Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats.

In high spinal paralysed cats electromyograms were recorded from nerves supplying lumbar back muscles (longissimus dorsi) and abdominal muscles (obliquus abdominis externus) during fictive locomotion induced by I.V. injection of nialamide and L‐DOPA. Activity in nerves to hind‐limb muscles was also recorded. During periods of stable 'locomotor' activity in the hind‐limb nerves the efferents to the back and abdominal trunk muscles were generally also rhythmically active. Three different patterns of activity were observed. The predominant rhythmic pattern showed a synchronous activation of the efferents to the back and abdominal muscles of one side together with an activation of the hind‐limb flexors of that side, alternating with activation of the efferents to the corresponding contralateral muscles. This pattern was very stable and could last for about 3 h. Such a pattern of activity would be expected during the alternate stepping characteristic of walking and trotting. The second type of rhythmic locomotor activity was characterized by a synchronous bilateral activation of the efferents to the back muscles, alternating with activation of the abdominal muscles on both sides. This pattern occurred only for short periods and appears to correspond to the activity during in‐phase stepping such as occurs during a gallop. Beside these well co‐ordinated patterns less well co‐ordinated rhythmic activities were also observed. These included regular rhythmic activity which occurred independently in different muscle groups as well as irregular rhythmic activity with unstable phase relations between different muscle groups. The rhythmic locomotor activity in efferents to trunk and limb muscles could be modulated by afferent nerve stimulation and by hypoxia. The results reveal that the spinal cord deprived of its supraspinal and peripheral control may generate a variety of different locomotor patterns, which incorporate the trunk muscles in an apparently meaningful way.

[1]  A. English,et al.  The functions of the lumbar spine during stepping in the cat , 1980, Journal of morphology.

[2]  M. L. Shik,et al.  Neurophysiology of locomotor automatism. , 1976, Physiological reviews.

[3]  S. Mori,et al.  Generation of spontaneous respiratory rhythm in high spinal cats , 1980, Brain Research.

[4]  P. Webb.  I. THRUST AND POWER OUTPUT AT CRUISING SPEEDS , 1971 .

[5]  T. Brown.  The intrinsic factors in the act of progression in the mammal , 1911 .

[6]  D. Viala,et al.  Evidence for respiratory and locomotor pattern generators in the rabbit cervico-thoracic cord and for their interactions , 2004, Experimental Brain Research.

[7]  P. Buser,et al.  Modalités d'obtention de rythmes locomoteurs chez le lapin spinal par traitements pharmacologiques (DOPA, 5-HTP,d-amphétamine) , 1971 .

[8]  S. Grillner,et al.  Peripheral control of the cat's step cycle. I. Phase dependent effects of ramp-movements of the hip during "fictive locomotion". , 1981, Acta physiologica Scandinavica.

[9]  S. Grillner,et al.  Central Generation of Locomotion in Vertebrates , 1976 .

[10]  S. Miller,et al.  The Function of Long Propriospinal Pathways in the Co-Ordination of Quadrupedal Stepping in the Cat , 1973 .

[11]  S. Grillner,et al.  Peripheral control of the spinal pattern generators for locomotion in cat , 1978, Brain Research.

[12]  Joshua R. Smith,et al.  Text-Atlas of Cat Anatomy , 1970 .

[13]  A. Lundberg,et al.  The effect of DOPA on the spinal cord. 6. Half-centre organization of interneurones transmitting effects from the flexor reflex afferents. , 1967, Acta physiologica Scandinavica.

[14]  J. Videler,et al.  On the interrelationships between morphology and movement in the tail of cichlid fish Tilapia nilotica (L.). , 1974 .

[15]  J. Halbertsma,et al.  Control of the trunk during walking in the cat. , 1979, Acta physiologica Scandinavica.

[16]  S. Grillner.  Locomotion in vertebrates: central mechanisms and reflex interaction. , 1975, Physiological reviews.

[17]  A. Blight.  THE MUSCULAR CONTROL OF VERTEBRATE SWIMMING MOVEMENTS , 1977 .

[18]  I. Engberg,et al.  An electromyographic analysis of muscular activity in the hindlimb of the cat during unrestrained locomotion. , 1969, Acta physiologica Scandinavica.

[19]  H. Steffens,et al.  Effects from fine muscle and cutaneous afferents on spinal locomotion in cats , 1981, The Journal of physiology.

[20]  E. Schomburg,et al.  Changes in segmental and propriospinal reflex pathways during spinal locomotion , 1981 .

[21]  Paul W. Webb,et al.  Fast-start Performance and Body Form in Seven Species of Teleost Fish , 1978 .

[22]  M. Hildebrand.  Motions of the Running Cheetah and Horse , 1959 .

[23]  Nervous rhythm arising from rivalry of antagonistic reflexes: Reflex stepping as outcome of double reciprocal innervation , 1913 .

[24]  T G Brown,et al.  On the activities of the central nervous system of the un‐born fœtus of the cat; with a discussion of the question whether progression (walking, etc.) is a “learnt” complex , 1915, The Journal of physiology.

[25]  T. Brown.  On the nature of the fundamental activity of the nervous centres; together with an analysis of the conditioning of rhythmic activity in progression, and a theory of the evolution of function in the nervous system , 1914, The Journal of physiology.

[26]  A. Lundberg,et al.  The effect of DOPA on the spinal cord. 5. Reciprocal organization of pathways transmitting excitatory action to alpha motoneurones of flexors and extensors. , 1967, Acta physiologica Scandinavica.

[27]  A. Lundberg.  HALF-CENTRES REVISITED , 1981 .

[28]  P. Zangger,et al.  Muscle spindle control during locomotor movements generated by the deafferented spinal cord. , 1976, Acta physiologica Scandinavica.

[29]  D. Viala,et al.  Coordinated rhythmic bursting in respiratory and locomotor muscle nerves in the spinal rabbit , 1979, Neuroscience Letters.

[30]  S. Grillner.  Control of Locomotion in Bipeds, Tetrapods, and Fish , 1981 .

[31]  A. Garrod.  Animal Locomotion , 1874, Nature.