Short and Long Term Maintenance of Sensorimotor Memories and Maps by PKMζ Dependent LTP.

Abstract

The primary somatosensory (S1) and primary motor cortex (M1) have roles in the learning of non-declarative memories. Previous studies suggest that this learning is subserved by long-term potentiation (LTP), which is in turn maintained by the persistently active kinase, PKMζ. Whereas the role of PKMζ in animal models of declarative knowledge is established, its involvement in the short and long term maintenance of procedural knowledge is not well understood. Here we show that injection of PKMζ pseudosubstrate inhibitor ZIP into the adult rat sensorimotor cortex disrupts both recently and developmentally acquired sensorimotor memories (> 1 year post-acquisition). Our data further suggests that these effects are due to a simultaneous disruption of sensory map borders and a net decrease in stimulus response amplitudes. Based on these findings we propose a model of permanent, ongoing maintenance of sensory map borders by LTPenabled center-surround inhibition. We present this model as a non-conflicting addendum to existing models which suggest a more temporary role of LTP in sensorimotor memory maintenance. Finally, our results represent the first demonstration that procedural, sensorimotor memories share the same underlying molecular mechanism for persistence as declarative memories.