The response of generalized motor activation in man

The effect of short acoustic and photic stimuli on the magnitude of the T- and H-reflexes was investigated in man. Two periods of increase in the amplitude and dispersion of the two test reflexes, disappearing during repetition of the stimulation, were found. Its first component differs from the second in the greater change in the T-reflex and the smaller extinction. The pattern of changes after photic and acoustic stimulation was the same but acoustic evoked a stronger response. The changes discovered are a subthreshold manifestation of the generalized response of motor activation evoked by a wide range of stimuli. It is postulated that its first component is determined by interaction between pyramidal impulses and the motor cortex and the second is due to the efferent volley from the primary cortical projection zones through the reticulo-spinal tract.     

Corticofugal influences on neurons of the main trigeminal sensory nucleus

The effects of stimulation of the ipsilateral sensomotor cortex were studied on 88 neurons in the region of the main trigeminal sensory nucleus of a cat. The cortex was stimulated via a coaxial electrode by single impulses. Stimulation of the cortex caused the appearance of EPSPs and action potentials in these neurons; a small number of these responses were monosynaptic. The polarity of the impulse applied to the cortex had a significant effect on the magnitude of the latent period of the response and the postsynaptic reaction, which is apparently caused by the stimulation of different types of cortex neurons. Apparently, corticofugal pulsation regulates the level of sensitivity of the trigeminal sensory neurons.A. A. Bogomolets' Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 47–53, July–August, 1969.     

Vasoactive properties of dihomo-gamma-linolenic acid and series one prostaglandins in a freshwater teleost, Channa maculata

1. Prostaglandins A1, B1, E1 and F1 alpha (2-120 micrograms/kg), arachidonic acid and dihomo-gamma-linolenic acid (0.1-2 mg/kg) were injected intravenously into Channa maculata and changes in arterial blood pressure were recorded. 2. Injection of PGF1 alpha had no significant effect on arterial blood pressure. Injection of PGA1 and PGE1 was followed by dose-dependent hypotension whereas injection of PGB1 elicited significant dose-dependent increase in arterial blood pressure. 3. Both dihomo-gamma-linolenic acid and arachidonic acid were also depressor agents but dihomo-gamma-linolenic acid was more potent. 4. A single bolus intravenous injection of indomethacin (5 mg/kg) or 4 daily intraperitoneal injections (4 x 10 mg/kg) significantly lowered arterial blood pressure. One hour after pre-treatment of indomethacin, the vascular effects of both prostaglandin precursors were abolished. 5. It appears that the vascular effects of prostaglandins in Channa maculata are qualitatively different from those reported for mammals.