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reference:ft_datatype_spike [2018/08/23 14:43] (current)
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 +=====  FT_DATATYPE_SPIKE =====
 +Note that this reference documentation is identical to the help that is displayed in MATLAB when you type "help ft_datatype_spike"​.
 +  <a href=/​reference/​ft_datatype_spike><​font color=green>​FT_DATATYPE_SPIKE</​font></​a>​ describes the FieldTrip MATLAB structure for spike data
 +  Spike data is obtained using <a href=/​reference/​ft_read_spike><​font color=green>​FT_READ_SPIKE</​font></​a>​ 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
 +  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, <a href=/​reference/​ft_spike_maketrials><​font color=green>​FT_SPIKE_MAKETRIALS</​font></​a>​ 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'​
 +          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: ​      ​{[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 <a href=/​reference/​ft_spiketriggeredspectrum><​font color=green>​FT_SPIKETRIGGEREDSPECTRUM</​font></​a>​ and FT_SPIKE_TRIGGEREDSPECTRUM)
 +    - hdr
 +    - cfg
 +  Deprecated fields:
 +    - origtime, origtrial
 +  Obsoleted fields:
 +    - &​lt;​unknown&​gt;​
 +  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.
 +  See also <a href=/​reference/​ft_datatype><​font color=green>​FT_DATATYPE</​font></​a>,​ <a href=/​reference/​ft_datatype_raw><​font color=green>​FT_DATATYPE_RAW</​font></​a>,​ <a href=/​reference/​ft_datatype_freq><​font color=green>​FT_DATATYPE_FREQ</​font></​a>,​ <a href=/​reference/​ft_datatype_timelock><​font color=green>​FT_DATATYPE_TIMELOCK</​font></​a>​