Data types, Spike trains – Multichannel Systems NeuroExplorer User Manual
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2.1. Data Types
NeuroExplorer supports several data types -- spike trains, behavioral events, time intervals,
continuously recorded data and other data types. The topics in this section describe the data types
used in NeuroExplorer, list the properties of data types, and show how to view and modify various
data types in NeuroExplorer.
2.1.1. Spike Trains
In NeuroExplorer, the most commonly used data type is a spike train. A spike train in NeuroExplorer
does not contain the spike waveforms, it represents only the spike timestamps (the times when the
spikes occurred). A special
data type is used to store the spike waveform values.
are very similar to spike trains. The only difference between spike trains and events is that
spike trains may contain additional information about recording sites, electrode numbers, etc. (for
example, spike trains contain positions of neurons used in the
).
Internally, the timestamps are stored as 32-bit signed integers. These integers are usually the
timestamps recorded by the data acquisition system and they represent time in the so-called time
ticks. For example, the typical time tick for the Plexon system is 25 microseconds, so an event
recorded at 1 sec will have the timestamp equal to 40000.
Limitations
The maximum number of timestamps (in each spike train) in NeuroExplorer is 2,147,483,647. In
reality, the limiting factor is the amount of virtual memory on your machine, since the timestamps of
all the variables of a data file should fit into memory. NeuroExplorer requires that in each spike train
all the timestamps are in ascending order, that is
timestamp[i+1] > timestamp[i] for all i.
NeuroExplorer also requires that
timestamp[i] >= 0 and timestamp[i] < 2,147,483,647 for all i.
The upper timestamp limit defines the maximum experiment length that can be safely analyzed in
NeuroExplorer. Thus, for the standard Plexon setup, the maximum duration of the experiment is
2147483647/40000 seconds, or 14 hours and 54 minutes.
Timestamped Variables in NexScript
You can get access to any timestamp in the current file. For example, to assign the value 0.5 (sec) to
the third timestamp of the variable DSP01a, you simply write:
doc = GetActiveDocument()
doc.DSP01a[3] = 0.5
Viewers
You can view the timestamps of the selected variables in graphical display ( View | 1D Data Viewer
menu command):
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