PPC-Striatal Projection Neurons Encode History-Based Behavioral Bias

Posterior Parietal Cortex (PPC) has been shown in the past to encode history-based behavioral biases independent of environmental stimuli. This was shown to be encoded prior to a given stimulus and inactivation of the region through optogenetics during an inter-trial interval prevented the formation of predictable behavior. We attempted to elucidate the neural circuit which was responsible for this behavioral formation. We found through the use of 2-photon microscopy, optogenetic inactivation and rabies tracing, that the neural somas projecting to the striatum are responsible for the production of this behavioral bias prior to the introduction of the visual stimulus. We also found that not only was the information not sent to the supplementary motor cortex, but that this region of the brain was more likely to be less active than the striatal projection neurons during the inter-trial interval