Final answer:
The exact gene that impairs fear association extinction in mice models is not specified in the provided literature. However, studies often focus on the role of the amygdala and related neurotransmitter systems, such as GABAergic receptors and corticotropin-releasing factor, in fear response and extinction.
Step-by-step explanation:
The gene in mice models that impairs fear association extinction pertains to the field of neurobiology. Extinction of fear association is a process where an organism learns to dissociate a previously learned fear response from the stimulus. In the context of the studies provided, animals, like mice, display fear responses such as those mediated by the amygdala, an essential brain structure for emotion processing. Rodent studies, such as those involving maternal presence and odor cues linked with electrical shocks, can lead to fear extinction when conditions are altered, for example, by the maternal presence.
However, when discussing specific genes that impair fear association extinction in mouse models, the literature does not provide a direct answer to this complex question within the provided references. Understanding such mechanisms often involves studying the roles of various neurotransmitters and brain structures. The relevant area of research may involve gene expression related to neurotransmitter systems, like the GABAergic system, and neuroendocrine pathways, such as those involving corticotropin-releasing factor (CRF).