whole-cell-patch-clamp-for-investigating-mechanisms-infrared-neural

Whole Cell Patch Clamp for Investigating the Mechanisms of Infrared Neural Stimulation

It has been  demonstrated in recent years that pulsed, infrared laser light can be used to  elicit electrical responses in neural tissue, independent of ...

The University of Melbourne

A direct commissural connection between cochlear nuclei provides a pathway by which binaural input can influence the processing of acoustic information through the ventral cochlear nucleus. Despite anatomical evidence to suggest the existence of such a pathway, its nature and behavior have not been investigated previously. This in vivo intracellular electrophysiological study provides direct evidence of monosynaptic (mean latency, 1.43 msec), inhibitory commissural input to T stellate cells. This inhibition is fast acting (duration, <10 msec), occurring with little synaptic delay ( approximately 0.3 msec). Electrical stimulation also revealed the initiation of antidromic responses in the onset chopper population, signifying D stellate neurons as a source of commissural inputs. Activation of the commissural connection was most evident in response to broadband stimuli. These results provide the first compelling evidence of a fast, monosynaptic commissural pathway arising from contralateral D stellate neurons providing broadband inhibitory input to T stellate cells.

Fast inhibition underlies the transmission of auditory information between cochlear nuclei.

Une connexion directe commissurale entre noyaux cochl&eacute;aires fournit une voie par laquelle binaurale entr&eacute;e peut influer sur le traitement de l&#39;information acoustique &agrave; travers le noyau cochl&eacute;aire ventral. Malgr&eacute; les preuves anatomiques pour sugg&eacute;rer l&#39;existence d&#39;une telle voie, son caract&egrave;re et son comportement n&#39;ont pas &eacute;tudi&eacute;s pr&eacute;c&eacute;demment. Cette &eacute;tude &eacute;lectrophysiologique intracellulaire in vivo fournit une preuve directe de monosynaptique (latence, 1,43 moyenne msec), inhibitrice entr&eacute;e commissurale aux cellules &eacute;toil&eacute;es de T. Cette inhibition est rapide (dur&eacute;e, &lt; 10 msec), se produisant avec un petit d&eacute;lai synaptique (environ 0,3 ms). La stimulation &eacute;lectrique a &eacute;galement r&eacute;v&eacute;l&eacute; l&#39;initiation des r&eacute;ponses antidromique dans la population de chopper apparition, signifiant des neurones &eacute;toil&eacute;s D comme source d&#39;entr&eacute;es commissurale. Activation de la connexion commissurale &eacute;tait la plus &eacute;vidente en r&eacute;ponse &agrave; des stimuli &agrave; large bande. Ces r&eacute;sultats fournissent la premi&egrave;re preuve convaincante d&#39;une voie rapide monosynaptique commissurale r&eacute;sultant de controlat&eacute;rales neurones &eacute;toil&eacute;s D, apportant une contribution inhibiteur &agrave; large bande aux cellules &eacute;toil&eacute;es de T.

L&#39;inhibition rapide repose sur la transmission de l&#39;information auditive entre les noyaux cochl&eacute;aires.

Un collegamento diretto commissural tra nuclei cocleari fornisce un percorso da quale ingresso binaurale pu&ograve; influenzare l&#39;elaborazione dell&#39;informazione acustica attraverso il nucleo coclea ventrale. Nonostante anatomica evidenze che suggeriscono l&#39;esistenza di un tale percorso, la natura e il comportamento non sono state indagate in precedenza. Questo studio elettrofisiologico intracellulare in vivo fornisce prove dirette di systemseizures (dire latenza, 1,43 msec), input inibitorio commissural a cellule stellate T. Questa inibizione &egrave; ad azione rapida (durata, &lt; 10 msec), che si verificano con poco ritardo sinaptico (circa 0,3 msec). Stimolazione elettrica ha anche rivelato l&#39;iniziazione delle risposte antidromica nella popolazione chopper insorgenza, indicante i neuroni stellati D come fonte di commissural ingressi. Attivazione della connessione commissural era pi&ugrave; evidente in risposta a stimoli a banda larga. Questi risultati forniscono la prima prova convincente di un pathway commissural veloce, systemseizures derivanti da controlaterale neuroni stellati D fornire input inibitorio a banda larga per le cellule stellate T.

L&#39;inibizione veloce sottende la trasmissione di informazioni uditive tra nuclei cocleari.

Dans le premier site de transformation de la voie auditive centrale, les neurones inhibiteurs (cellules &eacute;toil&eacute;es D) largement accord&eacute;s sur projet de fr&eacute;quence tonal &eacute;troitement r&eacute;gl&eacute;, neurones excitateurs sortie (cellules &eacute;toil&eacute;es de T). Ce dernier est cens&eacute; fournir une repr&eacute;sentation topographique du spectre sonore, tandis que l&#39;ancien est per&ccedil;ue d&#39;inhibition lat&eacute;rale qui am&eacute;liore le contraste spectral, en particulier dans le bruit. En r&eacute;ponse &agrave; des sons purs, le taux global de d&eacute;charge en cellules &eacute;toil&eacute;es T est peu susceptible d&#39;&ecirc;tre supprim&eacute; dramatiquement en cellules &eacute;toil&eacute;es D car ils r&eacute;pondent principalement au d&eacute;but de la stimulation et fournissent une inhibition rapide et de courte dur&eacute;e. Des enregistrements intracellulaires in vivo du noyau cochl&eacute;aire ventral (RCV) a montr&eacute; que, lorsque les tons ont &eacute;t&eacute; pr&eacute;sent&eacute;s au-dessus ou au-dessous de la fr&eacute;quence caract&eacute;ristique (CF) d&#39;un neurone stellaire T, elles sont inhib&eacute;es pendant la d&eacute;polarisation. Cela a entra&icirc;n&eacute; un retard dans le potentiel d&#39;action initial produit par les cellules &eacute;toil&eacute;es T. Cette capacit&eacute; d&#39;inhibition rapide de modifier le premier calendrier de spike d&#39;un neurone stellaire T a &eacute;t&eacute; confirm&eacute;e par &eacute;lectriquement activation de la voie de cellules &eacute;toil&eacute;es de D qui se pose dans le noyau cochl&eacute;aire controlat&eacute;ral. Retard est &eacute;galement induite lorsque deux tons ont &eacute;t&eacute; pr&eacute;sent&eacute;s : un &agrave; CF et l&#39;autre &agrave; l&#39;ext&eacute;rieur de la zone de r&eacute;ponse de fr&eacute;quence du neurone stellaire T. Ces r&eacute;sultats sugg&egrave;rent que la vision traditionnelle de l&#39;inhibition lat&eacute;rale au sein de la VCN incorpore retard comme l&#39;un de ses objectifs de principe.

L&#39;inhibition rapide modifie le premier calendrier de spike dans les neurones auditif du tronc c&eacute;r&eacute;bral.

Within the first processing site of the central auditory pathway, inhibitory neurons (D stellate cells) broadly tuned to tonal frequency project on narrowly tuned, excitatory output neurons (T stellate cells). The latter is thought to provide a topographic representation of sound spectrum, whereas the former is thought to provide lateral inhibition that improves spectral contrast, particularly in noise. In response to pure tones, the overall discharge rate in T stellate cells is unlikely to be suppressed dramatically by D stellate cells because they respond primarily to stimulus onset and provide fast, short-duration inhibition. In vivo intracellular recordings from the ventral cochlear nucleus (VCN) showed that, when tones were presented above or below the characteristic frequency (CF) of a T stellate neuron, they were inhibited during depolarization. This resulted in a delay in the initial action potential produced by T stellate cells. This ability of fast inhibition to alter the first spike timing of a T stellate neuron was confirmed by electrically activating the D stellate cell pathway that arises in the contralateral cochlear nucleus. Delay was also induced when two tones were presented: one at CF and one outside the frequency response area of the T stellate neuron. These findings suggest that the traditional view of lateral inhibition within the VCN should incorporate delay as one of its principle outcomes.

Fast inhibition alters first spike timing in auditory brainstem neurons.

All&#39;interno del sito di elaborazione primo della via uditiva centrale, i neuroni inibitori (cellule stellate D) ampiamente sintonizzati per progetto di frequenza tonale restrittivamente sintonizzato, neuroni di output eccitatorio (cellule stellate T). Quest&#39;ultimo &egrave; pensato per fornire una rappresentazione topografica di spettro sonoro, mentre il primo &egrave; pensato per fornire l&#39;inibizione laterale che migliora il contrasto spettrale, particolarmente nel rumore. In risposta a toni puri, il tasso complessivo di scarico nelle cellule stellate T &egrave; improbabile da essere soppresse drammaticamente da cellule stellate D perch&eacute; essi rispondono principalmente all&#39;insorgenza di stimolo e fornire inibizione rapida e di breve durata. Registrazioni intracellulari in vivo dal nucleo coclea ventrale (VCN) ha mostrato che, quando i toni sono stati presentati di sopra o di sotto della frequenza caratteristica (CF) di un neurone stellato T, sono stati inibiti durante la depolarizzazione. Ci&ograve; ha provocato un ritardo nel potenziale d&#39;azione iniziale prodotto da cellule stellate T. Questa capacit&agrave; di inibizione veloce di alterare la prima temporizzazione spike di un neurone stellato T &egrave; stata confermata da attivare elettricamente il percorso D cellule stellate che si pone nel nucleo coclea controlaterale. Ritardo &egrave; stata indotta anche quando sono stati presentati due toni: uno a CF e uno all&#39;esterno dell&#39;area di risposta di frequenza del neurone stellato T. Questi risultati suggeriscono che la visione tradizionale di inibizione laterale all&#39;interno del VCN dovrebbe incorporare ritardo come uno dei suoi esiti di principio.

Rapida inibizione altera la prima temporizzazione spike nei neuroni uditivi del tronco encefalico.

Ventral cochlear nucleus stellate cells respond to characteristic frequency (CF) tones with sustained (C(S)), transient (C(T)) or onset chopping (O(C)) activity. The mechanisms underlying these different response patterns are not fully understood, and the present study used in vivo intracellular recordings (n = 42) in urethane-anaesthetized rats to examine the possible influence of inhibition on action potential regularity. Hyperpolarization following the offset of a CF tone burst was used as a measure of on-CF inhibition. A cluster analysis based on several membrane potential features, including on-CF inhibition, discriminated three groups in addition to the C(S) response type - two types of C(T) responses and the O(C) type. The different patterns of firing regularity exhibited by C(S/T) neurons reflected different thresholds or degrees of overlap between these cells' narrowly tuned excitatory and inhibitory inputs. C(T) cells with closely matched inhibitory and excitatory response areas showed substantial on-CF inhibition and the greatest decline in firing regularity during a CF tone, whereas those with a mismatch between their response areas showed lateral inhibition and a less marked decline in firing regularity. The presence of inhibition in C(S) neurons did not alter their firing regularity, possibly because of the lower threshold for excitation compared with inhibition. The latency, duration and frequency extent of sustained hyperpolarization in C(S/T) cells is inconsistent with the response properties of O(C) neurons, suggesting that another source(s) of inhibition influences firing regularity, and presumably response magnitude, in these neurons.

Balanced inhibition and excitation underlies spike firing regularity in ventral cochlear nucleus chopper neurons.

Noyau cochl&eacute;aire ventral stellaire cellules r&eacute;agissent &agrave; des sons de fr&eacute;quence caract&eacute;ristique (CF) avec soutenue (C(S)), transitoire (C(T)) ou apparition hacher (activit&eacute; O(C)). Les m&eacute;canismes qui sous-tendent ces profils de r&eacute;ponse diff&eacute;rents ne sont pas totalement comprises, et la pr&eacute;sente &eacute;tude a utilis&eacute; des enregistrements intracellulaires in vivo (n = 42) chez des rats anesth&eacute;si&eacute;s &agrave; l&#39;ur&eacute;thane pour examiner l&#39;influence possible de l&#39;inhibition sur la r&eacute;gularit&eacute; du potentiel d&#39;action. Hyperpolarisation suivant le d&eacute;calage d&#39;une rafale de ton CF a &eacute;t&eacute; utilis&eacute;e comme une mesure d&#39;inhibition le-CF. Une analyse de groupement selon plusieurs caract&eacute;ristiques de potentiel de membrane, y compris l&#39;inhibition sur-CF, victime de trois groupes en plus du type de r&eacute;ponse C (S) - deux types de r&eacute;ponses de c (t) et le O(C) type. Les diff&eacute;rents modes de cuisson r&eacute;gularit&eacute; expos&eacute;e par les neurones C(S/T) refl&egrave;tent les diff&eacute;rents seuils ou degr&eacute;s de chevauchement entre les entr&eacute;es excitatrices et inhibitrices &eacute;troitement &agrave; l&#39;&eacute;coute de ces cellules. Les cellules de c (t) avec correspondant &eacute;troitement inhibitrice et r&eacute;ponse excitatrice r&eacute;gions pr&eacute;sentaient inhibition substantielle de sur-CF et la plus forte baisse en r&eacute;gularit&eacute; de mise &agrave; feu au cours d&#39;un ton de CF, tandis que ceux avec un d&eacute;calage entre leurs secteurs d&#39;intervention ont montr&eacute; une inhibition lat&eacute;rale et une baisse moins marqu&eacute;e dans la r&eacute;gularit&eacute; de tir. La pr&eacute;sence d&#39;inhibition dans les neurones de C (S) n&#39;a pas alt&eacute;r&eacute; leur r&eacute;gularit&eacute; de mise &agrave; feu, probablement en raison de la valeur limite inf&eacute;rieure pour l&#39;excitation par rapport &agrave; l&#39;inhibition. La mesure de latence, de dur&eacute;e et de fr&eacute;quence d&#39;hyperpolarisation soutenue dans les cellules C(S/T) est incompatible avec les propri&eacute;t&eacute;s de la r&eacute;ponse des neurones O(C), ce qui sugg&egrave;re qu&#39;une autre source d&#39;inhibition des influences r&eacute;gularit&eacute; de mise &agrave; feu et sans doute l&#39;ampleur de r&eacute;ponse, dans ces neurones.

Excitation et inhibition &eacute;quilibr&eacute;e sous-tend spike tir de r&eacute;gularit&eacute; dans les neurones de chopper noyau cochl&eacute;aire ventral.

Le cellule stellate nucleo cocleare ventrale rispondono a toni di frequenza caratteristica (CF) con sostenuta (C(S)), transitori (C(T)) o insorgenza tagliere (attivit&agrave; O(C)). I meccanismi alla base di questi modelli di risposta differenti non sono completamente chiari, e il presente studio utilizzato registrazioni intracellulari in vivo (n = 42) in ratti anestetizzati uretano per esaminare la possibile influenza di inibizione sulla regolarit&agrave; del potenziale d&#39;azione. Hyperpolarization seguendo l&#39;offset di una raffica di tono CF &egrave; stato utilizzato come una misura di inibizione sulla CF. Un&#39;analisi dei cluster basato su parecchie caratteristiche di potenziale della membrana, compreso inibizione su CF, discriminati tre gruppi oltre al tipo di risposta C (S) - due tipi di risposte c (t) e il O(C) tipo. I diversi modelli di infornamento regolarit&agrave; esposta dai neuroni C(S/T) riflettono diverse soglie o gradi di sovrapposizione tra gli ingressi inibitori ed eccitatori restrittivamente sintonizzati queste cellule. Cellule c (t) con abbinati strettamente inibitorio e aree di risposta eccitatoria mostrato sostanza inibizione su CF e il pi&ugrave; grande calo in cottura regolarit&agrave; durante un tono CF, mentre quelli con una mancata corrispondenza tra le loro aree di risposta ha mostrato inibizione laterale e un calo meno marcato nella regolarit&agrave; di infornamento. La presenza di inibizione in neuroni C (S) non alterava loro regolarit&agrave; di infornamento, forse a causa della soglia inferiore, confrontato con l&#39;inibizione di eccitazione. La misura latenza, durata e frequenza di hyperpolarization sostenuta nelle cellule C(S/T) &egrave; incompatibile con la propriet&agrave; di risposta dei neuroni O(C), suggerendo che un&#39;altra fonte o le fonti di inibizione influenzano cottura regolarit&agrave; e presumibilmente magnitudo di risposta, in questi neuroni.

Eccitazione e inibizione bilanciata sottende spike regolarit&agrave; nei neuroni chopper nucleo cocleare ventrale di infornamento.

The ventral cochlear nucleus (VCN) stellate cell population comprises two clusters: narrowly-tuned, excitatory T stellate neurons, and D stellate neurons, a broadly-tuned population of inhibitory cells. These neurons respond to best frequency (BF) tone bursts in a chopper or onset manner, respectively. Through extensive local and commissural projections the D stellate population provides a source of fast inhibitory input to both intrinsic and contralateral T stellate neurons. Whilst the nature of interactions between intrinsic stellate populations is difficult to examine, our previous intracellular investigations of the commissural pathway have provided a means by which to study this relationship in the in vivo preparation. It is the aim of this paper to both review and extend our understanding of the link between stellate populations and their involvement in the commissural pathway by presenting an overview of the results attained in our recently expanded study. The sample of 17 intracellular and 34 extracellular onset chopper (O(C)) and late/ideal (On(L)/On(I)) neurons revealed antidromic activity in 31.4% of neurons following contralateral stimulation, providing physiological evidence that On(L)/On(I) neurons also contribute projections to the commissural connection. Alternatively, 64.7% of the 34 intracellularly-recorded chopper neurons displayed fast, monosynaptic inhibitory potentials. This commissural input was found to influence the timing of neural activity in chopper neurons, providing insight into the relationship that exists between T and D stellate neurons.

Neural timing, inhibition and the nature of stellate cell interaction in the ventral cochlear nucleus.

La population de cellules &eacute;toil&eacute;es du noyau cochl&eacute;aire ventral (VCN) comprend deux groupes : &eacute;troitement r&eacute;gl&eacute;, excitatrices T stellaires neurones et des neurones &eacute;toil&eacute;s de D, une population largement &agrave; l&#39;&eacute;coute des cellules inhibitrices. Ces neurones r&eacute;pondent pour la meilleure fr&eacute;quence (BF) ton &eacute;clats dans un hacheur ou la mani&egrave;re de l&#39;apparition, respectivement. Par le biais de vastes projections locales et commissurale la population stellaire D fournit une source d&#39;entr&eacute;e rapide inhibiteur aux neurones &eacute;toil&eacute;s d&#39;intrins&egrave;ques et controlat&eacute;rales T. Alors que la nature des interactions entre les populations stellaires intrins&egrave;ques est difficile d&#39;examiner, nos enqu&ecirc;tes pr&eacute;c&eacute;dentes intracellulaires de la voie commissurale ont fourni un moyen d&#39;&eacute;tudier cette relation dans la pr&eacute;paration in vivo. C&#39;est l&#39;objectif de cette communication &agrave; revoir et &eacute;largir notre compr&eacute;hension du lien entre les populations stellaires et leur implication dans la voie commissurale en pr&eacute;sentant un aper&ccedil;u des r&eacute;sultats atteints dans notre &eacute;tude r&eacute;cemment &eacute;largie. L&#39;&eacute;chantillon de 17 intracellulaire et 34 apparition extracellulaire chopper (O(C)) et fin/id&eacute;al (neurones On(L)/On(I)) r&eacute;v&egrave;lent l&#39;activit&eacute; antidromique dans 31,4 % des neurones apr&egrave;s stimulation controlat&eacute;rale, en fournissant des donn&eacute;es physiologiques que les neurones On(L)/On(I) contribuent &eacute;galement des projections &agrave; la connexion commissurale. Alternativement, 64,7 % des 34 enregistr&eacute; intracellulairement hacheur de neurones affich&eacute;es rapide, monosynaptique potentiels inhibiteurs. Cette entr&eacute;e commissurale s&#39;est av&eacute;r&eacute;e pour influencer le moment de l&#39;activit&eacute; neuronale dans les neurones de hachoir, donnant un aper&ccedil;u dans la relation qui existe entre des neurones &eacute;toil&eacute;s T et D.

Synchronisation neuronale, l&#39;inhibition et la nature de l&#39;interaction des cellules &eacute;toil&eacute;es dans le noyau cochl&eacute;aire ventral.

La popolazione di cellule stellate nucleo cocleare ventrale (VCN) comprende due cluster: stretto sintonizzato, eccitatori T neuroni stellati e neuroni stellati D, una popolazione di cellule inibitorie ampiamente sintonizzati. Questi neuroni rispondono per miglior frequenza (BF) tono scoppia in un tritatutto o modo di insorgenza, rispettivamente. Attraverso il vaste locale e commissurale proiezioni della popolazione stellata D fornisce una fonte di input inibitorio veloce sia intrinseci e controlaterale neuroni stellati T. Mentre la natura delle interazioni tra le popolazioni stellate intrinseche &egrave; difficile da esaminare, nostri precedenti inchieste intracellulare del percorso commissural hanno fornito un mezzo studiare questa relazione nella preparazione in vivo. &Egrave; lo scopo di questa carta sia rivedere ed estendere la nostra comprensione del legame tra popolazioni stellate e loro coinvolgimento nella via della commissural presentando una panoramica dei risultati raggiunti nel nostro studio recentemente ampliato. Il campione di 17 intracellulare e 34 chopper insorgenza extracellulare (O(C)) e fine/ideale (neuroni On(L)/On(I)) hanno rivelato attivit&agrave; antidromica nel 31,4% dei neuroni in seguito a stimolazione controlaterale, fornendo prove fisiologiche che i neuroni On(L)/On(I) contribuiscono anche le proiezioni per il collegamento commissural. In alternativa, 64,7% dei 34 intracellularly-registrato chopper neuroni visualizzati veloce, systemseizures inibitori potenziali. Questo input commissural &egrave; stato trovato per influenzare i tempi di attivit&agrave; neurale in neuroni di chopper, che fornisce insight sul rapporto che esiste tra T e D i neuroni stellati.

Temporizzazione neurale, inibizione e la natura dell&#39;interazione delle cellule stellate nel nucleo coclea ventrale.

Un collegamento diretto commissural formato tra nuclei cocleari consente informazioni dall&#39;orecchio controlaterale per influenzare rapidamente l&#39;elaborazione del segnale acustico ascendente. Tra i gruppi neuronali proposti sia ricevere, e contribuire a, input commissural &egrave; la popolazione cellulare folta nel nucleo coclea ventrale (VCN). In questo studio elettrofisiologico in vivo esaminiamo le registrazioni intracellulari di folti neuroni durante la stimolazione elettrica del nucleo coclea controlaterale (CN) per la prova del loro contributo sia input da commissurale proiezioni. Attivazione del percorso commissural rivelato breve latenza veloce hyperpolarisation nel 19,5% dei neuroni folti 41 esaminati. I potenziali hyperpolarising erano piccoli in ampiezza, visualizzato un decorso molto variabile tra neuroni e in alcuni casi sono stati eliminati con iniezione di depolarising corrente. Non non c&#39;era nessuna indicazione di attivit&agrave; antidromica, o potenziali eccitatori breve latenza. Questi risultati suggeriscono che i) cespugliosi neuroni non contribuiscono le proiezioni per il collegamento commissural e ii) una piccola porzione di folti neuroni sono hyperpolarised dopo stimolazione commissurale.

Il pathway commissural e folta neuroni nucleo cocleare: un&#39;indagine in vivo intracellulare.

A direct commissural connection formed between cochlear nuclei allows information from the contralateral ear to rapidly influence the processing of the ascending auditory signal. Among the neuronal groups proposed to both receive, and contribute to, commissural input is the bushy cell population in the ventral cochlear nucleus (VCN). In this in vivo electrophysiological study we examine the intracellular recordings of bushy neurons during electrical stimulation of the contralateral cochlear nucleus (CN) for evidence of both their contribution to, and input from commissural projections. Activation of the commissural pathway revealed short-latency fast hyperpolarisation in 19.5% of the 41 bushy neurons examined. The hyperpolarising potentials were small in amplitude, displayed a highly variable time course between neurons, and in some cases were eliminated with injection of depolarising current. There was no indication of antidromic activity, or short-latency excitatory potentials. These results suggest that i) bushy neurons do not contribute projections to the commissural connection, and ii) a small portion of bushy neurons are hyperpolarised following commissural stimulation.

The commissural pathway and cochlear nucleus bushy neurons: an in vivo intracellular investigation.

Une connexion directe de commissurale form&eacute;e entre les noyaux cochl&eacute;aires permet l&#39;information de l&#39;oreille controlat&eacute;rale pour influencer rapidement le traitement du signal auditif ascendant. Parmi les groupes neurones a propos&eacute; des recevoir et contribuer &agrave;, entr&eacute;e commissurale est la population de cellules touffue dans le noyau cochl&eacute;aire ventral (VCN). Dans cette &eacute;tude &eacute;lectrophysiologique in vivo, nous examinons les enregistrements intracellulaires de neurones touffues au cours de la stimulation &eacute;lectrique du noyau cochl&eacute;aire controlat&eacute;rale (CN) pour les t&eacute;moignages de leur contribution et entr&eacute;e de projections commissurale. Activation de la voie commissurale a r&eacute;v&eacute;l&eacute; hyperpolarisation rapide courte latence dans 19,5 % des neurones touffues 41 examin&eacute;s. Les potentiels de hyperpolarising &eacute;taient de petites amplitude, affichent une &eacute;volution tr&egrave;s variable entre les neurones et dans certains cas, ont &eacute;t&eacute; &eacute;limin&eacute;s avec l&#39;injection de depolarising actuel. Il n&#39;y n&#39;avait aucune indication d&#39;activit&eacute; antidromique ou courte latence potentiels excitateurs. Ces r&eacute;sultats sugg&egrave;rent que les neurones i) touffues ne contribuent pas de projections vers la connexion commissurale, et ii) une petite partie des neurones touffues sont hyperpolaris&eacute; apr&egrave;s stimulation commissurale.

La voie commissurale et neurones touffue noyau cochl&eacute;aire : une enqu&ecirc;te intracellulaire in vivo.

The family of two-pore domain potassium (K(â‚‚P)) channels is important in setting and controlling the background potassium current of excitable cells. This study examines the localisation of the acid-sensitive channel, K(â‚‚P)9.1 (TASK3), in cells of the gastric mucosa. We observed K(â‚‚P)9.1 immunoreactivity in endocrine cells of the mucosal glands of the guinea-pig, rat and mouse but the channels were not detected in parietal, chief, or mucous cells. K(â‚‚P)9.1 channel immunoreactivity was consistently co-localised with histidine decarboxylase immunopositive enterochromaffin-like (ECL) cells, and with the majority of ghrelin immunoreactive X/A cells. Localisation in somatostatin immunoreactive D cells was rare in the guinea-pig, and did not occur in the stomach of rat, but, in the mouse, K(â‚‚P)9.1 channels were observed in the majority of somatostatin-immunoreactive D cells. Conversely, sections taken from the guinea-pig and mouse stomachs, but not rat stomach, revealed K(â‚‚P)9.1 in gastrin-containing G cells. These results demonstrate the presence of K(â‚‚P)9.1 channels in the entero-endocrine ECL, G and D cell populations of the stomach that regulate acid secretion through the release of histamine, gastrin and somatostatin. K(â‚‚P)9.1 channels were located in the ghrelin X/A cells that regulate food intake.

Identification of endocrine cells of the stomach that express acid-sensitive background potassium (K(2P)9.1/TASK3) channels.

La famille de potassium domaine deux pores (K(&#x2082;P)) canaux est important dans la d&eacute;finition et de contr&ocirc;ler le courant de potassium d&#39;arri&egrave;re-plan des cellules excitables. Cette &eacute;tude examine la localisation du canal sensibles aux acides, K (&#x2082;P) 9.1 (TASK3), dans les cellules de la muqueuse gastrique. Nous avons observ&eacute; l&#39;immunor&eacute;activit&eacute; K (&#x2082;P) 9.1 dans les cellules endocrines des glandes muqueuses du cobaye, rat et souris, mais les canaux n&#39;ont pas &eacute;t&eacute; d&eacute;tect&eacute;s dans les cellules pari&eacute;tales, chef ou muqueuses. L&#39;immunor&eacute;activit&eacute; de canal K (&#x2082;P) 9.1 &eacute;tait toujours co-localised avec l&#39;histidine d&eacute;carboxylase immunopositifs ent&eacute;rochromaffines-like (ECL) cellules et la majorit&eacute; de la ghr&eacute;line immunor&eacute;active X/A cellules. Localisation dans les cellules immunor&eacute;actives &agrave; D la somatostatine est rare chez le cobaye et n&#39;appara&icirc;t pas dans l&#39;estomac de rat, mais, chez la souris, les canaux K (&#x2082;P) 9.1 ont &eacute;t&eacute; observ&eacute;s dans la plupart des cellules somatostatin-immunor&eacute;actives &agrave; D. &Agrave; l&#39;inverse, sections tir&eacute;es du cobaye et estomacs de souris, mais pas estomac de rat, a r&eacute;v&eacute;l&eacute; K (&#x2082;P) 9.1 dans les cellules G contenant de la gastrine. Ces r&eacute;sultats d&eacute;montrent la pr&eacute;sence de canaux K (&#x2082;P) 9.1 dans l&#39;ent&eacute;ro-endocrines ECL, G et D populations de cellules de l&#39;estomac qui r&eacute;gulent la s&eacute;cr&eacute;tion d&#39;acide par la lib&eacute;ration d&#39;histamine, gastrine et la somatostatine. Canaux K (&#x2082;P) 9.1 se trouvaient dans la ghr&eacute;line X/A cellules qui r&eacute;gulent la prise alimentaire.

Identification de cellules endocrines de l&#39;estomac qui expriment le potassium fond sensibles aux acides (K(2P)9.1/TASK3) cha&icirc;nes.

La famiglia di potassio poro due dominio (K(&#x2082;P)) canali &egrave; importante nell&#39;impostazione e controllare la corrente di potassio sfondo delle cellule eccitabili. Questo studio esamina la localizzazione del canale acido-sensibili, K (&#x2082;P) 9.1 (TASK3), nelle cellule della mucosa gastrica. Abbiamo osservato immunoreattivit&agrave; K (&#x2082;P) 9.1 nelle cellule endocrine delle ghiandole mucose della cavia, ratto e topo, ma i canali non sono stati rilevati nelle cellule parietali, capo o mucose. Immunoreattivit&agrave; canale K (&#x2082;P) 9.1 era costantemente co-localised con cellule di istidina decarbossilasi immunopositive enterocromaffini-like (ECL) e con la maggioranza di grelina immunoreattiva X/A celle. Localizzazione nelle cellule D immunoreattive somatostatina era raro nella cavia e non si &egrave; verificato nello stomaco di ratto, ma, nel topo, canali K (&#x2082;P) 9.1 sono stati osservati nella maggior parte delle cellule D somatostatina-immunoreattive. Al contrario, sezioni adottate dalla cavia e stomaci del mouse, ma non lo stomaco di ratto, ha rivelato K (&#x2082;P) 9.1 nelle cellule G contenenti gastrina. Questi risultati dimostrano la presenza di canali K (&#x2082;P) 9.1 in popolazioni l&#39;entero-endocrine ECL, G e D delle cellule dello stomaco che regolano la secrezione di acido attraverso il rilascio di istamina, gastrina e somatostatina. Canali K (&#x2082;P) 9.1 si trovavano nella grelina X/A cellule che regolano l&#39;assunzione di cibo.

Identificazione delle cellule endocrine dello stomaco che esprimono potassio sfondo acido-sensibili (canali K(2P)9.1/TASK3).

Neurotrophins provide an effective tool for the rescue and regeneration of spiral ganglion neurons (SGNs) following sensorineural hearing loss. However, these nerve growth factors are also potent modulators of ion channel activity and expression, and in the peripheral auditory system brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3) have previously been shown to alter the firing properties of auditory neurons and differentially regulate the expression of some potassium channels in vitro. In this study we examined the activity of the hyperpolarization-mediated mixed-cation current (I(h)) in early post-natal cultured rat SGNs following exposure to combined BDNF and NT3. Whole-cell patch-clamp recordings made after 1 or 2 days in vitro revealed no change in the firing adaptation of neurons in the presence of BDNF and NT3. Resting membrane potentials were also maintained, but spike latency and firing threshold was subject to regulation by both neurotrophins and time in vitro. Current clamp recordings revealed an activity profile consistent with activation of the hyperpolarization-activated current. Rapid membrane hyperpolarization was followed by a voltage- and time-dependent depolarizing voltage sag. In voltage clamp, membrane hyperpolarization evoked a slowly-activating inward current that was reversibly blocked with cesium and inhibited by ZD7288. The amplitude and current density of I(h) was significantly larger in BDNF and NT3 supplemented cultures, but this did not translate to a significant alteration in voltage sag magnitude. Neurotrophins provided at 50 ng/ml produced a hyperpolarizing shift in the voltage-dependence and slower time course of I(h) activation compared to SGNs in control groups or cultured with 10 ng/ml BDNF and NT3. Our results indicate that combined BDNF and NT3 increase the activity of hyperpolarization-activated currents and that the voltage-dependence and activation kinetics of I(h) in SGNs are sensitive to changes in neurotrophin concentration. In addition, BDNF and NT3 applied together induce a decrease in firing threshold, but does not generate a shift in firing adaptation.

Combined application of brain-derived neurotrophic factor and neurotrophin-3 and its impact on spiral ganglion neuron firing properties and hyperpolarization-activated currents.

Neurotrophines constituer un outil efficace pour le sauvetage et la r&eacute;g&eacute;n&eacute;ration des neurones de ganglion spiral (SGNs) suite &agrave; une perte auditive neurosensorielle. Cependant, ces facteurs de croissance de nerf sont aussi puissants modulateurs d&#39;expression et l&#39;activit&eacute; des canaux ioniques et dans le facteur neurotrophique d&eacute;riv&eacute; du cerveau syst&egrave;me auditif p&eacute;riph&eacute;rique (BDNF) et neurotrophine 3 (NT3) ont d&eacute;j&agrave; d&eacute;montr&eacute; qu&#39;alt&eacute;rer les propri&eacute;t&eacute;s de mise &agrave; feu des neurones auditifs et diff&eacute;rentiellement r&eacute;gulent l&#39;expression de certains canaux de potassium in vitro. Dans cette &eacute;tude, nous avons examin&eacute; l&#39;activit&eacute; du courant mixte-cation induite par l&#39;hyperpolarisation (I(h)) au d&eacute;but postnatal cultured rat SGNs following exposure to BDNF et NT3 combin&eacute;s. Enregistrements de patch-clamp de la cellule enti&egrave;re faites apr&egrave;s 1 ou 2 jours in vitro ont r&eacute;v&eacute;l&eacute; aucun changement dans l&#39;adaptation de la mise &agrave; feu des neurones en pr&eacute;sence de BDNF et NT3. Potentiels de membrane au repos ont &eacute;t&eacute; &eacute;galement maintenus, mais seuil de latence et de mise &agrave; feu de spike &eacute;tait assujettie &agrave; la r&eacute;glementation par les neurotrophines et temps in vitro. Des enregistrements de pince actuel ont r&eacute;v&eacute;l&eacute; un profil d&#39;activit&eacute; compatible avec l&#39;activation du courant activ&eacute; par une hyperpolarisation. Hyperpolarisation de la membrane rapide a &eacute;t&eacute; suivie par un tension - et d&eacute;pendant du temps affaissement tension de d&eacute;polarisation. Bride de tension, hyperpolarisation de la membrane &eacute;voque un activation lentement courant entrant qui est r&eacute;versible bloqu&eacute; avec le c&eacute;sium et inhib&eacute; par ZD7288. L&#39;amplitude et la densit&eacute; de courant d&#39;i est significativement plus importante chez BDNF et NT3 compl&eacute;t&eacute;e des cultures, mais cela ne s&#39;est pas traduit &agrave; une modification notable dans l&#39;amplitude de tension sag. Neurotrophines condition &agrave; 50 ng/ml produit un glissement hyperpolarisant la voltage-d&eacute;pendance et plus lente &eacute;volution temporelle d&#39;activation i contre SGNs en groupes t&eacute;moins soit 10 ng/ml de culture BDNF et NT3. Nos r&eacute;sultats indiquent que les combin&eacute;s BDNF et NT3 augmentent l&#39;activit&eacute; des courants activ&eacute;s par une hyperpolarisation et que la d&eacute;pendance vis-&agrave;-vis de la tension et l&#39;activation cin&eacute;tique d&#39;i dans SGNs sont sensibles aux variations de concentration de la neurotrophine. En outre, BDNF et NT3 appliqu&eacute;es ensemble induisent une diminution seuil de mise &agrave; feu, mais ne g&eacute;n&egrave;re pas un changement dans l&#39;adaptation de tir.

Application combin&eacute;e de brain-derived neurotrophic factor et neurotrophine 3 et son impact sur le neurone de ganglion spiral tir propri&eacute;t&eacute;s et courants activ&eacute;s par une hyperpolarisation.

Neurotrofine forniscono un efficace strumento per il salvataggio e la rigenerazione dei neuroni di ganglio spirale (SGNs) dopo la perdita dell&#39;udito neurosensoriale. Tuttavia, questi fattori di crescita nervosi sono anche potenti modulatori di espressione e di attivit&agrave; del canale ionico con il sistema uditivo periferico brain-derived neurotrophic factor (BDNF) e neurotrophin-3 (NT3) sono stati indicati in precedenza per alterare le propriet&agrave; di infornamento dei neuroni uditivi e differenzialmente regolano l&#39;espressione di alcuni canali del potassio in vitro. In questo studio abbiamo esaminato l&#39;attivit&agrave; della corrente mista-cazione hyperpolarization-mediata (I(h)) in primi SGNs postnatali ratto coltivate seguendo l&#39;esposizione combinata BDNF e NT3. Cellule intere patch-clamp registrazioni dopo 1 o 2 giorni in vitro hanno rivelato nessun cambiamento nell&#39;adattamento del firing dei neuroni in presenza di BDNF e NT3. Potenziali di membrana di riposo erano anche mantenuti, ma soglia di latenza e cottura spike era soggetta a regolamento da neurotrofine e da tempo in vitro. Registrazioni morsetto attuale ha rivelato un profilo di attivit&agrave; coerente con l&#39;attivazione della corrente hyperpolarization-attivato. Hyperpolarization membrana rapida &egrave; stata seguita da un tensione - e tempo-dipendente depolarizzante abbassamento di tensione. Nel morsetto di tensione, hyperpolarization membrana evocato verso un lentamente attivando l&#39;attuale che &egrave; stato bloccato con cesio reversibilmente e inibito da ZD7288. L&#39;ampiezza e la densit&agrave; di corrente della lettera era significativamente pi&ugrave; grande di BDNF e NT3 integrate culture, ma questo non si tradussero in una significativa alterazione nella grandezza di abbassamento di tensione. Neurotrofine fornito a 50 ng/ml prodotto un cambiamento hyperpolarizing in tensione-dipendenza e decorso pi&ugrave; lento della lettera attivazione rispetto al SGNs nei gruppi di controllo o coltivate con 10 ng/ml BDNF e NT3. I nostri risultati indicano che combinato BDNF e NT3 aumentare l&#39;attivit&agrave; delle correnti hyperpolarization-attivato e che la cinetica di voltaggio-dipendenza e attivazione della lettera in SGNs sono sensibili alle variazioni di concentrazione neurotrophin. Inoltre, BDNF e NT3 applicato insieme inducono una diminuzione della soglia di infornamento, ma non genera un cambiamento nell&#39;adattamento di infornamento.

Applicazione combinata di brain-derived neurotrophic factor e neurotrophin-3 e il suo impatto sul neurone di ganglio spirale hyperpolarization-attivato correnti e propriet&agrave; di cottura.

In mammals, the sensory hair cells and auditory neurons do not spontaneously regenerate and their loss results in permanent hearing impairment. Stem cell therapy is one emerging strategy that is being investigated to overcome the loss of sensory cells after hearing loss. To successfully replace auditory neurons, stem cell-derived neurons must be electrically active, capable of organized outgrowth of processes, and of making functional connections with appropriate tissues. We have developed an in vitro assay to test these parameters using cocultures of developing cochlear explants together with neural progenitors derived from human embryonic stem cells (hESCs). We found that these neural progenitors are electrically active and extend their neurites toward the sensory hair cells in cochlear explants. Importantly, this neurite extension was found to be significantly greater when neural progenitors were predifferentiated toward a neural crest-like lineage. When grown in coculture with hair cells only (denervated cochlear explants), stem cell-derived processes were capable of locating and growing along the hair cell rows in an en passant-like manner. Many presynaptic terminals (synapsin 1-positive) were observed between hair cells and stem cell-derived processes in vitro. These results suggest that differentiated hESC-derived neural progenitors may be useful for developing therapies directed at auditory nerve replacement, including complementing emerging hair cell regeneration therapies.

An in vitro model of developmental synaptogenesis using cocultures of human neural progenitors and cochlear explants.

Chez les mammif&egrave;res, les cellules sensorielles de cheveux et neurones auditifs ne r&eacute;g&eacute;n&egrave;rent pas spontan&eacute;ment et leur perte se traduit par une d&eacute;ficience auditive permanente. Th&eacute;rapie de cellules souches est une nouvelle strat&eacute;gie qui est &agrave; l&#39;&eacute;tude pour surmonter la perte de cellules sensorielles apr&egrave;s la perte d&#39;audition. Pour remplacer avec succ&egrave;s les neurones auditifs, cellules souches d&eacute;riv&eacute;es de neurones doivent &ecirc;tre &eacute;lectriquement actives, capables d&#39;excroissance organis&eacute; des processus et d&#39;&eacute;tablir des liens fonctionnels avec des tissus appropri&eacute;s. Nous avons d&eacute;velopp&eacute; un test in vitro pour tester ces param&egrave;tres &agrave; l&#39;aide des cocultures de mettre au point des explants cochl&eacute;aires ainsi que des prog&eacute;niteurs neurones d&eacute;riv&eacute;s des cellules souches embryonnaires humaines (CSEh). Nous avons constat&eacute; que ces cellules souches neurales sont &eacute;lectriquement actifs et &eacute;tendent leur neurites vers les cellules cili&eacute;es sensorielles des explants de cochl&eacute;aire. Ce qui est important, cette extension de neurites s&#39;est av&eacute;r&eacute;e pour &ecirc;tre significativement sup&eacute;rieure lorsque les cellules souches neurales ont &eacute;t&eacute; predifferentiated vers une lign&eacute;e de cr&ecirc;te neurale-comme. Lorsqu&#39;il est cultiv&eacute; en coculture avec des cellules cili&eacute;es seul (explants cochl&eacute;aire d&eacute;nerv&eacute;), processus de cellules souches d&eacute;riv&eacute;es ont &eacute;t&eacute; capables de localiser et qui poussent sur les rang&eacute;es de cellules cili&eacute;es de mani&egrave;re semblable au fr. Nombreuses terminaisons pr&eacute;synaptiques (synapsine 1-positive) ont &eacute;t&eacute; observ&eacute;es entre les cellules cili&eacute;es et des cellules souches d&eacute;riv&eacute;es de processus in vitro. Ces r&eacute;sultats sugg&egrave;rent que diff&eacute;renci&eacute;es des prog&eacute;niteurs neurones d&eacute;riv&eacute;es de CSEh peuvent &ecirc;tre utiles pour le d&eacute;veloppement de th&eacute;rapies r&eacute;alis&eacute;s lors du remplacement du nerf auditif, y compris le compl&eacute;ment des nouvelles th&eacute;rapies de r&eacute;g&eacute;n&eacute;ration de cellules cili&eacute;es.

Un mod&egrave;le in vitro de la synaptog&eacute;n&egrave;se du d&eacute;veloppement &agrave; l&#39;aide des cocultures des prog&eacute;niteurs neurones humaines et cochl&eacute;aire des explants.

Nei mammiferi, non rigenerare spontaneamente le cellule ciliate sensoriali e neuroni uditivi e loro perdita provoca sordit&agrave; permanente. Terapia della cellula formativa &egrave; una strategia emergente che si sta analizzando per superare la perdita di cellule sensoriali dopo la perdita dell&#39;udito. Per sostituire con successo neuroni uditivi, neuroni cellule staminali derivate devono essere elettricamente attiva, capace di escrescenza organizzata dei processi e di effettuare i collegamenti funzionali con tessuti appropriati. Abbiamo sviluppato un test in vitro per testare questi parametri utilizzando cocultures di sviluppare cocleare espianti insieme ai progenitori neurali derivate da cellule staminali embrionali umane (hESC). Abbiamo scoperto che questi progenitori neurali sono elettricamente attivi ed estendono i loro neuriti verso le cellule ciliate sensoriali in espianti cocleare. Soprattutto, questa estensione dei neuriti &egrave; stata trovata per essere significativamente maggiore quando progenitori neurali erano predifferentiated verso un lignaggio come cresta neurale. Quando coltivate in coculture con cellule ciliate solo (Denervato cocleare espianti), cellule staminali derivate processi erano in grado di localizzare e crescono lungo le righe delle cellule dei capelli in maniera en passant-like. Molti terminali presinaptiche (synapsin 1-positivo) sono stati osservati tra cellule ciliate e cellule staminali derivate processi in vitro. Questi risultati suggeriscono che la differenziata progenitori neurali hESC-derivato possono essere utile per lo sviluppo di terapie dirette al nervo uditivo sostituzione, tra cui integrando emergenti terapie di rigenerazione delle cellule dei capelli.

Un modello in vitro di pervasivi dello sviluppo mediante cocultures di progenitori neurali umane e cocleare explants.

Dans le syst&egrave;me auditif, un sous-ensemble sp&eacute;cialis&eacute; de neurones sensoriels sont responsables pour relayer correctement l&#39;emplacement pr&eacute;cis et des rep&egrave;res temporels au cerveau. Chez les personnes ayant une d&eacute;ficience auditive neurosensorielle s&eacute;v&egrave;re &agrave; profonde que ces neurones sensoriels auditifs peuvent &ecirc;tre directement stimul&eacute;es par un implant cochl&eacute;aire, qui restaure sonore entr&eacute;e dans le tronc c&eacute;r&eacute;bral apr&egrave;s la perte des cellules cili&eacute;es. Cette proth&egrave;se neurale d&eacute;pend donc une population r&eacute;siduelle de neurones fonctionnels afin de fonctionner efficacement.

D&eacute;fis pour les cellules souches r&eacute;parer fonctionnellement le nerf auditif endommag&eacute;.

Il sistema uditivo, un sottoinsieme specifico dei neuroni sensoriali sono responsabili correttamente l&#39;inoltro intonazione precisa e spunti temporali al cervello. In individui con grave profonda ipoacusia neurosensoriale che questi neuroni sensoriali uditivi possono essere stimolati direttamente da un impianto cocleare, che ripristina audio ingresso al tronco cerebrale dopo la perdita di cellule ciliate. Questa protesi neurale dipende pertanto una residua popolazione di neuroni funzionali per poter funzionare efficacemente.

Sfide per le cellule staminali per la riparazione funzionale del nervo uditivo danneggiato.

In the auditory system, a specialized subset of sensory neurons are responsible for correctly relaying precise pitch and temporal cues to the brain. In individuals with severe-to-profound sensorineural hearing impairment these sensory auditory neurons can be directly stimulated by a cochlear implant, which restores sound input to the brainstem after the loss of hair cells. This neural prosthesis therefore depends on a residual population of functional neurons in order to function effectively.

Article	Year
Fast inhibition underlies the transmission of auditory information between cochlear nuclei. The Journal of neuroscience : the official journal of the Society for Neuroscience\| PubMed ID: 12867521	2003
Fast inhibition alters first spike timing in auditory brainstem neurons. Journal of neurophysiology\| PubMed ID: 15140909	2004
Balanced inhibition and excitation underlies spike firing regularity in ventral cochlear nucleus chopper neurons. The European journal of neuroscience\| PubMed ID: 15813933	2005
Neural timing, inhibition and the nature of stellate cell interaction in the ventral cochlear nucleus. Hearing research\| PubMed ID: 16554129	2006
The commissural pathway and cochlear nucleus bushy neurons: an in vivo intracellular investigation. Brain research\| PubMed ID: 17174943	2007
Identification of endocrine cells of the stomach that express acid-sensitive background potassium (K(2P)9.1/TASK3) channels. Journal of molecular histology\| PubMed ID: 20607593	2010
Combined application of brain-derived neurotrophic factor and neurotrophin-3 and its impact on spiral ganglion neuron firing properties and hyperpolarization-activated currents. Hearing research\| PubMed ID: 22796476	2012
An in vitro model of developmental synaptogenesis using cocultures of human neural progenitors and cochlear explants. Stem cells and development\| PubMed ID: 23078657	2013
Challenges for stem cells to functionally repair the damaged auditory nerve. Expert opinion on biological therapy\| PubMed ID: 23094991	2013

Karina Needham

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