Coding for spatial goals in the prelimbic/infralimbic area of the rat frontal cortex

TLDR

Spatial navigation relies on a distributed neural network, including hippocampal place cells, but an additional mechanism is needed to specify the animal’s goal. The study aims to demonstrate that medial prefrontal cortex neuron firing reflects the motivational salience of places. The authors recorded mPFC neurons during a place navigation task and found that many prelimbic/infralimbic cells exhibited place fields. Only a few dorsal anterior cingulate cells had place fields, whereas prelimbic/infralimbic cells overrepresented goal locations, suggesting mPFC encodes rat goals independent of reward sites.

Abstract

Finding one's way in space requires a distributed neural network to support accurate spatial navigation. In the rat, this network likely includes the hippocampus and its place cells. Although such cells allow the organism to locate itself in the environment, an additional mechanism is required to specify the animal's goal. Here, we show that firing activity of neurons in medial prefrontal cortex (mPFC) reflects the motivational salience of places. We recorded mPFC neurons from rats performing a place navigation task, and found that a substantial proportion of cells in the prelimbic/infralimbic area had place fields. A much smaller proportion of cells with such properties was found in the dorsal anterior cingulate area. Furthermore, the distribution of place fields in prelimbic/infralimbic cells was not homogeneous: goal locations were overrepresented. Because such locations were spatially dissociated from rewards, we suggest that mPFC neurons might be responsible for encoding the rat's goals, a process necessary for path planning.