Parvalbumin-positive interneurons mediate neocortical-hippocampal interactions that are necessary for memory consolidation

• Main Authors: Frances Xia, Blake A Richards, Matthew M Tran, Sheena A Josselyn, Kaori Takehara-Nishiuchi, Paul W Frankland
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2017-09-01
• Series: eLife
• Subjects: memory; consolidation; hippocampus; anterior cingulate cortex; ripple; spindle
• Online Access: https://elifesciences.org/articles/27868

Following learning, increased coupling between spindle oscillations in the medial prefrontal cortex (mPFC) and ripple oscillations in the hippocampus is thought to underlie memory consolidation. However, whether learning-induced increases in ripple-spindle coupling are necessary for successful memory consolidation has not been tested directly. In order to decouple ripple-spindle oscillations, here we chemogenetically inhibited parvalbumin-positive (PV+) interneurons, since their activity is important for regulating the timing of spiking activity during oscillations. We found that contextual fear conditioning increased ripple-spindle coupling in mice. However, inhibition of PV+ cells in either CA1 or mPFC eliminated this learning-induced increase in ripple-spindle coupling without affecting ripple or spindle incidence. Consistent with the hypothesized importance of ripple-spindle coupling in memory consolidation, post-training inhibition of PV+ cells disrupted contextual fear memory consolidation. These results indicate that successful memory consolidation requires coherent hippocampal-neocortical communication mediated by PV+ cells.