Stimulus-isolation units

Stimulus isolation units Iso-Hex (A.M.P.I., Jemsalem, Israel) provides either constant current or constant voltage stimulation. 

In some instances, a more sophisticated stimulus-isolation unit is used as is shown in block-diagram form in Figure 7.37 (Strong, 1970). 

The conventional stimulus-isolation-unit (SIU) method in neurological recording is illustrated in Figure 10.2a and its electric-circuit equivalent in 10.2b. Using Laplace transform notation,... 

Figure 10.2. (a) Neurological recording system using a stimulus-isolation unit, (b) Electrical circuit model of (a). 

Signal distortion in electrophysiological recording systems may arise from a variety of sources series ac polarization impedance developed at electrode-electrolyte interfaces fluid interfaces in glass microelectrode systems and associated fluctuations of tip potentials and related phenomena stimulus-isolation units residual and stray capacitances not corrected for by compensating preamplifiers contact problems thermal noise and noise generated by other sources. 

---