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

  FT_DATATYPE_SPIKE describes the FieldTrip MATLAB structure for spike data
  Spike data is obtained using FT_READ_SPIKE to read files from a Plexon,
  Neuralynx or other animal electrophysiology data acquisition system. It
  is characterised as a sparse point-process, i.e. each neuronal firing is
  only represented as the time at which the firing happened. Optionally,
  the spike waveform can also be represented. Using this waveform, the
  neuronal firing events can be sorted into their single units.
  A required characteristic of the SPIKE structure is a cell-array with the
  label of the (single or multi) units.
          label: {'unit1'  'unit2'  'unit3'}
  The fields of the SPIKE structure that contain the specific information
  per spike depends on the available information. A relevant distinction
  can be made between the representation of raw spikes that are not related
  to the temporal strucutre of the experimental design (i.e trials), and
  the data representation in which the spikes are related to the trial.
  For a continuous recording the SPIKE structure must contain a cell-array
  with the raw timestamps as recorded by the hardware system. As example,
  the original content of the .timestamp field can be
          timestamp:  {[1x504 uint64]  [1x50 uint64]  [1x101 uint64]}
  An optional field that is typically obtained from the raw recording
  contains the waveforms for every unit and label as a cell-array. For
  example, the content of this field may be
          waveform:   {[1x32x504 double] [1x32x50 double] [1x32x101 double]}
  If the data has been organised to reflect the temporal structure of the
  experiment (i.e. the trials), the SPIKE structure should contain a
  cell-array with the spike times relative to an experimental trigger. The
  FT_SPIKE_REDEFINETRIAL function can be used to reorganise the SPIKE
  structure such that the spike times are expressed relative to a trigger
  instead of relative to the acquisition devices internal timestamp clock.
  The time field then contains only those spikes that ocurred within one of
  the trials . The spike times are now expressed on seconds relative to the
          time:       {[1x504 double] [1x50 double] [1x101 double]}
  In addition, for every spike we register in which trial the spike was
          trial:      {[1x504 double] [1x50 double] [1x101 double]}
  To fully reconstruct the structure of the spike-train, it is required
  that the exact start- and end-point of the trial (in seconds) is
  represented. This is specified in a nTrials x 2 matrix.
          trialtime:  [100x2 double]
  As an example, FT_SPIKE_MAKETRIALS could result in the following
  SPIKE structure that represents the spikes of three units that were
  observed in 100 trials:
          label:           {'unit1'  'unit2'  'unit3'}
          timestamp:       {[1x504 double] [1x50 double] [1x101 double]}
          time:            {[1x504 double] [1x50 double] [1x101 double]}
          trial:           {[1x504 double] [1x50 double] [1x101 double]}
          trialtime:       [100x2 double]
          sampleinfo:      [100x2 double]
          waveform:        {[1x32x504 double] [1x32x50 double] [1x32x101 double]}
          waveformdimord: '{chan}_lead_time_spike'
  For analysing the relation between the spikes and the local field
  potential (e.g. phase-locking), the SPIKE structure can have additional
  fields such as fourierspctrm, lfplabel, freq and fourierspctrmdimord.
  For example, from the structure above we may obtain
          label:          {'unit1'  'unit2'  'unit3'}
          timestamp:      {[1x504 double] [1x50 double] [1x101 double]}
          time:           {[1x504 double] [1x50 double] [1x101 double]}
          trial:          {[1x504 double] [1x50 double] [1x101 double]}
          trialtime:      [100x2 double]
          waveform:       {[1x32x504 double] [1x32x50 double] [1x32x101 double]}
          waveformdimord: '{chan}_lead_time_spike'
          fourierspctrm:  {504x2x20, 50x2x20, 101x2x20}
          fourierspctrmdimord: '{chan}_spike_lfplabel_freq'
          lfplabel:       {'lfpchan1', 'lfpchan2'}
          freq:           [1x20 double]
  Required fields:
    - label
    - timestamp
  Optional fields:
    - unit
    - time, trial, trialtime
    - waveform, waveformdimord
    - fourierspctrm, fourierspctrmdimord, freq, lfplabel  (these are extra outputs from FT_SPIKETRIGGEREDSPECTRUM and FT_SPIKE_TRIGGEREDSPECTRUM)
    - hdr
    - cfg
  Deprecated fields:
    - origtime, origtrial
  Obsoleted fields:
    - <unknown>
  Revision history:
  (2012) Changed the dimensionality of the waveform to allow both
  stereotrode and tetrode data to be represented.
  (2011/latest) Defined a consistent spike data representation that can
  also contain the Fourier spectrum and other fields. Use the xxxdimord
  to indicate the dimensions of the field.
  (2010) Introduced the time and the trialtime fields.
  (2007) Introduced the spike data representation.