Yoshihisa Tanikawa

Image Stabilization for In Vivo Microscopy by High-Speed Visual Feedback Control

This paper presents image stabilization for microscopy using horizontal visual feedback control of the objective lens through a five-bar linkage and piezoelectric actuators, and its application to in vivo imaging. Even very small in vivo motion due to heartbeat and breathing makes microscopic observation difficult by blurring the microscope image or impossible by sending a region of interest out of view. In order to remove those unwanted effects of the motion, we have introduced motion-canceling robotic technologies into microscopy. Our image stabilization system through motion-canceling provides users with stabilized image sequences with respect to trembling of in vivo subjects. The developed image stabilization system, in term of robotics, corresponds to a visual feedback control system that consists of a robotic mechanism and a high-speed vision. A high-speed camera installed in the microscope detects the motion of the in vivo subject having topically applied fiducials. To virtually cancel this motion, we move the objective lens, synchronizing the motions of the subject and the lens to remove the relative motion between the two. As a result, we observe motion-free images to m. This technology is one of the very demanding technologies in biological research for in vivo observation with high resolution. In this paper, we verify the effectiveness of the developed system through in vivo experiments.

Rapid and local autoregulation of cerebrovascular blood flow: a deep-brain imaging study in the mouse

The brain obtains energy by keeping the cerebral blood flow constant against unexpected changes in systemic blood pressure. Although this homeostatic mechanism is widely known as cerebrovascular autoregulation, it is not understood how widely and how robustly it works in the brain. Using a needle‐like objective lens designed for deep‐tissue imaging, we quantified the degree of autoregulation in the mouse hippocampus with single‐capillary resolution. On average, hippocampal blood flow exhibited autoregulation over a comparatively broad range of arterial blood pressure and did not significantly respond to pressure changes induced by the pharmacological activation of autonomic nervous system receptors, whereas peripheral tissues showed linear blood flow changes. At the level of individual capillaries, however, about 40% of hippocampal capillaries did not undergo rapid autoregulation. This heterogeneity suggests the presence of a local baroreflex system to implement cerebral autoregulation.

In vivo imaging of the dendritic arbors of layer V pyramidal cells in the cerebral cortex using a laser scanning microscope with a stick-type objective lens.

In the field of neuroscience, low-invasive in vivo imaging would be a very useful method of monitoring the morphological dynamics of intact neurons in living animals. At present, there are two widely used in vivo imaging methods; one is the two-photon microscope method, and the other is the fiber optics method. However, these methods are not suitable for the in vivo imaging of deeper subcortical structures. In our study, we have developed a novel method for the in vivo imaging of pyramidal neurons in layer V of the cerebral cortex, utilizing a MicroLSM system and a stick-type objective lens that can be directly inserted into the target tissue. By using this method, we succeeded in obtaining clear images of pyramidal neurons in layer V of the cerebral cortex under a low-invasive condition. The MicroLSM system is a useful and versatile in vivo imaging system that will be applicable not only to the brain but also to other organs.