Optic tectum

Snow, D. M., Steindler, D. A., and Silver, J., Molecular and cellular characterisation of the glial roof plate of the spinal cord and optic tectum. A possible role for a proteoglycan in the development of an axonal barrier, Dev. Biol., 138, 359, 1990. 

As already pointed out, cells in the late phases of proliferation are born in radial columns of which the Muller cells form the core. The columnar organization is also found in other areas in the brain such as cortex (Rakic, 1972 Luskin et al., 1988), spinal cord (Leber et al., 1990), and optic tectum (Gray and Sanes, 1991) where the radial glia act as a scaffold for the migration of neurons (Hatten, 1990, 1993 Rakic et al., 1994 Rakic, 1995). Muller cells probably play an important role in guiding the clonal cells in columns. 

Gray GE, Sanes JR. 1991. Migratory paths and phenotypic choices of clonally related cells in the avian optic tectum. Neuron 6 211-225. 

Snow RL, Robson JA. 1995. Migration and differentiation of neurons in the retina and optic tectum of the chick. Exp Neurol 134 13-24. 

Johansson D, Nilsson GE, Doving KB. 1997 Anoxic depression of light-evoked potentials in retina and optic tectum of crucian carp. Neurosci Lett 237 73-76. 

Phaseolus vulgaris Trace development of optic tectum [155,156]... 

Cohen, J., Nurcombe, V., Jeffrey, P. and Edgar, D. (1989) Developmental loss of functional laminin receptors on retinal ganglion cells is regulated by their target tissue, the optic tectum. Development 107 381-387. 

J.R. (1990) Neurons and glia arise from a common progenitor in chick optic tectum demonstration with two retroviruses and cell type-specific antibodies. Proc. Natl. Acad. Sci. USA 87 458-462. 

Hartline PH, Kass L, Loop MS (1978) Merging of modalities in the optic tectum infrared and visual integration in rattlesnakes. Science 199 1225-1229... 

Newman EA, Hartline PH (1981) Integration of visual and infrared information in bimodal neurons of the rattlesnake optic tectum. Science 213 789-791... 

KinslerL.E., FreyA.R., Coppens A.B., and Sanders J.V. (1999). Fundamentals of Acoustics. New York Wiley. Knudsen E.I. and Knudsen P.F. (1983). Space-mapped auditory projections from the inferior colliculus to the optic tectum in the barn owl. /. Comp. Neurol. 218 187-196. 

Axonally transplanted gangliosides from retina were more highly labelled in the optic tectum of chicken exposed to light compared to those maintained in the dark. There was no difference in the labelling of retinal gangliosides between the two groups. 

Reubi ] and Cuenod M (1976) Release of exogenous glycine in the pigeon optic tectum during stimulation of a midbram nucleus Brain Res 112, 347-361... 

Itasaki N, Nakamura H (1996) A role for gradient en expression in positional specification of the optic tectum. Neuron 16 55-62. 

Logan C, Wizenmann A, Drescher U, Monschau B, Bonhoeffer F, Lumsden A (1996) Rostral optic tectum acquires caudal characteristics following ectopic engrailed expression. Curr Biol 6 1006-1014. 

Friedman, G, O Leary D (1996) Retroviral misexpiession of engrailed genes in the chick optic tectum perturbs the topographic targeting of retinal axons. J Neurosci 16 5498-5509. 

Similar protective effects of lesion of the major glutamatergic projection to the pigeon optic tectum have also been reported (Streit et a/.,... 

Streit, P., Stella, M., and Cuenod, M., 1980, Kainate-induced lesion in the optic tectum depending upon optic nerve afferents or glutamate. Brain Res. 187 47-57. 

In the rabbit brain, the Nadi (a-naphthol, dimethyl-p-phenylenediamine) reaction showed marked activity of cytochrome oxidase in the caudate nucleus, the putamen, the anterior nucleus of the thalamus, the optic tectum, the interpeduncular nucleus. Golfs and Burdach s nuclei, and the inferior ohvary nucleus (Shimizu et al. 1957). A moderate reaction was seen in the neocortex, hippocampus, dentate gyrus, substantia nigra, cerebellar cortex and the nuclei of the cranial nerves. 

Beriberi is associated with low transketolase activity in the blood, and determination of transketolase activity may be a helpful diagnostic tool in detecting mild forms of thiamine deficiencies. The fact that adding thiamine pyrophosphate to the system restores transketolase activity confers specificity to this procedure. Although the decrease in transketolase activity is easy to explain in view of the role that thiamine plays in that reaction, the mechanism of the alteration in adenosine-5 -phosphatase is not so obvious. The total activity is decreased despite a slight increase of adenosine phosphatase in the nuclei, and the decrease in total activity results from a marked decrease of adenosine phosphatase in the fibers. Increased thiamine pyrophosphate and alkaline phosphatase have also been observed in the optic tectum of the deficient chicken, but these changes remain unexplained. 

It has been reported that colchicine inhibits the migration of labeled proteins in peripheral nerves (Sjostrand et al., 1970 James et al., 1970). The labeling of gangliosides of the contralateral optic tectum and of its synaptosomal fraction was inhibited when colchicine was injected into the eye prior to the injection of labeled N-acetylmannosamine (Table 6). Since the sialylation in vitro of both retina and tectum gangliosides was not inhibited by the injection of colchicine (Table 6), it seems that colchicine acted on the mechanism of transport of gangliosides or of its precursors. 

Figure 2.3 Gene expression in developing chordate neural tubes (a) vertebrate. Hindbrain rhombomeres numbered, (b) Amphioxus. Pigment spots associated with the frontal eye and first ventral photoreceptor are shown, (c) Ascidian tunicate. Pigment spots associated with the otolith and photoreceptor are shown. Arrow indicates that presence of isthmic region is uncertain. D=diencephalon, F+AM=forebrain plus anterior midbrain, HB+SC=hindbrain pius spinai cord, MHB=midbrain/hindbrain boundary, M=mid-brain, OT=optic tectum, T=teiencephaion. Lines indicate anterior-posterior extent of Otx and Hox expression.

Lacalli (1996) described cells at the dorso-posterior end of the cerebral vesicle which apparently receive input from the frontal eye. He called these tectal cells, implying homology with the optic tectum of vertebrates, a dorsal midbrain structure which receives input from the eyes. However, whether this amphioxus structure is truly homologous to the vertebrate optic tectum has been questioned by Northcutt (1996), who pointed out a number of differences in the neural connections of the proposed amphioxus tectum and the optic tectum of vertebrates. For example, the amphioxus tectum, unlike that of vertebrates, receives primary sensory input from the dorsal spinal nerves. 

Ewert, J.P. (1984) Tectal mechanisms that underlie prey-catching and avoidance behaviors in toads. In Comparative Neurology of the Optic Tectum (ed H. Vaneges), Plenum Press, New York, pp. 247-416. 

Dudkin, E. A. Myers, R Z. Ramirez-Latorre, J. A. Gruberg, E. R. Calcium signals monitored from leopard frog optic tectum after the optic nerve has been selectively loaded with calcium sensitive dye. Neurosci. Lett. 1998, 258, 124—126. 

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