Using Brian2GeNN

Brian supports generating standalone code for multiple devices. In this mode, running a Brian script generates source code in a project tree for the target device/language. This code can then be compiled and run on the device, and modified if needed. The Brian2GeNN package provides such a ‘device’ to run Brian 2 code on the GeNN (GPU enhanced Neuronal Networks) backend. GeNN is in itself a code-generation based framework to generate and execute code for NVIDIA CUDA. Through Brian2GeNN one can hence generate and run CUDA code on NVIDIA GPUs based solely in Brian 2 input.

Installing the Brian2GeNN interface

In order to use the Brian2GeNN interface, all three Brian 2, GeNN and Brian2GeNN need to be fully installed. To install GeNN and Brian 2, refer to their respective documentation:

Note that you will have to also install the CUDA toolkit and driver necessary to run simulations on a NVIDIA graphics card. These will have to be installed manually, e.g. from NVIDIA’s web site (you can always run simulations in the “CPU-only” mode, but that of course defeats the main purpose of Brian2GeNN…). Depending on the installation method, you might also have to manually set the CUDA_PATH environment variable (or alternatively the devices.genn.cuda_backend.cuda_path preference) to point to CUDA’s installation directory.

To install brian2genn, use pip:

pip install brian2genn

(might require administrator privileges depending on the configuration of your system; add --user to force an installation with user privileges only).

As detailed in the GeNN installation instructions), you also need to ensure that GeNN’s bin directory is added to your path. Alternatively, you can set the devices.genn.path preference to your GeNN directory to achieve the same effect.


We no longer provide conda packages for Brian2GeNN. Conda packages for previous versions of Brian2GeNN have been tagged with the archive label and are still available in the brian-team channel.

Using the Brian2GeNN interface

To use the interface one then needs to import the brian2genn interface:

import brian2genn

The you need to choose the ‘genn’ device at the beginning of the Brian 2 script, i.e. after the import statements, add:


At the encounter of the first run statement (Brian2GeNN does currently only support a single run statement per script), code for GeNN will be generated, compiled and executed.

The set_device function can also take additional arguments, e.g. to run GeNN in its “CPU-only” mode and to get additional debugging output, use:

set_device('genn', use_GPU=False, debug=True)

Not all features of Brian work with Brian2GeNN. The current list of excluded features is detailed in Unsupported features in Brian2GeNN.