Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The presence of choline acetyltransferase-immunoreactive (ChATir) amacrine cells is reported for the first time in the retinas of three species of lamprey (Lampetra fluviatilis, Ichthyomyzon unicuspis, and Petromyzon marinus). In the three species, the ChATir cells were mainly distributed in the inner plexiform layer (IPL), which in lampreys extends from the inner nuclear layer (INL) to the inner limiting membrane. These cells had a bipolar, triangular or stellate appearance, and gave rise to processes coursing in the inner plexiform layer. In transforming lampreys, ChATir processes formed two asymmetrical inner and outer subplexuses in the inner plexiform layer, which is reminiscent of the distribution of processes of ChATir cells in the On and Off sublaminae reported in jawed vertebrates. The larval retina lacked ChAT immunoreactivity, and ChATir cells and processes appeared at early metamorphosis throughout the retina, exhibiting in late transforming stages an organization similar to that of adults. This first report of ChATir cells in the lamprey retina indicates that the appearance of cholinergic circuits in the retina of vertebrates occurred before the divergence of the agnathan and gnathostome lines.
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PMID:Choline acetyltransferase-immunoreactive neurons in the retina of adult and developing lampreys. 1464 41

A biophysically detailed description of the mechanisms of the primary vision is still being developed. We have incorporated a simplified, filter-based description of retino-thalamic visual signal processing into the detailed, conductance-based refractory density description of the neuronal population activity of the primary visual cortex. We compared four mechanisms of the direction selectivity (DS), three of them being based on asymmetrical projections of different types of thalamic neurons to the cortex, distinguishing between (i) lagged and nonlagged, (ii) transient and sustained, and (iii) On and Off neurons. The fourth mechanism implies a lack of subcortical bias and is an epiphenomenon of intracortical interactions between orientation columns. The simulations of the cortical response to moving gratings have verified that first three mechanisms provide DS to an extent compared with experimental data and that the biophysical model realistically reproduces characteristics of the visual cortex activity, such as membrane potential, firing rate, and synaptic conductances. The proposed model reveals the difference between the mechanisms of both the intact and the silenced cortex, favoring the second mechanism. In the fourth case, DS is weaker but significant; it completely vanishes in the silenced cortex.DS in the On-Off mechanism derives from the nonlinear interactions within the orientation map. Results of simulations can help to identify a prevailing mechanism of DS in V1. This is a step towards a comprehensive biophysical modeling of the primary visual system in the frameworks of the population rate coding concept.
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PMID:Refractory density model of cortical direction selectivity: Lagged-nonlagged, transient-sustained, and On-Off thalamic neuron-based mechanisms and intracortical amplification. 3305 99