| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The basis of rhythmic activity observed at the dorsal column nuclei (DCN) is still open to debate. This study has investigated the electrophysiological properties of isolated DCN neurones deprived of any synaptic influence, using the perforated-patch technique. About half of the DCN neurones (64/130) were spontaneously active. More than half of the spontaneous neurones (36/64) showed a low threshold membrane oscillation (LTO) with a mean frequency of 11.4 Hz (range: 4.3-22.1 Hz, n = 20; I = 0). Cells showing LTOs also invariably showed a rhythmic 1.2 Hz clustering activity (groups of 2-5 action potentials separated by silent LTO periods). Also, more than one-third of the silent neurones presented clustering activity, always accompanied by LTOs, when slightly depolarised. The frequency of LTOs was voltage dependent and could be abolished by TTX (0.5 µM) and riluzole (30 µM), suggesting the participation of a sodium current. LTOs were also abolished by TEA (15 mM), which transformed clustering into tonic activity. In voltage clamp, most DCN neurones (85 %) showed a TTX-/riluzole-sensitive persistent sodium current (INa,p), which activated at about -60 mV and had a half-maximum activation at -49.8 mV. An M-like, non-inactivating outward current was present in 95 % of DCN neurones, and TEA (15 mM) inhibited this current by 73.7 %. The non-inactivating outward current was also inhibited by barium (1 mM) and linopirdine (10 µM), which suggests its M-like nature; both drugs failed to block the LTOs, but induced a reduction in their frequency by 56 and 20 %, respectively. These results demonstrate for the first time that DCN neurones have a complex and intrinsically driven clustering discharge pattern, accompanied by subthreshold membrane oscillations. Subthreshold oscillations rely on the interplay of a persistent sodium current and a non-inactivating TEA-sensitive outward current.
This article has been cited by other articles:
|
|
 |
|
  E. V. S. Faustino and D. F. Donnelly An important functional role of persistent Na+ current in carotid body hypoxia transduction J Appl Physiol, October 1, 2006; 101(4): 1076 - 1084. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. B. Rubin and T. A. Cleland Dynamical Mechanisms of Odor Processing in Olfactory Bulb Mitral Cells J Neurophysiol, August 1, 2006; 96(2): 555 - 568. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. J. Kuo, R. H. Lee, L. Zhang, and C. J. Heckman Essential role of the persistent sodium current in spike initiation during slowly rising inputs in mouse spinal neurones J. Physiol., August 1, 2006; 574(3): 819 - 834. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Fernandez de Sevilla, M. Rodrigo-Angulo, A. Nunez, and W. Buno Cholinergic Modulation of Synaptic Transmission and Postsynaptic Excitability in the Rat Gracilis Dorsal Column Nucleus J. Neurosci., April 12, 2006; 26(15): 4015 - 4025. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Wu, A. Enomoto, S. Tanaka, C.-F. Hsiao, D. Q. Nykamp, E. Izhikevich, and S. H. Chandler Persistent Sodium Currents in Mesencephalic V Neurons Participate in Burst Generation and Control of Membrane Excitability J Neurophysiol, May 1, 2005; 93(5): 2710 - 2722. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Rosanova and I. Timofeev Neuronal mechanisms mediating the variability of somatosensory evoked potentials during sleep oscillations in cats J. Physiol., January 15, 2005; 562(2): 569 - 582. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
