Distinct contributions of dissociable brain networks and hippocampal subregions to memory fidelity

Brisbane Convention & Exhibition Centre 

A crucial function of memory is to distinguish between similar experiences. Mnemonic discrimination tasks that require participants to tell apart targets and highly similar lures can probe a brain region's ability to resolve interference (Stark et al., 2019). These tasks implicate hippocampal subfields dentate gyrus (DG) and CA3 in pattern separation (PS), a process to orthogonalize similar stimuli to reduce overlap. Cortical regions may also contribute to PS in a category-specific manner with some regions biased towards objects and others for scenes (Berron et al., 2018). To identify category-specific and -invariant neural correlates of mnemonic discrimination we leveraged 7-Tesla imaging. This method could overcome limitations of prior 3T human functional MRI studies which were unable to distinguish signals from the DG and CA3 hippocampal subfields, did not carry out voxel-wise analyses to assess differences in PS signals in the hippocampal long axis, and left out the amygdala despite its involvement in medial temporal lobe (MTL) memory networks.