Ultra high-resolution fMRI in monkeys with implanted RF coils.
Spatiotemporally resolved functional MRI (fMRI) in animals can reveal how wide-spread neural networks are organized and accompanying electrophysiological recordings can show how small neural assemblies contribute to this organization. Here we present a novel technique that yields high-resolution structural and functional images of the monkey brain with small, tissue-compatible, intraosteally implantable radiofrequency coils. Voxel sizes as small as 0.0113 microl with high signal-to-noise and contrast-to-noise ratios were obtained, revealing both structural and functional cortical architecture in great detail. Up to a certain point, contrast sensitivity increased with decreasing voxel size, probably because of the decreased partial volume effects. Spatial specificity was demonstrated by the lamina-specific activation in experiments comparing responses to moving and flickering stimuli. The implications of this technique for combined fMRI/electrophysiology experiments and its limitations in terms of spatial coverage are discussed.
Logothetis
Nikos
N
Max Planck Institute for Biological Cybernetics, Spemannstr. 38, Tuebingen, Germany. nikos.logothetis@tuebingen.mpg.de
Merkle
Hellmut
H
Augath
Mark
M
Trinath
Torsten
T
Ugurbil
Kâmil
K
D000818:Animals; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D004567:Electrodes, Implanted / Q000592:standards / Q000639:trends*; D005074:Evoked Potentials, Visual / Q000502:physiology; D000882:Haplorhini / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009482:Neurophysiology / Q000295:instrumentation / Q000379:methods*; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods; D010775:Photic Stimulation; D011846:Radio Waves; D012886:Skull / Q000033:anatomy & histology / Q000601:surgery*; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology