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In the last few years attention has been directed to the possible role of the ventrolateral area of the thalamus in the pathophysiology of tremor and rigor. Neurosurgical experience (Hassler and Riechert1; Cooper2) indicates that lesions of this region are able to influence favorably or to eliminate these pathological phenomena in patients with Parkinson's disease. An apparently plausible explanation for the success of these operations has been offered by Hassler.3 He subdivides into several zones, the nuclear area called by Walker4 and other American writers the nucleus ventralis lateralis. Of particular interest is the nucleus ventralis oralis anterior and posterior; the anterior nucleus receives impulses from the pallidum and it transmits them to the premotor cortex (area 6aα). Cerebellofugal impulses enter the nucleus ventralis oralis posterior; from here they are projected to the motor region (area 4γ). Hassler assumes that interruption of the cerebellothalamocortical pathway and

Laboratory studies, to be described presently, were performed on cerebrospinal fluid and blood of patients with infantile and juvenile amaurotic family idiocy. LIPASE STUDIES ON CEREBROSPINAL FLUID Much care was taken to improve Cherry and Crandell's method of lipase determination22 through purification of the olive oil, use of penicillin to prevent bacterial growth and standardization by means of comparison with the effects of commercial lipases. Table 1 summarizes our results indicating that the lipase content in Tay-Sachs' disease is essentially the same as in a number of other neurological disorders. It is evident that further studies will have to be directed to other enzyme systems in an attempt to detect some of the basic biochemical disturbances underlying this disease. SERUM PROTEIN STUDIES Paper electrophoresis for protein fractionation of the serum has been used by Saifer, Aronson, Zymaris and Volk in 7 cases of Tay-Sachs' disease.21 Our comparable studies

Methods for the study of electrical discharges of the brain and of the retina have been developed to such a degree that they are applied as clinical tests. Electrical discharges from the vestibular nerve have been studied in animals in which the electrodes were inserted into the inner ear or placed directly on parts of its nervous apparatus. Spiegel, Wycis, and Umlauf8 attempted in man to record the electrolabyrinthogram from parts of the external ear, particularly by meatal-retromastoid electrodes. In patients with unilateral eighth nerve tumors these authors compared the effects of rotation upon the normal and upon the affected side. At least in some instances, they found a postrotatory increase of the amplitude of the discharges on the side of the intact labyrinth or intact eighth nerve, as compared with the side of the tumor.In the course of these studies it became evident that it would be

The present study deals with the electrogram of the midbrain tegmentum in man and the influence of this region upon the electromyogram and the electroencephalogram, chiefly in Parkinsonian patients; it is part of a project attempting to influence static tremor, rigidity, and spasticity by placing lesions in an area remote from the pyramidal tract. Pallidal, as well as thalamic, lesions performed for the relief of these conditions may interfere with the function of the corticospinal pathway either by directly encroaching upon fibers of the internal capsule or by disturbing their blood supply. In order to avoid such a possible interference, the tegmentum of the rhombencephalon and mesencephalon seemed to offer a suitable location; in this region extrapyramidal fibers descend, and it contains in its so-called reticular formation cell groups which represent supraspinal centers of the static innervation (Spiegel and Bernis,1 1925, Magoun,2 1948); this innervation, when distorted, may

Electrography of the striatum and pallidum was guided by the consideration that it may provide an answer as to the participation of these structures in the mechanism of extrapyramidal and convulsive disorders. In an individual case such recordings may help to decide whether elimination or reduction of the activity, particularly of parts of the pallidum, may serve a useful purpose: postoperatively, such recordings may give an indication as to whether the procedure employed was able to change the functional state of the pallidum. MATERIAL AND METHODS Since the recordings and operative procedures had to be performed in several stages, a new type of stereoencephalotome (Model V) was constructed. It permits one to apply the apparatus repeatedly in exactly the same position. The apparatus is fixed to the skull by means of four screws that carry small steel balls, to which the feet of the stereoencephalotome may be attached in any

While the motor and postural effects of electric stimulation of the striatum have been repeatedly examined in acute experiments (Ferrier,11,12 1873, Danilewski,7 1875; Tower,40 1936; Mettler et al.,33 1939; Freeman and Krasno,14 1940; Gerebetzoff,16 1941; Akert and Andersson,3 1951; Kaada,26 1951; Heath and Hodes,21 1952; White and Himwich,43 1957; Umbach,41 1959), there are no reports on prolonged striatal stimulation as far as we could ascertain. Forman and Ward's13 "chronic experiments" deal with stimulation of a few seconds' duration applied through chronically implanted electrodes. It has been pointed out that uninterrupted, continuous electrical striatal stimulation is ineffectual (Mettler31). We have therefore tried to produce prolonged stimulation of this ganglion by injection of alumina cream and to analyze its rather obscure influence upon various parts of the brain by a combination of such stimulation with electrographic studies and extirpation