<p>Current flows from a high potential to a low potential, so if you inject a great deal of current via an electrode it will still flow into the body. However, even in the case of unipolar setups for deep brain stimulation (DBS), a second electrode is used, but relatively far away from the first one. Doing it this way is quite uncommon though: most electrical stimulation uses two poles (or even more), as it limits the spread of current to unwanted areas.</p>
<p><a href="https://i.sstatic.net/tYY0c.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/tYY0c.png" alt="Monopolar vs bipolar deep brain stimulation" /></a></p>
<p>Transcranial direct current stimulation (tDCS) will for instance use an electrode on one side of the scalp and one on the other side.</p>

CC BY-SA 4.0
2021-11-24T14:53:09.700Z
There's always a second pole, even in monopolar stimulation, it just may not be particularly close to the first one.
Bryan Krause
CC BY-SA 4.0
2021-11-24T15:48:22.353Z
@BryanKrause Although physically the current would flow, my answer was a bit misleading with respect to what you say, as a second electrode is indeed used even for monopolar stimulation, so I've amended it.
David Cian
CC BY-SA 4.0
2021-11-24T11:37:14.460Z
2021-11-24T15:49:39.250Z
2021-11-24T15:49:39.250Z
David Cian
<p>With electrostimulation or functional electrostimulation, a response from the neuron is generated by electrical impulses.</p>
<p>But I always read, for example, that a stimulating electrode is above position xy of the neuron (e.g. above the axon), but in order for current to flow, there must be a closed circuit? i.e. if cathodic stimulation is used (e.g. with a -0.5mA pulse lasting 0.05ms), then there must be an anodic pole somewhere so that the current can flow, or am I misunderstanding something?</p>

<neuroscience><cognitive-neuroscience><theoretical-neuroscience><neurophysiology><electrophysiology>
where is the second electrode in case of electrostimulation
CB95
# where is the second electrode in case of electrostimulation

(Asked by: username_0 on 2021-10-16)

With electrostimulation or functional electrostimulation, a response from the neuron is generated by electrical impulses.

But I always read, for example, that a stimulating electrode is above position xy of the neuron (e.g. above the axon), but in order for current to flow, there must be a closed circuit? i.e. if cathodic stimulation is used (e.g. with a -0.5mA pulse lasting 0.05ms), then there must be an anodic pole somewhere so that the current can flow, or am I misunderstanding something?

**Tags:** neuroscience, cognitive-neuroscience, theoretical-neuroscience, neurophysiology, electrophysiology


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## 1 answers

### Answer by username_1 on 2021-11-24. Score: 2

Current flows from a high potential to a low potential, so if you inject a great deal of current via an electrode it will still flow into the body. However, even in the case of unipolar setups for deep brain stimulation (DBS), a second electrode is used, but relatively far away from the first one. Doing it this way is quite uncommon though: most electrical stimulation uses two poles (or even more), as it limits the spread of current to unwanted areas.

[![Monopolar vs bipolar deep brain stimulation](https://i.sstatic.net/tYY0c.png)](https://i.sstatic.net/tYY0c.png)

Transcranial direct current stimulation (tDCS) will for instance use an electrode on one side of the scalp and one on the other side.

> **Comments:**
> **username_2**: There's always a second pole, even in monopolar stimulation, it just may not be particularly close to the first one.  
> **username_1**: @BryanKrause Although physically the current would flow, my answer was a bit misleading with respect to what you say, as a second electrode is indeed used even for monopolar stimulation, so I've amended it.  

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