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Summation

About: Summation is a research topic. Over the lifetime, 954 publications have been published within this topic receiving 45593 citations. The topic is also known as: summation & sum of a sequence.


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Book ChapterDOI
01 Jan 1982
TL;DR: In the central nervous system, the analysis of the postsynaptic action of putative neurotransmitter substances on single neurones is based on the assumption that the action of many excitatory and inhibitory substances may be explained by supposing that they open channels or pathways through the membrane for one or more ions.
Abstract: In the central nervous system, the analysis of the postsynaptic action of putative neurotransmitter substances on single neurones is based on the assumption that the action of many excitatory and inhibitory substances may be explained by supposing that they open channels or pathways through the membrane for one or more ions [see review by Ginsborg, 1967). For excitatory substances, the channels would be selective for Na+ and perhaps one other ion species and for inhibitory substances K+ or C1-. For the most part, the evidence comes from intracellular studies in which orthodromic stimulation of a particular pathway, or the extracellular iontophoresis of a particular substance is shown to alter both the excitability and electrical properties of the cell under study. It is convenient to describe the actions of putative transmitters in electrical terms.
Journal ArticleDOI
TL;DR: A new method to quantify generalization from components to compound in summation experiments, which is applied to over 250 measurements of summation in rabbits, pigeons, rats, and humans and confirms that more summation occurs with stimuli from different rather than from the same sensory modality.
Abstract: In summation experiments, responding to a compound stimulus is assessed after conditioning a response to each of its components. This simple experiment poses significant challenges to models of associative learning because of substantial variability in results. Here, I introduce a new method to quantify generalization from components to compound in summation experiments, which I apply to over 250 measurements of summation in rabbits, pigeons, rats, and humans. The analysis confirms that more summation occurs with stimuli from different rather than from the same sensory modality, although this is not the sole determinant of summation. A theoretical analysis shows that this finding is best accounted for by a model that includes both element sharing (Rescorla & Wagner, 1972) and element replacement (Brandon et al., 2000) in stimulus representations. I point out remaining gaps in our empirical and theoretical understanding of summation. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Journal ArticleDOI
TL;DR: In this paper , the authors used a near-infrared laser (1475 nm) to activate rat dorsal root ganglion (DRG) neurons with short punctate radiant heat pulses (55 µm diameter) and investigated temporal and spatial summation properties for the transduction process for noxious heat at a subcellular level.
Abstract: We studied the efficacy of a near-infrared laser (1475 nm) to activate rat dorsal root ganglion (DRG) neurons with short punctate radiant heat pulses (55 µm diameter) and investigated temporal and spatial summation properties for the transduction process for noxious heat at a subcellular level. Strength-duration curves (10-80 ms range) indicated a minimum power of 30.2mW for the induction of laser-induced calcium transients and a chronaxia of 13.9 ms. However, threshold energy increased with increasing stimulus duration suggesting substantial radial cooling of the laser spot. Increasing stimulus duration demonstrated suprathreshold intensity coding of calcium transients with less than linear gains (Stevens exponents 0.29/35mW, 0.38/60mW, 0.46/70mW). The competitive TRPV1 antagonist capsazepine blocked responses to short near-threshold stimuli and significantly reduced responses to longer duration suprathreshold heat. Heating 1/3 of the soma of a neuron was sufficient to induce calcium transients significantly above baseline (p < 0.05), but maximum amplitude was only achieved by centering the laser over the entire neuron. Heat-induced calcium increase was highest in heated cell parts but rapidly reached unstimulated areas reminiscent of spreading depolarization and opening of voltage-gated calcium channels. Full intracellular equilibrium took about 3 s, consistent with a diffusion process. In summary, we investigated transduction mechanisms for noxious laser heat pulses in native sensory neurons at milliseconds temporal and subcellular spatial resolution and characterized strength duration properties, intensity coding, and spatial summation within single neurons. Thermal excitation of parts of a nociceptor spread via both membrane depolarization and intracellular calcium diffusion.
Journal ArticleDOI
TL;DR: It is pointed out that the nociceptive system is more accurate than the tactile system when controlling for the stimulus modality and intensity in healthy pain-free individuals and shows that the pattern of distance-based and areabased spatial summation of pain is modality independent.
Abstract: Previous studies investigating spatial acuity measured by two-point discrimination threshold concluded that the nociceptive system is less accurate than the innocuous tactile system. In the discussed article, the authors point out that the nociceptive system is more accurate than the tactile system when controlling for the stimulus modality and intensity in healthy pain-free individuals. Furthermore, this article shows that the pattern of distance-based and areabased spatial summation of pain is modality independent.
01 Jan 1999
TL;DR: The experiments indicate that under certain conditions, both mechanisms may operate, but that the process of neural integration is an exclusive characteristic of the Pacinian (P) channel.
Abstract: Temporal summation, a decrease in the detection threshold that occurs when either the duration of a stimulus or the number of stimuli in a sequence is increased, has been attributed to the operations of either the mechanism of neural integration or of probability summation. Our experiments indicate that under certain conditions, both mechanisms may operate, but that the process of neural integration is an exclusive characteristic of the Pacinian (P) channel. The P channel was isolated by applying 250 Hz stimuli through a 1.5 cm 2 contactor to the thenar eminence of the hand and the NPII channel was isolated by applying the stimuli through a 0.01 cm 2 contactor. The finding that the slopes of the psychometric functions were the same within both channels indicated that probability summation could not account for temporal summation for stimulus durations less than 1 s. The finding that the threshold for the detection of multiple-pulse stimuli increased as the interpulse interval increased indicated that, for time intervals less than 800 ms, temporal summation results from neural integration. But for interstimulus intervals greater than 800 ms, probability summation accounts for temporal summation.

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202323
202234
202118
20204
201911
201812