Antidromic inhibition of presumed fusimotor neurones by repetitive stimulation of the ventral root in the decerebrate cat

Résumé On a enregistré des décharges de 17 fibres fusimotrices dont on suppose l'existence dans les filaments de racines ventrales des chats décérébrés. 8 fibres ont été inhibées par stimulation répétée de la portion centrale isolée du reste de la racine ventrale. Ces résultats montrent qu'il existe une inhibition antidromique dans les neurones fusimoteurs.     

Denervated taste buds. I. General ultrastructural observations

it]Riassunto La denervazione dei calici gustativi provoca due tipi fondamentali di alterazioni cellulari: il primo è rappresentato da lisosomi e citosegregosomi che colpiscono le cellule scarsamento differenziate, il secondo è invece rappresentato da lesioni che sconvolgono l'intera organizzazione citoplasmatica delle cellule di II tipo.The author wishes to thank Mr. M. DrIorio and Mr. V.Panetta for their techeical assistance.     

The avian nature of the brain and inner ear of Archaeopteryx

Archaeopteryx, the earliest known flying bird (avialan) from the Late Jurassic period, exhibits many shared primitive characters with more basal coelurosaurian dinosaurs (the clade including all theropods more bird-like than Allosaurus), such as teeth, a long bony tail and pinnate feathers. However, Archaeopteryx possessed asymmetrical flight feathers on its wings and tail, together with a wing feather arrangement shared with modern birds. This suggests some degree of powered flight capability but, until now, little was understood about the extent to which its brain and special senses were adapted for flight. We investigated this problem by computed tomography scanning and three-dimensional reconstruction of the braincase of the London specimen of Archaeopteryx. Here we show the reconstruction of the braincase from which we derived endocasts of the brain and inner ear. These suggest that Archaeopteryx closely resembled modern birds in the dominance of the sense of vision and in the possession of expanded auditory and spatial sensory perception in the ear. We conclude that Archaeopteryx had acquired the derived neurological and structural adaptations necessary for flight. An enlarged forebrain suggests that it had also developed enhanced somatosensory integration with these special senses demanded by a lifestyle involving flying ability.     

A confirmation of the general relativistic prediction of the Lense-Thirring effect

An important early prediction of Einstein's general relativity was the advance of the perihelion of Mercury's orbit, whose measurement provided one of the classical tests of Einstein's theory. The advance of the orbital point-of-closest-approach also applies to a binary pulsar system and to an Earth-orbiting satellite. General relativity also predicts that the rotation of a body like Earth will drag the local inertial frames of reference around it, which will affect the orbit of a satellite. This Lense-Thirring effect has hitherto not been detected with high accuracy, but its detection with an error of about 1 per cent is the main goal of Gravity Probe B--an ongoing space mission using orbiting gyroscopes. Here we report a measurement of the Lense-Thirring effect on two Earth satellites: it is 99 +/- 5 per cent of the value predicted by general relativity; the uncertainty of this measurement includes all known random and systematic errors, but we allow for a total +/- 10 per cent uncertainty to include underestimated and unknown sources of error.