Journal of Neurophysiology, Vol 52, Issue 2 264-277, Copyright © 1984 by APS

ARTICLES

Repetitive firing in layer V neurons from cat neocortex in vitro

C. E. Stafstrom, P. C. Schwindt and W. E. Crill

Input-output relations of large neurons from layer V of cat sensorimotor cortex were studied in an in vitro slice preparation using steps and ramps of intracellularly injected current. Depolarization attained during the interspike interval (ISI) was compared to the voltage levels required to activate a previously described (29) persistent sodium current (INaP). INaP was studied using a single-electrode voltage clamp in the same cells tested for firing behavior. Following an injected current step, firing rate declined smoothly to a steady level with a time course that was approximately exponential in most cells (tau, 9-43 ms). In most cells, the relation between firing rate and injected current (f-I relation) consisted of two linear segments, both for adapted, steady firing and for early intervals during adaptation. The slope of the steeper, initial (or sole) linear segment of the f-I curve averaged 26.2 Hz/nA during steady firing and was steeper when plotted for early interspike intervals. The variation of the depolarization at which spike initiation occurred (firing level) and the membrane potential between rhythmic spikes was examined during adaptation and steady firing. In most cells, firing level rose rapidly during a rhythmic train to a steady value. The steady firing level attained remained unchanged over a wide range of steady firing rates. Nevertheless, the mean depolarization during the interspike interval (V) increased approximately linearly with steady firing rate. Even at the slowest firing rates, V is sufficient to activate INaP. The use of injected current ramps demonstrated that neocortical cells were sensitive to rate of change of stimulus current (dI/dt) as well as its amplitude (I). The use of ramps followed by steady currents demonstrated that the repetitive response lagged behind changes in stimulus parameters and did not reach a steady state even during slow ramps; i.e., the response depended on time as well as on I and dI/dt. Instantaneous firing rate during the ramp increased linearly with time for a wide range of ramp slopes (dI/dt). The instantaneous firing rate of early interspike intervals was also linearly related to ramp slope for small ramp slopes. In spite of these linear relationships, quantitative analysis indicated that firing rate during ramp stimulation cannot, in general, be described by a simple linear combination of separate amplitude- and rate-dependent terms. The repetitive firing properties of the in vitro neurons are compared to those of in vivo neocortical neurons and other cell types.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				Y.-M. Chang and J. I. Luebke Electrophysiological Diversity of Layer 5 Pyramidal Cells in the Prefrontal Cortex of the Rhesus Monkey: In Vitro Slice Studies J Neurophysiol, November 1, 2007; 98(5): 2622 - 2632. [Abstract] [Full Text] [PDF]

				J. T. Walter and K. Khodakhah The Linear Computational Algorithm of Cerebellar Purkinje Cells J. Neurosci., December 13, 2006; 26(50): 12861 - 12872. [Abstract] [Full Text] [PDF]

				M. A. Perez, J. Lundbye-Jensen, and J. B. Nielsen Changes in corticospinal drive to spinal motoneurones following visuo-motor skill learning in humans J. Physiol., June 15, 2006; 573(3): 843 - 855. [Abstract] [Full Text] [PDF]

				D. Chen and E. E. Fetz Characteristic Membrane Potential Trajectories in Primate Sensorimotor Cortex Neurons Recorded In Vivo J Neurophysiol, October 1, 2005; 94(4): 2713 - 2725. [Abstract] [Full Text] [PDF]

				B. S. Gutkin, G. B. Ermentrout, and A. D. Reyes Phase-Response Curves Give the Responses of Neurons to Transient Inputs J Neurophysiol, August 1, 2005; 94(2): 1623 - 1635. [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]

				G. La Camera, A. Rauch, H.-R. Luscher, W. Senn, and S. Fusi Minimal Models of Adapted Neuronal Response to In Vivo-Like Input Currents Neural Comput., October 1, 2004; 16(10): 2101 - 2124. [Abstract] [Full Text] [PDF]

				O. Shriki, D. Hansel, and H. Sompolinsky Rate Models for Conductance-Based Cortical Neuronal Networks Neural Comput., August 1, 2003; 15(8): 1809 - 1841. [Abstract] [Full Text]

				S. Franceschetti, T. Lavazza, G. Curia, P. Aracri, F. Panzica, G. Sancini, G. Avanzini, and J. Magistretti Na+-Activated K+ Current Contributes to Postexcitatory Hyperpolarization in Neocortical Intrinsically Bursting Neurons J Neurophysiol, April 1, 2003; 89(4): 2101 - 2111. [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]

				G. Fuhrmann, H. Markram, and M. Tsodyks Spike Frequency Adaptation and Neocortical Rhythms J Neurophysiol, August 1, 2002; 88(2): 761 - 770. [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]

				L. Ris, M. Hachemaoui, N. Vibert, E. Godaux, P. P. Vidal, and L. E. Moore Resonance of Spike Discharge Modulation in Neurons of the Guinea Pig Medial Vestibular Nucleus J Neurophysiol, August 1, 2001; 86(2): 703 - 716. [Abstract] [Full Text] [PDF]

				S. N. Baker, R. Spinks, A. Jackson, and R. N. Lemon Synchronization in Monkey Motor Cortex During a Precision Grip Task. I. Task-Dependent Modulation in Single-Unit Synchrony J Neurophysiol, February 1, 2001; 85(2): 869 - 885. [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]

				M. D. Bevan and C. J. Wilson Mechanisms Underlying Spontaneous Oscillation and Rhythmic Firing in Rat Subthalamic Neurons J. Neurosci., September 1, 1999; 19(17): 7617 - 7628. [Abstract] [Full Text] [PDF]

				I. Lampl, P. Schwindt, and W. Crill Reduction of Cortical Pyramidal Neuron Excitability by the Action of Phenytoin on Persistent Na+ Current J. Pharmacol. Exp. Ther., January 1, 1998; 284(1): 228 - 237. [Abstract] [Full Text]

				P. Schwindt, J. A. O'Brien, and W. Crill Quantitative Analysis of Firing Properties of Pyramidal Neurons From Layer 5 of Rat Sensorimotor Cortex J Neurophysiol, May 1, 1997; 77(5): 2484 - 2498. [Abstract] [Full Text] [PDF]

				M Carandini and D. Heeger Summation and division by neurons in primate visual cortex Science, May 27, 1994; 264(5163): 1333 - 1336. [Abstract] [PDF]