Medial perforant path plasticity can be attenuated by 2-amino-5-phosphonovaleric acid (APV) infusions, whereas lateral perforant path plasticity can be attenuated by naloxone infusions. The present experiment was designed to evaluate the role of each entorhinal efferent pathway into the dorsal hippocampus for detection of spatial and nonspatial (visual object) changes in the overall configuration of environmental stimuli. Dorsal dentate gyrus infusions of either APV or naloxone attenuated detection of a spatial change, whereas only naloxone infusions disrupted novel object detection. Either APV or naloxone infusions into dorsal CA3 disrupted both spatial and novel object detection. APV infusions into dorsal CA1 attenuated detection of a spatial change, whereas naloxone infusions into dorsal CA1 disrupted novel object detection. These data suggest that each dorsal hippocampal subregion processes spatial and nonspatial (visual object) information from perforant path efferents in a unique manner that is consistent with the intrinsic properties of each subregion.
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