Is Conditioning Supported by Modulation of an Outward Current in Pyramidal Cells of the Motor Cortex of Cats?
Layer V pyramidal cells of the motor cortex of cats are necessary for short-latency blink conditioning (Woody et al., 1974). Increases in their excitability support production of this learned motor response (Woody et al., 1970; Woody and Engel, 1972; Woody and Black-Cleworth, 1973; Brons and Woody, 1980). Early evidence suggested (Woody and Black-Cleworth, 1973) that a decreased postsynaptic conductance might support the excitability increase. Further studies indicate that the input resistance (R m) of these cells is increased by acetylcholine (ACh), cGMP, and cGMP-dependent protein kinase (cGPK) but not by cAMP or Ca2+ (Woody et al., 1978, 1986; Swartz and Woody, 1979, 1984; Wallis et al., 1982; Bartfai et al., 1985; Woody and Gruen, 1986b). The increase in R m is persistent when depolarization-induced cell discharge accompanies application of ACh, cGMP, or cGPK. Recent studies using single-electrode voltage-clamp techniques in vivo now provide direct evidence that ACh and cGPK decrease a net outward current in these cells (Woody and Gruen, 1986a). We suggest that a persistent decrease in this current may mediate the excitability increase that supports short-latency conditioned blinking.
KeywordsMotor Cortex Outward Current Input Resistance Dendritic Tree Conditioned Eyeblink
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- Aou, S., Woody, C. D., Chapman, C. D., Oomura, Y., and Nishino, H., 1985, Reduced afterhyperpolarization and rapid activation of cortical cells produced by electrical stimulation of hypothalamus in monkey and cat, Soc. Neurosci. Abstr. 11: 983.Google Scholar
- Aou, S., Birt, D., and Woody, C. D., 1986, Activity and excitability of neurons of the cat pericruciate cortex after rapid acquisition of conditioned blink responses and during extinction, Soc. Neurosci. Abstr. 12: 555.Google Scholar
- Bartfai, T., Woody, C. D., Gruen, E., Nairn, A., and Greengard, P., 1985, Intracellular injection of cGMPdependent protein kinase results in increased input resistnce in neurons of the mammalian motor cortex, Soc. Neurosci. Abstr. 11: 1093.Google Scholar
- Holmes, W. R., and Woody, C. D., 1983, Effects on input currents of local increases in membrane resistance in cortical pyramidal cell dendrites explored using a passive cable model for determining the transient potential in a dendritic tree of known geometry, Soc. Neurosci. Abstr. 9: 603.Google Scholar
- Kmjevic, K., Pumain, R., and Renaud, L., 1971, The mechanism of excitation by acetylcholine in the cerebral cortex, J. Physiol. (Lond.) 215: 247–268.Google Scholar
- Matsumura, M., and Woody, C. D., 1982, Excitability changes of facial motoneurons of cats related to conditioned and unconditioned facial motor responses, in: Conditioning: Representation of Involved Neural Functions ( C. D. Woody, ed.), Plenum Press, New York, pp. 451–457.Google Scholar
- Rall, W., 1974, Dendritic spines, synaptic potency, and neuronal plasticity, in: Cellular Mechanisms Subserving Changes in Neuronal Activity (C.D. Woody, K. A. Brown, T. J. Crow, Jr., and J. D. Knispel, eds.), Brain Information Service, University of California, Los Angeles, pp. 13–21.Google Scholar
- Sakai, H., and Woody, C. D., 1980, Identification of auditory responsive cells in coronal—pericruciate cortex of awake cats, J Neuropohysiol. 44: 223–231.Google Scholar
- Swartz, B. E., and Woody, C. D., 1979, Correlated effects of acetylcholine and cyclic guanosine monophosphateGoogle Scholar
- on membrane properties of mammalian neocortical neurons, J. Neurobiol. 10:465–488.Google Scholar
- Thompson, S. H., 1977, Three pharmacologically distinct potassium channels in molluscan neurones, J. Physiol. (Lond.) 265: 465–488.Google Scholar
- Wallis, R. A., Woody, C. D., and Gruen, E., 1982, Effects of intracellular pressure injections of calcium ions in morphologically identified neurons of cat motor cortex, Soc. Neurosci. Abstr. 8: 909.Google Scholar
- Woody, C. D., and Brozek, G., 1969b, Changes in evoked responses from facial nucleus of cat with conditioning and extinction of eye blink, J. Neurosphysiol. 32: 717–726.Google Scholar
- Woody, C. D., and Gruen, E., 1986a, In-vivo effects of acetylcholine (ACh) and cGMP dependent protein kinase (cGPK) on outward currents of neurons of the motor cortex of awake cats, Soc. Neurosci. Abstr. 12: 725.Google Scholar
- Woody, C. D., and Wong, B., 1981, Intracellular recording of potassium in neurons of the motor cortex of awake cats following extracellular applications of acetylcholine, in: Ion-Selective Microelectrodes and Their Uses in Excitable Tissues (E. Sykova and L. Vyklicky, eds.), Plenum Press, New York, pp. 125132.Google Scholar
- Woody, C. D., Carpenter, D. O., Gruen, E., Knispel, J. D., Crow, T. W., and Black-Clewroth, P., 1976a, Persistent Increases in Membrane Resistance of Neurons in Cat Motor Cortex,AFRRI Scientific Report (February, 1976), Bethesda, pp. 1–31.Google Scholar
- Woody, C. D., Gruen, E., and McCarley, K., 1984b, Intradendritic recordings from neurons of the motor cortex of cats, J. Neurophysiol. 50: 925–938.Google Scholar
- Woody, C. D., Nenov, V., Gruen, E., and Donley, P., 1985, A voltage-dependent, 4-aminopyridine sensitive, outward current studied in vivo in cortical neurons of awake cats by voltage squeeze techniques, Soc. Neurosci. Abstr. 11: 955.Google Scholar