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Abstract Reverberation of cortical spreading depression (RCSD) around circular cortical lesions was studied in anesthetized rats. Reverberation was started by KCl injection into an area recovering from a first CSD wave in a narrow region between the lesion and the sagittal sulcus. Frontal lesions 3.3 mm in diameter yielded less reliable reverberation than lesions 5.2 mm in diameter. With continuing reverberation the spreading rate of CSD gradually decreased. Reverberation stopped when the CSD relocity dropped below 2.2 mm/min. With large lesions (5.2 mm in diameter) RCSD lasted longer with frontal (12.2 ± 2.0 cycles) than with parietal (4.0 ± 0.4) and occipital (4.4 ± 0.9) obstacles. Application of 10± KCl on the cortical area between the lesion and the sagittal sulcus could also elicit RCSD because the CSD waves spreading in the rostral and caudal directions were not generated simultaneously and some of them went round the obstacle without being intercepted by the opposite wave. The experimental data agree with the mathematical model of excitation spreading in simply connected sheets of excitable tissue and indicate regional differences in CSD susceptibility in the rat.
Shibata et al. (Tue,) studied this question.