Journal of Neurophysiology, Vol 41, Issue 4 1058-1069, Copyright © 1978 by APS

ARTICLES

Generation of scratching. II. Nonregular regimes of generation

M. B. Berkinblit, T. G. Deliagina, A. G. Feldman, I. M. Gelfand and G. N. Orlovsky

1. The activity of muscle nerves and that of spinal interneurons from the L4 and L5 segments was recorded during fictitious scratching (5), which was evoked in decerebrate curarized cats by stimulation of the cervical spinal cord. In some experiments, rhythmical generation was disturbed by stimulation of the fifth lumbar dorsal root (DL5). 2. Excluding the very beginning of scratching, rhythmical generation was usually rather regular: fluctuations of the cycle duration were less than +/-5%. But changes in the stimulation strength, in the stimulating electrode position, and in the hindlimb position led to changes of the generation regime. In different regimes, the mean value of the cycle duration could differ by 20-30%. No correlation was found between mean durations of flexor and extensor phases for different regimes. 3. Rhythmical generation was possible only if the hindlimb was put to "scratch posture," i.e., deflected forward. Generation immediately stopped when the limb was deflected backward, and immediately started when it was returned to scratch posture. 4. In some experiments, stimulation of the cervical spinal cord first resulted in generation of slow oscillations with the temporal pattern typical of stepping (cycle duration about 500 ms, flexor and extensor phases being almost equal to each other). Then, during 5-20 cycles, gradual transition to a normal scratch cycle (about 250 ms) occurred mainly due to considerable shortening (5-10 times) of the extensor phase. In some experiments, considerable spontaneous variations of the flexor phase were observed, while the extensor phase was constant. 5. A single stimulus applied to DL5 considerably affected the cycle duration. Repetitive DL5 stimulation,with a rhythm close to that of scratching, resulted in synchronization of the spinal generator by the stimuli. 6. Spinal interneurons recorded during transition from slow oscillations to a normal scratch cycle only slightly changed phases of their activity in relation to the activity of motoneurons. 7. A hypothesis is advanced that generation of different kinds of limb movements is produced by one and the same central spinal mechanism which can operate in different regimes. The role of sensory input for operation of this mechanism is discussed.

This article has been cited by other articles:

				A. Berkowitz Physiology and Morphology of Shared and Specialized Spinal Interneurons for Locomotion and Scratching J Neurophysiol, June 1, 2008; 99(6): 2887 - 2901. [Abstract] [Full Text] [PDF]

				W.-C. Li, B. Sautois, A. Roberts, and S. R. Soffe Reconfiguration of a Vertebrate Motor Network: Specific Neuron Recruitment and Context-Dependent Synaptic Plasticity J. Neurosci., November 7, 2007; 27(45): 12267 - 12276. [Abstract] [Full Text] [PDF]

				A. Prochazka and S. Yakovenko Predictive and reactive tuning of the locomotor CPG Integr. Comp. Biol., October 1, 2007; 47(4): 474 - 481. [Abstract] [Full Text] [PDF]

				K. E. Musselman and J. F. Yang Loading the Limb During Rhythmic Leg Movements Lengthens the Duration of Both Flexion and Extension in Human Infants J Neurophysiol, February 1, 2007; 97(2): 1247 - 1257. [Abstract] [Full Text] [PDF]

				K. I. Ustinova, A. G. Feldman, and M. F. Levin Central Resetting of Neuromuscular Steady States May Underlie Rhythmical Arm Movements J Neurophysiol, September 1, 2006; 96(3): 1124 - 1134. [Abstract] [Full Text] [PDF]

				M. G. Sirota, G. A. Pavlova, and I. N. Beloozerova Activity of the Motor Cortex During Scratching J Neurophysiol, February 1, 2006; 95(2): 753 - 765. [Abstract] [Full Text] [PDF]

				A. Berkowitz Physiology and Morphology Indicate That Individual Spinal Interneurons Contribute to Diverse Limb Movements J Neurophysiol, December 1, 2005; 94(6): 4455 - 4470. [Abstract] [Full Text] [PDF]

				S. Yakovenko, D. A. McCrea, K. Stecina, and A. Prochazka Control of Locomotor Cycle Durations J Neurophysiol, August 1, 2005; 94(2): 1057 - 1065. [Abstract] [Full Text] [PDF]

				M. Lafreniere-Roula and D. A. McCrea Deletions of Rhythmic Motoneuron Activity During Fictive Locomotion and Scratch Provide Clues to the Organization of the Mammalian Central Pattern Generator J Neurophysiol, August 1, 2005; 94(2): 1120 - 1132. [Abstract] [Full Text] [PDF]

				D. A. Ritter, D. H. Bhatt, and J. R. Fetcho In Vivo Imaging of Zebrafish Reveals Differences in the Spinal Networks for Escape and Swimming Movements J. Neurosci., November 15, 2001; 21(22): 8956 - 8965. [Abstract] [Full Text] [PDF]

				J. Juranek and S. N. Currie Electrically Evoked Fictive Swimming in the Low-Spinal Immobilized Turtle J Neurophysiol, January 1, 2000; 83(1): 146 - 155. [Abstract] [Full Text] [PDF]

				G. M. Earhart and P. S. G. Stein Scratch-Swim Hybrids in the Spinal Turtle: Blending of Rostral Scratch and Forward Swim J Neurophysiol, January 1, 2000; 83(1): 156 - 165. [Abstract] [Full Text] [PDF]

				A. M. Degtyarenko, E. S. Simon, T. Norden-Krichmar, and R. E. Burke Modulation of Oligosynaptic Cutaneous and Muscle Afferent Reflex Pathways During Fictive Locomotion and Scratching in the Cat J Neurophysiol, January 1, 1998; 79(1): 447 - 463. [Abstract] [Full Text] [PDF]

				L. G. Morris and S. L. Hooper Muscle Response to Changing Neuronal Input in the Lobster (Panulirus interruptus) Stomatogastric System: Spike Number- versus Spike Frequency-Dependent Domains J. Neurosci., August 1, 1997; 17(15): 5956 - 5971. [Abstract] [Full Text] [PDF]

				S. Hooper and M Moulins Switching of a neuron from one network to another by sensory-induced changes in membrane properties Science, June 30, 1989; 244(4912): 1587 - 1589. [Abstract] [PDF]

				A. Kramer, F. Krasne, and K. Bellman Different command neurons select different outputs from a shared premotor interneuron of crayfish tail-flip circuitry Science, November 13, 1981; 214(4522): 810 - 812. [Abstract] [PDF]