Journal of Neurophysiology, Vol 69, Issue 6 1865-1879, Copyright © 1993 by APS

ARTICLES

Electrophysiological characterization of different types of neurons recorded in vivo in the motor cortex of the cat. II. Membrane parameters, action potentials, current-induced voltage responses and electrotonic structures

A. Baranyi, M. B. Szente and C. D. Woody
Department of Comparative Physiology, Attila Jozsef University, Szeged, Hungary.

1. Electrical properties of four functional classes [inactivating bursting (ib), noninactivating bursting (nib), fast spiking (fsp), and regular spiking (rsp)] of neurons in the motor cortex of conscious cats were studied with the use of intracellular voltage recording and single-electrode voltage-clamp (SEVC) techniques. Evaluations were made of action potentials and afterpotentials, current-voltage (I-V) relationships, and passive cable properties. Values of membrane potential (Vm), input resistance (RN), membrane time constant (T0), and firing threshold (T50) were also measured. The data were used to extend the electrophysiological classifications of neurons described in the companion paper. 2. Average values of Vm (from -63 to -66 mV), action-potential amplitudes (from 72 to 77 mV), and firing threshold (-54 mV) were not statistically different in different types of neurons. However, the magnitude of intracellularly injected depolarizing current required to induce spike discharge at 50% probability varied significantly (from 0.6 to 1.1 nA) among cell types. The mean RN and T0 measured at Vm varied between 8.3 and 19.8 M omega, and 7.2 and 15.1 ms, respectively, in the cell classes. 3. Action potentials were overshooting. Their mean duration at half amplitude varied from 0.25 to 0.73 ms among different cell types. Three types of action-potential configurations were distinguished. Type I action potentials found in nib and rsp neurons were relatively fast and had a depolarizing afterpotential (DAP) as well as fast and slow after hyperpolarizations (fAHPs, sAHPs). Type II action potentials found in ib and rsp cells had relatively slow rise and decay phases, DAPs, and sAHPs. Their fAHPs were small or absent. Type III action potentials were found exclusively in fsp cells, had very short durations, prominent fAHPs, but no sAHPs. 4. Steady-state I-V relationships were determined by measuring voltage responses to 0.2- to 1.0-nA hyperpolarizing, rectangular current pulses at different membrane potentials. Both RN and T0 exhibited nonlinear behavior over wide ranges of membrane potential; however, between -65 and -75 mV, the I-V relationships varied little, and they appeared constant in most cells. The steady-state values of RN increased with decreasing, and decreased with increasing the membrane potential in all but fsp cells. The I-V relationships were virtually linear in fsp neurons. 5. Transient I-V relationships were studied by measuring voltage responses to depolarizing and hyperpolarizing, rectangular current pulses of increasing amplitude from a preset membrane potential of -70 mV.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				O. Valenti and A. A. Grace Entorhinal Cortex Inhibits Medial Prefrontal Cortex and Modulates the Activity States of Electrophysiologically Characterized Pyramidal Neurons In Vivo Cereb Cortex, July 16, 2008; (2008) bhn114v1. [Abstract] [Full Text] [PDF]

				M. Rudolph, M. Pospischil, I. Timofeev, and A. Destexhe Inhibition Determines Membrane Potential Dynamics and Controls Action Potential Generation in Awake and Sleeping Cat Cortex J. Neurosci., May 16, 2007; 27(20): 5280 - 5290. [Abstract] [Full Text] [PDF]

				T. Tateno and H. P. C. Robinson Phase Resetting Curves and Oscillatory Stability in Interneurons of Rat Somatosensory Cortex Biophys. J., January 15, 2007; 92(2): 683 - 695. [Abstract] [Full Text] [PDF]

				J. A. Luther and S. J. Birren Nerve Growth Factor Decreases Potassium Currents and Alters Repetitive Firing in Rat Sympathetic Neurons J Neurophysiol, August 1, 2006; 96(2): 946 - 958. [Abstract] [Full Text] [PDF]

				M. Rudolph, J. G. Pelletier, D. Pare, and A. Destexhe Characterization of Synaptic Conductances and Integrative Properties During Electrically Induced EEG-Activated States in Neocortical Neurons In Vivo J Neurophysiol, October 1, 2005; 94(4): 2805 - 2821. [Abstract] [Full Text] [PDF]

				S. K. Esser, S. L. Hill, and G. Tononi Modeling the Effects of Transcranial Magnetic Stimulation on Cortical Circuits J Neurophysiol, July 1, 2005; 94(1): 622 - 639. [Abstract] [Full Text] [PDF]

				S. Hill and G. Tononi Modeling Sleep and Wakefulness in the Thalamocortical System J Neurophysiol, March 1, 2005; 93(3): 1671 - 1698. [Abstract] [Full Text] [PDF]

				M. Rudolph and A. Destexhe Characterization of Subthreshold Voltage Fluctuations in Neuronal Membranes Neural Comput., November 1, 2003; 15(11): 2577 - 2618. [Abstract] [Full Text] [PDF]

				L. G. Nowak, R. Azouz, M. V. Sanchez-Vives, C. M. Gray, and D. A. McCormick Electrophysiological Classes of Cat Primary Visual Cortical Neurons In Vivo as Revealed by Quantitative Analyses J Neurophysiol, March 1, 2003; 89(3): 1541 - 1566. [Abstract] [Full Text] [PDF]

				D. M. Porcello, C. S. Ho, R. H. Joho, and J. R. Huguenard Resilient RTN Fast Spiking in Kv3.1 Null Mice Suggests Redundancy in the Action Potential Repolarization Mechanism J Neurophysiol, March 1, 2002; 87(3): 1303 - 1310. [Abstract] [Full Text] [PDF]

				E. Degenetais, A.-M. Thierry, J. Glowinski, and Y. Gioanni Electrophysiological Properties of Pyramidal Neurons in the Rat Prefrontal Cortex: An In Vivo Intracellular Recording Study Cereb Cortex, January 1, 2002; 12(1): 1 - 16. [Abstract] [Full Text] [PDF]

				P. Baraduc, E. Guigon, and Y. Burnod Recoding Arm Position to Learn Visuomotor Transformations Cereb Cortex, October 1, 2001; 11(10): 906 - 917. [Abstract] [Full Text] [PDF]

				B. J. Hefti and P. H. Smith Anatomy, Physiology, and Synaptic Responses of Rat Layer V Auditory Cortical Cells and Effects of Intracellular GABAA Blockade J Neurophysiol, May 1, 2000; 83(5): 2626 - 2638. [Abstract] [Full Text] [PDF]

				E. D. Lumer Effects of Spike Timing on Winner-Take-All Competition in Model Cortical Circuits Neural Comput., January 1, 2000; 12(1): 181 - 194. [Abstract] [Full Text]

				H. A. Swadlow, I. N. Beloozerova, and M. G. Sirota Sharp, Local Synchrony Among Putative Feed-Forward Inhibitory Interneurons of Rabbit Somatosensory Cortex J Neurophysiol, February 1, 1998; 79(2): 567 - 582. [Abstract] [Full Text] [PDF]

				M. Matsumura, D.-f. Chen, T. Sawaguchi, K. Kubota, and E. E. Fetz Synaptic Interactions between Primate Precentral Cortex Neurons Revealed by Spike-Triggered Averaging of Intracellular Membrane Potentials In Vivo J. Neurosci., December 1, 1996; 16(23): 7757 - 7767. [Abstract] [Full Text] [PDF]