Combined fMRI and electrical microstimulation to determine functional connections in visual areas of the primate brain

[摘要] (cont.) The luminance contrast of a stimulus presented in the MF was systematically varied to generate contrast response functions for many cortical areas, which were compared with existing data. Sub-threshold FEF-EM increased fMRI activity for the lowest contrasts and had little or even a suppressive influence at the highest contrasts, mainly in support of a contrast rather than activity gain effect. From these data, a simple spatial model explaining the interaction between bottom-up and top-down signals from the FEF was constructed, which could guide future psychophysical and electrophysiological experiments. The final outcome was a demonstration that artificially-increased FEF output could alter stimulus selectivity in visual cortex independent of stimulus saliency. This suggests that FEF relays not only spatial but also feature-relevant information to specific visual cortical areas.

[发布机构] Massachusetts Institute of Technology