scholarly journals Stimulus-Dependent Correlations in Threshold-Crossing Spiking Neurons

2009 ◽  
Vol 21 (8) ◽  
pp. 2269-2308 ◽  
Author(s):  
Yoram Burak ◽  
Sam Lewallen ◽  
Haim Sompolinsky
Keyword(s):  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Qualitative Properties ◽  
Fire Model ◽  
Integrate And Fire ◽  
Threshold Crossing ◽  
Cross Correlations ◽  
Bursting Events ◽  
The One ◽  
The Relationship

We consider a threshold-crossing spiking process as a simple model for the activity within a population of neurons. Assuming that these neurons are driven by a common fluctuating input with gaussian statistics, we evaluate the cross-correlation of spike trains in pairs of model neurons with different thresholds. This correlation function tends to be asymmetric in time, indicating a preference for the neuron with the lower threshold to fire before the one with the higher threshold, even if their inputs are identical. The relationship between these results and spike statistics in other models of neural activity is explored. In particular, we compare our model with an integrate-and-fire model in which the membrane voltage resets following each spike. The qualitative properties of spike cross-correlations, emerging from the threshold-crossing model, are similar to those of bursting events in the integrate-and-fire model. This is particularly true for generalized integrate-and-fire models in which spikes tend to occur in bursts, as observed, for example, in retinal ganglion cells driven by a rapidly fluctuating visual stimulus. The threshold-crossing model thus provides a simple, analytically tractable description of event onsets in these neurons.

Abnormally high variability in the uncrossed retinofugal pathway of mice with albino mosaicism

Development ◽  
1987 ◽  
Vol 101 (4) ◽  
pp. 857-867 ◽  
Author(s):  
R.W. Guillery ◽  
G. Jeffery ◽  
B.M. Cattanach
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Gene Dosage ◽  
Optic Tract ◽  
High Variability ◽  
Retinal Ganglion ◽  
Rare Occurrence ◽  
Autosome Translocation ◽  
Open Question ◽  
The Relationship

Female mice showing albino mosaicism due to an X-autosome translocation [Is(In7;X)Ct] have been studied in order to investigate the relationship between the distribution of melanin and the formation, early in development, of the abnormally small uncrossed retinofugal pathway characteristically found in all albino mammals. Earlier evidence indicates that cells normally bearing melanin play a role in producing the abnormality. In the mosaic mice, the albino gene is expressed in only about half of the cells due to random X-inactivation and the patches of normal and albino cells are extremely small relative to total retinal size (less than 1/50). We argued that if all the cells that would normally bear melanin play a role in producing the albino abnormality then the mosaic mice would have a pathway abnormality, about half the size of that in the albino mice. If, however, only a small patch of these cells plays a role, as has been proposed in earlier studies, then one would expect the size of the uncrossed pathway to be highly variable in the mosaic mice. The size of the uncrossed pathway was assessed by placing horseradish peroxidase in the region of the optic tract and lateral geniculate nucleus unilaterally and then counting the number of retrogradely labelled retinal ganglion cells on the same side. The mosaic mice showed a highly variable uncrossed pathway. In some of the mosaic mice, it was the same size as in the albinos and, in others, it was the same size as in normally pigmented mice. Surprisingly, in a small number of mosaic mice, the uncrossed pathway was larger than normal. Whether this relatively rare occurrence of a supernormal uncrossed pathway is due to the higher gene dosage or to the translocation itself remains an open question.

The Biomechanical Response of Normal and Glaucoma Human Sclera

2010 ◽  
Author(s):  
Baptiste Coudrillier ◽  
Kristin M. Myers ◽  
Thao D. Nguyen
Keyword(s):  
Retinal Ganglion Cells ◽  
Material Properties ◽  
Visual Information ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Progressive Degeneration ◽  
Biomechanical Response ◽  
Elevated Intraocular Pressure ◽  
The Relationship ◽  
The Brain

By 2010, 60 million people will have glaucoma, the second leading cause of blindness worldwide [1]. The disease is characterized by a progressive degeneration of the retinal ganglion cells (RGC), a type of neuron that transmits visual information to the brain. It is well know that elevated intraocular pressure (IOP) is a risk factor in the damage to the RGCs [3–5], but the relationship between the mechanical properties of the ocular connective tissue and how it affects cellular function is not well characterized. The cornea and the sclera are collage-rich structures that comprise the outer load-bearing shell of the eye. Their preferentially aligned collagen lamellae provide mechanical strength to resist ocular expansion. Previous uniaxial tension studies suggest that altered viscoelastic material properties of the eye wall play a role in glaucomatous damage [6].

Time-Series and Dynamic Cross-Correlations Analysis on Unexpected Information: Evidence from Media News and Online Postings

2019 ◽  
Vol 19 (02) ◽  
pp. 2050011
Author(s):  
Yan Li ◽  
Xiangyu Kong ◽  
Xiao Li ◽  
Zuochao Zhang
Keyword(s):  
Mass Media ◽  
New Media ◽  
Trading Volume ◽  
Cross Correlation ◽  
Short Term ◽  
Cross Correlations ◽  
The Cross ◽  
The One ◽  
The Relationship

In this paper, we investigate the relationship between unexpected information from postings and news, and the unexpected information is measured by the residual of regressions of trading volume on numbers of news or postings. We mainly find that (i) There are significant positive contemporaneous correlations between the unexpected information coming from postings and different kinds of news; the correlation between the unexpected information coming from postings and new media news is stronger than that between the unexpected information coming from postings and mass media news; (ii) The unexpected information coming from postings could cause the unexpected information coming from news, but only the unexpected information coming from the mass media news could cause that coming from postings; (iii) There are persistent power-law cross-correlations between the unexpected information coming from postings and that coming from mass media news and new media news. The cross-correlation between the unexpected information coming from postings and new media news is more persistent than the one between the unexpected information coming from postings and mass media news. The cross-correlations are all more stable in long term than in short term. We attribute our findings above to the dissemination speed of the information on the Internet.

scholarly journals The Relationship between Visual Field Index and Estimated Number of Retinal Ganglion Cells in Glaucoma

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e76590 ◽  
Author(s):  
Amir H. Marvasti ◽  
Andrew J. Tatham ◽  
Linda M. Zangwill ◽  
Christopher A. Girkin ◽  
Jeffrey M. Liebmann ◽  
...  
Keyword(s):  
Visual Field ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Visual Field Index ◽  
The Relationship

scholarly journals Demyelination of the Optic Nerve: An Underlying Factor in Glaucoma?

2021 ◽  
Vol 13 ◽  
Author(s):  
Jingfei Xue ◽  
Yingting Zhu ◽  
Zhe Liu ◽  
Jicheng Lin ◽  
Yangjiani Li ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Inflammatory Responses ◽  
Clinical Symptoms ◽  
Ganglion Cells ◽  
Neuronal Degeneration ◽  
Retinal Ganglion ◽  
Progressive Degeneration ◽  
Treatment Plans ◽  
The Central Nervous System ◽  
The Relationship

Neurodegenerative disorders are characterized by typical neuronal degeneration and axonal loss in the central nervous system (CNS). Demyelination occurs when myelin or oligodendrocytes experience damage. Pathological changes in demyelination contribute to neurodegenerative diseases and worsen clinical symptoms during disease progression. Glaucoma is a neurodegenerative disease characterized by progressive degeneration of retinal ganglion cells (RGCs) and the optic nerve. Since it is not yet well understood, we hypothesized that demyelination could play a significant role in glaucoma. Therefore, this study started with the morphological and functional manifestations of demyelination in the CNS. Then, we discussed the main mechanisms of demyelination in terms of oxidative stress, mitochondrial damage, and immuno-inflammatory responses. Finally, we summarized the existing research on the relationship between optic nerve demyelination and glaucoma, aiming to inspire effective treatment plans for glaucoma in the future.

Microcircuitry of the cat retina: Connections between arrays of neurons

1987 ◽  
Vol 45 ◽  
pp. 706-711
Author(s):  
Michael A. Freed ◽  
Peter Sterling
Keyword(s):  
Electron Microscope ◽  
Ganglion Cell ◽  
Ganglion Cells ◽  
Three Dimensional ◽  
Retinal Ganglion ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Rod Photoreceptors ◽  
Cat Retina ◽  
The Relationship

One of the most basic of structure-function relationships in the mammalian visual system is the relationship between the size of a ganglion cell's receptive field and the number of rod photoreceptors which are connected to it. There is also the flip side of the coin: how many ganglion cells does a single photoreceptor connect to? We have estimated the number of rods which converge upon an on-beta type of retinal ganglion cell; we have also estimated the number of on-beta ganglion cells which a single rod diverges to. Our method is to extract a three-dimensional circuit from a series of two-dimensional electron microscope sections. The results have implications for the preservation of the signal/noise ratio in the ganglion cell.There are two well-documented routes from the rods to the on-beta ganglion cell.

scholarly journals The Interaction Between Microglia and Macroglia in Glaucoma

2021 ◽  
Vol 15 ◽  
Author(s):  
Xiaohuan Zhao ◽  
Rou Sun ◽  
Xueting Luo ◽  
Feng Wang ◽  
Xiaodong Sun
Keyword(s):  
Glial Cells ◽  
Vision Loss ◽  
Inflammatory Responses ◽  
Ganglion Cells ◽  
Open Angle Glaucoma ◽  
Treatment Options ◽  
Cell Types ◽  
Retinal Ganglion ◽  
Underlying Mechanisms ◽  
The Relationship

Glaucoma, a neurodegenerative disease that leads to irreversible vision loss, is characterized by progressive loss of retinal ganglion cells (RGCs) and optic axons. To date, elevated intraocular pressure (IOP) has been recognized as the main phenotypic factor associated with glaucoma. However, some patients with normal IOP also have glaucomatous visual impairment and RGC loss. Unfortunately, the underlying mechanisms behind such cases remain unclear. Recent studies have suggested that retinal glia play significant roles in the initiation and progression of glaucoma. Multiple types of glial cells are activated in glaucoma. Microglia, for example, act as critical mediators that orchestrate the progression of neuroinflammation through pro-inflammatory cytokines. In contrast, macroglia (astrocytes and Müller cells) participate in retinal inflammatory responses as modulators and contribute to neuroprotection through the secretion of neurotrophic factors. Notably, research results have indicated that intricate interactions between microglia and macroglia might provide potential therapeutic targets for the prevention and treatment of glaucoma. In this review, we examine the specific roles of microglia and macroglia in open-angle glaucoma, including glaucoma in animal models, and analyze the interaction between these two cell types. In addition, we discuss potential treatment options based on the relationship between glial cells and neurons.

scholarly journals Analysis of Integrate-and-Fire Neurons: Synchronization of Synaptic Input and Spike Output

1999 ◽  
Vol 11 (4) ◽  
pp. 871-901 ◽  
Author(s):  
A. N. Burkitt ◽  
G. M. Clark
Keyword(s):  
Synaptic Input ◽  
Arrival Times ◽  
Fire Model ◽  
Integrate And Fire ◽  
Synchronization Problem ◽  
Layered Networks ◽  
A New Technique ◽  
The Times ◽  
The Relationship ◽  
Phase Differences

A new technique for analyzing the probability distribution of output spikes for the integrate-and-fire model is presented. This technique enables us to investigate models with arbitrary synaptic response functions that incorporate both leakage across the membrane and a rise time of the postsynaptic potential. The results, which are compared with numerical simulations, are exact in the limit of a large number of small-amplitude inputs. This method is applied to the synchronization problem, in which we examine the relationship between the spread in arrival times of the inputs (the temporal jitter of the synaptic input) and the resultant spread in the times at which the output spikes are generated (output jitter). The results of previous studies, which indicated that the ratio of the output jitter to the input jitter is consistently less than one and that it decreases for increasing numbers of inputs, are confirmed for three classes of the integrate-and-fire model. In addition to the previously identified factors of axonal propagation times and synaptic jitter, we identify the variation in the spike-generating thresholds of the neurons and the variation in the number of active inputs as being important factors that determine the timing jitter in layered networks. Previously observed phase differences between optimally and suboptimally stimulated neurons may be understood in terms of the relative time taken to reach threshold.

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