Manganese-enhanced MRI visualizes V1 in the non-human primate visual cortex

Area of Science:

• Neuroimaging
• Primate Neuroscience
• Magnetic Resonance Imaging

Background:

• Investigating manganese (Mn) accumulation in the brain is crucial for understanding its neurotoxic effects and potential as a contrast agent.
• High-field MRI, specifically 7 Tesla (7T), offers enhanced sensitivity for detecting subtle changes in brain tissue.

Purpose of the Study:

• To investigate manganese accumulation in the common marmoset monkey (Callithrix jacchus) visual cortex using 7T MRI.
• To evaluate the utility of manganese-enhanced MRI (MEMRI) for visualizing functional cortical areas in vivo.

Main Methods:

• Common marmoset monkeys received fractionated intravenous injections of manganese chloride (MnCl2).
• High-resolution 7T MRI was employed to assess T1-weighted signal changes.
• Manganese distribution was compared with histological staining for cytochrome oxidase (CO) activity.

Main Results:

• A statistically significant T1 shortening was observed in the primary (V1) and secondary (V2) visual cortex, indicating manganese accumulation.
• Differential T1 shortening between V1 and V2 allowed for robust in vivo delineation of the V1/V2 border.
• MEMRI accurately identified the extent of V1, correlating well with CO staining, and visualized other visual pathway areas like DM and MT.

Conclusions:

• MEMRI is an effective technique for visualizing functional cortical regions in vivo in marmoset monkeys.
• This method enables non-destructive localization of cortical areas, supporting longitudinal studies of cortical plasticity and guiding functional neuroimaging techniques.