Other facilities

DataView has several general-purpose analysis facilities, including the following.

Phase-Plane Analysis

In phase-plane analysis, one time-dependent variable is plotted against another. A common use of phase-plane plots in neuroscience is to provide an alternate visualization of the shapes of features such as spikes or PSPs, which is achieved by plotting the membrane potential (V) against its time derivative (dV/dt) at each moment in time over the duration of the feature. The phase-plane plot can reveal subtle changes in shape over time that are difficult to pick up in an extended record.

Above or left: A whole-cell patch recording from a spinal motorneurone in the tadpole. Below or right: A 3-D phase-plane display of the record, coloured with respect to time. Note the cycle between the yellow and green stages, where the spike failed.

Spike Shape Analysis

Spike threshold can be detected either as an absolute voltage threshold, or the voltage at which a user-specified rate of change of voltage occurs, or the voltage at which the rate of change of voltage changes most rapidly. From the threshold various metrics defining spike shape are calculated and can be displayed.

In this example threshold is defined as the location of the maximum second derivative on the rising phase of the action potential. This is just one possible definition, but it is objective and repeatable.
Spike shape analysis

Lorentz (Poincaré) Return Map

This technique simply involves plotting the value of an item in a sequence against the value of the next item in the sequence. Typically, each item could be the peak (or trough) value of successive cycles in an oscillating system. Plots of this sort can reveal “meta”-rhythms, i.e. rhythms within rhythms like the beat frequency of mixed oscillators, and is used in investigating biological phenomena such as heart beat and respiratory or locomotory rhythms.

Above or left: A noisy sine wave with a 25 ms cycle period. A regular event train have been generated with a 10 ms interval. This means that the events will return to approximately the same value in the data trace every 5th event (50 ms). So there will be 5 different values of Vn/Vn+1 associated with the events. Below or left: The plot of Vn/Vn+1 is a Lorentz return map. Note that because the sine wave is noisy, the values form clusters, rather than exactly-superimposing points. Again, the colour represents the time in the data trace for each point in the plot.

Waveform correlation

Auto- and cross-correlation analysis can be performed on both waveform and event data.

Above or left: A waveform that develops a strong oscillation pattern (it's actually a fly singing). Below or right: The autocorrelation of the waveform, up to a lag of 10 ms.
autocorrelation waveform     autocorrelation

Joint Peristimulus Time Histogram (JPSTH)

A JPSTH can be constructed as descibed by Aertsen et al. (1989, J. Neurophysiol. 61; 900-917), and the MU lab website.


Stimulus-Response Latency Raster

Raster plots can reveal the effects of a stimulus on spike frequency.

Raster plot

Audification (a.k.a. Sound)

Any data file can be played as a sound. You can either play the data at the recording frequency, or, if this is too low, you can select 5 or 11 kHz as the sound frequency. Listening to data played as sound can be a good way of detecting subtle changes in frequency or pattern within the data.
This facility utilises the DirectX sound capabiliy of PCs.

The play sound facility applied to an extracellular recording of the crayfish caudal photoreceptor (cpr) reacting to a light-on stimulus. [This is a screen-capture recording of selecting the Sound: Play menu command.]