juxtacellular-monitoring-localization-single-neurons-within-sub

Juxtacellular Monitoring and Localization of Single Neurons within Sub-cortical Brain Structures of Alert, Head-restrained Rats

There are a variety of techniques to monitor extracellular activity of single neuronal units. However, monitoring this activity from deep brain structures ...

University of California, San Diego

&#x63A2;&#x7D22;&#x6027;&#x6405;&#x62CC;&#x5728;&#x5927;&#x9F20;&#x662F;&#x81EA;&#x53D1;&#x7684;&#x8FD0;&#x52A8;&#xFF0C;&#x5BF9;&#x591A;&#x4E2A;&#x65F6;&#x95F4;&#x5C3A;&#x5EA6;&#x4E0A;&#xFF0C;&#x4ECE;&#x5355;&#x4E00;&#x6253;&#x86CB;&#x5668;&#x5468;&#x671F;&#x5185;&#x6405;&#x62CC;&#x5230;&#x808C;&#x8089;&#x6536;&#x7F29;&#x7684;&#x5FEB;&#x901F;&#x5E8F;&#x5217;&#x7684;&#x4FE1;&#x5C01;&#x4E2D;&#x7684;&#x7F13;&#x6162;&#x53D8;&#x5316;&#x7684;&#x4E00;&#x4E2A;&#x4F8B;&#x5B50;&#x3002;&#x6211;&#x4EEC;&#x53D1;&#x73B0;&#x4F5C;&#x4E3A;&#x4E00;&#x4E2A;&#x4EBA;&#x53E3;&#x7A57;&#x5217;&#x8F66;&#x4E3B;&#x89E6;&#x987B;&#x8FD0;&#x52A8;&#x76AE;&#x5C42;&#x4E2D;&#x5355;&#x4E2A;&#x5355;&#x4F4D;&#x62A5;&#x544A;&#x7684;&#x89E6;&#x987B;&#x4F4D;&#x7F6E;&#x7EDD;&#x5BF9;&#x89D2;&#x5EA6;&#x3002;&#x8FD9;&#x79CD;&#x8868;&#x793A;&#x5F62;&#x5F0F;&#x540E;&#x611F;&#x89C9;&#x795E;&#x7ECF;&#x5207;&#x65AD;&#xFF0C;&#x663E;&#x793A;&#x4F20;&#x51FA;&#x7684;&#x6765;&#x6E90;&#x4ECD;&#x7136;&#x5B58;&#x5728;&#x3002;&#x867D;&#x7136;&#x76F8;&#x5BF9;&#x8F83;&#x5C11;&#x7684;&#x5355;&#x4F4D;&#x6253;&#x86CB;&#x5668;&#x5468;&#x671F;&#x5185;&#x62A5;&#x544A;&#x4E2D;&#x4F4D;&#x7F6E;&#x7684;&#x5FEB;&#x901F;&#x53D8;&#x5316;&#xFF0C;&#x7EA6;&#x4E09;&#x5206;&#x4E4B;&#x4E8C;&#x7684;&#x5355;&#x4F4D;&#x88AB;&#x8C03;&#x5236;&#x800C;&#x6210;&#x7684;&#x6405;&#x62CC;&#xFF0C;&#x4FE1;&#x5C01;&#x7684;&#x7F13;&#x6162;&#x53D8;&#x5316;&#x3002;&#x7EFC;&#x5408;&#x7684;&#x7ED3;&#x679C;&#x4ECE;&#x8FD9;&#x9879;&#x7814;&#x7A76;&#x548C;&#x8FC7;&#x53BB;&#x7684;&#x6D4B;&#x91CF;&#xFF0C;&#x5176;&#x4E2D;&#x663E;&#x793A;&#x8BE5;&#x521D;&#x7EA7;&#x611F;&#x89C9;&#x76AE;&#x5C42;&#x7801;&#x6405;&#x62CC;&#x4FE1;&#x5C01;&#x4F5C;&#x4E3A;&#x7535;&#x673A;&#x526F;&#x672C;&#x7684;&#x4FE1;&#x53F7;&#xFF0C;&#x6697;&#x793A;&#x4FE1;&#x53F7;&#x5B58;&#x5728;&#x4E24;&#x79CD;&#x611F;&#x5B98;&#x548C;&#x7535;&#x673A;&#x76AE;&#x8D28;&#x662F;&#x5FC5;&#x8981;&#x8BA1;&#x7B97;&#x57FA;&#x4E8E;&#x89E6;&#x987B;&#x89E6;&#x6478;&#x89D2;&#x5750;&#x6807;&#x3002;

&#x8FD0;&#x52A8;&#x76AE;&#x5C42;&#x62A5;&#x544A;&#x4F20;&#x51FA;&#x7684;&#x89E6;&#x987B;&#x8FD0;&#x52A8;&#x63A7;&#x5236;&#x591A;&#x4E2A;&#x65F6;&#x95F4;&#x5C3A;&#x5EA6;&#x3002;

Exploratory whisking in rat is an example of self-generated movement on multiple timescales, from slow variations in the envelope of whisking to the rapid sequence of muscle contractions duringÂ a single whisk cycle. We find that, as a population, spike trains of single units in primary vibrissa motor cortex report the absolute angle of vibrissa position. This representation persists after sensory nerve transection, indicating an efferent source. About two-thirds of the units are modulated by slow variations in the envelope of whisking, while relatively few units report rapid changes in position within the whisk cycle. The combined results from this study and past measurements, which show that primary sensory cortex codes the whisking envelope asÂ a motor copy signal, imply that signals present in both sensory and motor cortices are necessary to compute angular coordinates based on vibrissa touch.

Primary motor cortex reports efferent control of vibrissa motion on multiple timescales.

Exploratoire en fouettant chez le rat est un exemple d&#x26;#39;auto-g&#xE9;n&#xE9;r&#xE9; mouvement sur des &#xE9;chelles de temps multiples, &#xE0; partir des variations lentes de l&#x26;#39;enveloppe de la fouettant &#xE0; la succession rapide des contractions musculaires au cours d&#x26;#39;une seule fouet cycle. Nous constatons que, en tant que population, trains de potentiels d&#x26;#39;unit&#xE9;s simples dans l&#x26;#39;enseignement primaire du cortex moteur vibrisse rapport de l&#x26;#39;angle de la position absolue vibrisse. Cette repr&#xE9;sentation persiste apr&#xE8;s section du nerf sensitif, ce qui indique une source eff&#xE9;rente. Environ les deux tiers des unit&#xE9;s sont modul&#xE9;s par les variations lentes de l&#x26;#39;enveloppe de la fouettant, tandis que les unit&#xE9;s relativement peu de rapport des changements rapides de position dans le cycle fouet. Les r&#xE9;sultats combin&#xE9;s de cette &#xE9;tude et de mesures ant&#xE9;rieures, qui indiquent que les codes cortex sensoriel primaire de l&#x26;#39;enveloppe en fouettant comme un signal de copie &#xE0; moteur, impliquent que les signaux pr&#xE9;sents dans les deux corticales sensorielles et motrices sont n&#xE9;cessaires pour calculer les coordonn&#xE9;es angulaires bas&#xE9;s sur le toucher vibrisse.

Cortex moteur primaire Rapports contr&#xF4;le eff&#xE9;rent de motion vibrisses sur des p&#xE9;riodes multiples

Explorative Quirlen in Ratte ist ein Beispiel f&uuml;r selbst generierte Bewegung auf mehrere Zeitskalen, langsame Ver&auml;nderungen in den Umschlag auf die schnelle Abfolge von Muskelkontraktionen w&auml;hrend eines einzigen Schneebesen Quirlen. Wir finden, dass als Einwohner, Spitze Z&uuml;ge der einzelnen Einheiten in prim&auml;ren Vibrissa motorischen Kortex den absoluten Winkel Vibrissa Position melden. Diese Darstellung bleibt nach sensorischen Nerven Transection, eine ableitendes Quelle angibt. Etwa zwei Drittel der Einheiten werden durch langsame Schwankungen der Umschlag von Quirlen, moduliert, obwohl nur relativ wenige Einheiten schnelle Ver&auml;nderungen in der Stellung innerhalb des Zyklus Schneebesen Berichten. Die kombinierten Ergebnisse aus dieser Studie und vorbei an Messungen, die zeigen, dass prim&auml;ren sensorischen Kortex-codes des whisking Umschlags als motor Kopie Signal, implizieren, dass Signale sowohl sensorische und Motor Cortices notwendig sind, um die kantige-Koordinaten basieren auf Vibrissa Touch zu berechnen.

Prim&auml;ren motorischen Kortex berichtet efferente Kontrolle der Vibrissa Bewegung &uuml;ber mehrere Zeitr&auml;ume.

Sbattere sperimentale nel ratto &egrave; un esempio di movimento autogenerato su scadenze multiple, da variazioni lenti nella busta di sbattere la rapida sequenza di contrazioni muscolari durante un ciclo di frusta singola. Troviamo che, come una popolazione, spike treni di singole unit&agrave; nella corteccia motoria primaria vibrissa relazione l&#39;angolo assoluto della posizione di Whiskers. Questa rappresentazione persiste dopo transezione nervi sensoriali, che indica un&#39;origine efferente. Circa due terzi delle unit&agrave; sono modulati dal lenti variazioni nella busta di sbattere, mentre relativamente poche unit&agrave; segnalazione rapidi cambiamenti di posizione all&#39;interno del ciclo di frusta. I risultati combinati da questo studio e misurazioni, che mostrano quella corteccia sensoriale primaria del passato i codici whisking busta come un segnale di motore copia, implicano che segnali presentano in entrambi sensoriale e cortecce di motore sono necessarie per calcolare le coordinate angolari basate sul tocco di Whiskers.

Corteccia motoria primaria Report controllo efferente del movimento vibrissa su scadenze multiple.

&#x30E9;&#x30C3;&#x30C8;&#x306E;&#x63A2;&#x7D22;whisking&#x306F;&#x3001;&#x5358;&#x4E00;&#x306E;&#x6CE1;&#x7ACB;&#x3066;&#x5668;&#x30B5;&#x30A4;&#x30AF;&#x30EB;&#x4E2D;&#x306B;&#x7B4B;&#x8089;&#x306E;&#x53CE;&#x7E2E;&#x306E;&#x6025;&#x901F;&#x306A;&#x30B7;&#x30FC;&#x30B1;&#x30F3;&#x30B9;&#x306B;whisking&#x306E;&#x5C01;&#x7B52;&#x3067;&#x9045;&#x3044;&#x5909;&#x5316;&#x304B;&#x3089;&#x3001;&#x8907;&#x6570;&#x306E;&#x30BF;&#x30A4;&#x30E0;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x306E;&#x81EA;&#x5DF1;&#x751F;&#x6210;&#x3055;&#x308C;&#x305F;&#x52D5;&#x304D;&#x306E;&#x4E00;&#x4F8B;&#x3067;&#x3059;&#x3002;&#x79C1;&#x305F;&#x3061;&#x306F;&#x3001;&#x96C6;&#x56E3;&#x3068;&#x3057;&#x3066;&#x3001;&#x4E3B;&#x8981;&#x306A;&#x9F3B;&#x6BDB;&#x904B;&#x52D5;&#x91CE;&#x306E;&#x5358;&#x4E00;&#x30E6;&#x30CB;&#x30C3;&#x30C8;&#x306E;&#x30B9;&#x30D1;&#x30A4;&#x30AF;&#x306F;&#x3001;&#x9F3B;&#x6BDB;&#x306E;&#x4F4D;&#x7F6E;&#x306E;&#x7D76;&#x5BFE;&#x89D2;&#x5EA6;&#x3092;&#x5831;&#x544A;&#x3057;&#x3001;&#x3053;&#x3068;&#x304C;&#x308F;&#x304B;&#x308A;&#x307E;&#x3059;&#x3002;&#x3053;&#x306E;&#x8868;&#x73FE;&#x306F;&#x3001;&#x9060;&#x5FC3;&#x6027;&#x306E;&#x30BD;&#x30FC;&#x30B9;&#x3092;&#x793A;&#x3059;&#x3001;&#x611F;&#x899A;&#x795E;&#x7D4C;&#x5207;&#x65AD;&#x5F8C;&#x3082;&#x4FDD;&#x6301;&#x3055;&#x308C;&#x307E;&#x3059;&#x3002;&#x6BD4;&#x8F03;&#x7684;&#x5C11;&#x6570;&#x306E;&#x30E6;&#x30CB;&#x30C3;&#x30C8;&#x306F;&#x3001;&#x6CE1;&#x7ACB;&#x3066;&#x5668;&#x30B5;&#x30A4;&#x30AF;&#x30EB;&#x5185;&#x3067;&#x306E;&#x4F4D;&#x7F6E;&#x306E;&#x6025;&#x6FC0;&#x306A;&#x5909;&#x5316;&#x3092;&#x5831;&#x544A;&#x3057;&#x306A;&#x304C;&#x3089;&#x3001;&#x30E6;&#x30CB;&#x30C3;&#x30C8;&#x306E;&#x7D04;3&#x5206;&#x306E;2&#x306F;&#x3001;whisking&#x306E;&#x5C01;&#x7B52;&#x304C;&#x9045;&#x3044;&#x5909;&#x52D5;&#x306B;&#x3088;&#x3063;&#x3066;&#x5909;&#x8ABF;&#x3055;&#x308C;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;&#x3053;&#x306E;&#x7814;&#x7A76;&#x306E;&#x7D50;&#x679C;&#x3092;&#x7D50;&#x5408;&#x3057;&#x3001;&#x30E2;&#x30FC;&#x30BF;&#x306E;&#x30B3;&#x30D4;&#x30FC;&#x4FE1;&#x53F7;&#x3068;&#x3057;&#x3066;whisking&#x30A8;&#x30F3;&#x30D9;&#x30ED;&#x30FC;&#x30D7;&#x305D;&#x306E;&#x4E00;&#x6B21;&#x611F;&#x899A;&#x76AE;&#x8CEA;&#x30B3;&#x30FC;&#x30C9;&#x3092;&#x8868;&#x793A;&#x904E;&#x53BB;&#x306E;&#x6E2C;&#x5B9A;&#x5024;&#x306F;&#x3001;&#x4E21;&#x65B9;&#x306E;&#x611F;&#x899A;&#x3068;&#x904B;&#x52D5;&#x76AE;&#x8CEA;&#x306B;&#x5B58;&#x5728;&#x3059;&#x308B;&#x305D;&#x306E;&#x4FE1;&#x53F7;&#x306F;&#x9F3B;&#x6BDB;&#x306E;&#x30BF;&#x30C3;&#x30C1;&#x306B;&#x57FA;&#x3065;&#x3044;&#x3066;&#x3001;&#x89D2;&#x5EA6;&#x306E;&#x5EA7;&#x6A19;&#x3092;&#x8A08;&#x7B97;&#x3059;&#x308B;&#x305F;&#x3081;&#x306B;&#x5FC5;&#x8981;&#x306A;&#x793A;&#x5506;&#x3057;&#x3066;&#x3044;&#x308B;&#x3002;

&#x4E00;&#x6B21;&#x904B;&#x52D5;&#x91CE;&#x3067;&#x306F;&#x3001;&#x8907;&#x6570;&#x306E;&#x30BF;&#x30A4;&#x30E0;&#x30B9;&#x30B1;&#x30FC;&#x30EB;&#x3067;&#x9F3B;&#x6BDB;&#xB7;&#x30E2;&#x30FC;&#x30B7;&#x30E7;&#x30F3;&#x306E;&#x9060;&#x5FC3;&#x6027;&#x30B3;&#x30F3;&#x30C8;&#x30ED;&#x30FC;&#x30EB;&#x3092;&#x30EC;&#x30DD;&#x30FC;&#x30C8;

&#xC950;&#xC5D0;&#xC11C; &#xD0D0;&#xAD6C; whisking &#xB2E8;&#xC77C; &#xD138; &#xC8FC;&#xAE30; &#xB3D9;&#xC548; &#xAE09;&#xC18D; &#xD55C; &#xC77C;&#xB828;&#xC758; &#xADFC;&#xC721; &#xC218;&#xCD95;&#xC5D0; &#xB0B4; &#xCAD3;&#xAE30;&#xC758; &#xBD09;&#xD22C;&#xC5D0; &#xC788;&#xB294; &#xB290;&#xB9B0; &#xBCC0;&#xD654;&#xC5D0;&#xC11C; &#xC5EC;&#xB7EC; timescales&#xC5D0; &#xC790;&#xAE30; &#xC6C0;&#xC9C1;&#xC784;&#xC758; &#xC608;&#xC785;&#xB2C8;&#xB2E4;. &#xC6B0;&#xB9AC;&#xB294;&#xB97C; &#xBAA8;&#xC9D1;&#xB2E8;&#xC73C;&#xB85C; &#xAE30;&#xBCF8; vibrissa &#xBAA8;&#xD130; &#xD53C; &#xC9C8;&#xC5D0; &#xC788;&#xB294; &#xB2E8;&#xC77C; &#xB2E8;&#xC704;&#xC758; &#xC2A4;&#xD30C;&#xC774;&#xD06C; &#xC5F4;&#xCC28; vibrissa &#xC704;&#xCE58;&#xC758; &#xC808;&#xB300; &#xAC01;&#xB3C4; &#xBCF4;&#xACE0; &#xCC3E;&#xC744; &#xC218; &#xC788;&#xC2B5;&#xB2C8;&#xB2E4;. &#xC774; &#xD45C;&#xD604;&#xC740; &#xAC10;&#xAC01; &#xC2E0;&#xACBD; transection, efferent &#xC18C;&#xC2A4;&#xB97C; &#xB098;&#xD0C0;&#xB0B4;&#xB294; &#xD6C4; &#xC720;&#xC9C0; &#xB429;&#xB2C8;&#xB2E4;. &#xC57D; 3 &#xBD84;&#xC758; 2&#xB294; &#xC0C1;&#xB300;&#xC801;&#xC73C;&#xB85C; &#xC801;&#xC740; &#xB2E8;&#xC704; &#xD138; &#xC8FC;&#xAE30; &#xB0B4;&#xC5D0;&#xC11C; &#xC704;&#xCE58;&#xC5D0; &#xAE09;&#xACA9; &#xD55C; &#xBCC0;&#xD654;&#xB97C; &#xBCF4;&#xACE0; &#xD558;&#xB294; &#xB3D9;&#xC548; &#xB0B4; &#xCAD3;&#xAE30;, &#xBD09;&#xD22C;&#xC758; &#xB290;&#xB9B0; &#xBCC0;&#xD654;&#xC5D0; &#xC758;&#xD574; &#xBCC0;&#xC870; &#xB418;&#xC5B4;. &#xACB0;&#xD569; &#xB41C; &#xACB0;&#xACFC;&#xC774; &#xC5F0;&#xAD6C;&#xC5D0;&#xC11C; &#xACFC;&#xAC70;&#xC758; &#xADF8; &#xAE30;&#xBCF8; &#xAC10;&#xAC01; &#xD53C; &#xC9C8;&#xC744; &#xD45C;&#xC2DC; &#xD558;&#xB294; &#xCE21;&#xC815; &#xCF54;&#xB4DC; &#xBAA8;&#xD130; &#xBCF5;&#xC0AC;&#xBCF8; &#xC2E0;&#xD638;&#xB85C; whisking &#xBD09;&#xD22C;, &#xBAA8;&#xB450; &#xAC10;&#xAC01; &#xC2E0;&#xD638;&#xB97C; &#xC81C;&#xC2DC; &#xD558; &#xACE0; &#xBAA8;&#xD130; &#xC678;&#xD53C;&#xAC00; &#xC788;&#xB2E4; vibrissa &#xD130;&#xCE58;&#xC5D0; &#xB530;&#xB77C; &#xAC01;&#xB3C4; &#xC88C;&#xD45C;&#xB97C; &#xACC4;&#xC0B0; &#xD558;&#xB294; &#xB370; &#xD544;&#xC694;&#xD55C; &#xC758;&#xBBF8; &#xD569;&#xB2C8;&#xB2E4;.

&#xAE30;&#xBCF8; &#xBAA8;&#xD130; &#xD53C; &#xC9C8; &#xC5EC;&#xB7EC; timescales efferent vibrissa &#xBAA8;&#xC158; &#xC81C;&#xC5B4;&#xB97C; &#xBCF4;&#xACE0;&#xD569;&#xB2C8;&#xB2E4;.

Exploratorio batiendo en la rata es un ejemplo de auto-generado movimientos en escalas de tiempo m&#xFA;ltiples, de las variaciones lentas en el sobre de batir a la secuencia r&#xE1;pida de las contracciones musculares durante un solo ciclo de batir. Nos parece que, como poblaci&#xF3;n, los trenes de espigas de las unidades individuales en la corteza primaria del motor vibrisas reportar el &#xE1;ngulo de la posici&#xF3;n absoluta de vibrisas. Esta representaci&#xF3;n persiste despu&#xE9;s de la transecci&#xF3;n del nervio sensorial, lo que indica una fuente eferente. Alrededor de dos tercios de las unidades son modulados por las variaciones lentas en el sobre de env&#xED;o r&#xE1;pido, mientras que las unidades relativamente pocos informar de los cambios r&#xE1;pidos de la posici&#xF3;n dentro del ciclo de batir. Los resultados combinados de este estudio y las mediciones anteriores, que muestran que los c&#xF3;digos sensoriales primarias corteza del sobre batiendo como una se&#xF1;al de copia de motor, implica que las se&#xF1;ales presentes en ambas cortezas sensoriales y motoras son necesarios para calcular las coordenadas angulares basadas en el tacto vibrisas.

Informes de la corteza motora primaria de control eferente del movimiento de vibrisas en escalas de tiempo m&#xFA;ltiples

Whisking and sniffing are predominant aspects of exploratory behaviour in rodents. Yet the neural mechanisms that generate and coordinate these and other orofacial motor patterns remain largely uncharacterized. Here we use anatomical, behavioural, electrophysiological and pharmacological tools to show that whisking and sniffing are coordinated by respiratory centres in the ventral medulla. We delineate a distinct region in the ventral medulla that provides rhythmic input to the facial motor neurons that drive protraction of the vibrissae. Neuronal output from this region is reset at each inspiration by direct input from the pre-Bötzinger complex, such that high-frequency sniffing has a one-to-one relationship with whisking, whereas basal respiration is accompanied by intervening whisks that occur between breaths. We conjecture that the respiratory nuclei, which project to other premotor regions for oral and facial control, function as a master clock for behaviours that coordinate with breathing.

Hierarchy of orofacial rhythms revealed through whisking and breathing.

When rodents engage in the exploration of novel stimuli, breathing occurs at an accelerated rate that is synchronous with whisking. We review the recently observed relationships between breathing and the sensations of smell and vibrissa-based touch. We consider the hypothesis that the breathing rhythm serves not only as a motor drive signal, but also as a common clock that binds these two senses into a common percept. This possibility may be extended to include taste through the coordination of licking with breathing. Here we evaluate the status of experimental evidence that pertains to this hypothesis.

More than a rhythm of life: breathing as a binder of orofacial sensation.

Mammals perform a multitude of well-coordinated orofacial behaviors such as breathing, sniffing, chewing, licking, swallowing, vocalizing, and in rodents, whisking. The coordination of these actions must occur without fault to prevent fatal blockages of the airway. Deciphering the neuronal circuitry that controls even a single action requires understanding the integration of sensory feedback and executive commands. A far greater challenge is to understand the coordination of multiple actions. Here, we focus on brainstem circuits that drive rhythmic orofacial actions. We discuss three neural computational mechanisms that may enable circuits for different actions to operate without interfering with each other. We conclude with proposed experimental programs for delineating the neural control principles that have evolved to coordinate orofacial behaviors.

How the brainstem controls orofacial behaviors comprised of rhythmic actions.

The rodent vibrissa system is a widely used experimental model of active sensation and motor control. Vibrissa-based touch in rodents involves stereotypic, rhythmic sweeping of the vibrissae as the animal explores its environment. Although pharmacologically induced rhythmic movements have long been used to understand the neural circuitry that underlies a variety of rhythmic behaviors, including locomotion, digestion and ingestion, these techniques have not been available for active sensory movements such as whisking. However, recent work that delineated the location of the central pattern generator for whisking has enabled pharmacological control over this behavior. Here we specify a protocol for the pharmacological induction of rhythmic vibrissa movements that mimic exploratory whisking. The rhythmic vibrissa movements are induced by local injection of a glutamatergic agonist, kainic acid. This protocol produces coordinated rhythmic vibrissa movements that are sustained for several hours in the anesthetized mouse or rat and thus provides unprecedented experimental control in studies related to vibrissa-based neuronal circuitry.

Activation and measurement of free whisking in the lightly anesthetized rodent.

Sensorimotor processing relies on hierarchical neuronal circuits to mediate sensory-driven behaviors. In the mouse vibrissa system, trigeminal brainstem circuits are thought to mediate the first stage of vibrissa scanning control via sensory feedback that provides reflexive protraction in response to stimulation. However, these circuits are not well defined. Here we describe a complete disynaptic sensory receptor-to-muscle circuit for positive feedback in vibrissa movement. We identified a novel region of trigeminal brainstem, spinal trigeminal nucleus pars muralis, which contains a class of vGluT2+ excitatory projection neurons involved in vibrissa motor control. Complementary single- and dual-labeling with traditional and virus tracers demonstrate that these neurons both receive primary inputs from vibrissa sensory afferent fibers and send monosynaptic connections to facial nucleus motoneurons that directly innervate vibrissa musculature. These anatomical results suggest a general role of disynaptic architecture in fast positive feedback for motor output that drives active sensation.

Feedback in the brainstem: an excitatory disynaptic pathway for control of whisking.

Signal transfer in neural circuits is dynamically modified by the recent history of neuronal activity. Short-term plasticity endows synapses with nonlinear transmission properties, yet synapses in sensory and motor circuits are capable of signaling linearly over a wide range of presynaptic firing rates. How do such synapses achieve rate-invariant transmission despite history-dependent nonlinearities? Here, ultrastructural, biophysical, and computational analyses demonstrate that concerted molecular, anatomical, and physiological refinements are required for central vestibular nerve synapses to linearly transmit rate-coded sensory signals. Vestibular synapses operate in a physiological regime of steady-state depression imposed by tonic firing. Rate-invariant transmission relies on brief presynaptic action potentials that delimit calcium influx, large pools of rapidly mobilized vesicles, multiple low-probability release sites, robust postsynaptic receptor sensitivity, and efficient transmitter clearance. Broadband linear synaptic filtering of head motion signals is thus achieved by coordinately tuned synaptic machinery that maintains physiological operation within inherent cell biological limitations.

Implementation of linear sensory signaling via multiple coordinated mechanisms at central vestibular nerve synapses.

Nerve degeneration after transection injury decreases intraoperative visibility under white light (WL), complicating surgical repair. We show here that the use of fluorescently labeled nerve binding probe (F-NP41) can improve intraoperative visualization of chronically (up to 9 months) denervated nerves. In a mouse model for the repair of chronically denervated facial nerves, the intraoperative use of fluorescent labeling decreased time to nerve identification by 40% compared to surgeries performed under WL alone. Cumulative functional post-operative recovery was also significantly improved in the fluorescence guided group as determined by quantitatively tracking of the recovery of whisker movement at time intervals for 6 weeks post-repair. To our knowledge, this is the first description of an injectable probe that increases visibility of chronically denervated nerves during surgical repair in live animals. Future translation of this probe may improve functional outcome for patients with chronic denervation undergoing surgical repair.

Fluorescently Labeled Peptide Increases Identification of Degenerated Facial Nerve Branches during Surgery and Improves Functional Outcome.

Whisking and sniffing are predominant aspects of exploratory behavior in rodents. We review evidence that these motor rhythms are coordinated by the respiratory patterning circuitry in the ventral medulla. A recently described region in the intermediate reticular zone of the medulla functions as an autonomous whisking oscillator, whose neuronal output is reset upon each breath by input from the pre-Bötzinger complex. Based on similarities between this neuronal circuit architecture and that of other orofacial behaviors, we propose that the pre-Bötzinger complex, which projects broadly to premotor regions throughout the intermediate reticular zone of the medulla, functions as a master clock to coordinate multiple orofacial actions involved in exploratory and ingestive behaviors. We then extend the analysis of whisking to the relatively slow control of the midpoint of the whisk. We conjecture, in a manner consistent with breathing as the "master clock" for all orofacial behaviors, that slow control optimizes the position of sensors whereas the breathing rhythm provides a means to perceptually bind the inputs from different orofacial modalities.

Article	Year
Primary motor cortex reports efferent control of vibrissa motion on multiple timescales. Neuron\| PubMed ID: 22017992	2011
Hierarchy of orofacial rhythms revealed through whisking and breathing. Nature\| PubMed ID: 23624373	2013
More than a rhythm of life: breathing as a binder of orofacial sensation. Nature neuroscience\| PubMed ID: 24762718	2014
How the brainstem controls orofacial behaviors comprised of rhythmic actions. Trends in neurosciences\| PubMed ID: 24890196	2014
Activation and measurement of free whisking in the lightly anesthetized rodent. Nature protocols\| PubMed ID: 24992095	2014
Feedback in the brainstem: an excitatory disynaptic pathway for control of whisking. The Journal of comparative neurology\| PubMed ID: 25503925	2015
Implementation of linear sensory signaling via multiple coordinated mechanisms at central vestibular nerve synapses. Neuron\| PubMed ID: 25704949	2015
Fluorescently Labeled Peptide Increases Identification of Degenerated Facial Nerve Branches during Surgery and Improves Functional Outcome. PloS one\| PubMed ID: 25751149	2015
The Brainstem Oscillator for Whisking and the Case for Breathing as the Master Clock for Orofacial Motor Actions. Cold Spring Harbor symposia on quantitative biology\| PubMed ID: 25876629	2015

Jeffrey D. Moore

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