Purpose of DasyView

This program aims to read .ddf files produced by DasyLab. The particular objectives are to have rapid redisplay, rapid zoom and to minimise the file size when exported to Word, Powerpoint or other applications, without any loss of the fidelity of the trace.

Problem: In my lab, long periods of data from snail nerve cells are recorded, with file sizes in excess of 10 Mbytes. Because of the large size, the file displays slowly when replayed off-line in DasyLab. Typical traces from nerve cells are periods of little activity alternating with action potentials, in which the voltage changes very quickly and then returns to rest, (see Figure). Thus in a normal display, many data points plot on the same pixel, while during activity simply averaging the data would lose information about how often the action potertials occur and how they relate to the underlying synaptic inputs. When zooming the trace to inspect it closely, on an expanded time scale, we need to maintain a high resolution.

Fig. 1 Traces from 2 snail neurons involved in feeding; the SO interneuron was stimulated at the arrow by turning on a steady positive current and the rhythmic feeding pattern resulted. Note that the voltage changes rapidly up and down during each action potential and only changes slowly in between.
Solution: The dasyview program uses a plotting routine in which the upper and lower limit of the trace in a particular time period is analysed and this controls the data storage. This routine maintains accuracy for nerve cell signals and contains the detail necessary for rapid zooming in and yet permits rapid redisplay. The program reads the files quite slowly, but allows for fast manipulation on screen.

The resolution of this version is set to that of a 300 dpi printed page, so that details which would not show on the page are not processed, making for a more rapid display on screen and quicker printing than in DasyLab. It is recommended that the trace is zoomed in dasyview before exporting to Word or Powerpoint.

.ddf files have a complex format, and not all sub-formats are supported.

Now go on to An Introduction to Using Dasyview or look at the kinds of plots DasyView can make

Page maintained by Chris Elliott

Dasyview 2 help
Last updated on 26/10/00 

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