Monitoring Effects Of Mild Hypothermia On Cortical Spreading Depression By Optical Imaging And Electrophysiological Recording

Optical imaging of functional brain is the international research hotspot to analysis the brain information processing and the advanced mechanism of neural function. The main thesis of this research is to design and realize a high-resolution multi-parameters optical imaging system for cortex function which combines the laser speckle imaging method and optical intrinsic signal imaging method. It can simultaneously access much cortex hemodynamic change information. Then we compare the various differences of hemodynamic parameters during the cortical spreading depression propagation when the cortex is in the normal temperature and mild hypothermia condition with the new designed system and traditional optical imaging method. The conclusions of the thesis are listed as following:(1)Design and realize a multi-parameters optical imaging system for brain function. The system uses a LED which has three wavelengths (735nm, 805nm, 850nm) and LD as imaging illuminants to combine the laser speckle imaging and optical intrinsic signal imaging. The micro controller unit is used to control the switch of the light sources. It also provides RS232 serial communication interface used for PC with real-time data transmission. The soft X-optical fiber is specifically designed to provide bilateral uniform illumination for the LED and LD. The spatial and temporal changes in oxy-hemoglobin, deoxy-hemoglobin, total hemoglobin concentration, cerebral blood flow, and the cerebral metabolic rate of oxygen in response to the brain activities are monitored by the system. Meanwhile the system can collect the extra-cellular electrophysiological signals by combining with electrophysiological recording module.(2)Using the multi-wavelengths parameters optical imaging system and electrophysiological recording system, as well as traditional optical intrinsic signal imaging system to monitor and measure the effect of mild hypothermia during cortical spreading depression in rat cortex. The research results indicate that the mild hypothermia would result in the increase of the amplitudes which are the changes of the HbO2, HbR and HbT; the decrease of the amplitudes which are the changes of the CBV and local field potential, the increase of the duration time of the change of the HbO2, HbR, HbT, CBV and local field potential during cortical spreading depression induced by electrical stimulation. And it would also lengthen the interval time of the close cortical spreading depression waves induced by KCl. The propagation speeds of the cortical spreading depression would become slower at mild hypothermia .These results show that the mild hypothermia condition would make the propagation of the CSD slow. The results provide some new examination evidences to research the mechanisms of the CSD and the mild hypothermia for brain protection...