<p>Measuring voltage at a synapse gives you a measure of the <em>input</em> to a cell.</p>
<p>Measuring voltage at the axon hillock (for a typical neuron, practically the soma can substitute as well) gives you a measure of the <em>output</em> of a cell: how near it is to threshold and/or if it has reached threshold and produced a spike.</p>
<p>Measuring voltage at intermediate sites in the dendritic tree can be a measure of spatial integration, which can be quite complex.</p>
<p>All of these measuring sites can be of interest, though there is a lot of variance in how difficult each will be.</p>

CC BY-SA 4.0
2021-02-19T02:15:24.363Z
Thanks for your answer. Yes, I am wondering what is such interest in measuring those miniature inputs at dendritic synapses (which may cancel out/sum up later). Because ultimately action potential depends upon status at the axon hillock.
Science123
CC BY-SA 4.0
2021-02-19T02:37:00.887Z
@Science123 Because sometimes what you're really studying is the inputs and things that modulate them. If you're only interested in output then you might as well just measure spikes. It would be like only being interested in final scores of sports matches, and not broadcasting or having fans in the stands for the rest of the match, because all that matters is the final score. The final score doesn't tell you much about how you got there.
Bryan Krause
CC BY-SA 4.0
2021-02-18T16:40:25.640Z
2021-02-18T16:40:25.640Z
Bryan Krause
<p>I have been reading literature regarding Neuronal potential measurement. Conventionally, researchers use electrode-based method to measure action potential. However, as it's of high invasiveness and low throughput several optical methods such as Genetically encoded voltage indicators (GEVIs) and chemical methods such as Voltage-sensitive dyes (VSDs) are emerging. One fundamental question I came across was GEVIs indeed can be targeted to the site of interest however, there only a few chemical methods targeting specific cell type have been developed. One such recent literature is this one: <a href="https://pubs.acs.org/doi/10.1021/jacs.0c00861" rel="nofollow noreferrer">https://pubs.acs.org/doi/10.1021/jacs.0c00861</a>.
I am wondering, are neuroscience researchers really interested in measuring neuronal potential at individual synapses (which is gradient) or only at the axon hillock (as it's the one which finally matters?). I mean does measuring gradient potential at a defined area is of any interest or is it just another piece of research making no use for neuroscience researchers? (I don't know whether it's useful to synapse plasticity research and all)</p>

<neuroscience><measurement><neurophysiology><neuroimaging>
Measuring postsynaptic potential vs action potential at axon hillock?
Science123
# Measuring postsynaptic potential vs action potential at axon hillock?

(Asked by: username_0 on 2021-02-18)

I have been reading literature regarding Neuronal potential measurement. Conventionally, researchers use electrode-based method to measure action potential. However, as it's of high invasiveness and low throughput several optical methods such as Genetically encoded voltage indicators (GEVIs) and chemical methods such as Voltage-sensitive dyes (VSDs) are emerging. One fundamental question I came across was GEVIs indeed can be targeted to the site of interest however, there only a few chemical methods targeting specific cell type have been developed. One such recent literature is this one: <https://pubs.acs.org/doi/10.1021/jacs.0c00861>.
I am wondering, are neuroscience researchers really interested in measuring neuronal potential at individual synapses (which is gradient) or only at the axon hillock (as it's the one which finally matters?). I mean does measuring gradient potential at a defined area is of any interest or is it just another piece of research making no use for neuroscience researchers? (I don't know whether it's useful to synapse plasticity research and all)

**Tags:** neuroscience, measurement, neurophysiology, neuroimaging


---

## 1 answers

### Answer by username_1 on 2021-02-18. Score: -1

Measuring voltage at a synapse gives you a measure of the *input* to a cell.

Measuring voltage at the axon hillock (for a typical neuron, practically the soma can substitute as well) gives you a measure of the *output* of a cell: how near it is to threshold and/or if it has reached threshold and produced a spike.

Measuring voltage at intermediate sites in the dendritic tree can be a measure of spatial integration, which can be quite complex.

All of these measuring sites can be of interest, though there is a lot of variance in how difficult each will be.

> **Comments:**
> **username_0**: Thanks for your answer. Yes, I am wondering what is such interest in measuring those miniature inputs at dendritic synapses (which may cancel out/sum up later). Because ultimately action potential depends upon status at the axon hillock.  
> **username_1**: @username_0 Because sometimes what you're really studying is the inputs and things that modulate them. If you're only interested in output then you might as well just measure spikes. It would be like only being interested in final scores of sports matches, and not broadcasting or having fans in the stands for the rest of the match, because all that matters is the final score. The final score doesn't tell you much about how you got there.  

---

