206 BOOK REVIEWS

The ability to avoid these post-operative in- voluntary movements, by recognising their sig- nificance when evoked by stimulation, was con- sidered the most valuable contribution of the technique. Similarly upper limb ataxia, associat- ed during stimulation with ill-defined sensory phenomena, was considered to be avoidable in future.

The conclusions regarding the value of stimu- lation as an aid to accurate siting of the elec- trode were limited. Motor effects in the lower limb were taken to indicate a position too post- erior, and strong motor jerks a too close approx- imation to capsular fibres. It did not appear that the effects of stimulation would give any reliable guide as to the clinical result of making a lesion at the position stimulated. These con- clusions followed the analysis of 480 stimulations in 80 patients.

Recent developments promise increasing ac- curacy in lesion-siting, by the use of electrodes permitting wider parenchymal exploration, by identification of individual thalamic nuclei by difference in background activity, or by the recording of potentials evoked by tactile body stimulation.

Meanwhile, the occurrence of complications in stereotaxy surgery are striking enough for the necessity that physiological clinical tests of the lesion be made in every case. Selection o f Contributions Treatment of hydrocephalus, by F. Mayo and H. N. Usarralde (Argentina). Treatment of herniated cervical intervertebral disc, by E. D. Rocca and E. Sabogal (Peru). Cervical disc, by W. B. Scoville (USA). Resorption of cervical vertebral spurs following spinal fusion, by A. E. Walker and R. A. Robin- son (USA). Diagnosis and localization of brain tumours with sodium radio-iodide, by H. C. Voris, R. D. Games and J. J. Imarisio (USA). Indications for use of stereotaxic methods in treatment of epilepsy, by M. David and J. Talairach (France). Value of stimulation in the surgery of the deep thalamic nuclei, by B. Hughes (United Kingdom) Affective and arousal effects elicited from dis- tinctive nuclei of the human diencephalon, by R. Hassler (Germany). Electrical stimulations of the temporal region in man, by L. Roberts (USA). EEG in cerebral cysticercosis, by J. Mateos and J. del Mercado (Mexico).

J. J. MACCABE

Contribution gt l'l~tude de l'l~,piddmiologie de la Ddbilit~ mentale. Une exp&ienee de Renovation de l'Ecole Primaire h La Louvidre (1951-1961), par J. CORDIER, 253 pages, I~ditions de l'Institut

de Sociologie Solva> dc l'Univcrsitd t.ibrv. Bruxelles, 1963.

Un neurologiste ne peut qu'fitre agreablemem surpris par la lecture de ce livre. En effet, l'au- teur a commence par se poser une sdrie de pro- blemes e t a ensuite essay~ de voir comment unc meilleure definition de I'arrieration mentale et de l'adaptation scolaire lui permettait de classer les enfants qu'il devait examiner. L'auteur insiste tout d'abord sur les difficultes de ddfinir l'arri- ~ration mentale et demontre que ces difficultes ont deux consequences:

(l) une certaine confusion dans la plupart des travaux consacres aux enfants arrieres;

(2) des difficultes quant /t la definition des mesures/t prendre ~. l'egard des enfants arrieres.

11 distingue parmi les enfants arrieres: les ar- rieres graves dont l'6tat est de /~ des lesions or- ganiques cerebrales, des debiles mentaux, ici en general de families de debiles mentaux, et enfin une majorite de cas de debilit6 presque toujours sans etiologic decelable. 11 s'agit dans cette derniere categoric d'une debilit6 dont il a essay6 de definir les conditions d'apparition. I1 a pu demontrer que dans l'apparition de cette debilit6 jouent un rele des facteurs sociaux, des facteurs culturels, des facteurs d'habitat. I1 a pu en arriver ainsi 5- la notion qu'il existe des regions off la debilit6 mentale est une reelle affection epidemi- que. Ce qui nous a particulierement frappes en rant que neurologiste, c'est cette nouvelle defi- nition de l'6piddmiologie.

L'dpiddmiologie, pour nous, n'dtait rien d'au- tre que la science qui s'occupait de la diffusion des maladies contagieuses et maladie contagieuse 6tait synonyme de maladie bacterienne ou de maladie virale.

DeiSt des travaux sur la sclerose laterale amyo- trophique avaient montr6 qu'il existait des mala- dies 6pidemiques dont l'etiologie etait real con- nue et dont 1'etiologic pouvait peut-etre etre genetique ou meme toxique.

Le travail du Dr. Cordier montre qu'une epidemic de debilit6 mentale peut se r~pandre dans certaines parties d'une ville pour des raisons sociales, economiques et culturelles. Ceci 6vi- demment est une notion toute neuve. C'est cela qui nous a fait penser qu'il 6tait utile de parler de ce livre ici.

Cet ouvrage comprend plus de 250 pages. L'auteur y a 6tudi6 la situation scolaire des en- fants qui ont 6t6 suivis, le milieu dans lequel des enfants vivent et en a tire des conclusions quant h l'arrieration mentale et ~t l'adaptation scolaire et sociale. L'importance de l'inadaptation sco- laire quantitativement, le fait qu'elle entralne souvent une inadaptation sociale, montrent toute l'importance de cet ouvrage. Les resultats detailles des investigations de l'auteur sont pre-

J. neurol. ScL (1964) 1 : 205- 208

BOOK REVIEWS 207

sent6s de faqon originale, les pronostics du per- sonnel enseignant sont compar6s aux r6sultats des diff6rents tests auxquels les enfants ont 6t6 soumis. De nombreux exemples concrets illus- trent le texte. Une longue bibliographic de plus de 10 pages conclut ce travail.

Le travail est r6dig6 dans une langue claire et harmonieuse. II apporte des renseignements compl+tement nouveaux dans un domaine trop souvent ignor6 ou m6pris6 par les neurologistes. 11 permet d'entrevoir l'application de la m6thode utilis6e ~t d'autres probl+mes 6pid6miologiques neurologiques. II constitue ~. notre avis un pro- gr6s consid6rable dans la fa9on dont le probl~me de I'arri6ration mentale et du retard scolaire dolt 6tre envisag6. A c e titre l'ouvrage est des plus pr6cieux.

A. LOWENTHAL

Nerve, Brain and Memory Models (Progress in Brain Research, Vol. 2), Amsterdam, by NOR- BERT WIENER AND J. P. SCHADF. (Eds.), viii + 280 pages, 1 table, 96 figs., 317 lit. refs., Elsevier Publishing Company, 1963, 80s, Dfl 40.--.

In this volume are collected 20 papers pre- sented at an interdisciplinary conference in Neurocybernetics. The emphasis is essentially theoretical for this type of cross-fertilization though mutually entertaining, rarely produces viable off-spring in the form of experimental results. However, as the exception which proves the rule, Latour presents an interesting finding that the chances of a visual perception are virtually zero about l0 milliseconds before the eye starts to move. This suggests that there may be some form of anticipatory mental blocking.

This well produced volume is the second number of a series which, the publishers tell us, aspires to be the leading guide for laboratory and clinical personnel concerned with the brain sciences.

J. A. V. BATES

The So-called Extrapyramidal System (Sympo- sium from the Sixteenth Congress of Scandina- vian Neurologists), by REFSOM, LOSSIUS AND DIETRICrtSON (Eds.), 363 pages, Scandinavian University Books (Universitetsforlaget), Oslo, 1962.

This volume is the record of a symposium at the 16th Congress of Scandinavian Neurologists, held in Oslo, 1962. It opens with a notable series of articles: Brodal reviewing the anatomy; Kaada, Bergstrom and Laursen providing three reviews on the physiology; and a review of the biochemistry of the extrapyramidal system by Walaas. In the next section there are 150 pages of discussion from ten contributors in which the clinical manifestations, classification, medical and surgical treatments, and pathology are pre-

sented. The volume is rounded off by 15 papers on general neurological topics.

The advances in neuro-anatomy, and to a lesser extent in neurophysiology are responsible for the qualification 'so-called' in the title of this excellent volume. As Brodal writes in the opening pages : 'to review the structures engaged in the performance of motor functions would almost amount to a survey of the anatomy of the entire nervous system.' It is clear that the classical pyramidal (voluntary) and extra- pyramidal (involuntary) dichotomy cannot correspond to the facts. The classical notion of the pyramidal tract has been crumbling away for 20 years since Lessek and Rasmussen correct- ed the picture of Holmes and Page May. We now appreciate not only that the tract has a more diffuse cerebral origin, but also that it sends collaterals to basal (extrapyramidal) nuclei, and that reticulo-spinal fibres partake in the 'pyra- midal' decussation. We appreciate with Flechsig that the 'pyramidal' tract has a suspiciously large element of individual variability to be saddled with such an elemental function as 'voluntary mo- vement'; that hemiplegia is more than a 'loss of voluntary movement'; and that the essential lesion in this characteristic syndrome is very much open to question. The massive capsular lesions seen in autopsy material from cases whose skilled movements have been benefited by stereotaxic surgery only strengthen the doubts raised by Bucy's pedunculotomies. We appre- ciate the close interconnection between thecere- bral cortex and components of the extrapyrami- dal system, whose number must now be extended to include at least the ventro-lateral thalamus, the reticular substance, and the efferent cere- bellar nuclei. And as Hassler has pointed out, at least quantitatively, the principal efferent route from all these 'extrapyramidal' nuclear masses must ultimately be via 'pyramidal' cortico-spinal fibres. It is complete anatomical interdependence of the efferent structures of the central nervous system that makes their func- tional separation an unreasonable working hypo- thesis if it is posed in terms of voluntary and involuntary movement. The trouble however only arises in relation to the proposal that there is an extrapyramidal 'system'; there is more justification in holding to the clinical separation of extrapyramidal diseases. It is true that in this group the correlation between symptoms and pathology is poor but it is improving. The minimal lesion in the monkey for rigidity, hypo- kinesia and tremor at rest, as well as hemiballis- mus, is known. In principle therefore there is now an animal technique for investigating some common clinical disorders, and a major advance will come if we can define the symptoms in terms

J. neuroL Sci. (1964) 1 : 205-208