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Les conductions nerveuses chez l'enfant normal
368 Les conductions nerveuses chez I'enfant normal. - J. Raimbaalt (Expansion Scientifique Franfaise, Paris, 1988, 132 p.)
This book is devoted to investigation of the peripheral nerve conduction velocities (NCV) in normal children, from birth to 15 years of age. It is largely based on the long professional experience of Dr. Raimbault in infant electromyography. In the first part of the book, the conduction properties of nerve fibers are recalled, and physiological backgrounds of impulse transmission briefly described. Some terms are inaccurately employed (e.g., motor flow; autonomic nerve). The physiological content of sentences can be misunderstood: ' T h e peripheral nerve fibers are myelinated ones'; in Table I, p. 9, Ia and Ib fibers are presented as motor fibers; preganglionic B fibers are assumed to be aminergic, whereas postganglionic aminergic C fibers are omitted. N C V measurement technics are then described. Relevant remarks are emphasized about peculiar conditions of stimulation and recording in children. More detailed information about size and physical properties of recording electrodes would be useful. Systematic utilization of intramuscular concentric needle electrodes for motor NCV measurement cannot be recommended where surface electrodes or subcutaneous fine needles can be used. Gross mistakes remain in the text, e.g., latency determinations must be made following supramaximal - and not supraliminar - stimulation; F wave is a reflex response; the M to H delay (H reflex) is to be determined on supramaximal responses, which requires 2 different levels of stimulation. Figs. 3 and 10 are unacceptable. Proprioceptive Ia fiber CVs cannot be measured using the Ellingson method (Fig. 9) if criteria of a true H response are not fulfilled in distal muscles. Also, these criteria are not discussed. It could have been useful to lay stress upon the fact that, in children, relative errors on distance evaluation between 2 stimulation sites are larger than in adults. Normative data are presented in the second part of the book for hind limb, upper limb and cranial nerves. This set of collected information is certainly the most interesting and useful contribution of this work, even if they can be found scattered elsewhere. Anatomical description of the nerve trunks should have been replaced by some clear figures. N C V differences between 2 adjacent trunks (peroneal and tibial nerves, median and cubital nerves) are given without statistical confirmation and are not discussed according to possible errors in measurement. Conduction velocity along the H reflex path is concerned with a mixed (afferent + efferent) loop and cannot be said to be a 'proprioceptive' NCV. The last chapter, devoted to cralaial nerves, is the most original one. However, conduction velocities are often determined using a concentric needle electrode, assuming that the same motor units are recruited by the 2 stimulations, despite conspicuous differences in shape between the 2 responses (Fig. 26). This short book will be of interest for electromyographers and pediatrists. They will find here, gathered together, a lot of useful tables of normal latencies and nerve conduction veloci-
B O O K REVIEWS ties in children. But they will have to keep a critical approach when facing some methodological recommendations and neurophysiological assertions that Dr. Raimbault has taken upon himself. P. Guiheneuc
HOpital G.R. Lab'nnec, Nantes (France)
How brain-like is the spinal cord? Interacting cell assemblies in the nervous system. In: Studies of brain function. - U. Windhorst (Springer, Berlin, 1988, 60 figs., 334 p., D M 198.00)
This is an extremely interesting book dealing with a variety of topics ranging from the analysis of correlation between spike trains of supraspinal and spinal neurones, to synaptic plasticity, to modelling of spinal circuits. The contents are organized in 5 main chapters, each subdivided in several sections which terminate with brief and useful summaries where the points of major interest are recalled to the reader. The Reference list is exhaustive and updated. It is not easy to extrapolate individual aspects of interest out of the body of this book, since the whole matter is tightly assembled in a pleasant blend of physiology, system theories and cybernetics. I personally found of extreme interest the section concerning the analysis of probability discharge of alpha-motoneurones (MNs) to differently correlated afferent inputs. This argument is of interest in view of the effect of input synchronization which may be about 10 times as effective in eliciting postsynaptic spikes as asynchronous input activity. The influence exerted on the time-course distribution of motoneuronal EPSP by the 'size principle' as well as by the type of afferents synapsing on the M N s is extensively treated. This includes the concept of Ia input 'partitioning' which reflects the fact that Ia afferents from different parts of the h o m o n y m o u s muscle evoke EPSP of different amplitudes in t h e i r ' target' alpha-MN. The possibility that R e n s h a w cells' (RCs) recurrent inhibition on alpha- and, possibly, g a m m a - M N s provokes either a broad peak synchronization or that, on the contrary, their action is to decorrelate the alpha-motoneuronal activity is discussed in detail. Moreover, a body of indirect evidence is prompted in favour of the existence of reverberating interneuronal circuits intercalated between la fibres and M N s at the spinal segmental level, which are presumably excited by circulating synchronized firing in closed 'synfire chains.' Dealing with the genesis of physiological and pathological tremor, non-linear interaction between different motor units, and the effect of motor unit contractions on spinal afferent discharge as well as on alpha-MN m e m b r a n e potential are treated. The role played in provoking tremor by spinal 'coupled oscillators' as those possibly formed by alpha-MN and RC leading to local negative feedback circuits is clearly illustrated. Another well treated aspect concerns the functional and spatial properties of the non-homogeneous distribution of recurrent inhibition. This is characterized by the fact that RCs
This book is devoted to investigation of the peripheral nerve conduction velocities (NCV) in normal children, from birth to 15 years of age. It is largely based on the long professional experience of Dr. Raimbault in infant electromyography. In the first part of the book, the conduction properties of nerve fibers are recalled, and physiological backgrounds of impulse transmission briefly described. Some terms are inaccurately employed (e.g., motor flow; autonomic nerve). The physiological content of sentences can be misunderstood: ' T h e peripheral nerve fibers are myelinated ones'; in Table I, p. 9, Ia and Ib fibers are presented as motor fibers; preganglionic B fibers are assumed to be aminergic, whereas postganglionic aminergic C fibers are omitted. N C V measurement technics are then described. Relevant remarks are emphasized about peculiar conditions of stimulation and recording in children. More detailed information about size and physical properties of recording electrodes would be useful. Systematic utilization of intramuscular concentric needle electrodes for motor NCV measurement cannot be recommended where surface electrodes or subcutaneous fine needles can be used. Gross mistakes remain in the text, e.g., latency determinations must be made following supramaximal - and not supraliminar - stimulation; F wave is a reflex response; the M to H delay (H reflex) is to be determined on supramaximal responses, which requires 2 different levels of stimulation. Figs. 3 and 10 are unacceptable. Proprioceptive Ia fiber CVs cannot be measured using the Ellingson method (Fig. 9) if criteria of a true H response are not fulfilled in distal muscles. Also, these criteria are not discussed. It could have been useful to lay stress upon the fact that, in children, relative errors on distance evaluation between 2 stimulation sites are larger than in adults. Normative data are presented in the second part of the book for hind limb, upper limb and cranial nerves. This set of collected information is certainly the most interesting and useful contribution of this work, even if they can be found scattered elsewhere. Anatomical description of the nerve trunks should have been replaced by some clear figures. N C V differences between 2 adjacent trunks (peroneal and tibial nerves, median and cubital nerves) are given without statistical confirmation and are not discussed according to possible errors in measurement. Conduction velocity along the H reflex path is concerned with a mixed (afferent + efferent) loop and cannot be said to be a 'proprioceptive' NCV. The last chapter, devoted to cralaial nerves, is the most original one. However, conduction velocities are often determined using a concentric needle electrode, assuming that the same motor units are recruited by the 2 stimulations, despite conspicuous differences in shape between the 2 responses (Fig. 26). This short book will be of interest for electromyographers and pediatrists. They will find here, gathered together, a lot of useful tables of normal latencies and nerve conduction veloci-
B O O K REVIEWS ties in children. But they will have to keep a critical approach when facing some methodological recommendations and neurophysiological assertions that Dr. Raimbault has taken upon himself. P. Guiheneuc
HOpital G.R. Lab'nnec, Nantes (France)
How brain-like is the spinal cord? Interacting cell assemblies in the nervous system. In: Studies of brain function. - U. Windhorst (Springer, Berlin, 1988, 60 figs., 334 p., D M 198.00)
This is an extremely interesting book dealing with a variety of topics ranging from the analysis of correlation between spike trains of supraspinal and spinal neurones, to synaptic plasticity, to modelling of spinal circuits. The contents are organized in 5 main chapters, each subdivided in several sections which terminate with brief and useful summaries where the points of major interest are recalled to the reader. The Reference list is exhaustive and updated. It is not easy to extrapolate individual aspects of interest out of the body of this book, since the whole matter is tightly assembled in a pleasant blend of physiology, system theories and cybernetics. I personally found of extreme interest the section concerning the analysis of probability discharge of alpha-motoneurones (MNs) to differently correlated afferent inputs. This argument is of interest in view of the effect of input synchronization which may be about 10 times as effective in eliciting postsynaptic spikes as asynchronous input activity. The influence exerted on the time-course distribution of motoneuronal EPSP by the 'size principle' as well as by the type of afferents synapsing on the M N s is extensively treated. This includes the concept of Ia input 'partitioning' which reflects the fact that Ia afferents from different parts of the h o m o n y m o u s muscle evoke EPSP of different amplitudes in t h e i r ' target' alpha-MN. The possibility that R e n s h a w cells' (RCs) recurrent inhibition on alpha- and, possibly, g a m m a - M N s provokes either a broad peak synchronization or that, on the contrary, their action is to decorrelate the alpha-motoneuronal activity is discussed in detail. Moreover, a body of indirect evidence is prompted in favour of the existence of reverberating interneuronal circuits intercalated between la fibres and M N s at the spinal segmental level, which are presumably excited by circulating synchronized firing in closed 'synfire chains.' Dealing with the genesis of physiological and pathological tremor, non-linear interaction between different motor units, and the effect of motor unit contractions on spinal afferent discharge as well as on alpha-MN m e m b r a n e potential are treated. The role played in provoking tremor by spinal 'coupled oscillators' as those possibly formed by alpha-MN and RC leading to local negative feedback circuits is clearly illustrated. Another well treated aspect concerns the functional and spatial properties of the non-homogeneous distribution of recurrent inhibition. This is characterized by the fact that RCs