> For the complete documentation index, see [llms.txt](https://engle-lab.gitbook.io/lab-manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://engle-lab.gitbook.io/lab-manual/study-protocols/muri/muri-session-3/iii.-impedance-check.md).

# III. Impedance Check

{% hint style="danger" %}
**Required PPE: Gloves, Lab Coat**
{% endhint %}

***

{% stepper %}
{% step %}

### Plug in the EEG Connector

* Plug in the connector with the <mark style="color:blue;">**wire pointing down**</mark> &#x20;
* Turn the lock mechanism to the <mark style="color:blue;">**right**</mark> to lock and close

<figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2FXicWWIIfEfHwmbEN48wz%2F9.gif?alt=media&amp;token=7ba19ed8-55ca-4dc7-a995-98f1faf0a9f9" alt="" width="188"><figcaption></figcaption></figure>
{% endstep %}

{% step %}

### Open & Run NetStation on the Mac

{% hint style="info" %}
**Mac Password:** geodesic
{% endhint %}

* Select the blue EEG icon, third from the left in the home bar

<figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2F0UAyQ3CoNGFMAbWw0RNI%2F10.gif?alt=media&amp;token=2c5713ca-27ad-4c89-96b3-3a07c8d125cf" alt="" width="188"><figcaption></figcaption></figure>

* Enter the participant ID: <mark style="color:blue;">**19XXX**</mark>
* Select the "On/Off" toggle in the top left corner for streaming the EEG signal

<figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2FVCqRxEdTfHs0b90qvn42%2F13.gif?alt=media&amp;token=2f81d046-816e-4c01-b50a-834bac5fabbe" alt="" width="188"><figcaption></figcaption></figure>

* Allow the signal to cycle once before moving on

<figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2FtoKC5kXxly2zXXDKSU1O%2F14.gif?alt=media&amp;token=a8447b4e-0cf2-41a6-a2bf-b4b0f5489273" alt="" width="188"><figcaption></figcaption></figure>
{% endstep %}

{% step %}

### Check Impedance

* Select the omega (<mark style="color:blue;">**Ω**</mark>) symbol in the bottom left corner

<figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2FtVHmO9vox9Lq4qfPr4w1%2F17.gif?alt=media&amp;token=7d462e71-8e11-4ae9-8e8c-ba175502fcfb" alt="" width="188"><figcaption></figcaption></figure>

* Locate the display switch under the researcher screen and press the **"**&#x53;elect" button on the right side of the device to switch the participant's computer display to the Mac's

  * Option 1: Participant PC
  * Option 2: EEG Mac

  <figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2FddRDgh53jRgQ0vrUhWcF%2F15.gif?alt=media&amp;token=9952f748-f74c-4446-abec-d8dadbe96281" alt="" width="188"><figcaption></figcaption></figure>
* Identify and adjust the high-impedance electrodes (<mark style="color:red;">**red**</mark> and <mark style="color:yellow;">**yellow**</mark>)

  * All electrodes ideally should be either <mark style="color:green;">**green**</mark> or <mark style="color:blue;">**blue**</mark>

    <figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2F6tDWeougA8hugOF9JqYO%2F18.gif?alt=media&amp;token=8fcc7fe1-7097-45fe-8105-362deeed6241" alt="" width="188"><figcaption></figcaption></figure>
  * Gently move the electrode around to make better contact the scalp
  * If necessary, add <mark style="color:blue;">**one small drop**</mark> of electrolyte solution using a pipet onto the sponge of the electrode

    <figure><img src="https://1783073691-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FXc1cErLYtkyOjWlG5P3Z%2Fuploads%2F0h9mkgDsNa2u4qy3BErP%2F19.gif?alt=media&amp;token=5304d1da-4c2c-491f-9ca2-1c20b17d15f9" alt="" width="188"><figcaption></figcaption></figure>

  <div data-gb-custom-block data-tag="hint" data-style="warning" class="hint hint-warning"><p><strong>Do not overuse electrolyte solution or soak the participant's scalp to avoid bridging electrodes</strong></p></div>

  * Select "Save" in the bottom right when finished
  * Switch the participant monitor back to its PC screen
    {% endstep %}
    {% endstepper %}