Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_read_header”.

  FT_READ_HEADER reads header information from a variety of EEG, MEG and LFP
  files and represents the header information in a common data-independent
  format. The supported formats are listed below.
  Use as
    hdr = ft_read_header(filename, ...)
  Additional options should be specified in key-value pairs and can be
    'headerformat'   = string
    'fallback'       = can be empty or 'biosig' (default = [])
    'checkmaxfilter' = boolean, whether to check that maxfilter has been correctly applied (default = true)
    'chanindx'       = list with channel indices in case of different sampling frequencies (only for EDF)
    'coordsys'       = string, 'head' or 'dewar' (default = 'head')
    'coilaccuracy'   = can be empty or a number (0, 1 or 2) to specify the accuracy (default = [])
  This returns a header structure with the following elements
    hdr.Fs                  sampling frequency
    hdr.nChans              number of channels
    hdr.nSamples            number of samples per trial
    hdr.nSamplesPre         number of pre-trigger samples in each trial
    hdr.nTrials             number of trials
    hdr.label               Nx1 cell-array with the label of each channel
    hdr.chantype            Nx1 cell-array with the channel type, see FT_CHANTYPE
    hdr.chanunit            Nx1 cell-array with the physical units, see FT_CHANUNIT
  For some data formats that are recorded on animal electrophysiology
  systems (e.g. Neuralynx, Plexon), the following optional fields are
  returned, which allows for relating the timing of spike and LFP data
    hdr.FirstTimeStamp      number, represented as 32 bit or 64 bit unsigned integer
    hdr.TimeStampPerSample  number, represented in double precision
  For continuously recorded data, nSamplesPre=0 and nTrials=1.
  Depending on the file format, additional header information can be
  returned in the hdr.orig subfield.
  The following MEG dataformats are supported
    CTF - VSM MedTech (*.ds, *.res4, *.meg4)
    Neuromag - Elekta (*.fif)
    BTi - 4D Neuroimaging (*.m4d, *.pdf, *.xyz)
    Yokogawa (*.ave, *.con, *.raw)
    NetMEG (*.nc)
    ITAB - Chieti (*.mhd)
    Tristan Babysquid (*.fif)
  The following EEG dataformats are supported
    ANT - Advanced Neuro Technology, EEProbe (*.avr, *.eeg, *.cnt)
    BCI2000 (*.dat)
    Biosemi (*.bdf)
    BrainVision (*.eeg, *.seg, *.dat, *.vhdr, *.vmrk)
    CED - Cambridge Electronic Design (*.smr)
    EGI - Electrical Geodesics, Inc. (*.egis, *.ave, *.gave, *.ses, *.raw, *.sbin, *.mff)
    GTec (*.mat)
    Generic data formats (*.edf, *.gdf)
    Megis/BESA (*.avr, *.swf, *.besa)
    NeuroScan (*.eeg, *.cnt, *.avg)
    Nexstim (*.nxe)
    TMSi (*.Poly5)
    Mega Neurone (directory)
    Natus/Nicolet/Nervus (.e files)
    Nihon Kohden (*.m00) 
  The following spike and LFP dataformats are supported
    Neuralynx (*.ncs, *.nse, *.nts, *.nev, *.nrd, *.dma, *.log)
    Plextor (*.nex, *.plx, *.ddt)
    CED - Cambridge Electronic Design (*.smr)
    MPI - Max Planck Institute (*.dap)
    Neurosim  (neurosim_spikes, neurosim_signals, neurosim_ds)
    Windaq (*.wdq)
  The following NIRS dataformats are supported
    BUCN - Birkbeck college, London (*.txt)
  The following Eyetracker dataformats are supported
    EyeLink - SR Research (*.asc)
    Tobii - (*.tsv)
    SensoMotoric Instruments - (*.txt)