Responsiveness of a neural pacemaker near the bifurcation point

• Published in: Neuroscience letters 2006-01, Vol.392 (1), p.105-109
• Main Authors: Yang, Jing, Duan, Yu-Bin, Xing, Jun-Ling, Zhu, Jun-Ling, Duan, Jian-Hong, Hu, San-Jue
• Format: Article
• Language: English
• Subjects: Action Potentials - physiology; Action Potentials - radiation effects; Animals; Bifurcation; Biological and medical sciences; Biological Clocks - drug effects; Biological Clocks - physiology; Calcium - metabolism; Chelating Agents - pharmacology; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Egtazic Acid - pharmacology; Electric Stimulation - methods; Female; Firing; Fundamental and applied biological sciences. Psychology; Male; Neural Inhibition - drug effects; Neural Inhibition - physiology; Neural Inhibition - radiation effects; Neurons; Neurons - drug effects; Neurons - physiology; Neurons - radiation effects; Nonlinear Dynamics; Pacemaker; Rats; Rats, Sprague-Dawley; Response; Sciatic Neuropathy - physiopathology; Stimulus; Vertebrates: nervous system and sense organs
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2005.09.007

We compared the responsiveness of a neural firing pacemaker in different dynamic states during the process of period-adding bifurcation to excitatory and inhibitory electrical field stimulus. In the region far from the bifurcation point, with the increase of the intensity of excitatory stimulus, the firing rate increased in an approximately linear manner and no firing pattern transition was observed. While in the region near the bifurcation point, the firing rate increased markedly higher accompanied with the transition of firing pattern when the intensity of excitatory stimulus remained the same. The stimulus-response of the region near the bifurcation point shifted upward significantly compared to that of the region far from the bifurcation point. Inhibitory stimulus with the same intensity, however, decreased the firing rate slightly without the transition of firing pattern in the region near the bifurcation point. These results suggest that the responsiveness in the region near the bifurcation point is more sensitive than that in the region far from the bifurcation point, which we named “critical sensitivity”, and this has directional selectivity.