The electroencephalogram of the normal “grade” pony in sleep and wakefulness

Abstract

1. 1. The basic characteristics of the stages of sleep and wakefulness in the “grade” pony as found in this study are summarized as follows: 2. 2. The waking EEG was composed of mostly fast frequency (16–25/sec) low voltage (10–50 μV) waves. 3. 3. Drowsiness was characterized by waves of 7–16/sec (50–70 μV) and 4–7/sec (50–100 μV), interspersed with runs of alpha (8–12/sec) and sleep spindles (usually around 5–8/sec). 4. 4. The rhythm of slow sleep was observed as having basically slow (1–4/sec), high voltage (100–200 μV) waves upon which faster waves of 10–12/sec (40–100 μV), 7–8/sec spikes (80–150 μV), and K complexes were superimposed. The heart rate and eye movement activity usually decreased from that of wakefulness. In this stage the animal was observed to be either standing with head low or sternally recumbent. 5. 5. Paradoxical sleep was marked by a fast (18–24/sec) low voltage ( 10–30 μV) desynchronized EEG pattern, hardly distinguishable from that of waking except for the frequent appearance of 3–4/sec sawtooth waves in REM. Rapid eye movements, an irregular heart rate, and a greatly diminished neck muscle tone were usually seen during this period. This state was seen only in animals in the sternal recumbent position. The lateral recumbent position was never seen in these experimental animals.