The looming stimulus-evoked flight response to approaching predators is a defensive behavior in most animals. However, how looming stimuli are detected in the retina and transmitted to the brain remains unclear. Here, we report that a group of GABAergic retinal ganglion cells (RGCs) projecting to the superior colliculus (SC) transmit looming signals from the retina to the brain, mediating the looming-evoked flight behavior by releasing GABA. GAD2-Cre and vGAT-Cre transgenic mice were used in combination with Cre-activated anterograde or retrograde tracer viruses to map the inputs to specific GABAergic RGC circuits. Optogenetic technology was used to assess the function of SC-projecting GABAergic RGCs (scpgRGCs) in the SC. FDIO-DTA (Flp-dependent Double-Floxed Inverted Open reading frame-Diphtheria toxin) combined with the FLP (Florfenicol, Lincomycin & Prednisolone) approach was used to ablate or silence scpgRGCs. In the mouse retina, GABAergic RGCs project to different brain areas, including the SC. ScpgRGCs are monosynaptically connected to parvalbumin-positive SC neurons known to be required for the looming-evoked flight response. Optogenetic activation of scpgRGCs triggers GABA-mediated inhibition in SC neurons. Ablation or silencing of scpgRGCs compromises looming-evoked flight responses without affecting image-forming functions. Our study reveals that scpgRGCs control the looming-evoked flight response by regulating SC neurons via GABA, providing novel insight into the regulation of innate defensive behaviors.
Animals ; Superior Colliculi/physiology* ; Retinal Ganglion Cells/physiology* ; GABAergic Neurons/physiology* ; Mice, Transgenic ; Mice ; Optogenetics ; Visual Pathways/physiology* ; Mice, Inbred C57BL ; Photic Stimulation/methods* ; gamma-Aminobutyric Acid/metabolism* ; Male

Objective To evaluate the value of 3D-PCASL in the pre-operation brain gliomas-grading.Methods 3D-PCASL images of 41 cases of gliomas comfirmed by pathology,including 20 cases of low-grade and 21 cases of high-grade were retrospectively analyzed. The cerebral blood flows of the solid region of tumor (TBF),1cm and 1 cm-2 cm brain tissue around the tumor,and contralateral normal brain CBF were obtained based on the region of interest (ROI),respectively.Results According to independent sample t-test,all had statisti-cally significant differences (P <0.001)between high and low-grade gliomas except the 1-2 cm region around the tumor.One-way ANO-VA displayed that all of them had its statistically significant between differences region (P <0.001)in high-grade gliomas,which had statisti-cally significant differences (P <0.001)except 1 cm and 1 -2 cm of peri-tumor in low-grade gliomas.ROC curve analysis of TBF/contralateral gray matter showed that the area under the curve was 0.96.When 2 was chosen as threshold of rCBF,there was the highest sensitivity (85.7%)and specificity (100%).The accurate rate of conventional MRI for gliomas dianosis was 76% and the ac-curate rate of conventional MRI with ASL was 93%,which was statistically significant difference (χ2 =6.61,P =0.01)between two methodson the chi-square test.Conclusion 3D-PCASL can improve the accuracy of diagnosis of different grade brain gliomas.Com-pared with others parameters,rCBF have a higher sensitivity and specificity.

Objective To study the mechanism by which a high-intensity pulsed electromagnetic field (HIPEMF) (0.1 Hz,4 T,8 pulses) facilitates the proliferation of neural stem cells by detecting the expression of β-catenin genes and protein.Methods Neural stem cells (NSCs) were isolated from the sub-ventricular zone (SVZ) of neonatal rats and cultured in supplemented,serum-free medium for two weeks.The NSCs were then divided into an experimental group exposed to a HIPEMF for 8 pulses and a control group given sham stimulation.The gene and prorein expression of β-catenin in the NSCs were assayed by RT-PCR and Western blotting on the 1st,3rd,5th and 7th day after the stimulation.Results The NSCs' cloned spheres were round and translucent,and showed red fluorescence after staining with anti-nestin (cy3).The RT-PCR results showed β-catenin genes were highly expressed in the exposed group (significantly more than in the controls).The Western blotting showed that expression of β-catenin protein was also higher in the experimental group,especially at the 7th day after stimulation,a difference which was also statistically significant Conclusion HIPEMF at 0.1 Hz,4 T,in 8 pulse trains can promote NSC proliferation,perhaps through the Wnt/β-catenin signaling pathways.