Afferent Control of Posture and Locomotion: (Progress in Brain Research)

How are the functions of control, integration and generation of motor commands performed by the brain? A view of the motor systems of the brain as hierarchically organized structures, where neurone populations and simple reflex pathways form elementary building blocks, answers this question. There are contradictory forecasts of how major advances in our understanding of posture and locomotion will develop. Some believe that the key to understanding lies in a detailed knowledge of the cortical and subcortical structures, while others regard a thorough grasp of spinal and brainstem neuronal circuitry as crucial. Yet another approach is to study human or animal postural and locomotive behaviour, looking for influences that act to select one of several potential motor patterns or strategies under a given set of circumstances. While each of these viewpoints has its strengths - and weaknesses - real progress can only be achieved through a constructive exchange of ideas, criticism and information. To make this possible, a group of scientists gathered in Switzerland in September 1988 to present and discuss their research. This book represents the scientific outcome of that meeting. Its subject matter reflects closely the different approaches of the participants: current research on sensory transduction, spinal integration, and higher order neuronal and behavioural control. Using a technique of overview and critique of each group of papers we hope that the non-specialist reader can also grasp the issues involved and the directions for further research in motor control.

Table of Contents:
List of Contributors. Preface. In Memoriam - Ian Alexander Boyd (23.5.27-14.9.87) (P.B.C. Matthews). Section I - Control and Actions of Proprioceptive Feedback. Overview and Critique of Papers 1-5 (Gladden, Ellaway, Taylor, Bessou, Dutia) (P.B.C. Matthews). 1. Fusimotor mechanisms determining the afferent output of muscle spindles (M. Dickson et al.). 2. Segmental influence of slowly-adapting cutaneous mechanoreceptors on gamma motoneurones revealed by cross-correlation of unit discharges in the cat (N.J. Davey and P.H. Ellaway). 3. Central mechanisms of selective fusimotor control (A. Taylor and R. Donga). 4. Discharge patterns of gamma motoneurone populations of extensor and flexor hindlimb muscles during walking in the thalamic cat (P. Bessou et al.). 5. Physiological properties of tandem muscle spindles in neck and hind-limb muscles (R.F. Price and M.B. Dutia). Overview and Critique of Papers 6-10 (Prochazka, Hoffer, Hulliger, Matthews, J.-P. Roll) (P.H. Ellaway). 6. Ensemble proprioceptive activity in the cat step cycle: towards a representative look-up chart (A. Prochazka et al.). 7. Roles of muscle activity and load on the relationship between muscle spindle length and whole muscle length in the freely walking cat (J.A. Hoffer et al.). 8. Flexible fusimotor control of muscle spindle feedback during a variety of natural movements (M. Hulliger). 9. Analysis of human long-latency reflexes by cooling the peripheral conduction pathway: which afferents are involved? (P.B.C. Matthews). 10. Eye, head and skeletal muscle spindle feedback in the elaboration of body references (J.-P. Roll, J.-P. Vedel and R. Roll). Section II - Control and Actions of Vestibular and Visual Inputs. Overview and Critique of Papers 11-14 (Hudspeth, Shinoda, Graf, Grantyn) (V. Henn). 11. Mechanoelectrical transduction by hair cells of the bullfrog's sacculus (A.J. Hudspeth). 12. Comparison of the branching patterns of lateral and medial vestibulospinal tract axons in the cervical spinal cord (Y. Shinoda et al.). 13. Afferents and efferents of the vestibular nuclei: the necessity of context specific interpretation (W. Graf and V.J. Wilson). 14. How visual inputs to the ponto-bulbar reticular formation are used in the synthesis of premotor signals during orienting (A. Grantyn). Overview and Critique of Papers 15-17 (Hoffmann, Grusser, Collewijn) (J.I. Simpson). 15. Control of the optokinetic reflex by the nucleus of the optic tract in primates (K.P. Hoffmann). 16. Open-loop and closed-loop optokinetic nystagmus in Squirrel monkeys (Saimiri sciureus) and in man (F. Behrens, O.-J. Grusser and P. Roggenkamper). 17. The vestibulo-ocular reflex: an outdated concept? (H. Collewijn). Overview and Critique of Papers 18-19 (Simpson, Waespe) (K.P. Hoffmann). 18. Representations of ocular rotations in the cerebellar flocculus of the rabbit (J.I. Simpson et al.). 19. Oculomotor functions of the flocculus and the vestibular nuclei after bilateral vestibular neurectomy (W. Waespe, U.