FieldTrip has a flexible way of supporting data formats. It uses three wrapper functions that provide a common interface to all electrophysiological (EEG/MEG) file formats: ft_read_header, ft_read_data and ft_read_event. These wrapper functions will call the low-level functions for each file format. Some of the low-level functions are written by ourselves, others are supplied by the manufacturers and again others are obtained from other open source toolboxes. You can find more technical information on the reading functions on this page.

Here is a summary of the data formats that are supported by FieldTrip. Below you can find more details on some of the formats, especially regarding the MEG systems and their auxiliary files (e.g. MRI and volume conduction models). We regularly implement new data formats and this documentation may be out of date, so if yours is not listed here, please check on the discussion list.

The following MEG data formats are supported

• CTF - VSM MedTech (*.ds, *.res4, *.meg4)
• Neuromag - Elekta (*.fif)
• BTi - 4D Neuroimaging (*.m4d, *.pdf, *.xyz, and 4d's raw datafiles)
• Yokogawa (*.ave, *.con, *.raw)
• ITAB data

The following EEG data formats are supported

• ANT - Advanced Neuro Technology, EEProbe (*.avr, *.eeg, *.cnt)
• Biosemi (*.bdf)
• CED - Cambridge Electronic Design (*. smr)
• Electrical Geodesics, Inc. (EGI)(*.egis, *.ave, *.gave, *.ses, *.raw, Meta File Format (mff))
• BESA (*.avr, *.swf)
• NeuroScan (*.eeg, *.cnt, *.avg)
• Nexstim (*.nxe)
• BrainVision (*.eeg, *.seg, *.dat, *.vhdr, *.vmrk)
• generic standard formats (*.edf, *.gdf)

The following EEG/MEG sensor formats are supported

• ASA electrode file
• FCDC Polhemus
• FIL Polhemus
• BESA positions (numeric file with accompanying *.elp and *.ela)
• BESA sfp
• MEG systems (CTF, Neuromag, Yokogawa, BTi-4D)
• SPM8 EEG
• Matlab file with elec or grad struct.

The following spike and LFP data formats are supported (with some limitations)

• Plexon (*.nex, *.plx, *.ddt)
• Neuralynx (*.ncs, *.nse, *.nts, *.nev, *.nrd, *.dma, *.log)
• CED - Cambridge Electronic Design (*.smr)
• MPI - Max Planck Institute (*.dap)
• Windaq (*.wdq)

The following anatomical MRI data formats are supported

• nifti (*.nii / *.nii.gz), using the Freesurfer toolbox
• mgz (*.mgz), using the Freesurfer toolbox
• Analzye (*.hdr, *.img), using the SPM toolbox
• MINC (*.mnc), using the SPM toolbox
• CTF (*.mri)
• ASA (*.mri, *.iso)
• dicom (*.ima)

The following NIRS data formats are supported

• ASCII-formatted data from the machine used at Birkbeck college, London (*.txt)