Layer Specific Detection of Inhibitory FMRI Response in Somatosensory Cortex Through Cortico-Cortical Interaction in Rats

Yoshiyuki Hirano¹, Alan P. Koretsky², Afonso C. Silva¹

We investigated the laminar dependence of cortico-cortical interactions induced by paired bi-lateral somatosensory stimulation in α-chloralose anesthetized rats. When compared to the response obtained at 0 ms ISI, the BOLD percent signal change in the S1FL responding to the late stimulus was decreased by 47 % at 40 ms ISI. The degree of suppression in layers III to V was stronger than suppression of fMRI changes in layers I-II and in bottom of layer VI. Our data shows that BOLD fMRI has sufficient spatial and temporal resolution to study cortical circuits, within functional columns and layers.