Application Of Strychnine Research Articles

On the effects of strychnine upon the myelinated nerve fibres of toads.

1. The effects of strychnine upon the nerve fibres of toads were investigated.2. Strychnine had little effect on the myelinated portion, while it had markedeffects on the node of Ranvier.3. The rheobasic voltage of the node was decreased by the application ofstrychnine solutions of lower concentration (from about10-17M to10-5M), butwas increased by higher strychnine concentrations (more than10-4M).4. The rheobase of the node in Ringer solution rose by strychnization of theneighbouring node.5. Thesholds for repetitive response to constant current was decreased bystrychnization of the fibre. The decreased threshold for repetitive response pro-duced by strychnization of the fibre was hardly possible to be restored to theinitial value by washing the fibre with fresh Ringer solution.6. The relative refractory phase of nerve fibres became shorter than in thenormal, and the supernormality of the fibre was increased and prolonged by weakstrychnization, but the recovery process was depressed by strong strychnization.7. The strychnine concentration, which was necessary to decrease therheobase of the fibre, became high by raising the room temperature over20°C.8. Repetitive responses due to single shock stimulation were observed instrychnine-treated nerve fibres (from about10-7M to10-4M) at temperatureshigher than about20°C.

On the mechanism of the cortical desynchronization elicited by volatile anesthetics

The EEG of cats with brain stem transections at different levels have been recorded and the influence thereon of volatile anesthetics was investigated. 1. 1. In order to produce constant and persistent synchronization of cortical rhythms, the brain stem transection must pass rostrally to entrance of the trigeminal fibers and to their main sensory nucleus in the pons. 2. 2. The inhalation of anesthetics in animals with a transection at this level, desynchronizes the EEG in a few seconds and blocks completely the convulsive waves produced by local application of dilute strychnine (0,1 per cent). 3. 3. Neither the normal EEG sleep patterns nor the strychnine waves were affected in the initial phase of anesthesia, when the brain stem had been interrupted at a mesencephalic level. 4. 4. The hypothesis is advanced that the fast cortical rhythms, characterizing the earlier stages of inhalation anesthesia, may be due to an excitatory influence upon the brain stem reticular formation.

Evidence for suppression from the temporal lobe in the monkey.

DUSSER de Barenne and McCulloch, 1 in 1939, described the phenomenon of cortical suppression following the application of strychnine or electrical stimulation to certain regions of the central cortex. They found after such stimulation a decrease in electrical activities in other areas of the central cortex and also a decrease in the function of the specific areas of the cortex. Somewhat similar phenomena have been described in the various forms of extinction and of spreading depressions of Leao. 2 Dusser de Barenne, Garol, and McCulloch 3 described particular areas of the cortex from which the suppression response could be elicited. They originally described Areas 4s, 2s, 8s, and 19s, and, later, Area 24, on the medial aspect of the hemisphere. But there has been some disagreement with their views. Marshall and Essig 4 maintained that the suppressor areas do not exist as such and that Dusser de Barenne and McCulloch

Development of Electrical Activity in the Cerebral Cortex of the Albino Rat.

Summary and Conclusion1. Electrocortico-grams were recorded from albino rats immobilized with various drugs. 2. Spontaneous electrical activity was irregular, intermittent, and of relatively low amplitude during the first week after birth. 3. Local application of strychnine to the cortex resulted in large, slow, spike potentials in rats several days old. 4. The general trend in the spontaneous activity from birth to about 10 days of age was towards increasing rhythmicity, regularity, continuousness, and amplitude. The strychnine-induced spikes gradually decreased in duration, and increased in amplitude and frequency of occurrence. 5. The ECoG of the 10-day-old rat was already basically similar to that of the adult.

ACTION OF ACETYLCHOLINE ON MOTOR CORTEX

Sjostrand1demonstrated an increase in electrical activity of the cortex on topical application of acetylcholine following previous application of strychnine and physostigmine. Miller, Stavraky and Woonton2and Chatfield and Dempsey3found that 1 per cent solutions of acetylcholine bromide and chloride, respectively, applied locally to the previously physostigminized cortex produced an increase of electrical activity. Brenner and Merritt4confirmed these observations and demonstrated that the cortical application of stronger solutions of acetylcholine chloride without previous physostigminization resulted in electrical discharges. Brenner and Merritt pointed out the similarity of these discharges to those encountered in clinical electroencephalographic studies, more particularly to the types of electrical activity found during grand mal seizures. Because of this similarity of electrical patterns and because the parenteral administration of acetylcholine can produce seizures, Brenner and Merritt suggested that disorders of acetylcholine metabolism may be important in the causation or mechanism of convulsive

The Action of Strychnine on the Cerebellar Cortex

THAT strychnine has a stimulating action on the cerebellar cortex was shown by me a few years ago—(Science, 51, 413, 1920). On the application of strychnine to the surface of the lobulus ansiformis or cerebellar hemisphere the motor manifestations consist in increased tonus, together with clonus, affecting particularly the ipsilateral hindleg, though affecting also, to some extent, the forelegs and the contralateral hindleg. My positive results obtained with strychnine in the cat agree with those of Shimazono (Arch. f. mik. Anat., 80, 397, 1912), who observed an ipsilateral increase of tonus after applying strychnine to the cerebellar cortex in the pigeon.

Cerebellar Localization by the Application of Strychnine

Cerebellar Localization by the Application of Strychnine

Cerebellar Localization by the Application of Strychnine

Cerebellar Localization by the Application of Strychnine

EXPERIMENTAL RESEARCHES ON SENSORY LOCALISATIONS IN THE CEREBRAL CORTEX

1. It is possible to investigate the sensory functions of the cerebral cortex by local application of strychnine.2. Consequent upon such local application to a certain area, which forms what may be termed the “active zone”of the cortex, constant and typical symptoms of excitation occur.3. The application of strychnine to parts of the convexity of the cortex outside this zone is not followed by like disturbances.4. The sensory disturbances produced affect both cutaneous and deep sensitivity.5. The disturbances in cutaneous sensitivity manifest themselves by (a) Symptoms of spontaneous excitation, paræsthesiæ. (b) Hyperæsthesia and hyperalgesia. (c) Exaggeration of Munk's “Berührungsreflexe.”6. The disturbances in deep sensitivity manifest themselves in an abnormal hypersensitivity to pinching and pressure of the bones, tendons, and muscles.7. So far as the sensory functions of the skin of the cat are concerned, both sides of the body are represented in the cortex of one hemisphere, but the opposite side most.8. The disturbances of deep sensitivity consequent on the application of the poison to the active zone of one hemisphere alone are always unilateral and on the contralateral side of the body.9. The so‐called “active” zone may be subdivided, according to the parts of the body where sensory disturbances show themselves, as follows:— (a) Head zone: this includes the sensory representation of the neck as well as of the head. (b) Fore‐limb zone: this includes the sensory representation of the trunk as well as of the fore‐limb. (c) Hind‐limb zone. (d) Zone of “crossed symptomatology.” On applying strychnine anywhere in this zone we find disturbances of cutaneous sensitivity provoked in the ipsilateral fore‐limb and in the contralateral hind‐limb.10. The following parts of the cortex are included in the head zone:— (a) The gyrus sigmoideus anterior. (b) The part of the gyrus sigmoideus posterior in front of the small fissure termed by Campbell “the compensatory ansate fissure.” (c) The frontal half of the gyrus suprasylvius anterior. The gyrus sigmoideus anterior forms the focal area of this zone.11. Included in the fore‐limb zone are the following parts:— (a) The gyrus sigmoideus anterior. (b) The part of the gyrus sigmoideus posterior in front of Campbell's “compensatory ansate fissure.” (c) The frontal half of the gyrus suprasylvius anterior. (d) The middle third of the gyrus ectosylvius anterior. The focal area of this fore‐limb zone is represented in the parts mentioned under (a) and (b).12. The hind‐limb zone occupies the frontal half of the gyrus inarginalis. The focal area of this zone lies in its anterior part.13. The following parts form the zone of “crossed symptomatology.” (a) The part of the gyrus sigmoideus posterior behind Campbell's “compensatory ansate fissure.”(b) A small part of the gyrus marginalis immediately behind the sulcus ansatus.(c) The frontal third of the gyrus suprasylvius medius and a sinall portion of the hinder part of the gyrus suprasylvius anterior.(d) The part of the cortex situated on the transition from the gyrus ectosylvius medius to the gyrus ectosylvius anterior. The more frontally in this zone the application of strychnine is made, the more marked are the resulting symptoms.14. The fore‐limb and head zones almost entirely overlap one another (contrary to the view taken by Munk and Rothmann).15. In so far as any sensory zone overlaps the motor area (the position of the latter being decided by methods different from those herein dealt with), there may be said to exist in the cat, and probably also in the dog, a common sensori‐motor cortical zone, as Munk and others have held.16. The sensory disturbances produced are, in almost all the experiments, most marked towards the distal parts of the extremities.17. Except in one instance, none of my thirty‐four experiments have furnished any proof of a segmental distribution of the sensory disturbances caused by strychnine application to the cortex.18. Except in one experiment, no genuine symptoms of motor excitation —such as muscle twitchings, hyper‐reflexia, and exaggeration of tendon and periosteum reflexes—have been observed. This absence of motor symptoms in my experiments, as compared with those of some other observers, may have been due to the fact that in mine the application of strychnine was always slight and the poison was probably confined to the more superficial layers of the cortex.19. The lobus frontalis has no sensory functions in the cat.

46. On the local application of Strychnine as a cure for Amaurosis.

46. On the local application of Strychnine as a cure for Amaurosis.

46. On the local application of Strychnine as a cure for Amaurosis.

46. On the local application of Strychnine as a cure for Amaurosis.