Effects of general stimulant drugs on the electrical responses of isolated slabs of cat's cerebral cortex.

1. In the neuronally isolated cortex of the cat, local application of bemegride, picrotoxin, nikethamide, caffeine and strychnine facilitated the surface positive response of the isolated cortex and lowered the stimulus threshold for this response. Excepting nikethamide, they all produced convulsive discharge in the isolated cortex unrelated to the applied stimulus.2. Local application of glutamate to the cortex produced spreading depression, which was sometimes preceded by spontaneous positive bursting.3. In contrast to the "general depressants" which produce a relatively consistent pattern of effects on the electrical responses of isolated cortex, the "general stimulants", although they all have excitatory effects on isolated cortex, each produced a greatly different type of electrical response in the isolated cortex, suggesting that several different mechanisms of action are responsible for their effects.