Topic
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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TL;DR: The use of high-definition transcranial direct current stimulation (HD-tDCS) has shown analgesic effects in some chronic pain patients, but limited anti-nociceptive effects in healthy asymptomatic subjects as mentioned in this paper .
3 citations
TL;DR: The rules for the detection of 2-component compound gratings are tested by extending the range of parameters used in previous experiments by finding clear evidence of suppressive interactions when the compound gratINGS are composed of a close to threshold low frequency component and a below-threshold higher spatial frequency component.
3 citations
01 Jan 1975-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: Latency measurements, measurements on conduction block (due to antidromic invasion of axon branches) and receptive field measurements were used to study the fine branching patterns of primary touch sensitive neurones (pTSN's) in the freshwater snailL. stagnalis.
Abstract: Latency measurements, measurements on conduction block (due to antidromic invasion of axon branches) and receptive field measurements were used to study the fine branching patterns of primary touch sensitive neurones (pTSN's) in the freshwater snailL. stagnalis. The general structure of the receptors of the pTSN's was investigated in experiments on spatial interactions (spatial summation, refractoriness). Axons of pTSN's have a tree-like branching pattern. Their branches end in the skin with many receptors. Each of them can evoke an action potential. The receptors are continuously distributed in the receptive fields of the pTSN's. The receptive fields have a low-threshold region surrounded by an area with high thresholds. The experiments on spatial interactions showed that, in the skin, the receptors can have a diameter of 0.3 mm. Probably, the receptors are dendritic trees. In the dendrites generator potentials arise which summate at the base of the tree to evoke an action potential. Differences in receptor thresholds are probably due to differences in dendritic density of the receptors. The region of the receptors where action potentials are generated is not invaded by antidromic action potentials. Probably this is due to considerable differences in diameter of the receptor and its axon.
3 citations
TL;DR: In this paper, the effect of affective touch on the temporal summation of second pain (TSSP) was investigated in patients with chronic pain, and it was found that AT brought about a decrease of participants' pain as opposed to both discriminative touch and no touch.
3 citations
01 Jan 2001
TL;DR: The implanted cuff electrode previously implanted around the right optic nerve of a blind retinitis pigmentosa patient appears stable in this human application and demonstrates a rather negligible long term drop in the average threshold.
Abstract: This study takes part in the analysis of phosphene perception thresholds as obtained by electrical stimulation through a spiral cuff electrode previously implanted around the right optic nerve of a blind retinitis pigmentosa patient. The enhanced efficiency of higher frequency or multiple pulse stimulation trains indicate temporal integration. Similarly, spatial summation takes place with increasing intensity. Considering a uniform population of typical axons, a rough model of phosphene perception thresholds can be constructed. Therefore, the strength-duration equation is combined with an S shaped axon recruitment curve. A simplified EPSP integrating synaptic mechanism takes temporal and spatial summation into account. Despite the crude approximations, a stable and well fitting model is identified, providing expected values against which all experimental values can be compared, showing obvious fluctuations. The observed changes demonstrate a rather negligible long term drop in the average threshold. The implanted cuff electrode thus appears stable in this human application.
3 citations