Frequency Dependant Brain Activation During Somatosensory Stimulation in Anaesthetised Rats: A Comparison Using Evoked Potentials, Quantitative 2-Deoxyglucose Autoradiography and FMRI

Diana Cash¹, Camilla Simmons¹, Alanna C. Easton², David J. Lythgoe¹, Steven CR Williams¹, Michel SB Mesquita¹

Forepaw sensory stimulation at 0.5 and 3 Hz in anaesthetized rats was characterized for BOLD fMRI, neural activity and regional glucose uptake. Electrical activity was greater at lower frequency whereas metabolic activity was greater at higher frequency. An expected increase in BOLD in forepaw cortex was detected at 3Hz, but a widespread negative BOLD signal was detected at 0.5Hz, suggesting the lack of neurovascular coupling at this slow stimulation rate.