The recruitment order of stapedius motoneurons in the acoustic reflex varies with sound laterality

In many muscles, motor units are recruited in a fixed order with increasing strength of muscular contraction. We show that for the stapedius muscle of the cat, vastly different recruitment orders can be obtained, depending on which ear is acoustically stimulated. The data support the idea that the distribution of inputs to a motoneuron pool can be inhomogeneous and a significant factor in determining recruitment order.

[1]  R. Baker,et al.  The locations of stapedius and tensor tympani motoneurons in the cat , 1983, The Journal of comparative neurology.

[2]  N. Kiang,et al.  Number and distribution of stapedius motoneurons in cats , 1985, The Journal of comparative neurology.

[3]  H. E. Desnedt,et al.  Spinal motoneuron recruitment in man: rank deordering with direction but not with speed of voluntary movement. , 1981, Science.

[4]  C E BLEVINS,et al.  Studies on the innervation of the stapedius muscle of the cat , 1964, The Anatomical record.

[5]  M. Lyon.  The central location of the motor neurons to the stapedius muscle in the cat , 1978, Brain Research.

[6]  G. Somjen,et al.  FUNCTIONAL SIGNIFICANCE OF CELL SIZE IN SPINAL MOTONEURONS. , 1965, Journal of neurophysiology.

[7]  J. Jerger,et al.  Studies in impedance audiometry. I. Normal and sensorineural ears. , 1972, Archives of otolaryngology.

[8]  E. M. Schmidt,et al.  Facility of motor unit control during tasks defined directly in terms of unit behaviors , 1978, Experimental Neurology.

[9]  C. C. A. M. Gielen,et al.  Changes in recruitment order of motor units in the human biceps muscle , 1982, Experimental Neurology.

[10]  R. Stein,et al.  Motor-unit recruitment in human first dorsal interosseous muscle for static contractions in three different directions. , 1986, Journal of neurophysiology.

[11]  R. Person,et al.  Rhythmic activity of a group of human motoneurones during voluntary contraction of a muscle. , 1974, Electroencephalography and clinical neurophysiology.

[12]  D. Irvine.  Interaural intensity differences in the cat: Changes in sound pressure level at the two ears associated with azimuthal displacements in the frontal horizontal plane , 1987, Hearing Research.