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Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI
Published on: July 12, 2012
Functional tracing of medial nociceptive pathways using activity-dependent manganese-enhanced MRI
Pai-Feng Yang1, Der-Yow Chen, James W Hu
1Interdisciplinary MRI/MRI Lab, Department of Electrical Engineering, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1065, USA Institute of Zoology, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan Faculty of Dentistry, University of Toronto, 124 Edward St., Toronto, Ontario, Canada M5G 1G6 Neurobiology and Cognitive Science Center, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan.
Manganese-enhanced MRI (MEMRI) visualizes pain pathways by tracking manganese ion (Mn(2+)) transport. Noxious stimuli enhanced Mn(2+) transport from the thalamus to brain regions involved in pain perception.
Area of Science:
- Neuroscience
- Medical Imaging
- Pain Research
Background:
- Manganese ion (Mn(2+)) acts as a paramagnetic contrast agent in T1-weighted MRI.
- Mn(2+) enters neural cells via voltage-gated calcium channels and is transported along axons and across synapses.
- This activity-dependent transport allows for tracing neural pathways.
Purpose of the Study:
- To investigate nociceptive medial thalamus projections using activity-dependent manganese-enhanced MRI (MEMRI).
- To map functional connections within the pain pathway in an animal model.
Main Methods:
- Rats were anesthetized and manganese chloride (MnCl(2)) was microinjected into the medial thalamus.
- Electrical stimuli (innocuous or noxious) were applied to the forepaw.
- Manganese transport was visualized using MRI, and the effect of morphine was assessed.
Main Results:
- Noxious stimulation significantly enhanced Mn(2+) transport from the medial thalamus to the anterior cingulate cortex, midcingulate cortex, retrosplenial cortex, ventral medial caudate-putamen, nucleus accumbens, and amygdala.
- Morphine administration attenuated Mn(2+) enhancement in several of these regions, except the retrosplenial cortex.
- Noxious stimulation specifically enhanced manganese transport to the cingulate cortex and medial striatum, but not the motor cortex.
Conclusions:
- MEMRI combined with activity-dependent contrast effectively delineates functional connections in the pain pathway.
- This technique provides insights into the neural circuitry underlying pain perception and modulation.
- The findings highlight the utility of MEMRI for studying neural pathways involved in pain processing.
