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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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Journal Article
TL;DR: In this article, the authors investigated the temporal summation of inner (ipRGC) and outer (rod/cone) retinal inputs to the pupil light reflex (PLR).
Abstract: Purpose: IpRGCs mediate non-image forming functions including photoentrainment and the pupil light reflex (PLR) Temporal summation increases visual sensitivity and decreases temporal resolution for image forming vision, but the summation properties of nonimage forming vision are unknown We investigated the temporal summation of inner (ipRGC) and outer (rod/cone) retinal inputs to the PLR Method: The consensual PLR of the left eye was measured in six participants with normal vision using a Maxwellian view infrared pupillometer Temporal summation was investigated using a double-pulse protocol (100 ms stimulus pairs; 0–1024 ms inter-stimulus interval, ISI) presented to the dilated fellow right eye (Tropicamide 1%) Stimulus lights (blue λmax = 460 nm; red λmax = 638 nm) biased activity to inneror outer retinal inputs to non-image forming vision Temporal summation was measured suprathreshold (152 log photonscm−2s−1 at the cornea) and subthreshold (114 log photonscm−2s−1 at the cornea) Results: RM-ANOVAs showed the suprathreshold and subthreshold 6 second post illumination pupil response (PIPR: expressed as percentage baseline diameter) did not significantly vary for red or blue stimuli (p > 05) The PIPR for a subthreshold red 16 ms double-pulse control condition did not significantly differ with ISI (p > 05) The maximum constriction amplitude for red and blue 100 ms double- pulse stimuli did not significantly vary with ISI (p > 05) Conclusion: The non-significant changes in suprathreshold PIPR and subthreshold maximum pupil constriction indicate that inner retinal ipRGC inputs and outer retinal photoreceptor inputs to the PLR do not show temporal summation The results suggest a fundamental difference between the temporal summation characteristics of image forming and non-image forming vision

1 citations

Dissertation
01 Dec 2012

1 citations

01 Jan 2009
TL;DR: It is demonstrated that certain interneuron subtypes are entrained by two convergent MF inputs to spatially separated regions of the dendritic tree, and this anatomical arrangement could make these interneurons considerably more responsive to the excitatory drive from dentate granule cells.
Abstract: Area CA3 receives two extrinsic excitatory inputs, the mossy fibers (MF), and the perforant path (PP). Interneurons with somata in str. lacunosum moleculare (L-M) of CA3 modulate the influ- ence of the MF and PP on pyramidal cell activity by providing strong feed-forward inhibitory influence to pyramidal cells. Here we report that L-M interneurons receive two separate MF inputs, one to the dorsal dendrites from the suprapyramidal blade of the dentate gyrus (MFSDG), and a second to ventral dendrites from the str. lucidum (MFSL). Responses elicited from MFSDG and MFSL stimulation sites have strong paired-pulse facilitation, similar DCG-IV sensitivity, amplitude, and decay kinetics but target spatially segregated domains on the inter- neuron dendrites. These data demonstrate that certain interneuron sub- types are entrained by two convergent MF inputs to spatially separated regions of the dendritic tree. This anatomical arrangement could make these interneurons considerably more responsive to the excitatory drive from dentate granule cells. Furthermore, temporal summation is linear or slightly sublinear between PP and MFSL but supralinear between PP and MFSDG. This specific boosting of the excitatory drive to interneur- ons from the SDG location may indicate that L-M interneurons could be specifically involved in the processing of the associational component of the recognition memory. V C 2009 Wiley-Liss, Inc.

1 citations


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