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

  FT_SPIKEDENSITY computes the spike density function of the spike trains by
  convolving the data with a window.
 
  Use as
    [sdf]          = ft_spike_density(cfg, data)
    [sdf, sdfdata] = ft_spike_density(cfg, data)
  
  If you specify one output argument, only the average and variance of spike density
  function across trials will be computed and individual trials are not kept. See
  cfg.winfunc below for more information on the smoothing kernel to use.
 
  Inputs:
    DATA should be organised in a RAW structure with binary spike
    representations obtained from FT_APPENDSPIKE or FT_CHECKDATA, or
    a SPIKE structure.
 
  Configurations:
    cfg.timwin         = [begin end], time of the smoothing kernel (default = [-0.05 0.05])
                         If cfg.winfunc = @alphawin, cfg.timwin(1) will be
                         set to 0. Hence, it is possible to use asymmetric
                         kernels. 
    cfg.outputunit     = 'rate' (default) or 'spikecount'. This determines the physical unit
                         of our spikedensityfunction, either in firing rate or in spikecount.
    cfg.winfunc        = (a) string or function handle, type of window to convolve with (def = 'gauss').
                         - 'gauss' (default)
                         - 'alphawin', given by win = x*exp(-x/timeconstant)
                         - For standard window functions in the signal processing toolbox see
                           WINDOW.
                         (b) vector of length nSamples, used directly as window
    cfg.winfuncopt     = options that go with cfg.winfunc
                         For cfg.winfunc = 'alpha': the timeconstant in seconds (default = 0.005s)
                         For cfg.winfunc = 'gauss': the standard deviation in seconds (default =
                                          1/4 of window duration in seconds)
                         For cfg.winfunc = 'wname' with 'wname' any standard window function
                                           see window opts in that function and add as cell array
                         If cfg.winfunctopt = [], default opts are taken.
    cfg.latency        = [begin end] in seconds, 'maxperiod' (default), 'minperiod',
                         'prestim'(t>=0), or 'poststim' (t>=0).
    cfg.vartriallen    = 'yes' (default) or 'no'.
                         'yes' - accept variable trial lengths and use all available trials
                          and the samples in every trial. Missing values will be ignored in
                          the computation of the average and the variance.
                         'no'  - only select those trials that fully cover the window as
                          specified by cfg.latency.
    cfg.spikechannel   = cell-array ,see FT_CHANNELSELECTION for details
    cfg.trials         =  numeric or logical selection of trials (default = 'all')
    cfg.keeptrials     = 'yes' or 'no' (default). If 'yes', we store the trials in a matrix
                          in the output SDF as well
    cfg.fsample        = additional user input that can be used when input
                         is a SPIKE structure, in that case a continuous
                         representation is created using cfg.fsample
                         (default = 1000)
 
  The SDF output is a data structure similar to the TIMELOCK structure from FT_TIMELOCKANALYSIS.
  For subsequent processing you can use for example
    FT_TIMELOCKSTATISTICS                Compute statistics on SDF
    FT_SPIKE_PLOT_RASTER                 Plot together with the raster plots
    FT_SINGLEPLOTER and FT_MULTIPLOTER   Plot spike-density alone
 
  The SDFDATA output is a data structure similar to DATA type structure from FT_PREPROCESSING.
  For subsequent processing you can use for example
    FT_TIMELOCKANALYSIS                  Compute time-locked average and variance
    FT_FREQANALYSIS                      Compute frequency and time-ferquency spectrum.