Headstage Tester Units
One of the most important components of a Plexon system is a Headstage Tester Unit (HTU). This seemingly insignificant, small part is actually an essential element when practicing with the system. It also helps with testing prior to data collection, as well as acting as the key component used in troubleshooting.
Plexon HTUs test the functionality of all Plexon data acquisition systems including the OmniPlex® Neural Data Acquisition Systems and the Multichannel Acquisition Processor (MAP) Data Acquisition System.
An HTU, previously known as a headstage test board (HTB) or more affectionately as the artificial rat (ARAT), is a passive breakout board to the headstage input that routes known signals from a function generator or audio source into the headstage input. Pre-recorded analog spike and field potential signals can be played into the HTU with the assistance of a test audio file that contains real recordings of neurons and/or a function generator. As part of this circuit, the HTU serves as an artificial electrode with a 500kΩ impedance.
The combination of using the test audio file with the HTU is especially useful for practice in setting gains and thresholds, running PCA and sorting. Using a function generator with the HTU is an appropriate tool for ensuring the voltage levels at the headstage input are being recorded properly.
Additional troubleshooting and verification can be done using either input source. For example, channel mapping can be verified by running a signal into all channels on the HTU and then shorting an individual channel to ground. Should you need to call Technical Support regarding functionality, the first step you would be asked to complete would be to connect your HTU to the acquisition system.