HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 94/5/3601    most recent 00281.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (25) Citing Articles via Google Scholar Google Scholar Articles by MacLean, J. N. Articles by Harris-Warrick, R. M. Search for Related Content PubMed PubMed Citation Articles by MacLean, J. N. Articles by Harris-Warrick, R. M.

Activity-Independent Coregulation of I_A and I_h in Rhythmically Active Neurons

¹Department of Neurobiology and Behavior, ²Center for Applied Mathematics, and ³Mathematics Department, Cornell University, Ithaca, New York

Submitted 15 March 2005; accepted in final form 27 June 2005

The fast transient potassium or A current (I_A) plays an important role in determining the activity of central pattern generator neurons. We have previously shown that the shal K⁺ channel gene encodes I_A in neurons of the pyloric network in the spiny lobster. To further study how I_A shapes pyloric neuron and network activity, we microinjected RNA for a shal-GFP fusion protein into four identified pyloric neuron types. Neurons expressing shal-GFP had a constant increase in I_A amplitude, regardless of cell type. This increase in I_A was paralleled by a concomitant increase in the hyperpolarization-activated cation current I_h in all pyloric neurons. Despite significant increases in these currents, only modest changes in cell firing properties were observed. We used models to test two hypotheses to explain this failure to change firing properties. First, this may reflect the mislocalization of the expressed shal protein solely to the somata and initial neurites of injected neurons, rendering it electrically remote from the integrating region in the neuropil. To test this hypothesis, we generated a multicompartment model where increases in I_A could be localized to the soma, initial neurite, or neuropil/axon compartments. Although spike activity was somewhat more sensitive to increases in neuropil/axon versus somatic/primary neurite I_A, increases in I_A limited to the soma and primary neurite still evoked much more dramatic changes than were seen in the shal-GFP–injected neurons. Second, the effect of the increased I_A could be compensated by the endogenous increase in I_h. To test this, we modeled the compensatory increases of I_A and I_h with a cycling two-cell model. We found that the increase in I_h was sufficient to compensate the effects of increased I_A, provided that they increase in a constant ratio, as we observed experimentally in both shal-injected and noninjected neurons. Thus an activity-independent homeostatic mechanism maintains constant neuronal activity in the face of dramatic increases in I_A.

This article has been cited by other articles:

				C. E. McKellar and C. J. Shatz Synaptogenesis in Purified Cortical Subplate Neurons Cereb Cortex, August 1, 2009; 19(8): 1723 - 1737. [Abstract] [Full Text] [PDF]

				A. L. Taylor, J.-M. Goaillard, and E. Marder How Multiple Conductances Determine Electrophysiological Properties in a Multicompartment Model J. Neurosci., April 29, 2009; 29(17): 5573 - 5586. [Abstract] [Full Text] [PDF]

				A. J. Fein, M. A. Wright, E. A. Slat, A. B. Ribera, and L. L. Isom scn1bb, a Zebrafish Ortholog of SCN1B Expressed in Excitable and Nonexcitable Cells, Affects Motor Neuron Axon Morphology and Touch Sensitivity J. Neurosci., November 19, 2008; 28(47): 12510 - 12522. [Abstract] [Full Text] [PDF]

				C. Gunay, J. R. Edgerton, and D. Jaeger Channel Density Distributions Explain Spiking Variability in the Globus Pallidus: A Combined Physiology and Computer Simulation Database Approach J. Neurosci., July 23, 2008; 28(30): 7476 - 7491. [Abstract] [Full Text] [PDF]

				K. H. Hobbs and S. L. Hooper Using Complicated, Wide Dynamic Range Driving to Develop Models of Single Neurons in Single Recording Sessions J Neurophysiol, April 1, 2008; 99(4): 1871 - 1883. [Abstract] [Full Text] [PDF]

				P. J. Sjostrom, E. A. Rancz, A. Roth, and M. Hausser Dendritic Excitability and Synaptic Plasticity Physiol Rev, April 1, 2008; 88(2): 769 - 840. [Abstract] [Full Text] [PDF]

				W. J. Brackenbury, T. H. Davis, C. Chen, E. A. Slat, M. J. Detrow, T. L. Dickendesher, B. Ranscht, and L. L. Isom Voltage-Gated Na+ Channel {beta}1 Subunit-Mediated Neurite Outgrowth Requires Fyn Kinase and Contributes to Postnatal CNS Development In Vivo J. Neurosci., March 19, 2008; 28(12): 3246 - 3256. [Abstract] [Full Text] [PDF]

				A. V. Olypher and R. L. Calabrese Using Constraints on Neuronal Activity to Reveal Compensatory Changes in Neuronal Parameters J Neurophysiol, December 1, 2007; 98(6): 3749 - 3758. [Abstract] [Full Text] [PDF]

				O. Khorkova and J. Golowasch Neuromodulators, Not Activity, Control Coordinated Expression of Ionic Currents J. Neurosci., August 8, 2007; 27(32): 8709 - 8718. [Abstract] [Full Text] [PDF]

				D. J. Schulz, J.-M. Goaillard, and E. E. Marder Quantitative expression profiling of identified neurons reveals cell-specific constraints on highly variable levels of gene expression PNAS, August 7, 2007; 104(32): 13187 - 13191. [Abstract] [Full Text] [PDF]

				A. H. Gittis and S. du Lac Firing Properties of GABAergic Versus Non-GABAergic Vestibular Nucleus Neurons Conferred by a Differential Balance of Potassium Currents J Neurophysiol, June 1, 2007; 97(6): 3986 - 3996. [Abstract] [Full Text] [PDF]

				Q. Ouyang, M. Goeritz, and R. M. Harris-Warrick Panulirus interruptus Ih-Channel Gene PIIH: Modification of Channel Properties by Alternative Splicing and Role in Rhythmic Activity J Neurophysiol, June 1, 2007; 97(6): 3880 - 3892. [Abstract] [Full Text] [PDF]

				A. L. Howard, A. Neu, R. J. Morgan, J. C. Echegoyen, and I. Soltesz Opposing Modifications in Intrinsic Currents and Synaptic Inputs in Post-Traumatic Mossy Cells: Evidence for Single-Cell Homeostasis in a Hyperexcitable Network J Neurophysiol, March 1, 2007; 97(3): 2394 - 2409. [Abstract] [Full Text] [PDF]

				D. J. Schulz Plasticity and stability in neuronal output via changes in intrinsic excitability: it's what's inside that counts J. Exp. Biol., December 15, 2006; 209(24): 4821 - 4827. [Abstract] [Full Text] [PDF]

				A. L. Taylor, T. J. Hickey, A. A. Prinz, and E. Marder Structure and Visualization of High-Dimensional Conductance Spaces J Neurophysiol, August 1, 2006; 96(2): 891 - 905. [Abstract] [Full Text] [PDF]