Temporal-spacial Relationship Between Facial Stimulation-evoked Filed Potential Responses In Mouse Cerebellar In Mouse Cerebellar Granular Layer And Molecular Layer

[Subject]Temporal-spacial relationship between facial stimulation-evoked filed potential responses in mouse cerebellar granular layer and molecular layer.[Objective]The cerebellum is an important motor central organ.This part of brain receives a wide variety of sensory inputs and generates motor-related outputs,which are critical for controlling motor coordination,planning and fine regulation of voluntary movement.However,the temporal and spatial relationship of external information transmission in the cerebellar cortex remains unclear.We investigated the temporal-spacial relationships between the facial stimulation-evoked field potential responses in granular layer(GL)and molecular layer(ML),by electrophysiological recording technique and pharmacological methods.[Methods]Adult ICR mice(6-8 weeks old)were selected,weighing 26-35g,intraperitoneal injection of urethane to reduce the exposure of the whisker pad.After tracheal intubation,the head of mice was fixed with bilateral ear sticks and maxilla on the stereotaxic brain locator and placed under a microscope.The muscle tissue attached to the brain was removed,the dura mater was removed to expose the brain tissue,and the artificial cerebrospinal fluid containing oxygen was perfused continuously.The field potential wave characteristics and time changes in the ML and GL of the cerebellum were recorded simultaneously by in vivo duo-electrophysiological recording method.[Results](1)The latency of sensory stimulation-induced field potentials was 11.0±0.47 ms in the ML and 9.3 ± 0.43 ms in the GL,with the difference of 1.7 ms.Consistent with the traditional theory,the results suggested that sensory information transferred to cerebellar cortex via Mossy fiber(MF)-Granular cell(GC)-Parallel fiber(PF)pathway.(2)The time to peak of excitatory components N1 in the ML was 4.3±0.45 ms and 5.3 ± 0.45 ms in the GL,and the latency of P1 in GL was 14.5±0.51 ms,and in different sites of ML were 14.5±0.46 ms.These results indicate that the sensory stimulation induces simultaneous inhibitory responses in GL and different horizontal sites of ML.(3)In the presence of AMPA recepters blocker,the mean amplitude of P1 in ML was 0.02 ± 0.01 mV,which was significant lower than control conditions 0.53±0.12 mV,and the mean amplitude of P1 in GL was 0.02 ± 0.01 mV,which was significant lower than control conditions 0.41±0.07mV.Suggesting that the facial stimulation evoked simultaneously excitation of MLIs and Golgi cells via activation of AMPA receptors.(4)In the presence of GABAA recepters antagonist,the mean amplitude of N2 in ML was-0.31 ± 0.05 mV,which was significant lower than control conditions 0.50±0.04 mV.The mean amplitude of P1 in GL was 0.017 ±0.01 mV,which was significant lower than control conditions 0.41±0.09 mV.These results indicate that the facial stimulation evoked a simultaneous inhibition in both ML and GL through parallel fiber pathway by activation of GABAA receptor.[Conclusion](1)The facial stimulation evoked simultaneous inhibitory components in GL and ML regardless the relative recording sites.(2)The facial stimulation evoked simultaneously excitation of MLIs and Golgi cells,resulting in a simultaneous GABAergic inhibitory response in ML and GL.