FieldTrip

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:  {[1x993 uint64]  [1x423 uint64]  [1x3424 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:   {[32x993 double] [32x423 double] [32x3224 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
  trigger.
 
          time:       {[1x504 double] [1x50 double] [1x101 double]}
 
  In addition, for every spike we register in which trial the spike was
  recorded:
 
          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_REDEFINETRIALS 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]
          waveform:   {[32x504 double] [32x50 double] [32x101 double]}
          cfg
 
  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:       {[32x504 double] [32x50 double] [32x101 double]}
          fourierspctrm:  {504x2x20, 50x2x20, 101x2x20}
          fourierspctrmdimord: '{chan}_spike_lfplabel_freq'
          lfplabel:       {'lfpchan1', 'lfpchan2'}
          freq:           [1x20 double]
          cfg
 
  Required fields:
    - the combination label and timestamp, or
    - the combination label, time, trial and trialtime
 
  Optional fields:
    - waveform
    - fourierspctrm, fourierspctrmdimord, freq, lfplabel  (these are extra outputs from FT_SPIKETRIGGEREDSPECTRUM and FT_SPIKE_TRIGGEREDSPECTRUM)
    - hdr
    - cfg
 
  Deprecated fields:
    - <unknown>
 
  Obsoleted fields:
    - <unknown>
 
  Revision history:
 
  (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.
 
  See also FT_DATATYPE, FT_DATATYPE_RAW, FT_DATATYPE_FREQ, FT_DATATYPE_TIMELOCK