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1.
Neuropsychologia ; 191: 108736, 2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-37995903

RESUMEN

Previous research has established a strong link between attention and visual mental imagery, but it's remained uncertain whether attention networks influence individual differences in the vividness of visual mental imagery. In our study, we examined 140 participants, assessing the vividness of imagery using the Vividness of Visual Imagery Questionnaire in both eyes-open and eyes-closed conditions. We employed the Attention Network Test, coupled with EEG recording, to characterize three attention sub-networks: alerting, orienting, and executive control. To pinpoint the specific attentional networks associated with the vividness of visual mental imagery, we utilized latent profile analysis to categorize participants into distinct subgroups. Additionally, we constructed a regression mixture model to explore how attention networks predict different latent categories of visual imagery vividness. Our findings revealed that the efficiency of the alerting network, as indicated by the N1 component, demonstrated a positive correlation with the vividness of visual imagery. This electrophysiological evidence underscores the role of the alerting network in shaping individual differences in the vividness of visual mental imagery.


Asunto(s)
Imaginación , Individualidad , Humanos , Imaginación/fisiología , Imágenes en Psicoterapia , Función Ejecutiva , Electroencefalografía
2.
J Cogn Neurosci ; 35(6): 1045-1060, 2023 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-37043235

RESUMEN

Visual perception and mental imagery have been shown to share a hierarchical topological visual structure of neural representation, despite the existence of dissociation of neural substrate between them in function and structure. However, we have limited knowledge about how the visual hierarchical cortex is involved in visual perception and visual imagery in a unique and shared fashion. In this study, a data set including a visual perception and an imagery experiment with human participants was used to train 2 types of voxel-wise encoding models. These models were based on Gabor features and voxel activity patterns of high-level visual cortex (i.e., fusiform face area, parahippocampal place area, and lateral occipital complex) to predict activity in the early visual cortex (EVC, i.e., V1, V2, V3) during perception, and then tested with respect to the generalization of these models to mental imagery. Our results showed that during perception and imagery, activities in the EVC could be independently predicted by the Gabor features and activity of high-level visual cortex via voxel-wise encoding models, which suggested that perception and imagery might share neural representation in the EVC. We further found Gabor-specific and non-Gabor-specific patterns of neural response to stimuli in the EVC, which were shared by perception and imagery. These findings provide insight into the mechanisms of how visual perception and imagery share representation in the EVC.


Asunto(s)
Imaginación , Corteza Visual , Humanos , Imaginación/fisiología , Percepción Visual/fisiología , Corteza Visual/diagnóstico por imagen , Corteza Visual/fisiología , Imagen por Resonancia Magnética
3.
Front Med (Lausanne) ; 9: 761419, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35707522

RESUMEN

Introduction: Antidepressants are the front-line treatments for major depressive disorder (MDD), but remain unsatisfactory in outcome. An increasing number of patients are interested in acupuncture and moxibustion treatment as complementary therapies. This study aims to evaluate the efficacy and safety of integrative acupuncture and moxibustion (iAM) treatment in patients with MDD. Methods and Analysis: This multicenter, single-blind, 2 × 2 factorial randomized trial will enroll 592 patients with MDD of moderate severity from nine hospitals. All patients will be randomized, in a ratio of 2:2:2:1, through a computerized central randomization system, into four groups (the combined, iAM-only, sertraline-only, and placebo groups). Participants will undergo a 12-week intervention with either 50 mg of sertraline or a placebo once a day and active/sham iAM treatment three times per week. The primary outcome is depression severity, assessed using the Hamilton Depression Scale-17. The secondary outcomes include self-rated depression severity, anxiety, and sleep quality. The primary and secondary outcomes will be measured at weeks 0, 4, 8, 12, and the 8th week posttreatment. Safety will be evaluated through liver and kidney function tests conducted before and after treatment and through monitoring of daily adverse events. An intent-to-treat principle will be followed for the outcome analyses. Conclusion: This trial will provide sufficient evidence to ascertain whether iAM is effective and safe for treating MDD and provides a suitable combination strategy for treating MDD. Clinical Trial Registration: [www.chictr.org.cn], identifier [ChiCTR2100042841].

4.
Front Hum Neurosci ; 15: 625888, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33867956

RESUMEN

Cognitive and neural processes underlying visual creativity have attracted substantial attention. The current research uses a critical time point analysis (CTPA) to examine how spontaneous activity in the primary visual area (PVA) is related to visual creativity. We acquired the functional magnetic resonance imaging (fMRI) data of 16 participants at the resting state and during performing a visual creative synthesis task. According to the CTPA, we then classified spontaneous activity in the PVA into critical time points (CTPs), which reflect the most useful and important functional meaning of the entire resting-state condition, and the remaining time points (RTPs). We constructed functional brain networks based on the brain activity at two different time points and then subsequently based on the brain activity at the task state in a separate manner. We explore the relationship between resting-state and task-fMRI (T-fMRI) functional brain networks. Our results found that: (1) the pattern of spontaneous activity in the PVA may associate with mental imagery, which plays an important role in visual creativity; (2) in comparison with the RTPs-based brain network, the CTP-network showed an increase in global efficiency and a decrease in local efficiency; (3) the regional integrated properties of the CTP-network could predict the integrated properties of the creative-network while the RTP-network could not. Thus, our findings indicated that spontaneous activity in the PVA at CTPs was associated with a visual creative task-evoked brain response. Our findings may provide an insight into how the visual cortex is related to visual creativity.

5.
Sheng Li Xue Bao ; 73(2): 286-294, 2021 Apr 25.
Artículo en Chino | MEDLINE | ID: mdl-33903890

RESUMEN

Many studies have shown that high-altitude exposure could significantly influence human cognition, and the approaches which could enhance the human cognition in high-altitude hypoxia environment attract great attention. In the present study, we recruited a total of 60 subjects who had been migrated to Tibet University as adults for more than one year. These participants were randomly divided into the experimental group and the control group. The participants in the experimental group were instructed to complete a hyperbaric oxygen treatment, and those in the control group just completed a wait condition. By using the attention network test (ANT), the changes of the attention function before and after a single session of hyperbaric oxygen treatment were explored. The results showed that single hyperbaric oxygen treatment significantly improved the orienting function of attention, with an obvious post-intervention effect, but not the alerting and conflict function of attention. We also found a strong association between alerting function and conflict function after the end of intervention, suggesting the change of the overall performance of attention function. The present findings might suggest that the improvement of attention function by a single session of hyperbaric oxygen intervention is derived from the increase of general cognitive resources, rather than the transfer of cognitive resources within the attention system.


Asunto(s)
Oxigenoterapia Hiperbárica , Migrantes , Adulto , Humanos , Orientación , Oxígeno , Tiempo de Reacción , Tibet
6.
Front Psychiatry ; 12: 772523, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-35095593

RESUMEN

Introduction: Perimenopausal depression is predominantly caused by hormone shock, but the underlying physical and psychological factors are still unclear. Objectives: To explore the constituent components of perimenopausal depression by dynamically depicting its influencing factors and interactive pathways from the perspective of embodied cognition. Methods: This is a randomized clinical controlled trial. In this study, electroacupuncture was compared with escitalopram. A total of 242 participants with mild to moderate perimenopausal depression were enrolled from 6 hospitals in China. Each participant had a 12-week intervention and a 12-week follow-up period. The primary outcome of this study is the Hamilton Depression Rating Scale (HAMD-17), and the secondary outcome is the menopause-specific quality of life scale (MENQOL), serum Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estrogen (E2) levels. Results: The structural equation model suggested that hormone levels were not directly associated with HAMD-17 (P = 0.852), while MENQOL was statistically correlated with HAMD-17 as an intermediary variable (P < 0.001). Electroacupuncture gradually showed positive impacts on MENQOL and HAMD-17 during the follow-up period (P < 0.05). Cognitive impairment is the dominant dimension of perimenopausal depression. Conclusions: Hormonal shock may affect clinical symptoms and poor quality of life to induce cognitive impairment leading perimenopausal depression, and this impact on cognition is embodied. Electroacupuncture has positive effect on perimenopausal depression and quality of life.

7.
Anim Sci J ; 91(1): e13391, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32558027

RESUMEN

One hundred Yorkshire × Landrace sows were randomly assigned to one of two dietary treatments (diet ND: 6,000 IU vitamin D3 /d feed; diet 25-D: 200 µg/day 25OHD3 feed). The experiment began on d 90 of gestation and continued until weaning on day 21 of lactation. In sows that received 25OHD3 , the growth rate of the piglets before weaning was significantly accelerated (0.266 kg/day, p < .05). Sow serum was collected after weaning, and those in the 25OHD3 group were found to have significantly higher serum calcium (CA) and phosphorus (PI) levels (p < .05). Interestingly, the oestrus cycle of sows fed 25OHD3 was significantly shortened (p < .05), the oestrus time was concentrated on the fifth day after weaning, and the piglets were born with a higher degree of uniformity (p < .05). Colostrum was collected on the day of delivery, and the colostrum of sows fed 25OHD3 contained higher milk fat content than the control group (p < .05). 25OHD3 supplementation increased the mRNA and protein expression of INSIG1 and SREBP1, which regulate milk fat synthesis, in the mammary gland of lactating sows (p < .05). In conclusion, 25OHD3 supplementation in maternal diets improved reproductive performance, milk fat content and the mRNA and protein levels of genes regulating milk fat synthesis in lactating sows.


Asunto(s)
25-Hidroxivitamina D 2/administración & dosificación , 25-Hidroxivitamina D 2/farmacología , Fenómenos Fisiológicos Nutricionales de los Animales/genética , Fenómenos Fisiológicos Nutricionales de los Animales/fisiología , Dieta/veterinaria , Suplementos Dietéticos , Expresión Génica/efectos de los fármacos , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Lactancia/genética , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Reproducción/efectos de los fármacos , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/genética , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Porcinos/genética , Porcinos/fisiología , Animales , Calcio/metabolismo , Estro/efectos de los fármacos , Femenino , Glucolípidos/metabolismo , Glicoproteínas/metabolismo , Lactancia/fisiología , Gotas Lipídicas , Fósforo/metabolismo , Embarazo , ARN Mensajero/genética , ARN Mensajero/metabolismo
8.
Mater Sci Eng C Mater Biol Appl ; 108: 110512, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31924017

RESUMEN

980-nm-upconverted 530 and 550 nm Er3+ green fluorescence spectra of Er3+/Yb3+-codoped NaGd(WO4)2 submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er3+. The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method.


Asunto(s)
Erbio/química , Fluorescencia , Fósforo/química , Termometría/métodos , Calor , Luminiscencia , Microscopía Electrónica de Rastreo , Nanopartículas/química , Nitratos , Reproducibilidad de los Resultados , Dispersión de Radiación , Difracción de Rayos X , Iterbio/química
9.
J BUON ; 23(4): 1174-1178, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30358228

RESUMEN

PURPOSE: Retinoblastoma is one of the lethal malignancies in children. Approximately half of the children that are diagnosed with retinoblastoma die of this disease. Enucleation is commonly used for the treatment of retinoblastoma but this leads to loss of vision. Therefore there is an urgent need to look for viable chemotherapeutic agents for the treatment of retinoblastoma. Consistent with this, natural products can produce efficient anticancer agents and in the present study a plant-derived phenylpropene methyl eugenol (ME) was evaluated against retinoblastoma RB355 cells. METHODS: The cytotoxic activity of this molecule was evaluated by MTT cell viability assay, while autophagic effects were evaluated by flow cytometry using acridine orange (AO)/monodansylcadaverine (AO/MDC) staining dyes. The effects on the cell cycle progression were analyzed by flow cytometry while the effects on mTOR/PI3K/Akt signalling pathway were assessed by western blot method. RESULTS: The results indicated that ME exhibited an IC50 value of 50 µM and exerted its cytotoxic effects in a dosedependent manner in RB355 cells. Moreover, it was observed that the ME lessens the cell viability and triggers G2/M cell cycle arrest. It was also observed that ME induced autophagy dose-dependently in retinoblastoma RB355 cells. Western blot analysis revealed that ME could modulate the mTOR/ PI3K/Akt signalling pathway in RB355 cells at the IC50 concentration. CONCLUSIONS: The above results clearly indicate that ME is a potent anticancer agent and may be developed further as a possible anticancer lead molecule against retinoblastoma provided further in depth in vivo studies are carried out.


Asunto(s)
Anticarcinógenos/uso terapéutico , Eugenol/análogos & derivados , Inhibidores de las Quinasa Fosfoinosítidos-3 , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Retinoblastoma/tratamiento farmacológico , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Anticarcinógenos/farmacología , Autofagia/efectos de los fármacos , Puntos de Control del Ciclo Celular/efectos de los fármacos , Eugenol/farmacología , Citometría de Flujo , Humanos , Pruebas de Sensibilidad Microbiana , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Retinoblastoma/metabolismo , Retinoblastoma/patología , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/metabolismo
10.
J Pharmacol Sci ; 137(3): 265-273, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30097377

RESUMEN

Mangiferin (MAN), a naturally occurring polyphenol commonly found in mango and papaya. However, little is known its anti-vascular injury effects and the underlying mechanisms. This paper investigated the anti-vascular injury effect of MAN and the mechanisms in high-fat diet (HFD)-induced C57BL/6J mice and oxidized low-density lipoprotein (ox-LDL) induced human umbilical vein endothelial cells (HUVECs). The levels of plasma lipid, inflammatory factors and nitric oxide (NO) in mice were evaluated. The expression levels of PI3K, AKT, eNOS, PTEN and their phosphorylated proteins were measured by western blots. In addition, the PTEN-siRNA HUVECs were also used. The result showed that MAN markedly decreased the plasma lipid, inflammatory level in HFD-induced vascular injury mice respectively. Furthermore, MAN alleviate ox-LDL-stimulated dysfunction of HUVECs, restored the diminished NO release, decreased the ROS generation, significantly increased the expression of p-Akt, p-eNOS, and decreased the expression of PTEN, but have no effect on PI3K. However, the protective effects of MAN were significantly reduced by co-treatment with PI3K inhibitor or abolished by eNOS inhibitor. In addition, MAN has no protective effect on ox-LDL induced PTEN-siRNA HUVECs injury. Collectively, MAN appeared to alleviate ox-LDL-stimulated dysfunction of HUVECs via the PTEN/Akt/eNOS signaling pathway, thus decrease vascular injury in HFD-administrated mice.


Asunto(s)
Dieta Alta en Grasa/efectos adversos , Expresión Génica/efectos de los fármacos , Expresión Génica/genética , Óxido Nítrico Sintasa de Tipo III/genética , Óxido Nítrico Sintasa de Tipo III/metabolismo , Fosfohidrolasa PTEN/genética , Fosfohidrolasa PTEN/metabolismo , Fitoterapia , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos , Enfermedades Vasculares/tratamiento farmacológico , Enfermedades Vasculares/genética , Xantonas/farmacología , Xantonas/uso terapéutico , Animales , Carica , Células Endoteliales de la Vena Umbilical Humana , Humanos , Mediadores de Inflamación/sangre , Lípidos/sangre , Lipoproteínas LDL/efectos adversos , Masculino , Mangifera , Ratones Endogámicos C57BL , Terapia Molecular Dirigida , Óxido Nítrico/sangre , Enfermedades Vasculares/sangre , Enfermedades Vasculares/etiología
11.
Neuroscience ; 379: 13-21, 2018 05 21.
Artículo en Inglés | MEDLINE | ID: mdl-29524639

RESUMEN

Previous studies have reported the essence of the sensory-based properties of human brain function, in which mental imagery is of great importance. In this study, we explored the association between the activities of two special regions, i.e., the primary visual area (PVA), which is the classically dominant sensory region, and the default mode network (DMN), which is the classical supra-sensory region, with a focus on their linkage in visual mental imagery. For this purpose, we collected fMRI data from 30 healthy participants (15 males; 22.37 ±â€¯2.52 years) during the resting state and a mental rotation task state. By using a critical time point analysis (CTPA), we investigated the association between the activities of the PVA and the DMN. As the results showed, there existed a PVA-related (i.e., prefrontal cortex, DMN, sensorimotor areas and medial temporal lobe (MTL)) and a DMN-related neural association pattern (i.e., PVA, prefrontal cortex and the MTL) in the human brain. Furthermore, the results showed the steady and tight intrinsic association between the activities of the PVA and the DMN, with the prefrontal cortex and the MTL regions being found to be consistently involved in the resting-state brain. It also was suggested that the observed association between the PVA and the DMN was highly reproducible for the mental rotation task. Together, these observations, from the perspective of visual mental imagery, provided experimental evidence for the robustness and stability of the detailed map of the associations between the activities of the PVA and the DMN.


Asunto(s)
Imaginación/fisiología , Corteza Visual/fisiología , Percepción Visual/fisiología , Mapeo Encefálico , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Vías Nerviosas/diagnóstico por imagen , Vías Nerviosas/fisiología , Descanso , Corteza Visual/diagnóstico por imagen , Adulto Joven
12.
Behav Brain Res ; 320: 233-243, 2017 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-28011171

RESUMEN

Neuroimaging studies have highlighted that intrinsic brain activity is modified to implement task demands. However, the relation between mental rotation and intrinsic brain activity remains unclear. To answer this question, we collected functional MRI (fMRI) data from 30 healthy participants in two mental rotation task periods (1st-task state, 2nd-task state) and two rest periods before (pre-task resting state) and after the task (post-task resting state) respectively. By combining the spatial independent component analysis (ICA) and voxel-wise functional connectivity strength (FCS), we identified FCS maps of 10 brain resting state networks (RSNs) within six different bands (i.e., 0-0.05, 0.05-0.1, 0.1-0.15, 0.15-0.2, 0.2-0.25, and 0.01-0.08Hz) corresponding to the four states for each subject. The maximum uncertainty linear discriminant analysis (MLDA) method showed that the FCS within the low frequency bandwidth of 0.05-0.1Hz could effectively classify the mental rotation task state from pre-/post-task resting states but failed to discriminate the pre- and post-task resting states. Discriminative FCSs were observed in the cognitive executive-control network (central executive and attention) and the imagery-based internal mental manipulation network (default mode, primary sensorimotor, and primary visual). Imagery manipulation is a stable mental element of mental rotation, and the involvement of executive control is dependent on the degree of task familiarity. Together, the present study provides evidence that mental rotation task specifically modifies intrinsic brain activity to complement cognitive demands, which provides further insight into the neural basis of mental rotation manipulation.


Asunto(s)
Mapeo Encefálico , Encéfalo/diagnóstico por imagen , Procesos Mentales/fisiología , Vías Nerviosas/diagnóstico por imagen , Rotación , Adulto , Atención/fisiología , Análisis Discriminante , Función Ejecutiva/fisiología , Femenino , Voluntarios Sanos , Humanos , Imagenología Tridimensional , Imagen por Resonancia Magnética , Masculino , Pruebas Neuropsicológicas , Oxígeno/sangre , Tiempo de Reacción/fisiología , Adulto Joven
13.
Zhongguo Zhen Jiu ; 35(10): 1005-9, 2015 Oct.
Artículo en Chino | MEDLINE | ID: mdl-26790206

RESUMEN

OBJECTIVE: To observe the impacts on pain matrix (PM) brain area in the patients of cervical spondylosis of neck type treated with acupuncture at single point and the multiple points. METHODS: Forty-nine patients of cervical spondylosis of neck type were randomized into a single-point group (25 cases) and a multiple-point group (24 cases), and treated with acupuncture at Bailao (EX-HN 15) singly or Bailao (EX-HN 15) and Hegu (LI 4) in combination correspondingly. At the same time, 19 healthy people were selected as a control group. The resting state functional magnetic resonance imaging (fMRI) was conducted in each group before and after treatment. The changes in the regional homogeneity (ReHo) of brain area PM were analyzed in terms of the different therapeutic programs. The relevant analysis was on the scores of the Northwick Park neck pain questionnaire (NPQ) and short form 36 questionnaire (SF-36) for life quality. RESULTS: Compared with the control group, ReHo value was increased in supplementary motor area (SMA) of PM in the patients, of cervical spondylosis of neck type. In the single-point group, after treatment, ReHo value was reduced in the bilateral medial superior frontal gyri of patients. In the multiple-point group, ReHo values were reduced in the left medial superior frontal gyrus and right SMA in PM area after treatment. In the single-point group, ReHo value in each brain area of PM was not significantly correlated with NPQ and SF-36 scores. In the multiple-point group, the changes of ReHo value in superior frontal gyrus were positively correlated with those of NPQ scores. CONCLUSION: Considering the clinical efficacy of acupunctrue for cervical spondylosis of neck type, the overall result in the multiple-point group is better than that in the single-point group. It is deduced that the advantages of the therapeutic program in the multiple-point group is relevant with the cooperative integration of the stimulation at multiple points in cerebral analgesic center.


Asunto(s)
Puntos de Acupuntura , Terapia por Acupuntura , Dolor de Cuello/terapia , Espondilosis/terapia , Adulto , Encéfalo/diagnóstico por imagen , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Dolor de Cuello/diagnóstico por imagen , Radiografía , Espondilosis/diagnóstico por imagen , Resultado del Tratamiento , Adulto Joven
14.
Acc Chem Res ; 47(8): 2282-90, 2014 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-24871269

RESUMEN

Traditionally, molecules are analyzed in a test tube. Taking biochemistry as an example, the majority of our knowledge about cellular content comes from analysis of fixed cells or tissue homogenates using tools such as immunoblotting and liquid chromatography-mass spectrometry. These tools can indicate the presence of molecules but do not provide information on their location or interaction with each other in real time, restricting our understanding of the functions of the molecule under study. For real-time imaging of labeled molecules in live cells, fluorescence microscopy is the tool of choice. Fluorescent labels, however, are too bulky for small molecules such as fatty acids, amino acids, and cholesterol. These challenges highlight a critical need for development of chemical imaging platforms that allow in situ or in vivo analysis of molecules. Vibrational spectroscopy based on spontaneous Raman scattering is widely used for label-free analysis of chemical content in cells and tissues. However, the Raman process is a weak effect, limiting its application for fast chemical imaging of a living system. With high imaging speed and 3D spatial resolution, coherent Raman scattering microscopy is enabling a new approach for real-time vibrational imaging of single cells in a living system. In most experiments, coherent Raman processes involve two excitation fields denoted as pump at ωp and Stokes at ωs. When the beating frequency between the pump and Stokes fields (ωp - ωs) is resonant with a Raman-active molecular vibration, four major coherent Raman scattering processes occur simultaneously, namely, coherent anti-Stokes Raman scattering (CARS) at (ωp - ωs) + ωp, coherent Stokes Raman scattering (CSRS) at ωs - (ωp - ωs), stimulated Raman gain (SRG) at ωs, and stimulated Raman loss (SRL) at ωp. In SRG, the Stokes beam experiences a gain in intensity, whereas in SRL, the pump beam experiences a loss. Both SRG and SRL belong to stimulated Raman scattering (SRS), in which the energy difference between the pump and Stokes fields is transferred to the molecule for vibrational excitation. The SRS signal appears at the same wavelengths as the excitation fields and is commonly extracted through a phase-sensitive detection scheme. The detected intensity change because of a Raman transition is proportional to Im[χ(3)]IpIs, where χ(3) represents the third-order nonlinear susceptibility, Ip and Is stand for the intensity of the pump and Stokes fields. In this Account, we discuss the most recent advances in the technical development and enabling applications of SRS microscopy. Compared to CARS, the SRS contrast is free of nonresonant background. Moreover, the SRS intensity is linearly proportional to the density of target molecules in focus. For single-frequency imaging, an SRS microscope offers a speed that is ∼1000 times faster than a line-scan Raman microscope and 10,000 times faster than a point-scan Raman microscope. It is important to emphasize that SRS and spontaneous Raman scattering are complementary to each other. Spontaneous Raman spectroscopy covers the entire window of molecular vibrations, which allows extraction of subtleties via multivariate analysis. SRS offers the speed advantage by focusing on either a single Raman band or a defined spectral window of target molecules. Integrating single-frequency SRS imaging and spontaneous Raman spectroscopy on a single platform allows quantitative compositional analysis of objects inside single live cells.


Asunto(s)
Microscopía , Espectrometría Raman , Animales , Células CHO , Cricetinae , Cricetulus , Células HeLa , Humanos , Análisis de los Mínimos Cuadrados , Hígado/patología , Ratones , Ácido Oleanólico/química , Ácido Palmítico/química , Análisis de Componente Principal , Piel/patología , Vibración
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