Evaluation of permanent implantation of electrodes within the brain

Electroencephalography and Clinical NeurophysiologyPublished 1 November 1955

JoséM.R. Delgado

Citations68

TL;DR

Conclusions 6, 7, and 8 indicate that the presence of electrodes disturbs the brain activity very little, or at least, that the experimental conditions do not change during the period of observation.

Abstract

1. Techniques of construction and implantation of multilead electrodes in the brain of animals are described. Technical problems of implantation are examined. 2. No operatory accidents occured, and no deficits were produced by electrode insertion. 3. After several months of implantation, plate electrodes produced a small impression on the brain surface without histological alteration of the neurons. Damage of the brain resulting from needle electrodes was generally less than 1 mm. in diameter. Infections were rare. Electrocoagulation was more hazardous. 4. Prolonged electrical stimulation of the brain did not cause any detectable local histological changes. 5. Cerebral stimulation was possible in cats and monkeys which had freedom of movement. This permitted studies concerning behavior, sensory phenomena, correlations between clinical manifestations and electrical activity of the brain, and also psychological testing of the animals. 6. Patterns of response evoked by electrical stimulation proved to be typical for each point, and reliable through time. 7. Thresholds of electrical stimulation proved to be rather constant throughout the months of observation. 8. "Spontaneous" electrical activity and patterns of evoked post discharges recorded by means of implanted electrodes were similar in recordings taken with weeks or months of interval. 9. Conclusions 6, 7, and 8 indicate that the presence of electrodes disturbs the brain activity very little, or at least, that the experimental conditions do not change during the period of observation.

Keywords

Neuroscience

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