Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
J Vis Exp ; (177)2021 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-34866625

RESUMEN

Fine motor skills are essential in everyday life and can be compromised in several nervous system disorders. The acquisition and performance of these tasks require sensory-motor integration and involve precise control of bilateral brain circuits. Implementing unimanual behavioral paradigms in animal models will improve the understanding of the contribution of brain structures, like the striatum, to complex motor behavior as it allows manipulation and recording of neural activity of specific nuclei in control conditions and disease during the performance of the task. Since its creation, optogenetics has been a dominant tool for interrogating the brain by enabling selective and targeted activation or inhibition of neuronal populations. The combination of optogenetics with behavioral assays sheds light on the underlying mechanisms of specific brain functions. Wireless head-mounted systems with miniaturized light-emitting diodes (LEDs) allow remote optogenetic control in an entirely free-moving animal. This avoids the limitations of a wired system being less restrictive for animals' behavior without compromising light emission efficiency. The current protocol combines a wireless optogenetics approach with high-speed videography in a unimanual dexterity task to dissect the contribution of specific neuronal populations to fine motor behavior.


Asunto(s)
Encéfalo , Optogenética , Animales , Conducta Animal , Encéfalo/fisiología , Cuerpo Estriado , Neuronas/fisiología , Optogenética/métodos , Tecnología Inalámbrica
2.
Cell Rep ; 34(3): 108651, 2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33472081

RESUMEN

Skilled motor behavior requires bihemispheric coordination, and participation of striatal outputs originating from two neuronal groups identified by distinctive expression of D1 or D2 dopamine receptors. We trained mice to reach for and grasp a single food pellet and determined how the output pathways differently affected forelimb trajectory and task efficiency. We found that inhibition and excitation of D1-expressing spiny projection neurons (D1SPNs) have a similar effect on kinematics results, as if excitation and inhibition disrupt the whole ensemble dynamics and not exclusively one kind of output. In contrast, D2SPNs participate in control of target accuracy. Further, ex vivo electrophysiological comparison of naive mice and mice exposed to the task showed stronger striatal neuronal connectivity for ipsilateral D1 and contralateral D2 neurons in relation to the paw used. In summary, while the output pathways work together to smoothly execute skill movements, practice of the movement itself changes synaptic patterns.


Asunto(s)
Cuerpo Estriado/fisiología , Miembro Anterior/fisiología , Movimiento/fisiología , Animales , Ratones
3.
Dev Biol ; 468(1-2): 93-100, 2020 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-32976839

RESUMEN

Fragile X mental retardation 1 (FMR1) encodes the RNA binding protein FMRP. Loss of FMRP drives Fragile X syndrome (FXS), the leading inherited cause of intellectual disability and a leading monogenic cause of autism. While cortical hyperexcitability is a hallmark of FXS, the reported phenotypes and underlying mechanisms, including alterations in synaptic transmission and ion channel properties, are heterogeneous and at times contradictory. Here, we report the generation of new isogenic FMR1y/+ and FMR1y/- human pluripotent stem cell (hPSC) lines using CRISPR-Cas9 to facilitate the study of how complete FMRP loss, independent of genetic background, drives molecular and cellular alterations relevant for FXS. After differentiating these stem cell tools into excitatory neurons, we systematically assessed the impact of FMRP loss on intrinsic membrane and synaptic properties over time. Using whole-cell patch clamp analyses, we found that FMR1y/- neurons overall showed an increased intrinsic membrane excitability compared to age-matched FMR1y/+ controls, with no discernable alternations in synaptic transmission. Surprisingly, longitudinal analyses of cell intrinsic defects revealed that a majority of significant changes emerged early following in vitro differentiation and some were not stable over time. Collectively, this study provides a new isogenic hPSC model which can be further leveraged by the scientific community to investigate basic mechanisms of FMR1 gene function relevant for FXS. Moreover, our results suggest that precocious changes in the intrinsic membrane properties during early developmental could be a critical cellular pathology ultimately contributing to cortical hyperexcitability in FXS.


Asunto(s)
Diferenciación Celular , Membrana Celular/metabolismo , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Células Madre Embrionarias Humanas/metabolismo , Potenciales de la Membrana , Neuronas/metabolismo , Transmisión Sináptica , Línea Celular , Membrana Celular/genética , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Células Madre Embrionarias Humanas/citología , Humanos
4.
Nature ; 583(7818): 819-824, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32699411

RESUMEN

The thalamic reticular nucleus (TRN), the major source of thalamic inhibition, regulates thalamocortical interactions that are critical for sensory processing, attention and cognition1-5. TRN dysfunction has been linked to sensory abnormality, attention deficit and sleep disturbance across multiple neurodevelopmental disorders6-9. However, little is known about the organizational principles that underlie its divergent functions. Here we performed an integrative study linking single-cell molecular and electrophysiological features of the mouse TRN to connectivity and systems-level function. We found that cellular heterogeneity in the TRN is characterized by a transcriptomic gradient of two negatively correlated gene-expression profiles, each containing hundreds of genes. Neurons in the extremes of this transcriptomic gradient express mutually exclusive markers, exhibit core or shell-like anatomical structure and have distinct electrophysiological properties. The two TRN subpopulations make differential connections with the functionally distinct first-order and higher-order thalamic nuclei to form molecularly defined TRN-thalamus subnetworks. Selective perturbation of the two subnetworks in vivo revealed their differential role in regulating sleep. In sum, our study provides a comprehensive atlas of TRN neurons at single-cell resolution and links molecularly defined subnetworks to the functional organization of thalamocortical circuits.


Asunto(s)
Redes Reguladoras de Genes , Núcleos Talámicos/citología , Núcleos Talámicos/metabolismo , Animales , Análisis por Conglomerados , Femenino , Perfilación de la Expresión Génica , Hibridación Fluorescente in Situ , Metaloendopeptidasas/metabolismo , Ratones , Vías Nerviosas , Neuronas/metabolismo , Osteopontina/metabolismo , Técnicas de Placa-Clamp , RNA-Seq , Análisis de la Célula Individual , Sueño/genética , Sueño/fisiología , Núcleos Talámicos/fisiología , Transcriptoma
5.
Transl Psychiatry ; 10(1): 29, 2020 01 23.
Artículo en Inglés | MEDLINE | ID: mdl-32066662

RESUMEN

CACNA1I, a schizophrenia risk gene, encodes a subtype of voltage-gated T-type calcium channel CaV3.3. We previously reported that a patient-derived missense de novo mutation (R1346H) of CACNA1I impaired CaV3.3 channel function. Here, we generated CaV3.3-RH knock-in animals, along with mice lacking CaV3.3, to investigate the biological impact of R1346H (RH) variation. We found that RH mutation altered cellular excitability in the thalamic reticular nucleus (TRN), where CaV3.3 is abundantly expressed. Moreover, RH mutation produced marked deficits in sleep spindle occurrence and morphology throughout non-rapid eye movement (NREM) sleep, while CaV3.3 haploinsufficiency gave rise to largely normal spindles. Therefore, mice harboring the RH mutation provide a patient derived genetic model not only to dissect the spindle biology but also to evaluate the effects of pharmacological reagents in normalizing sleep spindle deficits. Importantly, our analyses highlighted the significance of characterizing individual spindles and strengthen the inferences we can make across species over sleep spindles. In conclusion, this study established a translational link between a genetic allele and spindle deficits during NREM observed in schizophrenia patients, representing a key step toward testing the hypothesis that normalizing spindles may be beneficial for schizophrenia patients.


Asunto(s)
Canales de Calcio Tipo T , Esquizofrenia , Animales , Electroencefalografía , Humanos , Ratones , Esquizofrenia/genética , Sueño , Sueño REM
6.
Artículo en Inglés | MEDLINE | ID: mdl-30774584

RESUMEN

Dopaminergic and serotonergic neurons modulate and control processes ranging from reward signaling to regulation of motor outputs. Further, dysfunction of these neurons is involved in both degenerative and psychiatric disorders. Elucidating the roles of these neurons has been greatly facilitated by bacterial artificial chromosome (BAC) transgenic mouse lines expressing channelrhodopsin to readily enable cell-type specific activation. However, corresponding lines to silence these monoaminergic neurons have been lacking. We have generated two BAC transgenic mouse lines expressing the outward proton pump, enhanced ArchT3.0 (eArchT3.0), and GFP under control of the regulatory elements of either the dopamine transporter (DAT; Jax# 031663) or the tryptophan hydroxylase 2 (TPH2; Jax# 031662) gene locus. We demonstrate highly faithful and specific expression of these lines in dopaminergic and serotonergic neurons respectively. Additionally we validate effective and sensitive eArchT3.0-mediated silencing of these neurons using slice electrophysiology as well as with a well-established behavioral assay. These new transgenic tools will help expedite the study of dopaminergic and serotonergic system function in normal behavior and disease.


Asunto(s)
Neuronas Dopaminérgicas/fisiología , Optogenética , Neuronas Serotoninérgicas/fisiología , Potenciales de Acción/genética , Animales , Encéfalo/citología , Channelrhodopsins/genética , Channelrhodopsins/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/genética , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Estimulación Eléctrica , Vectores Genéticos/genética , Vectores Genéticos/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Células HEK293 , Humanos , Técnicas In Vitro , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Técnicas de Placa-Clamp , ARN Mensajero/metabolismo , Transfección , Triptófano Hidroxilasa/genética , Triptófano Hidroxilasa/metabolismo , Tirosina 3-Monooxigenasa/metabolismo
8.
Brain Struct Funct ; 221(3): 1737-49, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25652680

RESUMEN

The striosome (or patch) was first identified with anatomical techniques as neurons organized in a three-dimensional labyrinth inserted in and interdigitating the rest of neostriatum: the matrix. Striosome and matrix rapidly became known as two neuronal compartments expressing different biochemical markers, embryonic development and afferent and efferent connectivity. In spite of extensive intrinsic neuronal axonal and dendritic extensions supposed to exchange information between matrix and striosomes, evidence suggested the presence of independent areas. Here, we report that indeed these two areas do not exchange synaptic information. We used genetic expression of channel rhodopsin 2 carried by adeno-associated virus serotype 10 (AAVrh10) that only expresses in neurons of the matrix compartment. Whole-cell patch-clamp recordings of matrix neurons activated by light pulses consistently produced inhibitory postsynaptic currents (IPSCs), but the same manipulation did not evoke IPSCs in striosome neurons. The matrix contains both direct and indirect striatal output pathways. By targeting striatal matrix expression of designer receptors exclusively activated by a designer drug (DREADD) hM3di carried by AAVrh10, we were able to inhibit the matrix neuronal compartment of the dorsolateral striatum during performance of a learned single-pellet reach-to-grasp task. As expected, inhibition of matrix neurons by systemic administration of DREADD agonist clozapine-n-oxide interfered with performance of the learned task.


Asunto(s)
Interneuronas/fisiología , Neostriado/fisiología , Neuronas/fisiología , Animales , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Clozapina/administración & dosificación , Clozapina/análogos & derivados , Drogas de Diseño/administración & dosificación , Femenino , Potenciales Postsinápticos Inhibidores , Interneuronas/citología , Interneuronas/efectos de los fármacos , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Actividad Motora/efectos de los fármacos , Neostriado/citología , Neostriado/efectos de los fármacos , Neuronas/citología , Neuronas/efectos de los fármacos
9.
Int J Neural Syst ; 25(7): 1550026, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26173906

RESUMEN

The cell assembly (CA) hypothesis has been used as a conceptual framework to explain how groups of neurons form memories. CAs are defined as neuronal pools with synchronous, recurrent and sequential activity patterns. However, neuronal interactions and synaptic properties that define CAs signatures have been difficult to examine because identities and locations of assembly members are usually unknown. In order to study synaptic properties that define CAs, we used optical and electrophysiological approaches to record activity of identified neurons in mouse cortical cultures. Population analysis and graph theory techniques allowed us to find sequential patterns that represent repetitive transitions between network states. Whole cell pair recordings of neurons participating in repeated sequences demonstrated that synchrony is exhibited by groups of neurons with strong synaptic connectivity (concomitant firing) showing short-term synaptic depression (STD), whereas alternation (sequential firing) is seen in groups of neurons with weaker synaptic connections showing short-term synaptic facilitation (STF). Decreasing synaptic weights of a network promoted the generation of sequential activity patterns, whereas increasing synaptic weights restricted state transitions. Thus in simple cortical networks of real neurons, basic signatures of CAs, the properties that underlie perception and memory in Hebb's original description, are already present.


Asunto(s)
Encéfalo/fisiología , Modelos Neurológicos , Plasticidad Neuronal/fisiología , Neuronas/fisiología , Potenciales de Acción/fisiología , Animales , Calcio/metabolismo , Células Cultivadas , Ratones , Vías Nerviosas/fisiología , Imagen Óptica , Técnicas de Placa-Clamp , Procesamiento de Señales Asistido por Computador
10.
Neuropharmacology ; 89: 54-63, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25239809

RESUMEN

N-methyl-D-aspartate receptors (NMDAR) are crucial for the function of excitatory neurotransmission and are present at the synapse and on the extrasynaptic membrane. The major nucleus of the basal ganglia, striatum, receives a large glutamatergic excitatory input carrying information about movements and associated sensory stimulation for its proper function. Such bombardment of glutamate synaptic release results in a large extracellular concentration of glutamate that can overcome the neuronal and glial uptake homeostatic systems therefore allowing the stimulation of extrasynaptic glutamate receptors. Here we have studied the participation of their extrasynaptic type in cortically evoked responses or in the presence of NMDARs stimulation. We report that extrasynaptic NMDAR blocker memantine, reduced in a dose-dependent manner cortically induced NMDA excitatory currents in striatal neurons (recorded in zero-Mg(++) plus DNQX 10 µM). Moreover, memantine (2-4 µM) significantly reduced the NMDAR-dependent membrane potential oscillations called up and down states. Recordings of neuronal striatal networks with a fluorescent calcium indicator or with multielectrode arrays (MEA) also showed that memantine reduced in a dose-dependent manner, NMDA-induced excitatory currents and network behavior. We used multielectrode arrays (MEA) to grow segregated cortical and striatal neurons. Once synaptic contacts were developed (>21DIV) recordings of extracellular activity confirmed the cortical drive of spontaneous synchronous discharges in both compartments. After severing connections between compartments, active striatal neurons in the presence of memantine (1 µM) and CNQX (10 µM) were predominantly fast spiking interneurons (FSI). The significance of extrasynaptic receptors in the regulation of striatal function and neuronal network activity is evident.


Asunto(s)
Cuerpo Estriado/fisiología , Receptores de N-Metil-D-Aspartato/fisiología , Sinapsis/fisiología , Animales , Células Cultivadas , Cuerpo Estriado/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Antagonistas de Aminoácidos Excitadores/farmacología , Ratones , Ratones Transgénicos , Técnicas de Cultivo de Órganos , Receptores de Glutamato/fisiología , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Sinapsis/efectos de los fármacos
11.
J Neurosci ; 33(11): 4964-75, 2013 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-23486967

RESUMEN

Inhibitory connections among striatal projection neurons (SPNs) called "feedback inhibition," have been proposed to endow the striatal microcircuit with computational capabilities, such as motor sequence selection, filtering, and the emergence of alternating network states. These properties are disrupted in models of Parkinsonism. However, the impact of feedback inhibition in the striatal network has remained under debate. Here, we test this inhibition at the microcircuit level. We used optical and electrophysiological recordings in mice and rats to demonstrate the action of striatal feedback transmission in normal and pathological conditions. Dynamic calcium imaging with single-cell resolution revealed the synchronous activation of a pool of identified SPNs by antidromic stimulation. Using bacterial artificial chromosome-transgenic mice, we demonstrate that the activated neuron pool equally possessed cells from the direct and indirect basal ganglia pathways. This pool inhibits itself because of its own GABA release when stimuli are frequent enough, demonstrating functional and significant inhibition. Blockade of GABAA receptors doubled the number of responsive neurons to the same stimulus, revealing a second postsynaptic neuron pool whose firing was being arrested by the first pool. Stronger connections arise from indirect SPNs. Dopamine deprivation impaired striatal feedback transmission disrupting the ability of a neuronal pool to arrest the firing of another neuronal pool. We demonstrate that feedback inhibition among SPNs is strong enough to control the firing of cell ensembles in the striatal microcircuit. However, to be effective, feedback inhibition should arise from synchronized pools of SPNs whose targets are other SPNs pools.


Asunto(s)
Retroalimentación Fisiológica/fisiología , Neostriado/patología , Neuronas/fisiología , Trastornos Parkinsonianos/patología , Transmisión Sináptica/fisiología , 6-Ciano 7-nitroquinoxalina 2,3-diona/farmacología , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/genética , Adrenérgicos/toxicidad , Anestésicos Locales/farmacología , Animales , Animales Recién Nacidos , Bicuculina/farmacología , Biofisica , Calcio/metabolismo , Modelos Animales de Enfermedad , Estimulación Eléctrica , Antagonistas de Aminoácidos Excitadores/farmacología , Antagonistas del GABA/farmacología , Proteínas Fluorescentes Verdes/genética , Técnicas In Vitro , Lidocaína/análogos & derivados , Lidocaína/farmacología , Lisina/análogos & derivados , Lisina/metabolismo , Masculino , Ratones , Ratones Transgénicos , Método de Montecarlo , Neostriado/citología , Neostriado/metabolismo , Inhibición Neural/efectos de los fármacos , Inhibición Neural/genética , Vías Nerviosas/efectos de los fármacos , Vías Nerviosas/fisiología , Neuronas/efectos de los fármacos , Oxidopamina/toxicidad , Trastornos Parkinsonianos/inducido químicamente , Trastornos Parkinsonianos/metabolismo , Técnicas de Placa-Clamp , Piridazinas/farmacología , Ratas , Ratas Wistar , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/genética , Receptores de Dopamina D1/genética , Receptores de Dopamina D2/genética , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/genética , Factores de Tiempo , Valina/análogos & derivados , Valina/farmacología , Ácido gamma-Aminobutírico/metabolismo
12.
J Neurophysiol ; 108(4): 1032-43, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22623487

RESUMEN

Somatostatin (SST) is a peptide synthesized and released by a class of neostriatal local GABAergic interneurons, which, to some extent, are in charge of the feedforward inhibitory circuit. Spiny projection neurons (SPNs) make synapses with each other via their local axon collaterals, shaping the feedback inhibitory circuit. Both inhibitory circuits, feedforward and feedback, are related through SST, which, being released by interneurons, presynaptically inhibits connections among SPNs. Here, we studied SST presynaptic modulation of synapses among SPNs in the 6-hydroxydopamine (6-OHDA) rodent model of parkinsonism. We performed antidromic field stimulation from the external globus pallidus and whole cell voltage-clamp recordings of antidromically evoked inhibitory postsynaptic currents (IPSCs) among SPNs. SST presynaptically reduced IPSCs by ∼34% in all control synapses tested. However, after striatal dopamine deprivation, three changes became evident. First, it was harder to evoke feedback inhibition. Second, presynaptic inhibition of some SPNs connections was larger than in controls: 57% reduction in ∼53% of evoked IPSCs. Presynaptic inhibition was recorded from direct pathway neurons (direct SPNs). Finally, SST also induced presynaptic facilitation in some SPNs connections, with 82% enhancement in ∼43% of evoked IPSCs. Presynaptic facilitation was recorded from indirect pathway neurons (indirect SPNs). Both inhibition and facilitation were accompanied by corresponding changes in the paired pulse ratio. It was demonstrated that after dopamine deprivation, SST modulation is altered in surviving feedback inhibitory synapses. It may underlie a homeostatic mechanism trying to compensate for the excitability imbalance between direct and indirect basal ganglia pathways found during parkinsonism.


Asunto(s)
Modelos Animales de Enfermedad , Neostriado/fisiología , Trastornos Parkinsonianos/fisiopatología , Terminales Presinápticos/fisiología , Somatostatina/fisiología , Animales , Potenciales Postsinápticos Inhibidores/efectos de los fármacos , Potenciales Postsinápticos Inhibidores/fisiología , Masculino , Neostriado/efectos de los fármacos , Técnicas de Cultivo de Órganos , Terminales Presinápticos/efectos de los fármacos , Ratas , Ratas Wistar , Somatostatina/farmacología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...