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The excitability of the visual system was studied in ten adult chronic cats. Visual evoked potentials were recorded, using decreasing interstimulus intervals. A decrease of the excitability of the visual system is observed when interstimulus intervals are less than 800 milliseconds. Clinical applications with regard to visual evoked potential recording on comatose patients are suggested.

The axes: amplitude, frequency, time, define a trihedral where the most usual representations occur in time domain (plane defined by the axes amplitude-time). The frequency of an action with respect to time is represented in the plane defined by the axes frequency-time in the so called "Modulation Domain", it is being considered very useful, expressive and easy to construct in the automatic treatment of signals.

Research of the alcohol action mechanism on the SNC in acute alcoholic intoxication (AAI) has been dealt in various ways. On one side the alcohol action--apparently most unspecific--on cellular membranes has been studied. Other authors, instead, have studied more specific alcohol effects on three types of neurotransmitters: opioid peptides, GABA and catecholamines. The effect of alcohol on cellular membranes seems to be beyond any doubt. Alcohol action on specific neurotransmitters is the object of controversy, especially in the case of endogenous opioids. There are data which strongly support the participation of the GABA receptors in the AAI. Modifications produced in the cellular membrane by alcohol action can modify the structure of the function of the membrane receptors. On the other hand, distinct receptors may be localized in the same neuron, while the existence of interactions between different neurotransmitters is well known. Therefore, the various hypotheses previously stated are not mutually exclusive.

The effect of an i.v. bolus injection of nicotine 50 micrograms/kg-1, was compared in 6 awake dogs with the effect of nicotine injection after naloxone, 400 micrograms/kg-1. Respiratory inhibition was produced immediately after beginning the nicotine injection, followed by hyperpnea. Naloxone produced a significant decrease of the respiratory inhibition followed by hyperpnea increase compared to the trial with only nicotine.