Abstract #0101

Opto-fMRI in Awake Rodents: Activation & Deactivation fMRI Signals Induced by Excitation & Inhibition of Neurons

Lino Becerra^1,2, Gary Brenner^2,3, James Bishop¹, Pei-Ching Chang¹, Hae-Sook Shin³, Aimei Yang⁴, Michael Baratta⁴, Patrick Monahan⁴, Edward Boyden^4,5, David Borsook^1,2

¹A. Martinos Center, Massachusetts General Hospital, Boston, MA, USA; ²Harvard Medical School, Boston, MA, USA; ³Anesthesiology & Critical Care, Massachusetts General Hospital, Boston, MA, USA; ⁴Media Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA; ⁵Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA

In fMRI studies, positive activation is associated with increased neuronal firing. Negative (deactivation) fMRI BOLD signals have been indirectly associated with inhibition. Using opto-genetic techniques neurons in rat cingulate and somatosensory cortices were trasfected to be photosensitive. Specifically, cingulate neurons were inhibited upon optical stimulation while somatosensory neurons were excited when illuminated. Positive BOLD signal changes were observed in somatosensory cortex while negative ones were observed in cingulate cortex upon illumination. Furthermore, inhibition of cingulate resulted in fMRI activation of other structures. This work confirms that neuronal excitation results in positive BOLD signals and neuronal inhibition produces negative BOLD signals.