In one of thy1.2-channelrhodopsin 2 (ChR2)-Venus transgenic rat lines, W-TChR2V4, the ChR2 was expressed in the mechanoreceptive subpopulation of trigeminal ganglion neurons which innervate whisker follicles. It is thus well expected that a whisker-related sensory perception should be induced by the photostimulation of their follicles. To test this, the barrel cortex responses were examined using electrophysiological recordings and functional magnetic resonance imaging (fMRI). Under anesthesia with urethane (1.3g/kg i.p.), the whiskers were trimmed and connected with optic fibers of which other endings were connected to LEDs. Pulsative irradiation of blue LED light was used as a test and that of red LED light as control. We found that the blue light irradiation of whisker follicles evoked enhanced unit activities as well as a local field potential in the barrel field of contralateral somatosensory cortex whereas the red light did not. The blue light irradiation also induced blood oxygenation level-dependent (BOLD) and cerebral blood volume (CBV) responses in the barrel field of contralateral somatosensory cortex. It is suggested that the optogenetic whisker stimulation could activate the whisker-barrel cortical pathway of mechanoreceptive signaling. This method would facilitate to study how the spatio-temporal pattern of the whisker mechanoreception would be integrated in the cortex. All animal procedures were conducted in accordance with the guiding principles of Physiological Society of Japan and NIH.