不同时限单眼斜视和剥夺猫的多导程图形视觉诱发电位研究

Experimental studies on the pathogenic mechanisms of MS and MD kittens in different periods of visual development using MPVEPs in the visual system

目的 :探讨敏感期内和敏感期末单眼斜视(monocularstrabismus,MS)和单眼剥夺 (monoculardeprivation ,MD)幼猫视觉系统可塑性变化的多导程图形视觉诱发电位变化规律 ,为临床防治儿童斜视和剥夺性弱视提供参考依据。方法 :对敏感期内 (2～ 4w)和敏感期末 (10～ 12w)龄幼猫用手术制做人工MS和MD弱视动物模型。手术前将 32只动物随机分为MS1、MD1、MS2 、MD2 和N共 5组。在第 16周后应用多导程图形视觉诱发电位 (multi channelsofpatternvisualevokedpattential,MPVEPs)仪检测正常发育 (N) ,敏感期内 (MS1和MD1)与敏感期末 (MS2 和MD2 )实验幼猫视觉系统的电生理学塑性变化和弱视形成的特点 ,对N、MS1、MD1、MS2和MD2 组幼猫给予双眼、单眼、全视野和半视野以及 4档不同空间频率 (0 .0 6、0 .1、0 .2 5和 0 .5cpd)的棋盘格图形翻转视刺激 ,用 6导电极记录各组幼猫的MPVEPs曲线变化。结果 :①N组幼猫双眼、单眼、全视野和半视野的各导程MPVEPs值为P1峰潜时与发育前比明显提前 ,N1 P1波幅值升高。在空间频率为 0 .0 6和 0 .1cpd时 ,NR(L)眼与MS1和MD1眼比较以及在敏感期内斜视的对侧眼 (thefelloweyeofMS1,MS1F)与MS1眼和MD1F眼与MD1眼比较差异都具有非常显著性 (P<0 .0 0 0 1) ,显示了MS1及MD1视反应的抑制?

Objective:The goals of our experiment are to investigate and discuss the mechanisms of strabismic and deprivation amblyopia and to seek effective methods for the prevention and therapy of these conditions during the critical period of visual development and at the end of the critical period for visual development. Six-channel pattern visual evoked potentials(6CPVEPs) were used to analyze the visual system of the kittens.Methods:Surgery was performed on kittens during the critical period of visual development(at age 2～4 wks) and at the end of the critical period of visual development (at age 10～12 wks) to establish models of monocular strabismus(MS) and monocular deprivation(MD). Surgery was done on the kittens by sectioning the lateral rectal muscle of one eye for esotropia and suturing the lid for MD. Before surgery,the kittens were randomly divided into 5 groups:normal group(N),monocular strabismus 1(MS 1),and monocular deprivation 1(MD 1,MS 2 and MD 2). All kittens were raised for sixteen weeks under the same visual environment conditions,N,MS 1,MD 1,MS 2 and MD 2 were then examined with 6CPVEPs. This was done by implanting 6-channel stainless steel electrodes into the cranial periosteum of the occipital pole and the cranial center and recording from them. Each channel was exposed on the cranial surface and was separated by 1 cm to record changes in the plasticity of the 6CPVEPs. Binocular,monocular(right or left) eye,total visual field and half visual field of N,MS 1,MD 1,MS 2 and MD 2 kittens were measured by MPVEPs with visual stimulation. Stimulation consisted of moving a reversed black and white square pattern at 4 different grades of spatial frequencies(SF=0.06,0.1,0.25,0.5 cpd).Results:①The latency of the P 1 wave in all channels of the total visual field and half visual field for binocular and monocular viewing(right,left) of the kittens at the end of the critical period was short in the N group and the N 1-P 1 amplitude was greater during the critical period for visual development. Data from all 6CPVEPs was analyzed with a two-factor ANOVA by an SAS statistical computer program. When SF was at 0.06 and 0.1 cpd,N(R)L/MS 1,N(R)L/MD 1,MS 1F/MS 1 and MD 1F/MD 1 revealed a very significant difference(P<0.0001). However,N(R)L/MS 2,N(R)L/MD 2,MS 2F/MS 2 and MD 2F/MD 2 had no significant differences(P>0.05).②The changes in the underlying patterns of the visual response in all channels of 6CPVEPs in normal kittens were as follows:visual response of the total visual field for binocular viewing > that for the total visual field of monocular (R)L viewing > that of the temporal visual field on monocular (R)L viewing > that of the paranasal visual field of monocular (R)L viewing. All of the above observations indicate that the effects of the visual response in experimental kitten eyes to 6CPVEPs are in direct proportion to the total area of the receptive field receiving visual stimulation. The visual response of the paranasal visual field of monocular (R)L viewing was lowest when the paranasal visual field was stimulated. Because the paranasal retina was not involved in the visual stimulation process,response components in the paranasal visual field were reduced and only weakly stimulated. Therefore,the effect of the visual response in the visual field of the paranasal retina was not correlated with its depression. The visual response of the temporal visual field for monocular (R)L viewing was lower than that of the total visual field for monocular (R)L viewing because the entire visual field of the retina was completely involved in the visual stimulation process even though the visual angle became smaller or was reduced in half.③P 1 latency of each group at high spatial frequencies (0.25 and 0.5 cpd) compared as follows:N(R)L/MS 1,N(R)L/MD 1,MS 1F/MS 1 and MD 1F/MD 1 had significant differences(P<0.01,P<0.0001),and N(R)L/MS 2,N(R)L/MD 2,MS 2F/MS 2 and MD 2F/MD 2 had no significant differences(P>0.05). N 1-P 1 amplitudes for all groups were compared with each other and show