Optical imaging with high resolution is significant to reveal the functional activities of brain and the mechanism of
disease, and has grown into a diverse field. The high-resolution multi-parameters optical imaging system which
combines the laser speckle contrast imaging method and optical intrinsic signal imaging method can obtain more
hemodynamic information in cortex simultaneously. However, most of current optical imaging systems use He-Ne laser
and mercury xenon arc lamp as the light source. Meanwhile, the control unit of the system which includes a personal
computer, is not portable. In this paper, we develop a multiple parameters hemodynamic imaging system based on ARM.
To make the system more compact, three wavelengths light-emitting diode and laser diode as imaging illuminants were
adopted. In addition, the real-time embedded operation system (μC/OS-II) and embedded Graphic User Interface
(μC/GUI) were introduced. Animal experimental results also show that changes in oxyhemoglobin, deoxyhemoglobin,
total hemoglobin concentration and cerebral blood flow during Cortical Spreading Depression can be simultaneously
accessed using this optical imaging system based on embedded ARM.
Laser Speckle Contrast Imaging (LSCI) is becoming a promising optical technique that generates two-dimensional map of
blood flow of biological tissues in vivo with high spatiotemporal resolution. Experimental considerations for effective
implementation of this technique have been extensively discussed. However, the influence of magnification of imaging
system on laser speckle contrast imaging has not been sufficiently studied. In this study, we employ a porcelain plate model
experiment to investigate the impact of magnification on statistical characteristic of speckle pattern and on the sensitivity
of the measurement. We show that dynamic speckle contrast decreases with increasing magnification while static speckle
contrast keeps constant with that. The sensitivity of LSCI has insignificant change throughout the magnifications in our
experiments. Our results suggest that dynamic scattering areas with very slow speeds can be discriminated from the static
ones, such as discriminating some small vessels from the cortex in cerebral blood flow imaging more efficiently when
larger magnification is used.
Spreading depression (SD) shows as propagating suppression of electrical activity, which relates with migraine and focal
cerebral ischaemia. The putative mechanism of SD is the reaction-diffusion hypothesis involving potassium ions. In part
inspired by optical imaging of two SD waves collision, we aimed to show the merged and large wavefront but not
annihilation during collision by experimental and computational study. This paper modified Reggia et al established
bistable equation with recovery to compute and visualize SD. Firstly, the media tissue of SD was assumed as
one-dimensional continuum. The Crank-Nicholson method was used to solve the modified equations with recovery term.
Then, the computation results were extended to two-dimensional space by symmetry. One individual SD was visualized
as a concentric wave initiating from the stimulation point. The mergence but not annihilation of two colliding waves of
SD was demonstrated. In addition, the dynamics of SD depending on the parameters was studied and presented. The
results allied SD with the emerging concepts of volume transmission. This work not only supplied a paradigm to
compute and visualize SD but also became a tool to explore the mechanisms of SD.