Nerve cell excitation can be measured optically with a voltage sensitive fluorescence dye.
Activity of nerve cells can be measured by recording their membrane potential. Activated nerve cells fire action potentials. We use a Multi- Site Optical Recording Technique (MSORT) to detect signals from a potentiometric dye (Di-8-ANEPPS) which is incorporated into the cell membrane. The dye changes its fluorescence according to the membrane potential of the cell. These changes are recorded by photodiode or CCD chips technology.
Neuro imaging example
This is an example for the Neuro-Imaging technique we use. The film shows the effect of the neurotransmitter Serotonin (5-HT) on a ganglion of the human submucosal plexus. The outline of the ganglion with several neurons can be seen in black and white in the background. Activity of the neurons is shown colour coded: Red stands for the firing of an action potential.
The film is in slow motion (1:100) and repeated ad infinitum. The original process lasted approximately 0.25s.