Functional mapping of rat barrel activation following whisker stimulation using activity-induced manganese-dependent contrast

Jun-Cheng Weng, Jyh-Horng Chen, Pai-Feng Yang, Wen-Yih I. Tseng,
NeuroImage. Volume 36, Issue 4, 15 July 2007, Pages 1179–1188

In this paper they studied the well-established neuroanatomy of the rat sensory cortical whisker barrels, but with MEMRI. Previous functional imaging methods involved imaging WHILE stimulating the whiskers, so they decided to use MEMRI to identify the neuronal uptake of manganese BEFORE imaging.
They gave i.p. manganese and used mannitol to rupture the blood brain barrier, anesthetized the rats, and then hooked their whiskers up to a speaker for 3 hours (with the cone torn out to eliminate sound). For controls, they cut the contralateral whiskers, as well as imaging a separate group of sham/non-stimulated rats.
They subtracted the image intensity of control rats from experimental rats to eliminate non-whisker-related image enhancement (e.g. hippocampus, hypothalamus, and amygdala). The only enhanced contrast that remained was in the whisker barrel barrel that corresponded to the stimulated whiskers. -DH