Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.032
Filtrar
1.
Nat Commun ; 11(1): 3342, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620835

RESUMO

Subdivisions of mouse whisker somatosensory thalamus project to cortex in a region-specific and layer-specific manner. However, a clear anatomical dissection of these pathways and their functional properties during whisker sensation is lacking. Here, we use anterograde trans-synaptic viral vectors to identify three specific thalamic subpopulations based on their connectivity with brainstem. The principal trigeminal nucleus innervates ventral posterior medial thalamus, which conveys whisker-selective tactile information to layer 4 primary somatosensory cortex that is highly sensitive to self-initiated movements. The spinal trigeminal nucleus innervates a rostral part of the posterior medial (POm) thalamus, signaling whisker-selective sensory information, as well as decision-related information during a goal-directed behavior, to layer 4 secondary somatosensory cortex. A caudal part of the POm, which apparently does not receive brainstem input, innervates layer 1 and 5A, responding with little whisker selectivity, but showing decision-related modulation. Our results suggest the existence of complementary segregated information streams to somatosensory cortices.


Assuntos
Córtex Cerebral/fisiologia , Vias Neurais/fisiologia , Córtex Somatossensorial/fisiologia , Tálamo/fisiologia , Tato/fisiologia , Vibrissas/fisiologia , Animais , Tronco Encefálico/citologia , Tronco Encefálico/fisiologia , Córtex Cerebral/citologia , Feminino , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/fisiologia , Córtex Somatossensorial/citologia , Transmissão Sináptica , Tálamo/citologia , Vibrissas/inervação
2.
Proc Natl Acad Sci U S A ; 117(26): 15270-15280, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32541017

RESUMO

The default mode network (DMN) has been defined in functional brain imaging studies as a set of highly connected brain areas, which are active during wakeful rest and inactivated during task-based stimulation. DMN function is characteristically impaired in major neuropsychiatric diseases, emphasizing its interest for translational research. However, in the mouse, a major preclinical rodent model, there is still no functional imaging evidence supporting DMN deactivation and deconnection during high-demanding cognitive/sensory tasks. Here we have developed functional ultrasound (fUS) imaging to properly visualize both activation levels and functional connectivity patterns, in head-restrained awake and behaving mice, and investigated their modulation during a sensory-task, whisker stimulation. We identified reproducible and highly symmetric resting-state networks, with overall connectivity strength directly proportional to the wakefulness level of the animal. We show that unilateral whisker stimulation leads to the expected activation of the contralateral barrel cortex in lightly sedated mice, while interhemispheric inhibition reduces activity in the ipsilateral barrel cortex. Whisker stimulation also leads to elevated bilateral connectivity in the hippocampus. Importantly, in addition to functional changes in these major hubs of tactile information processing, whisker stimulation during genuine awake resting-state periods leads to highly specific reductions both in activation and interhemispheric correlation within the restrosplenial cortex, a major hub of the DMN. These results validate an imaging technique for the study of activation and connectivity in the lightly sedated awake mouse brain and provide evidence supporting an evolutionary preserved function of the DMN, putatively improving translational relevance of preclinical models of neuropsychiatric diseases.


Assuntos
Encéfalo/diagnóstico por imagem , Neuroimagem Funcional , Rede Nervosa/fisiologia , Ultrassonografia/métodos , Animais , Mapeamento Encefálico/métodos , Masculino , Camundongos , Vibrissas/fisiologia
3.
Nan Fang Yi Ke Da Xue Xue Bao ; 40(3): 413-417, 2020 Mar 30.
Artigo em Chinês | MEDLINE | ID: mdl-32376570

RESUMO

OBJECTIVE: To study the behavioral characteristics of memory maintenance and regression in a mouse model of combined learning and memory training with fluoxetine treatment and explore the neural basis for learning and memory in the barrel area of the brain. METHODS: Twenty-six 16-day-old C57 mice were randomized into two equal groups and were given daily intraperitoneal injection of saline (control) or fluoxetine. The mice were subjected to stimulation of the right whiskers using a multi-sensory stimulation simulator and were given simultaneously olfactory stimulation with butyl acetate. In the initial 10 days of the experiment, the mice were given corresponding drug treatment followed by whisker and olfactory stimulations on a daily basis; from day 11 to day 17, only the drugs were administered without the stimulations; on day 18, both the drugs and stimulations were administered. The daily performance of the mice was recorded and analyzed. In the field potential experiment, the left barrel cortex of the mouse brain was selected to record the frequency of field potential signals in response to whisker stimulation. RESULTS: In the behavioral test, the mice treated with fluoxetine showed greater increments of the frequency and angle of whisker deflection than the control mice (P < 0.01). Compared with the peak levels that occurred on the 10th day, the swing angle and frequency of the whisker deflection decreased on the 17th day decreased in both groups, and the reduction was more obvious in the control group (P < 0.05). During the training on the 18th day, the whisker movement of the mice increased rapidly to the peak level and showed significant differences between the two groups (P < 0.05). In the field potential experiment on the 10th and 17th day, the frequencies of field potential signal in response to whisker stimulation was significantly higher in fluoxetine group than in the control group (P < 0.05). CONCLUSIONS: Combined training of the mice results in the formation of combined memory. Fluoxetine can enhance combined learning and memory abilities and prolong such memories in mice by promoting the function of the barrel cortex cells.


Assuntos
Aprendizagem , Córtex Somatossensorial , Animais , Fluoxetina , Camundongos , Neurônios , Vibrissas
4.
Neuron ; 106(3): 363-365, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32380049

RESUMO

Cortical sensory areas are supposed to encode immediate sensory inputs. In this issue of Neuron, Condylis et al. (2020) show that they can also recall information about a past event when in need of comparing two temporally segregated sensory inputs.


Assuntos
Córtex Somatossensorial , Vibrissas , Animais , Neurônios , Sensação
5.
PLoS Biol ; 18(5): e3000571, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32453721

RESUMO

Animals actively move their sensory organs in order to acquire sensory information. Some rodents, such as mice and rats, employ cyclic scanning motions of their facial whiskers to explore their proximal surrounding, a behavior known as whisking. Here, we investigated the contingency of whisking kinematics on the animal's behavioral context that arises from both internal processes (attention and expectations) and external constraints (available sensory and motor degrees of freedom). We recorded rat whisking at high temporal resolution in 2 experimental contexts-freely moving or head-fixed-and 2 spatial sensory configurations-a single row or 3 caudal whiskers on each side of the snout. We found that rapid sensorimotor twitches, called pumps, occurring during free-air whisking carry information about the rat's upcoming exploratory direction, as demonstrated by the ability of these pumps to predict consequent head and body locomotion. Specifically, pump behavior during both voluntary motionlessness and imposed head fixation exposed a backward redistribution of sensorimotor exploratory resources. Further, head-fixed rats employed a wide range of whisking profiles to compensate for the loss of head- and body-motor degrees of freedom. Finally, changing the number of intact vibrissae available to a rat resulted in an alteration of whisking strategy consistent with the rat actively reallocating its remaining resources. In sum, this work shows that rats adapt their active exploratory behavior in a homeostatic attempt to preserve sensorimotor coverage under changing environmental conditions and changing sensory capacities, including those imposed by various laboratory conditions.


Assuntos
Adaptação Fisiológica , Comportamento Exploratório/fisiologia , Retroalimentação Sensorial , Movimentos da Cabeça , Vibrissas/fisiologia , Animais , Fenômenos Biomecânicos , Locomoção , Masculino , Ratos Wistar
6.
J Headache Pain ; 21(1): 35, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32316909

RESUMO

BACKGROUND: The neurochemical background of the evolution of headache disorders, still remains partially undiscovered. Accordingly, our aim was to further explore the neurochemical profile of Complete Freund's adjuvant (CFA)-induced orofacial pain, involving finding the shift point regarding small molecule neurotransmitter concentrations changes vs. that of the previously characterized headache-related neuropeptides. The investigated neurotransmitters consisted of glutamate, γ-aminobutyric acid, noradrenalin and serotonin. Furthermore, in light of its influence on glutamatergic neurotransmission, we measured the level of kynurenic acid (KYNA) and its precursors in the kynurenine (KYN) pathway (KP) of tryptophan metabolism. METHODS: The effect of CFA was evaluated in male Sprague Dawley rats. Animals were injected with CFA (1 mg/ml, 50 µl/animal) into the right whisker pad. We applied high-performance liquid chromatography to determine the concentrations of the above-mentioned compounds from the trigeminal nucleus caudalis (TNC) and somatosensory cortex (ssCX) of rats. Furthermore, we measured some of these metabolites from the cerebrospinal fluid and plasma as well. Afterwards, we carried out permutation t-tests as post hoc analysis for pairwise comparison. RESULTS: Our results demonstrated that 24 h after CFA treatment, the level of glutamate, KYNA and that of its precursor, KYN was still elevated in the TNC, all diminishing by 48 h. In the ssCX, significant concentration increases of KYNA and serotonin were found. CONCLUSION: This is the first study assessing neurotransmitter changes in the TNC and ssCX following CFA treatment, confirming the dominant role of glutamate in early pain processing and a compensatory elevation of KYNA with anti-glutamatergic properties. Furthermore, the current findings draw attention to the limited time interval where medications can target the glutamatergic pathways.


Assuntos
Dor Facial/metabolismo , Ácido Glutâmico/metabolismo , Ácido Cinurênico/metabolismo , Norepinefrina/metabolismo , Serotonina/metabolismo , Triptofano/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Dor Facial/induzido quimicamente , Adjuvante de Freund , Masculino , Ratos , Ratos Sprague-Dawley , Núcleo Inferior Caudal do Nervo Trigêmeo/metabolismo , Vibrissas/efeitos dos fármacos
7.
Nat Commun ; 11(1): 1693, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32245963

RESUMO

The cortex modulates activity in superior colliculus via a direct projection. What is largely unknown is whether (and if so how) the superior colliculus modulates activity in the cortex. Here, we investigate this issue and show that optogenetic activation of superior colliculus changes the input-output relationship of neurons in somatosensory cortex, enhancing responses to low amplitude whisker deflections. While there is no direct pathway from superior colliculus to somatosensory cortex, we found that activation of superior colliculus drives spiking in the posterior medial (POm) nucleus of the thalamus via a powerful monosynaptic pathway. Furthermore, POm neurons receiving input from superior colliculus provide monosynaptic excitatory input to somatosensory cortex. Silencing POm abolished the capacity of superior colliculus to modulate cortical whisker responses. Our findings indicate that the superior colliculus, which plays a key role in attention, modulates sensory processing in somatosensory cortex via a powerful di-synaptic pathway through the thalamus.


Assuntos
Córtex Somatossensorial/fisiologia , Colículos Superiores/fisiologia , Núcleos Ventrais do Tálamo/fisiologia , Vibrissas/fisiologia , Animais , Eletrodos Implantados , Masculino , Camundongos , Vias Neurais/fisiologia , Neurônios/fisiologia , Optogenética , Córtex Somatossensorial/citologia , Técnicas Estereotáxicas , Núcleos Ventrais do Tálamo/citologia
8.
Neuron ; 106(3): 515-525.e5, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32164873

RESUMO

To interpret the environment, our brain must evaluate external stimuli against internal representations from past experiences. How primary (S1) and secondary (S2) somatosensory cortices process stimuli depending on recent experiences is unclear. Using simultaneous multi-area population imaging of projection neurons and focal optogenetic inactivation, we studied mice performing a whisker-based working memory task. We find that activity reflecting a current stimulus, the recollection of a previous stimulus (cued recall), and the stimulus category are distributed across S1 and S2. Despite this overlapping representation, S2 is important for processing cued recall responses and transmitting these responses to S1. S2 network properties differ from S1, wherein S2 persistently encodes cued recall and the stimulus category under passive conditions. Although both areas encode the stimulus category, only information in S1 is important for task performance through pathways that do not necessarily include S2. These findings reveal both distributed and segregated roles for S1 and S2 in context-dependent sensory processing.


Assuntos
Memória de Curto Prazo , Córtex Somatossensorial/fisiologia , Percepção do Tato , Animais , Masculino , Camundongos , Modelos Neurológicos , Neurônios/fisiologia , Córtex Somatossensorial/citologia , Vibrissas/citologia , Vibrissas/fisiologia
9.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 38(1): 59-68, 2020 Feb 01.
Artigo em Chinês | MEDLINE | ID: mdl-32037768

RESUMO

OBJECTIVE: To systematically evaluate the repairing effect of stem cells on facial nerve defects. METHODS: Articles regarding the regenerating effect of stem cells on facial nerves in animals were collected from the databases of Pubmed, Cochrane Library, Web of Science, Embase, Scopus, and CBM. Two professionals independently completed the article screening, data extraction, and bias risk assessment. RevMan 5.3 and random-effects models were used for the statistical analysis, and the results were presented in the form of mean differences (MD) with a 95%CI. The results of functional evaluation (vibrissae movement, facial paralysis) and histological evaluation (density of myelinated fibers, diameter of fibers, thickness of myelin sheath, G ratio) of facial nerve were Meta-analyzed. RESULTS: A total of 4 614 articles were retrieved from the 6 databases, and 15 of these articles were included in the Meta-analysis. For vibrissae movement and facial paralysis, the stem cell group scored significantly higher than the non-stem cell group (P<0.05). The density of myelinated fibers and thickness of the myelin sheath in the stem cell group were higher than those in the non-stem cell group (P<0.05). The G ratio in the stem cell group was smaller than that in the non-stem cell group (P=0.001). There was no significant difference in fiber diameter (P=0.08). CONCLUSIONS: Stem cells have potential in promoting facial nerve regeneration.


Assuntos
Nervo Facial , Paralisia Facial , Animais , Regeneração Nervosa , Células-Tronco , Vibrissas
10.
J Neurosci ; 40(13): 2663-2679, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32054677

RESUMO

Thalamocortical posterior nucleus (Po) axons innervating the vibrissal somatosensory (S1) and motor (MC) cortices are key links in the brain neuronal network that allows rodents to explore the environment whisking with their motile snout vibrissae. Here, using fine-scale high-end 3D electron microscopy, we demonstrate in adult male C57BL/6 wild-type mice marked differences between MC versus S1 Po synapses in (1) bouton and active zone size, (2) neurotransmitter vesicle pool size, (3) distribution of mitochondria around synapses, and (4) proportion of synapses established on dendritic spines and dendritic shafts. These differences are as large, or even more pronounced, than those between Po and ventro-posterior thalamic nucleus synapses in S1. Moreover, using single-axon transfection labeling, we demonstrate that the above differences actually occur on the MC versus the S1 branches of individual Po cell axons that innervate both areas. Along with recently-discovered divergences in efficacy and plasticity, the synaptic structure differences reported here thus reveal a new subcellular level of complexity. This is a finding that upends current models of thalamocortical circuitry, and that might as well illuminate the functional logic of other branched projection axon systems.SIGNIFICANCE STATEMENT Many long-distance brain connections depend on neurons whose branched axons target separate regions. Using 3D electron microscopy and single-cell transfection, we investigated the mouse Posterior thalamic nucleus (Po) cell axons that simultaneously innervate motor and sensory areas of the cerebral cortex involved in whisker movement control. We demonstrate significant differences in the size of the boutons made in each area by individual Po axons, as well as in functionally-relevant parameters in the composition of their synapses. In addition, we found similarly large differences between the synapses of Po versus ventral posteromedial thalamic nucleus axons in the whisker sensory cortex. Area-specific synapse structure in individual axons implies a new, unsuspected level of complexity in long-distance brain connections.


Assuntos
Axônios/fisiologia , Rede Nervosa/fisiologia , Neurônios/fisiologia , Córtex Somatossensorial/fisiologia , Sinapses/fisiologia , Tálamo/fisiologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Vias Neurais/fisiologia , Vibrissas/fisiologia
11.
Nature ; 579(7797): 106-110, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32076269

RESUMO

Proper brain function depends on neurovascular coupling: neural activity rapidly increases local blood flow to meet moment-to-moment changes in regional brain energy demand1. Neurovascular coupling is the basis for functional brain imaging2, and impaired neurovascular coupling is implicated in neurodegeneration1. The underlying molecular and cellular mechanisms of neurovascular coupling remain poorly understood. The conventional view is that neurons or astrocytes release vasodilatory factors that act directly on smooth muscle cells (SMCs) to induce arterial dilation and increase local blood flow1. Here, using two-photon microscopy to image neural activity and vascular dynamics simultaneously in the barrel cortex of awake mice under whisker stimulation, we found that arteriolar endothelial cells (aECs) have an active role in mediating neurovascular coupling. We found that aECs, unlike other vascular segments of endothelial cells in the central nervous system, have abundant caveolae. Acute genetic perturbations that eliminated caveolae in aECs, but not in neighbouring SMCs, impaired neurovascular coupling. Notably, caveolae function in aECs is independent of the endothelial NO synthase (eNOS)-mediated NO pathway. Ablation of both caveolae and eNOS completely abolished neurovascular coupling, whereas the single mutants exhibited partial impairment, revealing that the caveolae-mediated pathway in aECs is a major contributor to neurovascular coupling. Our findings indicate that vasodilation is largely mediated by endothelial cells that actively relay signals from the central nervous system to SMCs via a caveolae-dependent pathway.


Assuntos
Arteríolas/citologia , Arteríolas/metabolismo , Cavéolas/metabolismo , Sistema Nervoso Central/citologia , Acoplamento Neurovascular , Animais , Córtex Cerebral/citologia , Células Endoteliais/metabolismo , Feminino , Masculino , Camundongos , Microscopia de Fluorescência por Excitação Multifotônica , Óxido Nítrico Sintase Tipo III/deficiência , Óxido Nítrico Sintase Tipo III/metabolismo , Vasodilatação , Vibrissas/fisiologia
12.
Artigo em Inglês | MEDLINE | ID: mdl-32109749

RESUMO

Obtaining longitudinal endocrinological data from free-ranging animals remains challenging. Steroid hormones can be extracted sequentially from non-invasively sampled biologically inert keratinous tissues, such as feathers, nails, hair and whiskers. However, uncertainty regarding the type and levels of steroids incorporated into such tissues complicates their utility in wildlife studies. Here, we developed a novel, comprehensive method to analyze fourteen C19 and fourteen C21 steroids deposited chronologically along the length of seal whiskers in a single, 6-minute chromatographic step, using ultra-performance convergence chromatography-tandem mass spectrometry. The limits of detection and quantification ranged from 0.01 to 2 ng/mL and from 0.1 to 10 ng/mL, respectively. The accuracy and precision were within acceptable limits for steroids at concentrations ≥2 ng/mL. The recovery (mean = 107.5% at 200 ng/mL), matrix effect and process efficiency of steroids evaluated, using blanked whisker matrix samples, were acceptable. The method was applied to the analysis of steroid hormone levels in adult female whisker segments obtained from southern elephant seals (Mirounga leonina), n = 10, and two fur seal species, Antarctic fur seals (Arctocephalus gazella; n = 5) and subantarctic fur seals (Arctocephalus tropicalis; n = 5), sampled between 2012 and 2017. In the whisker subsamples analyzed (n = 71), the median concentration of steroid hormones detected above the LOQ ranged from 2.0 to 273.7 pg/mg. This was the first extraction of multiple C19 and C21 steroids, including their C11-oxy metabolites, from the whiskers of mammals. Measuring hormones sequentially along the whisker lengths can contribute to our understanding of the impact of stress associated with environmental/climate changes that affect the health, survival of organisms, as well as to delineate the reproductive cycles of free-living mammals with cryptic life stages.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Esteroides/análise , Espectrometria de Massas em Tandem/métodos , Vibrissas/química , Androgênios/análise , Animais , Feminino , Otárias , Glucocorticoides/análise , Ensaios de Triagem em Larga Escala , Limite de Detecção , Modelos Lineares , Progestinas/análise , Reprodutibilidade dos Testes
13.
PLoS Biol ; 18(2): e3000613, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32027647

RESUMO

Cortical interneurons expressing vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT) are sparsely distributed throughout the neocortex, constituting only 0.5% of its neuronal population. The co-expression of VIP and ChAT suggests that these VIP/ChAT interneurons (VChIs) can release both γ-aminobutyric acid (GABA) and acetylcholine (ACh). In vitro physiological studies quantified the response properties and local connectivity patterns of the VChIs; however, the function of VChIs has not been explored in vivo. To study the role of VChIs in cortical network dynamics and their long-range connectivity pattern, we used in vivo electrophysiology and rabies virus tracing in the barrel cortex of mice. We found that VChIs have a low spontaneous spiking rate (approximately 1 spike/s) in the barrel cortex of anesthetized mice; nevertheless, they responded with higher fidelity to whisker stimulation than the neighboring layer 2/3 pyramidal neurons (Pyrs). Analysis of long-range inputs to VChIs with monosynaptic rabies virus tracing revealed that direct thalamic projections are a significant input source to these cells. Optogenetic activation of VChIs in the barrel cortex of awake mice suppresses the sensory responses of excitatory neurons in intermediate amplitudes of whisker deflections while increasing the evoked spike latency. The effect of VChI activation on the response was similar for both high-whisking (HW) and low-whisking (LW) conditions. Our findings demonstrate that, despite their sparsity, VChIs can effectively modulate sensory processing in the cortical microcircuit.


Assuntos
Colina O-Acetiltransferase/metabolismo , Interneurônios/fisiologia , Córtex Somatossensorial/citologia , Peptídeo Intestinal Vasoativo/metabolismo , Animais , Colina O-Acetiltransferase/genética , Potenciais Evocados , Potenciais Pós-Sinápticos Inibidores , Integrases/genética , Interneurônios/metabolismo , Camundongos , Camundongos Transgênicos , Vias Neurais , Neurônios/metabolismo , Neurônios/fisiologia , Optogenética , Córtex Somatossensorial/metabolismo , Peptídeo Intestinal Vasoativo/genética , Núcleos Ventrais do Tálamo/metabolismo , Vibrissas
14.
PLoS One ; 15(2): e0228881, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023321

RESUMO

Urban environments are unique because fragments of natural or semi-natural habitat are embedded within a potentially permeable matrix of human-dominated areas, creating increased landscape and, potentially, habitat heterogeneity. In addition, urban areas can provide diet subsidies for wildlife species in the form of fruiting ornamental plants, trash, and domestic animals. Ecological opportunity in the forms of habitat and food heterogeneity are thought to be important mechanisms in maintaining individual specialization. Identifying which contexts, traits, and mechanisms determine the success or failure of individuals within an urban wildlife population could potentially provide predictions about which populations may succeed in human-dominated landscapes and which may experience local extinction. We used both scat and stable isotope analysis of whiskers to investigate the degree to which coyotes (Canis latrans) utilized anthropogenic subsidies and exhibited individual diet specialization across the urban-rural gradient in southern California. Land use surrounding scat and isotope sample locations was also evaluated to determine the effect of land cover on diet. Human food constituted a significant portion of urban coyote diet (22% of scats, 38% of diet estimated by stable isotope analysis). Domestic cats (Felis catus) and ornamental fruit and seeds were also important items in urban coyote diets. Consumption of anthropogenic items decreased with decreasing urbanization. In suburban areas, seasonality influenced the frequency of occurrence of anthropogenic subsidies with increased consumption in the dry season. The amount of altered open space (areas such as golf courses, cemeteries, and landscaped parks) nearby had a negative effect on the consumption of anthropogenic items in both urban and suburban areas. Contrary to our hypothesis, urban coyotes displayed reduced between-individual variation compared to suburban and rural coyotes. It is possible that the core urban areas of cities are so densely developed and subsidized that wildlife inhabiting these areas actually have reduced ecological opportunity. Suburban animals had the broadest isotopic niches and maintained similar individual specialization to rural coyotes. Wildlife in suburban areas still have access to relatively undisturbed natural areas while being able to take advantage of anthropogenic subsidies in neighboring residential areas. Therefore, areas with intermediate urban development may be associated with increased ecological opportunity and specialization.


Assuntos
Coiotes/fisiologia , Animais , Animais Selvagens , California , Isótopos de Carbono/análise , Cidades , Dieta , Ecossistema , Fezes/química , Feminino , Humanos , Masculino , Modelos Biológicos , Recursos Naturais , Isótopos de Nitrogênio/análise , Estações do Ano , Urbanização , Vibrissas/química
15.
J Neurosci ; 40(11): 2228-2245, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32001612

RESUMO

Sensory cortex exhibits receptive field plasticity throughout life in response to changes in sensory experience and offers the experimental possibility of aligning functional changes in receptive field properties with underpinning structural changes in synapses. We looked at the effects on structural plasticity of two different patterns of whisker deprivation in male and female mice: chessboard deprivation, which causes functional plasticity; and all deprived, which does not. Using 2-photon microscopy and chronic imaging through a cranial window over the barrel cortex, we found that layer 2/3 neurones exhibit robust structural plasticity, but only in response to whisker deprivation patterns that cause functional plasticity. Chessboard pattern deprivation caused dual-component plasticity in layer 2/3 by (1) increasing production of new spines that subsequently persisted for weeks and (2) enlarging spine head sizes in the preexisting stable spine population. Structural plasticity occurred on basal dendrites, but not apical dendrites. Both components of plasticity were absent in αCaMKII-T286A mutants that lack LTP and experience-dependent potentiation in barrel cortex, implying that αCaMKII autophosphorylation is not only important for stabilization and enlargement of spines, but also for new spine production. These studies therefore reveal the relationship between spared whisker potentiation in layer 2/3 neurones and the form and mechanisms of structural plasticity processes that underlie them.SIGNIFICANCE STATEMENT This study provides a missing link in a chain of reasoning that connects LTP to experience-dependent functional plasticity in vivo We found that increases in dendritic spine formation and spine enlargement (both of which are characteristic of LTP) only occurred in barrel cortex during sensory deprivation that produced potentiation of sensory responses. Furthermore, the dendritic spine plasticity did not occur during sensory deprivation in mice lacking LTP and experience-dependent potentiation (αCaMKII autophosphorylation mutants). We also found that the dual-component dendritic spine plasticity only occurred on basal dendrites and not on apical dendrites, thereby resolving a paradox in the literature suggesting that layer 2/3 neurones lack structural plasticity in response to sensory deprivation.


Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/fisiologia , Espinhas Dendríticas/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/enzimologia , Privação Sensorial/fisiologia , Córtex Somatossensorial/fisiopatologia , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/deficiência , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Tamanho Celular , Espinhas Dendríticas/ultraestrutura , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/ultraestrutura , Fosforilação , Processamento de Proteína Pós-Traducional , Técnica de Janela Cutânea , Córtex Somatossensorial/citologia , Distúrbios Somatossensoriais/fisiopatologia , Vibrissas/lesões , Vibrissas/inervação
16.
Cell ; 180(3): 521-535.e18, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-31978320

RESUMO

Cortical layer 1 (L1) interneurons have been proposed as a hub for attentional modulation of underlying cortex, but the transformations that this circuit implements are not known. We combined genetically targeted voltage imaging with optogenetic activation and silencing to study the mechanisms underlying sensory processing in mouse barrel cortex L1. Whisker stimuli evoked precisely timed single spikes in L1 interneurons, followed by strong lateral inhibition. A mild aversive stimulus activated cholinergic inputs and evoked a bimodal distribution of spiking responses in L1. A simple conductance-based model that only contained lateral inhibition within L1 recapitulated the sensory responses and the winner-takes-all cholinergic responses, and the model correctly predicted that the network would function as a spatial and temporal high-pass filter for excitatory inputs. Our results demonstrate that all-optical electrophysiology can reveal basic principles of neural circuit function in vivo and suggest an intuitive picture for how L1 transforms sensory and modulatory inputs. VIDEO ABSTRACT.


Assuntos
Eletrofisiologia/métodos , Potenciais Somatossensoriais Evocados/fisiologia , Interneurônios/fisiologia , Inibição Neural/fisiologia , Imagem Óptica/métodos , Córtex Somatossensorial/citologia , Potenciais de Ação/fisiologia , Animais , Neurônios Colinérgicos/fisiologia , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Técnicas de Patch-Clamp/métodos , Potenciais Sinápticos/fisiologia , Vibrissas/fisiologia
17.
Epilepsia ; 61(2): 330-341, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31912497

RESUMO

OBJECTIVE: The neuronal underpinnings of impaired consciousness during absence seizures remain largely unknown. Spike-and-wave (SW) activity associated with absences imposes two extremely different states in cortical neurons, which transition from suprathreshold synaptic depolarizations during spike phases to membrane hyperpolarization and electrical silence during wave phases. To investigate whether this rhythmic alternation of neuronal states affects the processing of sensory information during seizures, we examined cortical and thalamic responsiveness to brief sensory stimuli in the different phases of the epileptic cycle. METHODS: Electrocorticographic (ECoG) monitoring from the primary somatosensory cortex combined with intracellular recordings of subjacent pyramidal neurons, or extracellular recordings of somatosensory thalamic neurons, were performed in the Genetic Absence Epilepsy Rat From Strasbourg. Sensory stimuli consisted of pulses of compressed air applied to the contralateral whiskers. RESULTS: Whisker stimuli delivered during spike phases evoked smaller depolarizing synaptic potentials and fewer action potentials in cortical neurons compared to stimuli occurring during wave phases. This spike-related attenuation of cortical responsiveness was accompanied by a reduced neuronal membrane resistance, likely due to the large increase in synaptic conductance. Sensory-evoked firing in thalamocortical neurons was also decreased during ECoG spikes as compared to wave phases, indicating that time-to-time changes in the thalamocortical volley may also contribute to the variability of cortical responses during seizures. SIGNIFICANCE: These findings demonstrate that thalamocortical sensory processing during absence seizures is nonstationary and strongly suggest that the cortical impact of a given environmental stimulus is conditioned by its exact timing relative to the SW cycle. The lack of stability of thalamic and cortical responses along seizures may contribute to impaired conscious sensory perception during absences.


Assuntos
Córtex Cerebral/fisiopatologia , Epilepsia/fisiopatologia , Sensação , Tálamo/fisiopatologia , Animais , Membrana Celular , Eletrocorticografia , Epilepsia Tipo Ausência/fisiopatologia , Neurônios , Células Piramidais , Ratos , Córtex Somatossensorial/fisiopatologia , Vibrissas/inervação
18.
PLoS Comput Biol ; 16(1): e1007402, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31978043

RESUMO

Quantification of behaviour is essential for biology. Since the whisker system is a popular model, it is important to have methods for measuring whisker movements from behaving animals. Here, we developed a high-speed imaging system that measures whisker movements simultaneously from two vantage points. We developed a whisker tracker algorithm that automatically reconstructs 3D whisker information directly from the 'stereo' video data. The tracker is controlled via a Graphical User Interface that also allows user-friendly curation. The algorithm tracks whiskers, by fitting a 3D Bezier curve to the basal section of each target whisker. By using prior knowledge of natural whisker motion and natural whisker shape to constrain the fits and by minimising the number of fitted parameters, the algorithm is able to track multiple whiskers in parallel with low error rate. We used the output of the tracker to produce a 3D description of each tracked whisker, including its 3D orientation and 3D shape, as well as bending-related mechanical force. In conclusion, we present a non-invasive, automatic system to track whiskers in 3D from high-speed video, creating the opportunity for comprehensive 3D analysis of sensorimotor behaviour and its neural basis.


Assuntos
Imageamento Tridimensional/métodos , Vibrissas/diagnóstico por imagem , Vibrissas/fisiologia , Algoritmos , Animais , Fenômenos Biomecânicos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
19.
Neuron ; 105(1): 93-105.e4, 2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31780328

RESUMO

The developmental journey of cortical interneurons encounters several activity-dependent milestones. During the early postnatal period in developing mice, GABAergic neurons are transient preferential recipients of thalamic inputs and undergo activity-dependent migration arrest, wiring, and programmed cell-death. Despite their importance for the emergence of sensory experience and the role of activity in their integration into cortical networks, the collective dynamics of GABAergic neurons during that neonatal period remain unknown. Here, we study coordinated activity in GABAergic cells of the mouse barrel cortex using in vivo calcium imaging. We uncover a transient structure in GABAergic population dynamics that disappears in a sensory-dependent process. Its building blocks are anatomically clustered GABAergic assemblies mostly composed by prospective parvalbumin-expressing cells. These progressively widen their territories until forming a uniform perisomatic GABAergic network. Such transient patterning of GABAergic activity is a functional scaffold that links the cortex to the external world prior to active exploration. VIDEO ABSTRACT.


Assuntos
Neurônios GABAérgicos/fisiologia , Interneurônios/fisiologia , Córtex Somatossensorial/crescimento & desenvolvimento , Córtex Somatossensorial/fisiologia , Tálamo/fisiologia , Animais , Animais Recém-Nascidos , Cálcio/metabolismo , Feminino , Glutamato Descarboxilase/genética , Masculino , Camundongos , Camundongos Transgênicos , Vias Neurais/crescimento & desenvolvimento , Vias Neurais/fisiologia , Neuroimagem , Parvalbuminas/metabolismo , Privação Sensorial/fisiologia , Córtex Somatossensorial/metabolismo , Somatostatina/metabolismo , Vibrissas/patologia
20.
Ann Anat ; 227: 151410, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31394169

RESUMO

Animal models of nerve function have been subject to extensive study in order to understand and investigate methods which may improve axon regeneration and promote functional outcomes following nerve injury and repair. As the facial nerve is a cranial nerve, there is mounting evidence that cranial nerve regeneration differs from peripheral, and outcome models specifically addressing the facial nerve are required. Murine models are the most commonly utilized, with a variety of methods employed to measure the actions of whisking, eye closure, or ear movement as indicators of facial nerve regeneration. Each method of measurement is reviewed in terms of validity, strengths, limitations, and the specific outcome data provided. The authors propose that prior to choosing an outcome model, the goals and objectives of a planned study should be well defined, as various outcome measures may be useful depending on the information which is desired. The aim of this paper, therefore, is to provide the reader with a concise review which may facilitate project design.


Assuntos
Nervo Facial/fisiologia , Camundongos/fisiologia , Modelos Animais , Regeneração Nervosa/fisiologia , Ratos/fisiologia , Animais , Orelha Externa/fisiologia , Eletromiografia , Pálpebras/fisiologia , Camundongos/anatomia & histologia , Microscopia Confocal , Microscopia de Fluorescência , Ratos/anatomia & histologia , Espectrofotometria Infravermelho , Vibrissas/fisiologia , Gravação em Vídeo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA