|
|
||||||||
Journal of Neurophysiology, Vol 60, Issue 3 869-878, Copyright © 1988 by APS
ARTICLES |
R. Llinas and J. Lopez-Barneo
Department of Physiology and Biophysics, New York University Medical Center, New York 10016.
1. The long-term adaptation of repetitive firing in guinea pig superior colliculus neurons was studied in a mesencephalic slice preparation using intracellular recording techniques. 2. This long-term adaptation was characterized by a decrease in the number of action potentials generated by a depolarizing pulse of constant amplitude applied at frequencies of 0.5-2 Hz. Long-term adaptation appeared in all cells tested regardless of whether they showed short-term spike frequency adaptation during each pulse. 3. Long-term adaptation had a close-to-exponential time course with a time constant of 4.085 +/- 0.675 s (mean +/- SD, n = 8). This phenomenon developed more rapidly as the stimulus frequency increased and was paralleled by a progressive hyperpolarization of the membrane potential which, at the termination of the train of stimuli, remained 6-10 mV more negative than the resting value. 4. The hyperpolarization and the spike frequency adaptation recovered spontaneously in approximately 60 s. The time constant of recovery was 14.66 +/- 1.189 s (n = 4). 5. The afterhyperpolarization (AHP) was also paralleled by a decrease in the input resistance of the cells. This response and the adaptation disappeared after removal of Ca2+ or after addition of Cd2+ to the external solution. This suggests that Ca2+ entry during trains of action potentials activates a Ca2+-dependent K+ conductance with an unusually slow kinetics. 6. This conductance appears to differ from other Ca2+-dependent K+ conductances in that it was blocked by 4-aminopyridine. 7. The properties of this long-term adaptation are remarkably similar to those reported for visual habituation; thus this newly described K+ conductance may be pertinent to the understanding of this behavioral phenomenon.
This article has been cited by other articles:
![]() |
R. Nargeot Long-Lasting Reconfiguration of Two Interacting Networks by a Cooperation of Presynaptic and Postsynaptic Plasticity J. Neurosci., May 1, 2001; 21(9): 3282 - 3294. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. V. Sanchez-Vives, L. G. Nowak, and D. A. McCormick Cellular Mechanisms of Long-Lasting Adaptation in Visual Cortical Neurons In Vitro J. Neurosci., June 1, 2000; 20(11): 4286 - 4299. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Llinas The intrinsic electrophysiological properties of mammalian neurons: insights into central nervous system function Science, December 23, 1988; 242(4886): 1654 - 1664. [Abstract] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |