Abstract
In the past 3 years many papers have appeared on the subject of audiogenic seizures. In continuation of previous work 1 it was felt that better insight into the phenomenon would be obtained if a method of recording the physiological factors involved could be devised. This paper describes such a method.
The heart rate was recorded by a Davis electroencephalograph. The 3 electrode leads were soldered to the tops of 3 bicycle valve caps; these caps were held on the animal by suction∗ applied through tubes leading to each of the caps. The electrodes were applied behind the right and left shoulders and on the midline ventrally. The hair on these areas was trimmed and Cambridge electrode jelly was applied. From these electrodes the heart rate of the animal was recorded (Fig. 1). Respiration (Fig. 1) was recorded by means of a Phipps and Bird accordion type pneumograph, on the tape of the electroencephalograph.
To obtain maximum quiescence during recording, advantage was taken of the rat's fear of height. The animal was placed about 5 feet from the ground with its forefeet and hindfeet on separate perches. These perches were one quarter inch wide and projected 2 inches from the middle of a vertical board. The distance between them could be adjusted to the size of the animal. With this procedure the rat remained almost motionless, and it was possible to adjust the pneumograph around the animal so that it was in contact with the animal only and did not touch any part of the apparatus. The weight of the pneumograph was counterbalanced by a weight on a pulley over the vertical board. This method also facilitated the placing of the ventral electrode.
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