Hippocampal and Parahippocampal Neuronal Responses to Spatial and Non-Spatial Factors in Rats and Monkeys

Rat hippocampal (HF) neurons were recorded while the rat ran on a treadmill affixed to a motion stage that was translocated along a figure 8-shaped track. Comparison of HF spatial firing patterns across different experimental conditions indicated that place neuron activity encodes intra-maze multiple information including location of animals, locomotion, the reinforcement episodes, and vestibular sensation or optic flow. Place neurons were also recorded from the monkey HF during virtual navigation. Most place-differential responses disappeared or changed their spatial tuning (i.e., remapping) when the arrangements, of the distal cues were altered/moved in the Virtual spaces. The results suggest that the HF encodes multifold information within the maze, which are gated by the extra-maze distal cues.