Visual gamma stimulation causes prolonged enhancement of low-frequency blood flow oscillations across cortical regions in mice

IntroductionGamma entrainment using sensory stimuli (GENUS) uses 40Hz-pulsed sensory stimuli to entrain neural activity in the gamma band (30-150Hz). However, the effect of GENUS on low-frequency vascular oscillations has not been fully explored. ObjectivesThe objective of this study is to elucidate the effect of GENUS on vasomotion in healthy mice and potential confounds for future application in disease studies. MethodsHead-fixed, awake C57Bl/6 mice (n=18; 9M 9F) aged between 18 to 60 weeks were subjected to white light of either 40Hz visual flicker (GENUS), or constant stimulus (control). Blood flow was imaged using laser speckle contrast imaging (LSCI) before, during, immediately after 1 hour of stimulus, and 30min after the stimulus termination. ResultsA linear mixed-effects model showed that GENUS enhanced the magnitude of 0.2-0.4Hz blood flow oscillations by 38% during stimulation and by 30% at 30 minutes after stimulation compared to control when controlled for age, sex, and other factors. The effect on vasomotion was distributed across many cortical regions not limited to visual areas and lasted beyond 24 hours post-stimulus. ConclusionThese results support the exploration of GENUS for increasing vasomotion in therapeutic contexts. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/729102v1_ufig1.gif" ALT="Figure 1"> View larger version (67K): org.highwire.dtl.DTLVardef@1deee2eorg.highwire.dtl.DTLVardef@e71833org.highwire.dtl.DTLVardef@1e5c4f0org.highwire.dtl.DTLVardef@1e4832e_HPS_FORMAT_FIGEXP M_FIG C_FIG