Summary
Spatial context, or the physical surroundings that form the background of an experience, is an essential component of episodic memory. The rodent postrhinal cortex and its primate homolog, the parahippocampal cortex, are thought to preferentially process visuospatial information to represent the spatial features of contexts and scenes. In this study, we addressed open questions about postrhinal function and about how context modulates behavior and cognition. The first question was whether the postrhinal cortex also represents nonspatial contexts. The second question was how representations of context might interact with other cues in the environment. We recorded postrhinal neurons as rats performed a visual nonspatial biconditional discrimination task in which the pattern on the floor determined which object in a pair was correct. Critically, this task design allowed dissociation of location from non-spatial context. We found that postrhinal ensembles and neurons signaled changes in non-spatial context and coded for conjunctions of non-spatial context and objects. Importantly, postrhinal neurons coded for conjunctions of context and objects more often than they coded for conjunctions of location and object. The pattern of findings suggests that postrhinal representations of context may behave like occasion setters by modulating the meaning of other cues in the environment.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
1 VHM is now at Roger Williams University, 1 Old Ferry Rd, Bristol, RI 02809. MAS is now at the University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
This version has been revised to 1) clarify impact on the field (abstract), 2) correct mistakes in Table 3A (lower panel), and 3) use multiway chi-square analyses instead of multiple 2-way chi-square.