Spectral dependence of the intrinsic optical signal of excited states of central gray matter and conformational changes at membrane interfaces

Abstract

Excitation waves and other no-propagation excited states change the optical properties of central gray matter. In transparent tissue, as the retina and the lens are, the intrinsic optical signals (IOS) are macroscopic. This optical signal is created by light scatter and has different components at the red and blue end of the spectrum. The scatter of red light is closely coupled to ionic flow in the extracellular space whereas the blue/green component is the hallmark of propagation onset and probably is coupled to membrane optical properties. The interpretation of the early red scatter as arising from conformational changes coupled to membrane activity led to the prediction that a macroscopic IOS would be present in the transparent lens and that it should present wavelike propagation. Experiments confirmed this prediction.