More precise experimental techniques are beginning to define the microcircuit components within the BLA-mPFC circuit responsible for the expression and regulation of fear. Fear learning recruits specific populations of neurons within the amygdala, which are required for fear recall (Han et al., 2009). Different subpopulations of amygdala neurons are recruited during fear memory recall and after extinction (Herry et al., 2008), with fear recall neurons preferentially projecting to the PL and extinction neurons preferentially projecting to the IL (Senn et al., 2014). Thus, the observed involvement of the PL in fear (Burgos-Robles et al., 2009) and the IL in safety (Milad and Quirk, 2002) may be defined by segregated amygdala afferents.
