The Experts below are selected from a list of 20523 Experts worldwide ranked by ideXlab platform
Robert G Smith - One of the best experts on this subject based on the ideXlab platform.
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spike generator limits efficiency of information transfer in a retinal ganglion cell
The Journal of Neuroscience, 2004Co-Authors: Narender K Dhingra, Robert G SmithAbstract:The quality of the signal a retinal ganglion cell transmits to the brain is important for preception because it sets the minimum detectable stimulus. The ganglion cell converts Graded Potentials into a spike train with a selective filter but in the process adds noise. To explore how efficiently information is transferred to spikes, we measured contrast detection threshold and increment threshold from Graded Potential and spike responses of brisk-transient ganglion cells. Intracellular responses to a spot flashed over the receptive field center of the cell were recorded in an intact mammalian retina maintained in vitro at 37°C. Thresholds were measured in a single-interval forced-choice procedure with an ideal observer. The Graded Potential gave a detection threshold of 1.5% contrast, whereas spikes gave 3.8%. The Graded Potential also gave increment thresholds approximately twofold lower and carried ∼60% more gray levels. Increment threshold “dipped” below the detection threshold at a low contrast (<5%) but increased rapidly at higher contrasts. The magnitude of the “dipper” for both Graded Potential and spikes could be predicted from a threshold nonlinearity in the responses. Depolarization of the cell by current injection reduced the detection threshold for spikes but also reduced the range of contrasts they can transmit. This suggests that contrast sensitivity and dynamic range are related in an essential trade-off.
Narender K Dhingra - One of the best experts on this subject based on the ideXlab platform.
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spike generator limits efficiency of information transfer in a retinal ganglion cell
The Journal of Neuroscience, 2004Co-Authors: Narender K Dhingra, Robert G SmithAbstract:The quality of the signal a retinal ganglion cell transmits to the brain is important for preception because it sets the minimum detectable stimulus. The ganglion cell converts Graded Potentials into a spike train with a selective filter but in the process adds noise. To explore how efficiently information is transferred to spikes, we measured contrast detection threshold and increment threshold from Graded Potential and spike responses of brisk-transient ganglion cells. Intracellular responses to a spot flashed over the receptive field center of the cell were recorded in an intact mammalian retina maintained in vitro at 37°C. Thresholds were measured in a single-interval forced-choice procedure with an ideal observer. The Graded Potential gave a detection threshold of 1.5% contrast, whereas spikes gave 3.8%. The Graded Potential also gave increment thresholds approximately twofold lower and carried ∼60% more gray levels. Increment threshold “dipped” below the detection threshold at a low contrast (<5%) but increased rapidly at higher contrasts. The magnitude of the “dipper” for both Graded Potential and spikes could be predicted from a threshold nonlinearity in the responses. Depolarization of the cell by current injection reduced the detection threshold for spikes but also reduced the range of contrasts they can transmit. This suggests that contrast sensitivity and dynamic range are related in an essential trade-off.
Ramendra N Saha - One of the best experts on this subject based on the ideXlab platform.
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mild membrane depolarization in neurons induces immediate early gene transcription and acutely subdues responses to successive stimulus
bioRxiv, 2020Co-Authors: Kira D A Rienecker, Robert G Poston, Joshua Segales, Ramendra N SahaAbstract:Abstract The transcriptional profile of immediate early genes (IEGs) is indicative of the duration of neuronal activity, but it is unknown whether it affected by the strength of depolarization. Also unknown is whether an activity history of Graded Potential changes influences further neuronal activity. In this work with dissociated rat cortical neurons, we found mild depolarization – mediated by elevated extracellular KCl – not only induces a wide array of rapid IEGs, but also transiently depresses transcriptional and signaling responses to a successive stimulus. This latter effect was independent of de novo transcription, translation, calcineurin (CaN) signaling, and MAPK signaling downstream of PKC. Furthermore, as measured by multiple electrode arrays, mild depolarization acutely subdues subsequent spontaneous and bicuculline-evoked activity. Collectively, this work suggests that a recent history of Graded Potential changes acutely depresses neuronal intrinsic properties and subsequent responses. Such effects may have several Potential downstream implications, including reducing signal-to-noise ratio during Hebbian plasticity processes.
Najafi M. N. - One of the best experts on this subject based on the ideXlab platform.
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On the role of anaxonic local neurons in the crossover to continuously varying exponents for avalanche activity
2020Co-Authors: Rahimi-majd M., Seifi M. A., De Arcangelis L., Najafi M. N.Abstract:Local anaxonic neurons with Graded Potential release are important ingredients of nervous systems, present in the olfactory bulb system of mammalians, in the human visual system, as well as in arthropods and nematodes. We develop a neuronal network model including both axonic and anaxonic neurons and monitor the activity tuned by the following parameters: The decay length of the Graded Potential in local neurons, the fraction of local neurons, the largest eigenvalue of the adjacency matrix and the range of connections of the local neurons. Tuning the fraction of local neurons, we derive the phase diagram including two transition lines: A critical line separating subcritical and supercritical regions, characterized by power law distributions of avalanche sizes and durations, and a bifurcation line. We find that the overall behavior of the system is controlled by a parameter tuning the relevance of local neuron transmission with respect to the axonal one. The statistical properties of spontaneous activity are affected by local neurons at large fractions and in the condition that the Graded Potential transmission dominates the axonal one. In this case the scaling properties of spontaneous activity exhibit continuously varying exponents, rather than the mean field branching model universality class
John S Kauer - One of the best experts on this subject based on the ideXlab platform.
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robust stimulus encoding in olfactory processing hyperacuity and efficient signal transmission
Lecture Notes in Computer Science, 2001Co-Authors: Tim C Pearce, Paul F M J Verschure, Joel White, John S KauerAbstract:We investigate how efficient signal transmission and reconstruction can be achieved within the olfactory system. We consider a theoretical model of signal integration within the olfactory pathway that derives from its convergent architecture and results in increased sensitivity to chemical stimuli between the first and second stages of the system. This phenomenon of signal integration in the olfactory system is formalised as an instance of hyperacuity. By exploiting a large population of chemically sensitive microbeads, we demonstrate how such a signal integration technique can lead to real gains in sensitivity in machine olfaction. In a separate computational model of the early olfactory pathway that is driven by real-world chemosensor input, we investigate how spike-based signal and Graded-Potential signalling compares for supporting the accuracy of reconstruction of the chemical stimulus at later stages of neuronal processing.
