the disruption of reconsolidation changes “the core memory trace” in that way that there is no generalization produced after successful reacquisition. Meaning that the disruption of reconsolidation changes the way stimuli are (re)learned in a successive acquisition.
Additionally the authors challenge the universality of the finding of Schiller and colleagues (D Schiller et al. 2010). Schiller et al provided evidence that fear memories can be deleted by behavioral manipulations in humans. Nevertheless Soeter and Kindt, here using a stronger conditioning protocol (80% vs. 30% reinforcement, fear relevant objects vs. geometric figures), demonstrate that for their paradigm this behavioral manipulation does not erase the memory.
In sum the study suggests that behavioral manipulation does not prevent stronger fear memory from return. However the study shows that the pharmacological disruption of reconsolidation specifically deletes fear memory and its category related aspects.
Soeter, M., & Kindt, M. (2011). Disrupting reconsolidation: Pharmacological and behavioral manipulations Learning & Memory, 18 (6), 357-366 DOI: 10.1101/lm.2148511
Tags: conditioning, Fear, learning, Memory, reconsolidation
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