The cerebral ventricles were perfused with sterile artificial cerebrospinal fluid in unanaesthetized dogs from a cannula in the lateral ventricle to a cannula either in the upper cervical subarachnoid space or in the aqueduct of Sylvius. The perfusate was assayed for acetylcholine on rat blood pressure or frog rectus muscle. Even when no eserine was added to the perfusion fluid the output of acetylcholine in 475 samples taken during wakeful state was between 0.01 to 5ng/min in 354 (74.5%) and above 5 ng in 53 (11.2%). No acetylcholine was detected in 68 samples (14.3%). In 129 samples obtained during sleep (excluding periods of REM sleep) no acetylcholine was detected in 75 (58%) samples and an output of less than 1 ng/min was observed in the rest. Acetylcholine appeared in the effluent of samples taken during sleep when rapid eye movements occurred or before waking.

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1. In the lightly anesthetized cats, ambiguus neurons were impaled with glass microelectrodes. Forty-seven neurons were identified as motoneurons by their antidromic activation from the vagal nerve.
2. Stimulation of the vagal nerve produced not only the antidromic spikes but also EPSPs and IPSPs polysynaptically.
3. Stimulation of the superior laryngeal nerve produced EPSPs followed by IPSPs. These responses were also polysynaptic.
4. Effects of repetitive stimulation of superior laryngeal nerve upon sizes of these EPSPs and IPSPs were studied.

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The effect of Pentylenetetrazol (PTZ, Metrazol) upon the identified neurons of Japanese land snail was studied.
1) In the pleuro-parieto-visceral ganglion of Japanese land snail, Euhadra peliomphala, three types of cells can be differentiated morphologically and functionally as those; depolarized by acetylcholine (D-cell), hyperpolarized by acetylcholine (H-cell) and indifferent to acetylcholine (I-cell).
2) PTZ produces a phasic depolarization followed by a sustained depolarization in the D- and H-cells.
3) PTZ has no specific effect upon the I-cell.
4) By application of d-tubocurarine, atropine and hexamethonium, the typical phasic activity evoked by PTZ is not affected in either the D- or H-cells, suggesting that the effect of PTZ is not of synaptic origin but of endogeneous origin.
5) Neither cholinergic nor noncholinergic inhibitory input to the Dand H-cells are affected even at the peak of PTZ activity.

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1. Impulse discharges in single chorda tympani fibers of the cat in response to gustatory and thermal stimulations of the tongue were recorded. Fibers were classified into water-sensitive and -insensitive ones; the magnitudes of responses to 0.5 M LiCl, NaCl, CaCl₂ and SrCl₂ were significantly greater in the latter than in the former.
2. The water response in water-sensitive fibers was depressed when a small amount of salts was added to water. The maximum depressing effects were compared among cations of Cl salts and the following order was obtained: Li⁺>Na⁺>Sr⁺⁺>K⁺>Mg⁺⁺>Ca⁺⁺>NH₄⁺. An approximately inverse order was obtained regarding the stimulating action of these cations on water-sensitive fibers.
3. Statistical calculations of the frequency of responses of chorda tympani fibers to single gustatory stimuli or combinations of stimuli were made, assuming that responsiveness to any one stimulus is independent of that to other stimuli. No evidence of relatively specific sensitivity to a particular stimulus or a particular combination of stimuli was obtained in the cat.
4. Across-fiber correlation coefficients between the degrees of response to a pair of stimuli were calculated. Highly significant correlations were found between HCl and cooling, LiCl and NaCl, CaCl₂ and SrCl₂, and KCl and either MgCl₂ or NH₄Cl.

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Effects of various drugs on the collicular auditory neurons were examined by means of pressure microinjection and microelectrophoresis methods.
1. Acetylcholine had stimulating action on 67% of the nuerons tested. Most of them showed a relatively fast onset and a slow recovery.
2. Monosodium-L-glutamate excited 85% of the neurons tested. The action was exerted with a relatively fast time course and by smaller doses than those required for acetylcholine.
3. L-aspartic acid also had an excitatory action. It was clearly much weaker than L-glutamate.
4. Eserine sulphate stimulated 60% of the neurons tested.
5.γ-Aminobutyric acid exerted a potent inhibitory action on both spontaneous discharges and tone-induced responses. The recovery required a much longer time than that needed for the onset of the effect.
6. Glycine caused a powerful depression comparable to that of GABA. The neurons tested were of a fast time course of action.
7. Atropine sulphate, dihydro-β-erythroidine hydrobromide and d-tubocurarine blocked tone-induced excitation. Atropine had the strongest action among these cholinergic antagonists.
8. Disinhibitory effect by picrotoxin was observed with 43% of the “on” type neurons examined, that is, “on” responses were changed to sustained responses. The action of picrotoxin was time-limited in duration to 40-80 msec and mainly affected the discharges during the beginning of the stimulation period.
9. Strychnine sulphate was found to have no effect upon “on” type neurons.
10. 5-Hydroxytryptamine was also found to have no effect.
11. Irreversible blocking effect was observed with tetrodotoxin.
12. It is suggested that the receptor sites of the collicular auditory neurons are cholinergic in nature for mediating the excitatory process. GABA may be a principal candidate as an inhibitory transmitter which may produces “on” type responses in the inferior colliculus.

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The effect of procaine on the bullfrog urinary bladder smooth muscle was studied with the Rapid Cooling technique, with the following results.
1. Procaine induced contracture in the bullfrog urinary bladder smooth muscle in normal Ringer's solution, but it induced a relaxing effect in isotonic potassium Ringer's solution.
2. Procaine-induced contracture was inhibited in a low pH Ringer's solution and potentiated in a high solution.
3. Mn++ inhibited the procaine-induced contracture, but tetrodotoxin produced no effect.
4. The bullfrog urinary bladder smooth muscle contracted in normal and potassium Ringer's solutions when the temperature of the solution was lowered rapidly from 26-28° to 2-4°(Rapid Cooling Contracture, RCC).
5. The RCC of the bullfrog urinary bladder in normal and potassium Ringer's solutions was potentiated by procaine, and was inhibited by Mn++.
6. The mechanism of the procaine-induced contracture and the effect of Mn++ are discussed with respect to the origin of Ca++. It is postulated that the effect of procaine on bullfrog urinary bladder smooth muscles was produced by mobilization of intracellular bound Ca++, and the inhibitory effect of Mn++ on the procaine-induced contracture and the rapid cooling contracture may be produced by inhibition of its mobilization.

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The olfactory bulbar responses induced by chemical stimulation of the nares of rainbow trout were computer analyzed into frequency components. The spontaneous activity of the bulb was predominated by low-frequency components (2-6 Hz). Upon stimulation this immediately shifted to high-frequency components (7-11 Hz). The peak frequency pattern was characteristic of each single chemical tested regardless of the stimulus intensity. Multi-peak spectra were obtained on stimulation with compound stimuli such as food extract. The frequency component coding mechanism for olfactory receptive discriminatory function in the olfactory bulb is discussed.

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