ORIGINAL RESEARCH article
Front. Neurosci.
Sec. Neural Technology
Volume 19 - 2025 | doi: 10.3389/fnins.2025.1620654
This article is part of the Research TopicOptical interrogation of the nervous system: recent advances in optical techniques and their applicationsView all articles
Contribution of individual excitatory synapses on dendritic spines to electrical signalling
Provisionally accepted
- 1Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, Connecticut, United States
- 2Brain research Center Tsing Hua University, Hsinchu, 30013, Taiwan
- 3Volume Institute, Portland, Oregon, United States
- 4Volume Institute, Portland, United States
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Dendritic spines, ~1 µm protrusions from neuronal dendrites that receive most of the excitatory synaptic inputs in the mammalian brain, are widely considered the elementary computational units in the nervous system. The electrical signalling in spines is not fully understood, primarily for methodological reasons. We combined the techniques of whole-cell recording and voltage imaging to study excitatory postsynaptic potentials evoked by two-photon glutamate uncaging (uEPSPs) on individual dendritic spines on basal dendrites in rat cortical slices. We analyzed the initiation, temporal summation, and propagation of uEPSPs from the spine head to the parent dendrites in three principal neocortical pyramidal neuron classes. The data show no significant attenuation of uEPSPs across the spine neck in most tested mushroom spines on basal dendrites. This result implies that synapses on examined spines are not electrically isolated from parent dendrites and that spines do not serve a meaningful electrical role. Using the same imaging techniques, we characterized the temporal summation of uEPSPs induced by repetitive glutamate uncaging, mimicking the burst activity of presynaptic neurons. We found that summing responses to high-frequency repetitive quantal EPSPs is strictly limited in amplitude and waveform. This finding reveals a biophysical mechanism for preventing synaptic saturation.
Keywords: Spines, Dendrites, Synapses, AMPA, Voltage Imaging
Received: 30 Apr 2025; Accepted: 13 Jun 2025.
Copyright: © 2025 Zecevic, Weng and Ceballos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dejan Zecevic, Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, 06520, Connecticut, United States
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