SEPTAL NEURONAL RESPONSES RELATED TO SPATIAL REPRESENTATION IN MONKEYS

Neuronal activity in the monkey septal nuclei was recorded during perf ormance of a place-dependent go/no-go task in which reward contingenci es of the objects were variable with reference to the spatial location of a monkey's cab in one of four places in an experimental room. Of 4 30 septal neurons recorded, 58 responded differentially to views outsi de the cab at the four locations of the monkey (place-differential neu rons). To investigate the possibility that an ensemble of place-differ ential neurons represents a space by encoding different scenes (views) , responses of the 58 place-differential neurons were analyzed by mult idimensional scaling (MDS). The MDS transformed relationships among th e four places, expressed as correlation coefficients between all possi ble pairs of two places based on the 58 place-differential responses, into geometrical relationships in a two-dimensional virtual space. The four places distributed at relative positions in a two-dimensional vi rtual space derived from the MDS were similar to those in the real exp erimental room. Furthermore, these correlation coefficients derived fr om 58 place-differential responses significantly and negatively correl ated to behavioral performance in the discrimination of the four place s. The results suggest that the ensemble of place-differential respons es in the septal nuclei may predict behavioral performance to discrimi nate places and may represent a space based on the scenes viewed from different locations. (C) 1997 Wiley-Liss, Inc.