Optogenetic activation of nonhuman primate cortical and subcortical brain circuits highlights detection capabilities of MEG source imaging

ABSTRACTMagnetoencephalography (MEG) measures neuromagnetic activity with high temporal, and theoretically, high spatial resolution. However, the ability of magnetic source imaging (MSI) to localize deep sources is uncertain. We developed an experimental platform combining MEG-compatible optogenetic techniques in non-human primates (NHPs) to test the ability of MEG/MSI to image deep signals. We demonstrate localization of optogenetically-evoked signals to known sources in the superficial arcuate sulcus of cortex and in CA3 of hippocampus at a resolution of 750 µm3. In response to stimulation of arcuate sulcus and hippocampus, we detected activation in subcortical and thalamic structures, or extended temporal networks, respectively. This is the first demonstration of accurate localization of deep sources within an intact brain using a novel combination of optogenetics with MEG/MSI. This approach is suitable for exploring causal relationships between discrete brain regions through precise optogenetic control and simultaneous whole brain recording.

A Specular Shape-from-Shading Method with Constrained Inpaiting

The existence of specular highlights is a great obstacle of shape-from-Shading. For a single gray-scale image with only intensity information, the existed highlights detection methods based on chroma or polarization analysis cannot directly be applied on it. So, a method using surface shape is provided, it makes full use of the imaging process. Through the surface normal estimation, compute the maximum a posteriori probability of each reflection composition under simulated annealing and detect the highlights areas. Finally, remove the highlights based on the assumption of curvature continuity. Experiments reveal that this method is effective on synthetic and real-world images, improves the accuracy of surface recovery for image combined specular highlights.