Protein kinase Mzeta maintains fear memory in the amygdala but not in the hippocampus.

Recent work on the long-term stability of memory and synaptic plasticity has identified a potentially critical role for protein kinase Mzeta (PKMzeta). PKMzeta is a constitutively active, atypical isoform of protein kinase C that is believed to maintain long term potentiation at hippocampal synapses in vitro. In behaving animals, local inhibition of PKMzeta disrupts spatial memory in the hippocampus and conditioned taste aversion memory in the insular cortex. The role of PKMzeta in context fear memory is less clear. This study examined the role of PKMzeta in amygdala and hippocampal neurons following a standard fear conditioning protocol. The results indicate that PKMzeta inhibition in the amygdala, but not in the hippocampus, can disrupt fear memory. This suggests that PKMzeta may only maintain select forms of memory in specific brain structures and does not participate in a universal memory storage mechanism.