Correlation of the electrical and intrinsic optical signals in the chicken spreading depression phenomenon

This paper presents some results on the correlation between the electrophysiological and intrinsic optical signals (IOS) of spreading depression waves in chicken retinae. We first show that the peak of the time derivative of the electrophysiological wave occurs precisely when the optical signal reaches the electrode tip. Second, by comparing bath applications of propranolol and glycerol it can be shown that the slow potential shift is not directly correlated to the intrinsic optical signal. Propranolol depresses the amplitude of the electrical wave, although the intrinsic optical signal continues being visible. On the other hand, we observe total absence of the IOS under glycerol, while the electrical wave is always present. Correlations of this kind are relevant for a deeper understanding of the underlying mechanisms of the spreading depression phenomenon.