雏鸡中脑视顶盖I层细胞构筑研究

为进一步阐明鸟类视觉通路的结构特征,试验采用Golgi-Cox法,灌流固定后尼氏体(Nissl bodies)染色和羰花青荧光染料DiI(1,1-’dioctadecyl-3,3,3’,3-t’etramethylindocarbo-cyanine perchlorate)逆向神经标记技术,对雏鸡视顶盖I层的厚度和该层的细胞形态、大小进行了观察研究和数理统计。结果表明,I层细胞多数呈梭形,还有少数呈圆形、椭圆形、锥形、三角形和不规则形状等。I层外侧部较背侧部和腹侧部厚。按照胞体面积大小将细胞分为4类:巨细胞、大细胞、中细胞和小细胞,I层背侧、腹侧和外侧以巨细胞最少,其中背侧、腹侧以小细胞为主,外侧以中细胞数量最多。I细胞具有2~6个主树突,其中有2个主树突的细胞最多(60.7%,n=128)。     

雏鸡投射向外侧膝状体腹侧核的视顶盖细胞形态研究

鸟类的一些视觉信息经由视顶盖Ⅰ层细胞（Ⅰ细胞）传递到外侧膝状体腹侧核（nucleus geniculatus lateralis ventralis,GLv）,用于色觉、瞳孔反射和视觉运动.使用羰花青荧光染料DiI逆向神经标记技术研究了这些投射向GLv核的视顶盖Ⅰ细胞的形态特征.根据标记细胞的胞体和树突野大小及树突分枝特点,雏鸡投射到GLv核的视顶盖Ⅰ细胞可分为“矛状树突Ⅰ细胞”和“叉状树突Ⅰ细胞”,前者具有小型纺锤状的细胞体和垂直伸延的1支尖端树突,后者具有较大三角形或多角形的细胞体和多支上行性树突.多数标记树突的末端部水平分布于视顶盖F层,和终止于此层的视神经终末部的形态相一致.     

Histopathologic effect of in ovo exposure to methotrexate at early embryonic stage on optic tectum of Japanese quail (Coturnix japonica)

The optic tectum of Japanese quail embryos with in ovo exposure to methotrexate 100 ng/g egg on embryonic day 4 was examined from 3 to 24 hour after treatment. At 9 hour after methotrexate exposure, several apoptotic neuroepithelial cells appeared in the ventricular zone of the optic tectum; these increased in number and were diffusely distributed throughout all layers of the ventricular zone of the optic tectum at 12 hour. At 24 hour, neuroepithelial cells in the ventricular zone of the optic tectum were eliminated and showed sparse cell density. Throughout the experimental period, proliferation of neuroepithelial cells in the ventricular zone of the optic tectum of methotrexate-treated embryos was inhibited. These results suggest that neuroepithelial cells in the ventricular zone of the optic tectum in Japanese quail embryos can be affected by folic acid antimetabolites, methotrexate, at an early embryonic stage.     

雏鸡中脑视顶盖中央灰质层细胞构筑研究

为了进一步阐明鸟类视觉通路的结构特征,本试验用尼氏体染色法、Golgi-CoxⅡ法及羰花青荧光染料DiI逆行神经标记3种方法对雏鸡视顶盖的中央灰质层(Stratum griseum centrale,SGC)细胞形态特征进行了观察和统计分析。结果表明:视顶盖SGC层背侧的厚度小于腹侧和外侧。SGC层细胞以大、中型细胞为主,多具有三角形、多边形及纺锤形的胞体。在高尔基镀银法(Golgi-CoxⅡ)染色和DiI逆行神经标记法标记出的细胞中,其树突清晰可见。三角形及纺锤形的细胞多从胞体发出2~3支主树突,树突野较大;多边形和少数三角形的细胞由胞体发出多支树突,树突野较小。     

First spike latency of ON/OFF neurons in the optic tectum of pigeons

Some shallow and middle optic tectum (OT) neurons have stable, asymmetric full‐screen ON and OFF stimulus response properties, which makes them candidates for delay encoding. In this paper, we investigated the delay encoding mechanism for the neuronal clusters in the OT region of pigeons and determined the mechanism of delay coding in the OT region. By analyzing the responses of the neuron cluster under full‐screen switch‐on and switch‐off stimulation, we found that the delay coding was widespread in the OT region where the ON/OFF stimulation time difference was 4–6 ms. Information theory analysis under grating stimulation and experiments based on single‐neuron character reconstruction of neurons showed that OT neuron clusters use the first spike latency (FSL) for the rapid transfer of spatial structure information. Furthermore, 4 models were used to predict the first spike latency of these OT neurons. The best simulation results were obtained using an architecture where the ON and OFF paths of multiple retinal ganglion cells (RGCs) were integrated and summed, respectively.     

三日龄雏鸡中脑视顶盖H层神经元形态研究

为深入了解禽类中脑视顶盖的内部构造,用羰花青荧光染料DiI(1,1-’dioctadecyl-3,3,3’3-’tetramethyl-indocarbo-cyanine perchlorate)神经标记技术,对雏鸡视顶盖H层神经元形态进行了观察。结果显示,DiI标记H层神经元可分为2种类型,Ⅰ型神经元数量较多,胞体为多边形,树突野大,树突的数量和分支多,伸展较远,树突末端最远可达视顶盖A层;Ⅱ型神经元较少,胞体呈梨形、梭形、三角形等多种形态,树突野小,树突数量与分支少,伸展较近,最远只达视顶盖E层。     

Spatial cognition and its neural basis in teleost fishes

The present review is focused on recent laboratory studies revealing that the spatial behaviour of fishes is as complex and elaborate as described in land vertebrates. In addition, the data presented here indicate that the remarkable richness and plasticity of spatial behaviour in fishes are based on learning and memory mechanisms and cognitive processes that depend on particular brain circuits, possibly homologous to those identified in mammals and birds. For example, there is evidence that the fish hippocampal pallium is essential for processing and encoding complex spatial information to form map‐like representations of the environment. In contrast, body‐centred orientation strategies or emotional learning are subserved by different cerebral structures, such as the optic tectum, the cerebellum or the amygdalar pallium. These results that suggest a striking similarity in some cognitive processes and their neural basis between fish and land vertebrates are consistent with the possibility that these vertebrate groups share a common basic pattern of brain and behaviour organisation inherited from a common ancestor and conserved through a long history of separate evolution.