Ultra high-resolution fMRI in monkeys with implanted RF coils

Area of Science:

• Neuroimaging
• Primate Neuroscience
• Functional Magnetic Resonance Imaging

Background:

• Spatiotemporally resolved functional MRI (fMRI) in animals is crucial for understanding neural network organization.
• Electrophysiological recordings complement fMRI by detailing the contribution of small neural assemblies.
• High-resolution imaging is needed to bridge the gap between network-level and assembly-level brain function.

Purpose of the Study:

• To present a novel technique for high-resolution structural and functional imaging of the monkey brain.
• To demonstrate the capability of this technique to reveal detailed cortical architecture.
• To explore the implications for combined fMRI/electrophysiology experiments.

Main Methods:

• Development of small, tissue-compatible, intraosteally implantable radiofrequency coils.
• Acquisition of high-resolution structural and functional images of the monkey brain.
• Voxel sizes as small as 0.0113 microl with high signal-to-noise and contrast-to-noise ratios achieved.

Main Results:

• Detailed visualization of both structural and functional cortical architecture.
• Increased contrast sensitivity with decreasing voxel size, likely due to reduced partial volume effects.
• Demonstrated spatial specificity through lamina-specific activation in response to visual stimuli.

Conclusions:

• The novel technique provides unprecedented detail in monkey brain imaging.
• This method enhances the potential for combined fMRI/electrophysiology studies.
• Limitations regarding spatial coverage were acknowledged and discussed.