Intan RHD USB#

Annotated settings interface for the Intan RHD USB plugin
Streams data from an Intan RHD USB Interface Board.#

Plugin Type



Windows, Linux, macOS

Built in?

No; install via Rhythm Plugins

Key Developers

Josh Siegle, Aarón Cuevas López

Source Code


Installing and upgrading#

The Intan RHD USB plugin is not included by default in the Open Ephys GUI. To install, use ctrl-P or ⌘P to open the Plugin Installer, browse to the “Rhythm Plugins”, and click the “Install” button. After installation, Intan RHD USB will appear in the processor list on the left side of the GUI’s main window.

The Plugin Installer also allows you to upgrade to the latest version of this plugin, if it’s already installed. The plugin must be removed from the signal chain prior to upgrading.

Plugin configuration#


On the left-hand side of the module, there are slots for each of 8 possible headstages (A1, A2, B1, B2, etc.). Each row corresponds to one 12-channel Omnetics connector on the input board (from left to right, there are A, B, C, and D), and each column corresponds to one headstage on that input. Up to two headstages can be connected to each input using a dual headstage adapter. The module will automatically detect headstages that are connected, as well as whether they contain a 64- or 32-channel Intan chip. However, if you add or remove headstages after the module has been loaded, you need to press the “RESCAN” button.

Using 16-channel headstages#

Clicking on the button for one of the detected headstages will toggle it between 32-channel and 16-channel mode. This is necessary because the difference between 16-channel and 32-channel headstages cannot detected in software, and has to be selected manually.

Sample rate selection#

Sample rates between 1 and 30 kHz can be selected with this drop-down menu. This will determine the sample rate for all headstages, digital inputs, and ADCs.

Bandwidth interface#

Used to determine the settings for the analog high and low cut filters on the Intan chip. Because only certain values are possible for each, the number that appears may be different from the number you typed in; the chip will automatically select the nearest value, and that will be indicated in the GUI.

Turning on AUX channels#

Pressing the “AUX” button toggles the headstage AUX inputs on and off. Each Intan chip can communicate with up to 3 “auxiliary” inputs, which are connected to a 3-axis accelerometer on some headstages. If the button is off (gray), the AUX channels on each headstage will be ignored. If the button is on (yellow), they will be sent as parallel data channels, with the same sampling rate as the neural data.

Turning on ADC channels#

Pressing the “ADC” button toggles the ADC inputs on and off. If the button is off (gray), the ADC channels acquired by the board will be discarded. If the button is on (yellow), they will be sent as parallel data channels, with the same sampling rate as the neural data.

Audio output#

The “AUDIO OUT” interface will allow you select up to 2 channels to preview in real time, directly from the board. There is an audio jack on the board that’s mirrored to the first two analog output channels. To select a channel for monitoring, click on one of the two “Audio Out” buttons to reveal the pop-up channel selector.


In general, we recommend using the Audio Monitor plugin to listen to spikes through your computer’s speakers, as it is much more flexible.

Noise slicer#

Sets the threshold for the noise slicer on the hardware audio outputs (sets any values below threshold to zero, to improve the signal-to-noise ratio). In practice, this doesn’t work particularly well.

Clock divider#

The BNC connector on the back of the board will send a digital pulse each time a new sample is acquired. The clock divided makes it possible to downsample this clock, so a pulse is sent every N samples. Note that N can only be one or an even number, even though this is not enforced via the settings interface.

DSP button#

in addition to the analog filters, the Intan chips also have an on-chip DSP high-pass filter for removing the DC offset on each channel. This can be toggled on and off by clicking the “DSP” button (yellow = on), and the cutoff frequency can be changed by typing a value into the associated text box. Again, there are only certain values for the cutoff frequency; the chip will choose the one closest to what you selected and return this value to the GUI.


When this button is on, the digital-to-analog converter (DAC) will generate TTL outputs whenever the output signal crosses a threshold. Note that this is an untested feature and not recommended for experiments.

DAC High-pass filter#

Sets the high-pass filter cutoff frequency for the DAC outputs.

TTL settle#

Ties one of the digital inputs on the acquisition board/evaluation board to the “fast-settle” functionality of the Intan chips. If the selected digital input channel goes high, it will trigger the reset of the amplifiers across all headstages.

Impedance testing#

To open the impedance measurement interface, click the “window” or “tab” buttons at the top of the plugin editor. This will bring up an impedance measurement interface that looks like this:

Annotated impedance measurement interface