Cerebral blood flow (CBF) change of mice during whisker stimulation is measured by laser speckle flowgraphy (LSFG)
and laser Doppler flowmetry (LDF). Laser speckle flowgraphy (LSFG) has been used to obtain the two-dimensional
distribution of the blood flow in tissue as well as scanning laser Doppler flowmetry (LDF). There are several parameters
of LSFG to obtain the blood flow maps and the distribution change of blood flow. In this study, we calculate four
parameters from the speckle pattern to measure CBF in awake mice. The temporal resolution of LSFG is likely to be less
than that of LDF. The temporal changes in CBF obtained from the four parameters calculated from the speckle pattern
detected by a common CCD camera are compared with those measured by LDF. The time courses of CBF change
measured by LSFG highly correlate with those by LDF. The results indicate that the temporal response of LSFG is
sufficient to measure CBF change evoked by brain activations.
The concentration changes in oxygenated and deoxygenated haemoglobin in the exposed cortex of guinea pigs evoked
by the auditory stimulation are measured by the multi-spectral imaging to investigate the relationship between spatial
extent of the brain activation determined by the statistical analysis and the SNR of the concentration changes in
oxygenated and deoxygenated haemoglobin. The SNR of the concentration change in oxygenated haemoglobin measured
by the multi-spectral imaging is generally greater than that of deoxygenated haemoglobin. The difference in SNR tends
to affect the result of the spatial extent of brain activation estimated from the changes in oxygenated and deoxygenated
haemoglobin. The influence of the SNR on the spatial extent is evaluated by a numerical experiment. The results of the
numerical experiment are compared with the spatial extent of the brain activation estimated from the changes in
oxygenated and deoxygenated haemoglobin in the exposed cortex of guinea pigs evoked by the auditory stimulation. It is
found that the spatial extent of the brain activation decreases with a decrease in SNR of the concentration change. The
difference in spatial extent of the brain activation estimated from the concentration changes in oxygenated and
deoxygenated haemoglobin is affected by the SNR of signal.
The changes in cortical blood flow and blood volume of guinea pigs during auditory stimulation are measured by optical
imaging systems. In this study, the change in blood flow distribution was measured by the laser speckle method and the
change in blood volume was measured by the multi-spectral imaging system. The significant increase in blood flow and
volume was observed around one side of the auditory area just after the onset of the stimulation. The decrease in blood
volume around the other side of the auditory area was observed whereas the blood flow surrounding the auditory area is
decreased during the post-resting period.
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