Presynaptic depolarization of olfactory afferent fibers in cat prepyriform cortex

Resumen El efecto de estímulos condicionantes sobre el potencial evocado del área prepiriforme fué estudiado en gatos. La estimulación del bulbo olfatorio y de la corteza prepiriforme contralateral provocan inhibiciones de larga duración (> de 100 mseg); estas pertenecen al tipo presináptico a juzgar por la depolarización aferente primaria (DAP) de los terminales axónicos y los efectos desinhibitorios de la picrotoxina.     

Presynaptic inhibition of trigeminal afferent fibres during the rapid eye movements of desynchronized sleep

Riassunto Durante i movimenti oculari rapidi nel sonno desincronizzato ed al momenta del risveglio si assiste ad un aumento in ampiezza della risposta antidromica evocata nel nervo infraorbitario dalla stimolazione microelettrodica del tratto spinale del trigemino a livello pontino. Tali variazioni suggeriscono un processo di inibizione presinaptica che agisce fasicamente sulle terminazioni afferenti primarie del trigemino.     

Presynaptic and postsynaptic inhibition on transmission of cutaneous afferent volleys through the cuneate nucleus during sleep

Riassunto Durante i movimenti rapidi oculari caratteristici della fase desincronizzata di sonno si osserva una depressione fasica della risposta lemniscale alla stimolazione di fibre cutanée. Questa modulazione ipnica della risposta lemniscale è dovuta a meccanismi di inibizione presinaptica e postsinaptica.     

The effects of primary afferent depolarization on excitability fluctuations of Ia terminals within the motor nucleus

Résumé Sur la préparation de chat spinal aigue, les réponses antidromiques des fibres afférentes la dans un noyeau de motoneurones montrent des fluctuations considérables réduites par des volées afférentes qui provoquent une dépolarisation des afférences primaires. Les réponses provoquées par activation directe des motoneurones sont très stables, et leurs fluctuations non affectées par la stimulation afférente. Ces faits suggèrent que la variabilité du réflexe monosynaptique est principalement due aux fluctuations du potentiel de membrane des parties terminales des fibres afférentes Ia.     

Pentobarbital: Presynaptic effect in the squid giant synapse

Summary In concentrations that produced synaptic blockade in the squid giant synapse, sodium pentobarbital produced a dose-related, reversible decrease of the calcium spike of the presynaptic terminal.This work was performed while Dr Morgan was a Grass Foundation Fellow at the Marine Biological Laboratory, Woods Hole, Massachusetts, USA.The authors thank Dr J. Z. Yeh for the loan of the 4-aminopyridine and Dr G. H. Acheson for helpful suggestions.     

Presynaptic inhibition in the lumbar cord evoked from the brain stem

Zusammenfassung Es wird gezeigt, dass eine elektrische Medulla oblongata- oder Pons(kaudal)-Stimulation eine Depolarisation (präsynaptische Inhibition) von Ia-, Ib-und Flexor-Reflex-Afferenz im Lumbalmark verursachen kann.     

Modulation of Kv7 channels and excitability in the brain

Neuronal Kv7 channels underlie a voltage-gated non-inactivating potassium current known as the M-current. Due to its particular characteristics, Kv7 channels show pronounced control over the excitability of neurons. We will discuss various factors that have been shown to drastically alter the activity of this channel such as protein and phospholipid interactions, phosphorylation, calcium, and numerous neurotransmitters. Kv7 channels locate to key areas for the control of action potential initiation and propagation. Moreover, we will explore the dynamic surface expression of the channel modulated by neurotransmitters and neural activity. We will also focus on known principle functions of neural Kv7 channels: control of resting membrane potential and spiking threshold, setting the firing frequency, afterhyperpolarization after burst firing, theta resonance, and transient hyperexcitability from neurotransmitter-induced suppression of the M-current. Finally, we will discuss the contribution of altered Kv7 activity to pathologies such as epilepsy and cognitive deficits.     

Hypnotic effect of serotonin administered in the vago-aortic afferent pathway

A minute amount of serotonin injected in the nodose ganglion circulation area develops abrupt myosis and general electrocortical synchronization activity in "encéphale isolé" Cat preparation. This hypnogenic effect of serotonin can still be reproduced after transection of vago-aortic nerves caudally to the nodose ganglia. The same injections become ineffective after rostral transection of the same pathway. These results suggest that serotonin may trigger some signs of sleep through peripheric nervous elements in which are probably localized in the nodose ganglia.     

Depolarization of tooth pulp primary afferent fibers in the medulla oblongata

Zusammenfassung Die zentralen Endigungen der primären afferenten Fasern der Zahnpulpa, welche ausschliesslich der A--Gruppe angehören, können sowohl durch Impulse in A-- und-Trigeminus-Fasern als auch in A afferenten Fasern der Pulpa eines anderen Zahnes depolarisiert werden.     

Acetylcholinesterase decrease in the optic lobe after unilateral eye deprivation

Summary Unilateral eye enucleation in a teleost and a turtle results in progressive AChE decrease in the optic lobe controlateral to the extirpated eye. The final difference reaches 15% in teleost and more than 20% in turtle. No drastic differences in localization, but a rearrangement of histochemical pattern, due to the degeneration of retinal fibres, is noticed.     

Acetylcholinesterase decrease in the optic lobe after unilateral eye deprivation

Unilateral eye enucleation in a teleost and a turtle results in progressive AChE decrease in the optic lobe controlateral to the extirpated eye. The final difference reaches 15% in teleost and more than 20% in turtle. No drastic differences in localization, but a rearrangement of histochemical pattern, due to the degeneration of retinal fibres, is noticed.     

Effects of D-glucose anomers on afferent discharge in the hepatic vagus nerve

Summary Intraportal injections of -D-glucose, optically equilibrated D-glucose and -D-glucose reduced afferent discharges in the hepatic vagus nerve of anaesthesized rats. -D-Glucose was most potent in decreasing the discharge.