Interaction between visual activation and proprioceptive activation in neurons of the superior colliculus]

Units located in the superficial and intermediate layers of the superior colliculus are activated by proprioceptive stimulation of the extraocular muscle nerves as well as by specific visual stimuli. Units of the deep layer of the colliculus, not sensitive to visual activation, are inhibited by proprioceptive stimulation. A few of the units showed interaction between the two types of stimulation, the proprioceptive response appearing only when spontaneous activity was decreased by a visual stimulus.     

Activation of purkinje neurons through climbing fibres after chronic lesions of the olivo-cerebellar pathway

Résumé Les décharges évoquées dans les cellules de Purkinje lors de l'activation des fibres grimpantes ont été testées par stimulation afférente dans un groupe d'animaux intact et dans un groupe d'animaux avec lésion chronique totale et bilatérale de la voie olivo-cerebelleuse. On a démontré qu'une partie seulement des fibres qui atteignent la région vermienne du lobe postérieur du cervelet ont leur origine dans l'olive inférieure.     

Spectral efficiency as function of latency in the visual mechanism of insect (Tenebrio molitor L.)

Zusammenfassung Bei Untersuchungen der elektrophysiologischen Reaktion des Facettenauges beim MehlkäferTenebrio molitor wurde die Maximalreaktion zwischen 510 und 530 nm gefunden. Latenz und Amplitude dienten als Kriterien der facettären Spektraleffizienz.     

Topography of the tecto-tectal component of the main ipsilateral visual pathway of the frog (Rana esculenta L.)]

The detailed topography of the tecto-tectal component of the Frog's ipsilateral visual pathway is electrophysiologically obtained by mapping the optic lobes. This linkage transfers the visual information explored along a transversal tectal row on to an homologous line oriented at 130 degrees on the opposite tectum. The ipsilateral projection of the temporo-nasal axis of the retina, but not of the antero-posterior axis of the visual field, is reversed compared to its contralateral projection. Finally, the majority of the homologous tectal points are asymmetrical with respect to the animal's sagittal axis.     

Targeting of olfactory neurons

Olfactory sensory neurons detect an enormous variety of small volatile molecules with extremely high sensitivity and specificity. The actual recognition and discrimination of odorous compounds is accomplished by specific receptor proteins located in the ciliary membrane of the sensory neurons. Axonal connections into the olfactory bulb, the first relay station for odor processing in the brain, are organized such that all neurons expressing the same odorant receptor converge their axons onto common glomeruli which are located at similar positions in all individuals from one species. For the establishment of this precise targeting of olfactory axons to their appropriate glomeruli, combinatorial functions of axon-associated cell adhesion molecules and odorant receptor proteins appear to be required. Odorants that stimulate distinct receptor cell populations will thereby activate a specific combination of glomeruli in the bulb; this characteristic activity pattern may be used by the system to encode the quality of a particular odorant.     

Maintenance of visual cells in vitro

Résumé Des fragments de rétine et des cellules visuelles isolées de la grenouilleRana pipiens ont été cultivés dans la chambre de Rose. Bien qu'une dégénérescence morphologique des segments extérieurs des cellules visuelles ait été observée pendant la culture, le pouvoir de réfraction normal et la présence du pigment visuel ont été constatés dans ces segments, les segments intérieurs avec leurs noyaux étant conservés. Mais, l'intensité du pigment visuel a été plus faible que dans la rétine fraîche. Ces résultats montrent que la cellule individuelle du photorécepteur se prête à l'étude physiologiquein vitro.

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Aided by a grant from the National Society for the Prevention of Blindness.     

Evidence for a neurological zoom system in vision from angular changes in some receptive fields of single neurons with changes in fixation distance in the human visual cortex

Résumé Dans le cortex visuel humain de 3 champs réceptifs de neurones individuels 2 présentent des changements d'angle correspondant aux changements de perception à distance. Ces changements peuvent être la base neurologique du système perceptif de stabilité, de «zoom» ou de graduation de la vision.     

Morphometric characterization of central molluscan neurons

Resumen Se realiza en la masa ganglionar ventral del moluscoCryptomphallus aspersa (Gasteropoda, Pulmonata) la caracterización morfologico-estadística de las neuronas centrales y células gliales. Se establece la existencia de tres tipos neuronales, las características de su basofilia y la relación entre los tipos, lo que se discute en relación a los hallazgos obtenidos en otras especies por diversos autores.     

Modification of visual signals by nigral stimulation

Summary Responses of the lateral geniculate neurons to light were modified by stimulation of the substantia nigra. Nigral stimulation often caused enhancement of firing in neurons responding primarily to flash, but it usually had the contrary effect on units inhibited by light.     

A visual pigment of the sturgeon retina

The visual pigments of hybrid sturgeon (a cross between Acipenser ruthenus (male) and Huso huso (female) have been studied both by the methods of incomplete partial bleaching and HPLC analysis. On the basis of the results obtained the relationship between the structure of opsins and the spectral characteristics of visual pigments is discussed.     

Biochemistry of the non-mevalonate isoprenoid pathway

The non-mevalonate pathway of isoprenoid (terpenoid) biosynthesis is essential in many eubacteria including the major human pathogen, Mycobacterium tuberculosis, in apicomplexan protozoa including the Plasmodium spp. causing malaria, and in the plastids of plants. The metabolic route is absent in humans and is therefore qualified as a promising target for new anti-infective drugs and herbicides. Biochemical and structural knowledge about all enzymes involved in the pathway established the basis for discovery and development of inhibitors by high-throughput screening of compound libraries and/or structure-based rational design.     

Photopic sensitivity mediated by visual purple

Zusammenfassung Bei Reizung der helladaptierten Kaninchen-Netzhaut mit intermittierenden Lichtreizen werden elektroretinographisch Fusionsfrequenzen bis etwa 70/s, das heisst deutliche Zapfenfunktion, registriert. Die hierbei gemessene spektrale Netzhaut-Sensitivität zeigt im Gegensatz zu den unter gleichen Versuchsbedingungen an der Katzen-Netzhaut erhobenen Befunden keine Purkinje-Verschiebung, sondern folgt der Absorptionskurve des Sehpurpurs.