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

  FT_SPIKETRIGGEREDSPECTRUM computes the Fourier spectrup (amplitude and phase) of
  the LFP around the spikes. A phase of zero corresponds to the spike being on the
  peak of the LFP oscillation. A phase of 180 degree corresponds to the spike being in
  the through of the oscillation. A phase of 45 degrees corresponds to the spike being
  just after the peak in the LFP.
 
  Use as
    [sts] = ft_spiketriggeredspectrum(cfg, data)
  or
    [sts] = ft_spiketriggeredspectrum(cfg, data, spike) 
 
  Configurations:
     cfg.method = 'mtmfft' or 'mtmconvol' (see below)
 
  If you specify the method 'mtmconvol', FT_SPIKETRIGGEREDSPECTRUM_CONVOL is used. If
  you specify 'mtmfft', FT_SPIKETRIGGEREDSPECTRUM_FFT is used (which corresponds to the
  old FT_SPIKETRIGGEREDSPECTRUM).
 
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  FT_SPIKETRIGGEREDSPECTRUM_FFT determines the spike phases by taking the
  FFT locally around every spike, for one unit. This is an efficient
  algorithm when we have few neurons recorded simultaneously with low
  firing rates. All frequencies are computed using the same time-window.
 
  The function must then be called as
    [sts] = ft_spiketriggeredspectrum(cfg, data)
  where some channels of DATA are spike channels, and data is in the raw
  format.
 
  For configuration options see FT_SPIKETRIGGEREDSPECTRUM_FFT.
 
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  FT_SPIKETRIGGEREDSPECTRUM_CONVOL computes the Fourier spectrum of the LFP
  around the spikes using convolution of the complete LFP traces. 
  This is a very efficient algorithm if we many spikes per trial. The
  function allows to compute phases for multiple neurons at the same time.
  An additional feature is that every frequency is processed separately (as
  its done through convolution), such that different time-windows can be
  used per frequency.
  Finally, the function can be called by adding a third input (SPIKE) which
  has the same trial definitions as DATA.
 
  The function must then be called as
    [sts] = ft_spiketriggeredspectrum(cfg, data)
  or
    [sts] = ft_spiketriggeredspectrum(cfg, data, spike)
  where the spiking information can either be represented  in the first data
  input or in the second spike input structure.
 
  For configurations options see FT_SPIKETRIGGEREDSPECTRUM_CONVOL
 
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  The output STS data structure can be further analyzed using FT_SPIKETRIGGEREDSPECTRUM_STAT