Motor pattern production in reciprocally inhibitory neurons exhibiting postinhibitory rebound

Pairs of neurons which inhibit each other can produce regular alternating bursts of impulses if they also exhibit postinhibitory rebound (PIR). Computer studies show that stable patterns occur spontaneously in systems of pacemaker neurons with PIR, and can be triggered in systems of nonpacemakers without requiring tonic excitation. The repetition rates of these patterns are determined largely by the PIR parameters. The patterns resist perturbation by phasic synaptic inputs, but can be modulated or turned off by tonic inputs. One pair of PIR neurons can be entrained by another pair with a different repetition rate to produce more complex firing patterns.     

Quantitative autoradiography of [3H]muscimol binding in rat brain

A simple quantitative autoradiographic technique for the study of neurotransmitter receptors that includes the use of a tritium-sensitive film permits saturation, kinetic, and competition studies of brain samples as small as 0.01 cubic millimeter. This technique was used to study [3H]muscimol binding in rat brain. Unilateral gamma-aminobutyric acid receptor supersensitivity was observed in the substantia nigra pars reticulata after production of localized lesions of the ipsilateral corpus striatum.     

Opioid inhibition of dopamine release from nervous tissue of Mytilus edulis and Octopus bimaculatus

Morphine and D-Ala2-Met-enkephalin as well as other opioids suppress potassium-stimulated release of 3H-labeled dopamine from neurons tissue of two marine invertebrates, Mytilus edulis and Octopus bimaculatus. Naloxone reverses the inhibitory effects in both species. Potassium-stimulated release of 3H-labeled serotonin is not altered by opioids. It is postulated that opiate receptors and their endogenous effectors play a prominent role in regulation of transmitter release in invertebrates.     

Arginine and pyrimidine biogenesis in Neurospora

The growth-promoting activity of propionic acid and related compounds for the pyrimidine-less strain, Neurospora crassa 1298, is markedly inhibited by arginine. The data suggest that arginine exerts an inhibitory effect upon or represses the synthesis of an enzyme involved in pyrimidine formation.     

Air pollution: sensitive detection of ten pollutant gases by carbon monoxide and carbon dioxide lasers

Detection sensitivities of a few parts per billion for ten gaseous pollutants have been evaluated by measuring the strength of the absorption of infrared radiation from carbon monoxide and carbon dioxide lasers. Ethylene concentrations as small as 5 parts per billion have been detected in air. The measured absorption strengths indicate that in mixtures of pollutants, such as nitrogen dioxide and water vapor, the sensitivity is reduced by overlapping absorption bands. However, calculations indicate that it should be possible to detect nitrogen dioxide concentrations of 0.01 part per million in the presence of water vapor concentrations of 105 parts per million.