उच्च संकल्प कार्यात्मक मानव मध्यमस्तिष्क के लिए चुंबकीय अनुनाद इमेजिंग तरीके
Summary
इस लेख के मानव मध्यमस्तिष्क और subcortical संरचनाओं एक 3T स्कैनर का उपयोग कर में 1.2 मिमी नमूना के साथ उच्च संकल्प कार्यात्मक चुंबकीय अनुनाद इमेजिंग प्रदर्शन के लिए तकनीक का वर्णन करता है. मानव बेहतर colliculus (अनुसूचित जाति) में दृश्य उत्तेजना के स्थलाकृतिक नक्शे को हल करने के लिए इन तकनीकों का प्रयोग करने के लिए एक उदाहरण के रूप में दिया जाता है.
Abstract
Functional MRI (fMRI) is a widely used tool for non-invasively measuring correlates of human brain activity. However, its use has mostly been focused upon measuring activity on the surface of cerebral cortex rather than in subcortical regions such as midbrain and brainstem. Subcortical fMRI must overcome two challenges: spatial resolution and physiological noise. Here we describe an optimized set of techniques developed to perform high-resolution fMRI in human SC, a structure on the dorsal surface of the midbrain; the methods can also be used to image other brainstem and subcortical structures.
High-resolution (1.2 mm voxels) fMRI of the SC requires a non-conventional approach. The desired spatial sampling is obtained using a multi-shot (interleaved) spiral acquisition1. Since, T2* of SC tissue is longer than in cortex, a correspondingly longer echo time (TE ~ 40 msec) is used to maximize functional contrast. To cover the full extent of the SC, 8-10 slices are obtained. For each session a structural anatomy with the same slice prescription as the fMRI is also obtained, which is used to align the functional data to a high-resolution reference volume.
In a separate session, for each subject, we create a high-resolution (0.7 mm sampling) reference volume using a T1-weighted sequence that gives good tissue contrast. In the reference volume, the midbrain region is segmented using the ITK-SNAP software application2. This segmentation is used to create a 3D surface representation of the midbrain that is both smooth and accurate3. The surface vertices and normals are used to create a map of depth from the midbrain surface within the tissue4.
Functional data is transformed into the coordinate system of the segmented reference volume. Depth associations of the voxels enable the averaging of fMRI time series data within specified depth ranges to improve signal quality. Data is rendered on the 3D surface for visualization.
In our lab we use this technique for measuring topographic maps of visual stimulation and covert and overt visual attention within the SC1. As an example, we demonstrate the topographic representation of polar angle to visual stimulation in SC.
Protocol
Discussion
हमारे अधिग्रहण और डेटा विश्लेषण तकनीक subcortical उच्च संकल्प (1.2 मिमी voxels) में मानव मस्तिष्क संरचना में तंत्रिका गतिविधि की माप सकें. 3 शॉट सर्पिल अधिग्रहण शारीरिक शोर है कि विशेष रूप से मध्यमस्तिष्क चारों ओर fMR…
Declarações
The authors have nothing to disclose.
Acknowledgements
यह सामग्री अनुदान 1063774 BCS के अंतर्गत राष्ट्रीय विज्ञान फाउंडेशन द्वारा समर्थित काम पर आधारित है.
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