optogenetic-perturbation-neural-activity-with-laser-illumination-semi

Optogenetic Perturbation of Neural Activity with Laser Illumination in Semi-intact <em>Drosophila</em> Larvae in Motion

Drosophila larval locomotion is a splendid model system in developmental and physiological neuroscience, by virtue of the genetic accessibility of the ...

The University of Tokyo

the university of tokyo

How are functional neural circuits formed during development? Despite recent advances in our understanding of the development of individual neurons, little is known about how complex circuits are assembled to generate specific behaviors. Here, we describe the ways in which Drosophila motor circuits serve as an excellent model system to tackle this problem. We first summarize what has been learned during the past decades on the connectivity and development of component neurons, in particular motor neurons and sensory feedback neurons. We then review recent progress in our understanding of the development of the circuits as well as studies that apply optogenetics and other innovative techniques to dissect the circuit diagram. New approaches using Drosophila as a model system are now making it possible to search for developmental rules that regulate the construction of neural circuits.

Development of larval motor circuits in Drosophila.

Comment sont forment les circuits neurones fonctionnels au cours du d&eacute;veloppement ? Malgr&eacute; les progr&egrave;s r&eacute;cents dans notre compr&eacute;hension du d&eacute;veloppement de neurones individuels, peu est connu sur des circuits complexes soient-ils, sont assembl&eacute;s pour g&eacute;n&eacute;rer des comportements sp&eacute;cifiques. Nous d&eacute;crivons ici la fa&ccedil;on dans laquelle Drosophila circuits du moteur servent un syst&egrave;me excellent mod&egrave;le pour s&#39;attaquer &agrave; ce probl&egrave;me. Tout d&#39;abord, nous r&eacute;sumons ce qui a &eacute;t&eacute; appris durant les derni&egrave;res d&eacute;cennies sur la connectivit&eacute; et le d&eacute;veloppement des neurones composant, en particuliers des neurones moteurs et les neurones de la r&eacute;troaction sensorielle. Nous passons en revue puis les progr&egrave;s r&eacute;cents dans notre compr&eacute;hension du d&eacute;veloppement de la circuits ainsi que les &eacute;tudes qui s&#39;appliquent &agrave; optogenetics et autres techniques innovantes de diss&eacute;quer le sch&eacute;ma de c&acirc;blage. Nouvelles approches &agrave; l&#39;aide de la drosophile comme mod&egrave;le sont maintenant permettant de rechercher des r&egrave;gles du d&eacute;veloppement qui r&eacute;gissent la construction de circuits neuronaux.

D&eacute;veloppement des circuits de moteurs larvaires chez la drosophile.

Come si formano i circuiti neurali funzionali durante lo sviluppo? Nonostante i recenti progressi nella nostra comprensione dello sviluppo dei singoli neuroni, poco &egrave; conosciuto circa come complessi circuiti sono assemblati per generare comportamenti specifici. Qui, descriviamo i modi in cui drosofila circuiti motori servono come sistema modello eccellente per affrontare questo problema. Riassumiamo in primo luogo ci&ograve; che &egrave; stato appreso nel corso degli ultimi decenni sulla connettivit&agrave; e sviluppo dei neuroni del componente, in particolari dei motoneuroni e i neuroni sensoriali feedback. Poi passiamo in rassegna i recenti progressi nella comprensione dello sviluppo dei circuiti, nonch&eacute; di studi che si applicano optogenetics e altre tecniche innovative per sezionare il diagramma del circuito. Nuovi approcci utilizzando Drosophila come sistema modello sono ora rendendo possibile la ricerca per lo sviluppo norme che regolano la costruzione dei circuiti neurali.

Sviluppo larvale circuiti motore in drosofila.

Circuiti neuronali sono formati secondo un programma geneticamente predeterminato e quindi ricostruiti in maniera dipendente dalla esperienza. Mentre &egrave; stata dimostrata l&#39;esistenza di plasticit&agrave; esperienza-dipendente per il visual e altri sistemi sensoriali, rimane sconosciuto se questo &egrave; anche il caso di sistemi a motore. Qui abbiamo esaminato gli effetti di eliminare gli input sensoriali sullo sviluppo dei movimenti peristaltici in drosofila embrioni e larve. La peristalsi sono inizialmente lenta e scoordinata, ma gradualmente si sviluppa in un modello maturo durante fasi embrionali. Abbiamo testato sia inibendo la trasmissione dei neuroni sensoriali specifici durante questo periodo avrebbe avuto effetti sulle propriet&agrave; dei circuiti sensitivo-motoria duraturi. Abbiamo applicato l&#39;inibizione mediata da Shibiresasu per sei ore durante lo sviluppo embrionale (15-21 h dopo uovo posa [AEL]) e ha studiato gli effetti sulla peristalsi nelle larve mature di seconda e terza instar. Abbiamo trovato che l&#39;inibizione degli organi chordotonal, ma non multidendritic neuroni, ha portati ad una diminuzione duratura nella velocit&agrave; di locomozione delle larve. Per restringere il periodo sensibile, abbiamo applicato pi&ugrave; breve inibizione a vari stadi embrionale e larvale e trovato che l&#39;inibizione di due ore durante 16-20 h AEL, ma non nelle fasi precedenti o successive, &egrave; stato sufficiente a causare l&#39;effetto. Questi risultati suggeriscono che attivit&agrave; neuronale mediata dai neuroni sensoriali specifici &egrave; coinvolto nella maturazione dei circuiti sensitivo-motoria in Drosophila e che c&#39;&egrave; un periodo critico per questo cambiamento in plastica. Coerente con un ruolo di neuroni chordotonal feedback sensoriali, questi neuroni sono stati attivati durante la peristalsi larvale e inibizione acuta della loro attivit&agrave; diminuita la velocit&agrave; di locomozione delle larve.

Ruolo dell&#39;esperienza sensoriale in funzionali allo sviluppo dei circuiti motori della drosofila.

Circuits neuronaux sont form&eacute;s suivant un programme g&eacute;n&eacute;tiquement pr&eacute;d&eacute;termin&eacute; et puis reconstruites d&#39;une mani&egrave;re d&eacute;pendante de l&#39;exp&eacute;rience. Bien que l&#39;existence de la plasticit&eacute; de l&#39;exp&eacute;rience-d&eacute;pendante a &eacute;t&eacute; d&eacute;montr&eacute;e pour le visuel et les autres syst&egrave;mes sensoriels, il reste inconnu si c&#39;est aussi le cas pour les syst&egrave;mes moteurs. Ici, nous avons examin&eacute; les effets de l&#39;&eacute;limination des inputs sensoriels sur le d&eacute;veloppement des mouvements p&eacute;ristaltiques dans des embryons de drosophile et les larves. Le p&eacute;ristaltisme est initialement lente et non coordonn&eacute;e, mais se d&eacute;veloppe progressivement dans un mod&egrave;le de maturit&eacute; au cours des derniers stades embryonnaires. Nous avons test&eacute; si inhibant la transmission des neurones sensoriels sp&eacute;cifiques au cours de cette p&eacute;riode, il aurait des effets durables sur les propri&eacute;t&eacute;s des circuits sensorimotrices. Nous avons appliqu&eacute; inhibition par Shibire pendant six heures au cours du d&eacute;veloppement embryonnaire (15-21 h apr&egrave;s la ponte [AEL]) et &eacute;tudi&eacute; ses effets sur le p&eacute;ristaltisme chez les larves de deuxi&egrave;me et troisi&egrave;me-stades matures. Nous avons trouv&eacute; que l&#39;inhibition des organes chordotonaux, mais pas multidendritic neurones, a entra&icirc;n&eacute; une diminution durable de la vitesse de locomotion larvaire. Pour affiner la p&eacute;riode sensible, nous avons appliqu&eacute; une inhibition plus courte &agrave; divers stades de d&eacute;veloppement embryonnaires et larvaires et a conclu que l&#39;inhibition de deux heures pendant 16-20 h AEL, mais pas &agrave; des stades plus t&ocirc;t ou plus tard, &eacute;tait suffisante pour provoquer l&#39;effet. Ces r&eacute;sultats sugg&egrave;rent que l&#39;activit&eacute; neurale m&eacute;di&eacute;e par les neurones sensoriels sp&eacute;cifiques est impliqu&eacute;e dans la maturation des circuits sensori-moteur chez la drosophile et qu&#39;il y a une p&eacute;riode critique pour ce changement en plastique. Conform&eacute;ment &agrave; un r&ocirc;le des neurones chordotonaux en r&eacute;troaction sensorielle, ces neurones sont activ&eacute;s pendant le p&eacute;ristaltisme larvaire et inhibition aigu&euml; de leur activit&eacute; a diminu&eacute; la vitesse de locomotion larvaire.

R&ocirc;le de l&#39;exp&eacute;rience sensorielle en d&eacute;veloppement fonctionnel des circuits de moteurs de drosophile.

Neuronal circuits are formed according to a genetically predetermined program and then reconstructed in an experience-dependent manner. While the existence of experience-dependent plasticity has been demonstrated for the visual and other sensory systems, it remains unknown whether this is also the case for motor systems. Here we examined the effects of eliminating sensory inputs on the development of peristaltic movements in Drosophila embryos and larvae. The peristalsis is initially slow and uncoordinated, but gradually develops into a mature pattern during late embryonic stages. We tested whether inhibiting the transmission of specific sensory neurons during this period would have lasting effects on the properties of the sensorimotor circuits. We applied Shibire-mediated inhibition for six hours during embryonic development (15-21 h after egg laying [AEL]) and studied its effects on peristalsis in the mature second- and third-instar larvae. We found that inhibition of chordotonal organs, but not multidendritic neurons, led to a lasting decrease in the speed of larval locomotion. To narrow down the sensitive period, we applied shorter inhibition at various embryonic and larval stages and found that two-hour inhibition during 16-20 h AEL, but not at earlier or later stages, was sufficient to cause the effect. These results suggest that neural activity mediated by specific sensory neurons is involved in the maturation of sensorimotor circuits in Drosophila and that there is a critical period for this plastic change. Consistent with a role of chordotonal neurons in sensory feedback, these neurons were activated during larval peristalsis and acute inhibition of their activity decreased the speed of larval locomotion.

Akira Fushiki

Department of Complexity Science and Engineering,
Graduate School of Frontier Sciences,
Department of Complexity Science and Engineering, Graduate School of Frontier Sciences

The University of Tokyo

Optogenetic Perturbation of Neural Activity with Laser Illumination in Semi-intact Drosophila Larvae in Motion

Akira Fushiki

Department of Complexity Science and Engineering,Graduate School of Frontier Sciences,Department of Complexity Science and Engineering, Graduate School of Frontier Sciences

The University of Tokyo

Optogenetic Perturbation of Neural Activity with Laser Illumination in Semi-intact Drosophila Larvae in Motion

Department of Complexity Science and Engineering,
Graduate School of Frontier Sciences,
Department of Complexity Science and Engineering, Graduate School of Frontier Sciences