小脑皮质颗粒层对感觉刺激反应的场电位特征

Characterization of the sensory stimulation-evoked field potential responses in cerebellar granule layer in vivo in mice

[目的]观察在体小鼠小脑皮质颗粒层对感觉刺激三叉神经的场电位反应特征.[方法]选取昆明种小鼠,经腹腔注射给予乌拉坦麻醉后,在小脑CrusⅡ小叶行开颅手术,开孔直径约为1.5mm,去除硬脑膜后,脑表面持续灌流给予人工脑脊液;感觉刺激选用一定压力的瞬间吹风刺激同侧胡须垫（10~500ms,60psi）,刺激装置由电脑和膜片钳记录软件控制MASTER-8,且与电生理记录同步,电生理记录采用颗粒层场电位记录.[结果]吹风刺激可诱发小脑CrusⅡ区颗粒细胞层产生场电位反应.当刺激持续时间为10ms时,可诱发单峰场电位反应;当刺激持续时间大于30ms时,可诱发双峰反应,第1个峰值为刺激开始反应,具有全和无特征,第2峰值为刺激结束反应,振幅随着刺激持续时间的增加而增大.小脑皮质颗粒层对感觉刺激的反应具有高保真特性,刺激频率1~33Hz的刺激串均可诱发颗粒细胞层反应.随着刺激频率的增高,在第1个反应后可出现不同程度的反应压抑现象,刺激频率大于8Hz时,反应压抑现象显著（P〈0.05）.[结论]颗粒细胞层对感觉信息的传递具有高频、高保真特性,可精确反映刺激的开始和结束信息.

OBJECTIVE To study the characterization of cerebellar granule cell layer in response to sensory stimulation of trigeminal nerve evoked local field potential in vivo in mice.METHODSFollowing Kunming mice were anesthetized by intraperitoneal injection with urathane,and craniotomy with opening1.5mm in diameter was performed to expose the surface of cerebellar cortex lobule Crus II.After removed the dura,the surface of cerebellum was continually perfused by artificial cerebrospinal fluid.Sensory stimulation was carried out by air-puff（10-500 ms,60psi）of ipsilateral whisker pad,and the stimulus device was controlled by apersonal computer and patch-clamp recording software with Master 8 that was synchronized with electrophysiological recorder with recording the field potentials of granule layer.RESULTS Air-puff stimulation of ipsilateral whisker-pad evoked field potential responses in granule cell layer Crus II.When the stimulation duration for 10 ms,the evoked responses expressed single peak,and when the stimulation duration over 30 ms,the stimulation evoked double peak responses,the first peak was initiation respons of stimulation with expressed all or none and the second peak was terminate response of stimulation with the more increase of stimulation duration,the more stronger amplitude.The field potential responses evoked by sensory stimulation in cerebellar cortical granule cell layer expressed high fidelity properties,and sensory stimulation train at1-33 Hz could evoke granule cell layer responses.However,with the increase of stimulation frequency,the responses expressed different degree of inhibition after the first stimulation.When the stimulation frequency was 8Hz,the peak of second response was significantly decrease（P〈0.05）.CONCLUSIONThe granule cell layer expresses high frequency and fidelity during the sensory information transmission with exactly present of the information of stimulation on and stimulation off.