PT  - JOURNAL ARTICLE
AU  - Xiaoyang Long
AU  - Sheng-Jia Zhang
TI  - A novel somatosensory spatial navigation system outside the hippocampal formation
AID  - 10.1101/473090
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 473090
4099  - http://biorxiv.org/content/early/2018/12/16/473090.short
4100  - http://biorxiv.org/content/early/2018/12/16/473090.full
AB  - The hippocampal-parahippocampal formation has long been regarded as the only central site for the brain’s spatial navigation system. Nevertheless, studies from patients with large medial temporal lobe lesions suggest that the hippocampal formation is not essential for space memory, indicating that spatial navigation might be computed with another still unknown representation system outside the medial temporal lobe structures. Such an extra-hippocampal navigational system has never been identified, however. Here we report the existence, in the rat somatosensory cortex only, of a novel “all-in-one” navigational system, which contains the full spectrum of all distinct spatial cell types including place, head-direction, border/boundary, conjunctive, speed and grid cells. All recorded somatosensory spatial cells, from freely behaving rats with microelectrodes, show similar firing characteristics to those detected previously in the hippocampal-parahippocampal structures. The somatosensory navigational system extends the classical theory of a cognitive map about space beyond two discrete hippocampal-entorhinal regions only into another single highly hierarchical neocortical domain, providing possible alternative and more sophisticated computational algorithms for spatial memory and cognitive mapping.