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. Author manuscript; available in PMC: 2011 Apr 1.
Published in final edited form as: Physiol Rev. 2010 Apr;90(2):419–463. doi: 10.1152/physrev.00037.2009

Fig. 9. Molecular mechanisms of unlearning and new learning related to early and late stages of fear extinction.

Fig. 9

Reversal of conditioned fear (unlearning) involves activation of the phosphatase calcineurin and regulated AMPA receptor endocytosis. Extinction learning and consolidation (new learning) involve activation of NMDA receptors (in particular the NR2B subtype), kinase pathways (for instance the mitogen-activated protein kinase (MAPK), extracellular regulated kinase (ERK) pathway), transcriptional regulation (via transcription factors, such as cAMP response element binding protein (CREB)), and structural organization (involving cytoskeletal proteins such as actin).