Abstract
1. The discharge patterns of some units (neuron or neuron group) in strychnized spinal cord of the frog are investigated. The lead-off electrode was made of glass capillary in which a small silver Wire (less than 10μ) Was inserted until the tip. The diameter of the capillary was less than 20μ at the tip.
2. When the electrode is inserted in spinal cord, the firing of a single spinal unit is usually seen probably by the mechanical penetration, but it does not develop to a typical strychnine spasm.
3. During the strychnine spasm most of the units discharged synchronously with the same rhythm as the spasm, but some uuits discharged even in the resting period, in which no discharge was observed at the peripheral nerves or muscles.
4. By the simultaneous recording from two positions in spinal cord, it was observed that there are not only synchronized units but also asynchronized units in the strychnized spinal cord.
5. The discharge frequency observed in strychnized spinal unit was usually twice as high as that in nonstrychnized unit (50c/sec).
The firing frequency during the strychnine spasm. increased to about 140c/sec, which was higher than the frequency of discharge elicited by mechanical penetration of the electrode.
6. It was proposed that in the process of strychnine tetanus there are at least two types of unit (neuron gpoup) in the spinal cord, and that one has an excitatory effect and the other has an inhibitory effect on motoneurones. For the formation of the discharge pattern of strychnine spasm the coordination of these two units would play the important roll, especially the activity of inhibitory units may result in the silent period between discharge groups.
