FRIEND is a graphic-oriented user-friendly software for real-time fMRI processing, multivoxel pattern decoding and neurofeedback. The package integrates routines for image preprocessing in real-time, ROI-based feedback (single-ROI percent signal change and functional connectivity) and brain decoding-based feedback using the FSL and libSVM libraries. FRIEND enables users to create or employ pre-specified visual stimuli for neurofeedback experiments. FRIEND also allows extensive control of processing parameters and includes quality control features.
FRIEND currently comes in two flavours: FRIEND for Windows and FRIEND Engine. The standalone Windows® version runs embedded FSL and libSVM functions and provides a simple, straightforward solution. The FRIEND Engine is a multiplatform (Mac/Linux) toolbox that incorporates the same processing capabilities as noted above, but in which the frontend is separated from the processing module. This allows users to develop their own frontend GUIs while employing FRIEND processing capabilities through TCP/IP communication services. Advanced users can develop plugins to extend the original pipeline provided by the engine (e.g., Matlab functions for data preprocessing and multivariate classification, or stimulus presentation features from standard packages such as E-Prime, for customized feedback). A fully functional frontend is also provided along with the FRIEND Engine distribution.