Freiburg Evoked Potentials (EP2000)

Downloads: EP2000 (data acquisition module)EP2000-Plot.pxp (analysis module)Preferences fileep2000-setup.rtf (Jan 2005) • Stimulusparadigms (incomplete) [all are outdated, contact me for the new versions.]

     —Recent Papers—

“Freiburg Evoked Potentials”(EP2000) fully implements stimulation, recording and analysis of visual evoked potentials, be it from the retina (ERG, PERG) or the cortex (VEP). It runs on any standard recent Macintosh computer in demo mode, and requires just a second graphics card with monitor and the data acquisition card “PCI- MIO-16XE-50” from National Instruments. The system consists of two modules, a program for data acquisition (implemented in C++) and an analysis package running under IGOR Pro by Wavemetrics (the latter comes with full source code). [March 2004: an excellent solution now is to use the PowerMac G4 (1.25 GHz) with the video card “ATI Radeon 9000 Pro”. This model supports Mac OS 9 boot, and the video card can drive two monitors. An “ADC adaptor” to connect the second monitor is necessary. I have just tried this in London and it worked “out of the box”.]

Since Jan 2005 it is no longer possible to buy a suitable Mac from Apple – they don't offer any more OS9-bootable machines. All the more pressing it is to work on the OS X version. We’ll see, I need it myself.

In Jan 2005 EP2000 is routinely in used in 5 labs: Michelle McKerral, Montréal, Canada; Vaegan, Visiontest, Sydney, Australia; Jaegle, Tübingen, Germany; Potter, Boston, USA; and my own. EP2000 has already provided data for a number of publications.

Future roadmap: Analysis tools for grand means (done). Conversion to OS X, EEG acquisition via sound inputs, and plug-in architecture for custom stimuli still under way – I started by porting my ERG & EOG recording systems to OS X, was finished in 2007. Multifocal paradigm planned. Analysis tools are constantly updated in the lab. Should you want to use the system, don't hesitate to request the latest versions, the present page will not be regularly updated. 

     —Some History—


Acquisition module / das Messprogramm

A screenshot of acquisition module just after a 3-checksize sequence has been acquired.

screenshot 1

This is a newer version of the control dialog (bottom left in the figure above) which may help you to appraise some of the options (balloon help is on).

screenshot 1


Analysis module / das Plotprogramm
Two printouts from the analysis package [NB: I choose a pathological VEP here on purpose]:

screenshot plot output 1

The 3 VEP traces on the right were record to 3 different check sizes as shown on the left. The small dots represent the original, unfiltered trace, digitally low-pass filtering at 45 Hz results in the continuous line. All peaks were detected automatically.

The peak latencies of 125 and 122 ms are clearly in the pathologic range, the amplitudes are lower than the normal mean but still in the normal range. There is significant noise intrusion, so (as always, not depicted here) a second recording was performed to assess the reliability of these peaks. 

screenshot plot output 2

4 PERGs: two eyes, two check sizes, rapid stimulus (steady state) with corresponding Fourier spectra on the right.

EP2000 has been used in the following publications: