Superficial Layers Of Optic Tectum Research Articles

A Moving Target Detection Model Inspired by Spatio-Temporal Information Accumulation of Avian Tectal Neurons

Moving target detection in cluttered backgrounds is always considered a challenging problem for artificial visual systems, but it is an innate instinct of many animal species, especially the avian. It has been reported that spatio-temporal information accumulation computation may contribute to the high efficiency and sensitivity of avian tectal neurons in detecting moving targets. However, its functional roles for moving target detection are not clear. Here we established a novel computational model for detecting moving targets. The proposed model mainly consists of three layers: retina layer, superficial layers of optic tectum, and intermediate-deep layers of optic tectum; in the last of which motion information would be enhanced by the accumulation process. The validity and reliability of this model were tested on synthetic videos and natural scenes. Compared to EMD, without the process of information accumulation, this model satisfactorily reproduces the characteristics of tectal response. Furthermore, experimental results showed the proposed model has significant improvements over existing models (EMD, DSTMD, and STMD plus) on STNS and RIST datasets. These findings do not only contribute to the understanding of the complicated processing of visual motion in avians, but also further provide a potential solution for detecting moving targets against cluttered environments.

Autoradiographic characterization of fhio-cyano-p-nitroquinoxaline-2,3-dione binding sites in adult chick brain

The non N-methyl- d-aspartate binding sites have been characterized in chick brain using quantitative autoradiography, and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) as a radioligand. phjcnqx binding sites were densely localized in the molecular layer of cerebellum. Other areas of prominent binding were the superficial layers of optic tectum, one of the isthmic nuclei, the hippocampus, the hyperstriatum accessorium and the archistriatum ventrale. Analysis of equilibrium binding data in the eerebellar molecular layer indicated that [ 3H]CNQX bound to a single class of sites ( K d= 78.9 ± 11.8 nM and B max = 41.2± 3.0 pmol/mg protein). Competition experiments in six different regions of chick brain gave the K i and B max values for the inhibition of [ 3H]CNQX binding by various standard compounds and indicated that: (i) [ 3H]JCNQX labelled non N-methyl- d-aspartate binding sites with high affinity for (RS)-α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate, (ii) the displacement curves for AMPA and kainate were biphasic in all regions studied, and (iii) the potencies of AMPA and kainate in displacing [ 3H]CNQX binding were different in the regions studied. Our results indicate that [ 3H]CNQX labelled non N-methyl- d-aspartate binding sites in chick brain. In the cerebellar molecular layer, these sites were more sensitive to kainate than AMPA, as were the binding sites in the superficial layers of optic tectum and nucleus isthmi magnocellularis. However, non N-methyl- d-aspartate binding sites in forebrain regions such as hippocampus and hyperstriatum ventrale appeared to be different in being equally sensitive to AMPA and kainate.

Ganglion cell types of the turtle retina that project to the optic tectum: Intracellular HRP injections of retrogradely, rhodamine-marked cell bodies.

The turtle retina has been shown to have a variety of different morphological ganglion cell types as well as distinct physiological ganglion cell types. The major projection of the retina to the brain in nonmammalian vertebrates is to the optic tectum. In this study, we address the question of which retinal ganglion cell types project to the optic tectum in the turtle. Fluorescent rhodamine-labeled microspheres were used to trace the retinal ganglion cell projection to the superficial layers of the optic tectum. The fluorescent ganglion cell somata, retrogradely marked by transport from the contralateral optic tectum, were impaled with micropipettes containing rhodamine-horseradish peroxidase solution and this dye was iontophoresed into the cells under visual control. Most of the morphological ganglion cell types described in Golgi studies (Kolb, 1982; Kolb et al., 1988) were stained. Thus, the small cell types G1, G2, G3, G5, G6, and G7; the medium-sized types G10, G11, G12, G13, and G14; and the large-sized types G15, G16, G19, G20, and G21 project to the optic tectum in the turtle. We have added a new type, G2a, which proves to have some differences from the original G2 in branching pattern. We were unable to stain the small type G4, the medium-sized types G8 and G9, and the large cell types G17 and G18: this suggests that they might not project to the superficial layers of the dorsolateral optic tectum, at least, in the turtle.