Neurophotonics最新文献

{"title":"Early changes in spatiotemporal dynamics of remapped circuits and global networks predict functional recovery after stroke in mice.","authors":"Ryan M Bowen, Jake Lee, Brendon Wang, Keith R Lohse, Hanyang Miao, Jonah A Padawer-Curry, Asher J Albertson, Eric C Landsness, Adam Q Bauer, Jin-Moo Lee","doi":"10.1117/1.NPh.12.S1.S14604","DOIUrl":"10.1117/1.NPh.12.S1.S14604","url":null,"abstract":"<p><strong>Significance: </strong>Stroke is the leading cause of chronic disability in the United States. How stroke size affects post-stroke repair and recovery is poorly understood.</p><p><strong>Aim: </strong>We aim to investigate the effects of stroke size on early repair patterns and determine how early changes in neuronal circuits and networks predict functional outcomes after stroke.</p><p><strong>Approach: </strong>We used wide-field optical imaging, photothrombosis, and the cylinder-rearing assay to examine changes in neuronal circuit and network activity in the context of functional recovery after stroke.</p><p><strong>Results: </strong>Larger strokes ablating <math><mrow><mi>S</mi> <msub><mrow><mn>1</mn></mrow> <mrow><mi>FP</mi></mrow> </msub> </mrow> </math> caused diffuse and widespread forepaw stimulus-evoked cortical activation, including contralesional regions evolving within 4 weeks post-stroke; smaller strokes resulted in more focused ipsilesional activation. Larger strokes decreased neuronal fidelity and bilateral coherence during stimulation of either the affected or unaffected forepaw within this 4-week period. Mice in the larger lesion group demonstrated hyperconnectivity within the contralesional hemisphere at the resting state. Greater degrees of remapping diffusivity, neuronal fidelity degradation, and hyperconnectivity predicted worse 8-week recovery after statistically controlling for the effect of infarct size.</p><p><strong>Conclusions: </strong>These results suggest that diffuse patterns of remapping, and desynchronization and hyperconnectivity of cortical networks, evolving early after stroke may reflect maladaptive plasticity, predicting poor long-term functional recovery.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 Suppl 1","pages":"S14604"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11661640/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142878434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting equivalent optical properties for cerebrospinal fluid to improve diffusion-based modeling accuracy in the brain.","authors":"Aiden Vincent Lewis, Qianqian Fang","doi":"10.1117/1.NPh.12.1.015009","DOIUrl":"10.1117/1.NPh.12.1.015009","url":null,"abstract":"<p><strong>Significance: </strong>The diffusion approximation (DA) is used in functional near-infrared spectroscopy (fNIRS) studies despite its known limitations due to the presence of cerebrospinal fluid (CSF). Many of these studies rely on a set of empirical CSF optical properties, recommended by a previous simulation study, that were not selected for the purpose of minimizing DA modeling errors.</p><p><strong>Aim: </strong>We aim to directly quantify the accuracy of DA solutions in brain models by comparing those with the gold-standard solutions produced by the mesh-based Monte Carlo (MMC), based on which we derive updated recommendations.</p><p><strong>Approach: </strong>For both a five-layer head and Colin27 atlas models, we obtain DA solutions by independently sweeping the CSF absorption ( <math> <mrow><msub><mi>μ</mi> <mi>a</mi></msub> </mrow> </math> ) and reduced scattering ( <math> <mrow> <msub><mrow><mi>μ</mi></mrow> <mrow> <msup><mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msup> </mrow> </msub> </mrow> </math> ) coefficients. Using an MMC solution with literature CSF optical properties as a reference, we compute the errors for surface fluence, total brain sensitivity, and brain energy deposition, and identify the optimized settings where such error is minimized.</p><p><strong>Results: </strong>Our results suggest that previously recommended CSF properties can cause significant errors (8.7% to 52%) in multiple tested metrics. By simultaneously sweeping <math> <mrow><msub><mi>μ</mi> <mi>a</mi></msub> </mrow> </math> and <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> </mrow> </math> , we can identify infinite numbers of solutions that can exactly match DA with MMC solutions for any single tested metric. Furthermore, it is also possible to simultaneously minimize multiple metrics at multiple source/detector separations, leading to our updated recommendation of setting <math> <mrow> <msubsup><mrow><mi>μ</mi></mrow> <mrow><mi>s</mi></mrow> <mrow><mo>'</mo></mrow> </msubsup> <mo>=</mo> <mn>0.15</mn> <mtext>  </mtext> <msup><mrow><mi>mm</mi></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msup> </mrow> </math> while maintaining physiological <math> <mrow><msub><mi>μ</mi> <mi>a</mi></msub> </mrow> </math> for CSF in DA simulations.</p><p><strong>Conclusions: </strong>Our updated recommendation of CSF equivalent optical properties can greatly reduce the model mismatches between DA and MMC solutions at multiple metrics without sacrificing computational speed. We also show that it is possible to eliminate such a mismatch for a single or a pair of metrics of interest.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015009"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11828630/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143433727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Zika virus encephalitis causes transient reduction of functional cortical connectivity.","authors":"Shannon C Agner, Lindsey M Brier, Jeremy D Hill, Ethan Y Liu, Annie Bice, Rachel M Rahn, Shengxuan Chen, Joseph P Culver, Robyn S Klein","doi":"10.1117/1.NPh.12.S1.S14603","DOIUrl":"10.1117/1.NPh.12.S1.S14603","url":null,"abstract":"<p><strong>Significance: </strong>Determining the long-term cognitive impact of infections is clinically challenging. Using functional cortical connectivity, we demonstrate that interhemispheric cortical connectivity is decreased in individuals with acute Zika virus (ZIKV) encephalitis. This correlates with decreased presynaptic terminals in the somatosensory cortex. During recovery from ZIKV infection, presynaptic terminals recover, which is associated with recovered interhemispheric connectivity. This supports the contribution of synapses in the cortex to functional networks in the brain, which can be detected by widefield optical imaging. Although myeloid cell and astrocyte numbers are still increased during recovery, RNA transcription of multiple proinflammatory cytokines that increase during acute infection decreases to levels comparable to mock-infected mice during recovery. These findings also suggest that the immune response and cytokine-mediated neuroinflammation play significant roles in the integrity of brain networks during and after viral encephalitis.</p><p><strong>Aim: </strong>We hypothesized that widefield optical imaging would allow us to assess functional cortical network disruption by ZIKV, including hippocampal-cortical networks.</p><p><strong>Approach: </strong>We use widefield optical imaging to measure cortical functional connectivity (FC) in mice during acute infection with, and recovery from, intracranial infection with a mouse-adapted strain of ZIKV.</p><p><strong>Results: </strong>Acute ZIKV infection leads to high levels of myeloid cell activation, with loss of neurons and presynaptic termini in the cerebral cortex and associated loss of FC primarily within the somatosensory cortex. During recovery, neuron numbers, synapses, and FC recover to levels near those of healthy mice. However, hippocampal injury and impaired spatial cognition persist. The magnitude of activated myeloid cells during acute infection predicted both recovery of synapses and the degree of FC recovery after recovery from ZIKV infection.</p><p><strong>Conclusions: </strong>These findings suggest that a robust inflammatory response may contribute to the health of functional brain networks after recovery from infection.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 Suppl 1","pages":"S14603"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11603678/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142752353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intra-subject test-retest reliability for auditory-evoked functional near-infrared spectroscopy responses: effects of systemic physiology correction.","authors":"Victoria C Sinfield, Dalton Aaker, Abigail Metzger, Yunjie Tong, Maureen J Shader","doi":"10.1117/1.NPh.12.1.015015","DOIUrl":"10.1117/1.NPh.12.1.015015","url":null,"abstract":"<p><strong>Significance: </strong>Functional near-infrared spectroscopy (fNIRS) is a valuable neuroimaging tool for non-invasively measuring hemodynamic changes in response to neural activity, particularly in auditory research. Although fNIRS shows strong test-retest reliability at the group level, individual-subject level reliability is often compromised by systemic noise.</p><p><strong>Aim: </strong>We investigate how correcting for systemic-physiological signals affects reliability in single-subject fNIRS data.</p><p><strong>Approach: </strong>fNIRS data were collected from one participant over 10 sessions during a passive auditory task. Using general linear modeling, six correction approaches were compared: no correction, physiology correction, short-channel correction, short-channel + physiology correction, short-channel + physiology + lag correction, and short-channel + tCCA correction.</p><p><strong>Results: </strong>Intraclass correlation coefficient analysis revealed that physiology correction yielded the highest test-retest reliability score, whereas short-channel correction had the lowest. These results align with previous findings suggesting that global systemic artifacts bolster reliability, and regressing such artifacts enhances the clarity of the observed neuronal response, as supported by visual comparisons of raw and denoised signals.</p><p><strong>Conclusions: </strong>We highlight the impact of correcting for extra-cerebral signals in single-subject auditory research and demonstrate that, while incorporating short channels in fNIRS data collection may reduce reliability, it offers a more accurate representation of the neuronal response.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015015"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11924667/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143671858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Site- and electroencephalogram-frequency-specific effects of 800-nm prefrontal transcranial photobiomodulation on electroencephalogram global network topology in young adults.","authors":"Shu Kang, Lin Li, Sadra Shahdadian, Anqi Wu, Hanli Liu","doi":"10.1117/1.NPh.12.1.015011","DOIUrl":"10.1117/1.NPh.12.1.015011","url":null,"abstract":"<p><strong>Significance: </strong>Transcranial photobiomodulation (tPBM) is an optical intervention that effectively enhances human cognition. However, limited studies have reported the effects of tPBM on electrophysiological brain networks.</p><p><strong>Aim: </strong>We aimed to investigate the site- and electroencephalogram (EEG)-frequency-specific effects of 800-nm prefrontal tPBM on the EEG global network topology of the human brain, so a better understanding of how tPBM alters EEG brain networks can be achieved.</p><p><strong>Approach: </strong>A total of 26 healthy young adults participated in the study, with multiple visits when either active or sham tPBM interventions were delivered to either the left or right forehead. A 19-channel EEG cap recorded the time series before and after the 8-min tPBM/sham. We used graph theory analysis (GTA) and formulated adjacency matrices in five frequency bands, followed by quantification of normalized changes in GTA-based global topographical metrics induced by the respective left and right tPBM/sham interventions.</p><p><strong>Results: </strong>Statistical analysis indicated that the effects of 800-nm prefrontal tPBM on the EEG global topological networks are both site- and EEG-frequency-dependent. Specifically, our results demonstrated that the left 800-nm tPBM primarily enhanced the alpha network efficiency and information transmission, whereas the right 800-nm tPBM augmented the clustering ability of the EEG topological networks and improved the formation of small-worldness of the beta waves across the entire brain.</p><p><strong>Conclusions: </strong>The study concluded that 800-nm prefrontal tPBM can enhance global connectivity patterns and information transmission in the human brain, with effects that are site- and EEG-frequency-specific. To further confirm and better understand these findings, future research should correlate post-tPBM cognitive assessments with EEG network analysis.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015011"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11866628/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143525168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Low-cost physiology and behavioral monitor for intravital imaging in small mammals.","authors":"Yuntao Li, Alfredo Cardenas-Rivera, Chang Liu, Zhengyi Lu, Jaime Anton, Mohammed Alfadhel, Mohammad A Yaseen","doi":"10.1117/1.NPh.12.1.015004","DOIUrl":"10.1117/1.NPh.12.1.015004","url":null,"abstract":"<p><strong>Significance: </strong>Functional brain imaging experiments in awake animals require meticulous monitoring of animal behavior to screen for spontaneous behavioral events. Although these events occur naturally, they can alter cell signaling and hemodynamic activity in the brain and confound functional brain imaging measurements.</p><p><strong>Aim: </strong>We developed a centralized, user-friendly, and stand-alone platform that includes an animal fixation frame, compact peripheral sensors, and a portable data acquisition system. The affordable, integrated platform can benefit imaging experiments by monitoring animal behavior for motion detection and alertness levels as complementary readouts for brain activity measurements.</p><p><strong>Approach: </strong>A custom acquisition system was designed using a powerful, inexpensive microcomputer. We customized an accelerometer and miniature camera modules for efficient, real-time monitoring of animal motion detection and pupil diameter. We then tested and validated the platform's performance with optical intrinsic signal imaging and GCaMP fluorescence calcium imaging in functional activation experiments in awake mice.</p><p><strong>Results: </strong>The integrated platform shows promise for detecting spontaneous motion and pupil dilation while imaging. Stimulus-induced pupil dilation was found to initiate earlier than cortical hemodynamics with a slower rise time. Compared with neuronal calcium response, stimulus-induced pupil dilation initiated later with a slower rise time.</p><p><strong>Conclusions: </strong>We developed an integrated platform to monitor animal motion and pupil dynamics. The device can be easily coupled and synchronized with optical brain imaging systems to monitor behavior, alertness, and spontaneous motion for awake animal studies.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015004"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11759666/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143048578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiplexed fiber meta-tip-based circular polarimetry for label-free pathological analysis of ischemic stroke.","authors":"Wenlin Luan, Qingcheng Song, Quancheng Cheng, Chunhua Chen, Xia Yu","doi":"10.1117/1.NPh.12.1.015012","DOIUrl":"10.1117/1.NPh.12.1.015012","url":null,"abstract":"<p><strong>Significance: </strong>We present an optical technology for a full-process label-free method for brain slice screening. This proposed multiplexed circular polarimetric method has the advantages of simple operation and high accuracy which may provide easily accessible evidence for the future diagnosis of related diseases.</p><p><strong>Aim: </strong>One of its missions is to provide a quantifiable, reproducible analysis methodology that can replace or supplement traditional qualitative, subjective pathological analysis.</p><p><strong>Approach: </strong>A label-free, sensitive, and rapid circular polarimetric method based on a multiplexed optical fiber meta-tip is proposed for the digital pathology of ischemic stroke. Polarization information of forward-scattered light is used to identify pathological variations of axon distribution in ischemic stroke tissues. The newly designed optical fiber meta-tip with four channels offers miniature illumination in the multiplexed circular polarimetry method.</p><p><strong>Results: </strong>Our automated approach achieves more than 90% area under the curve in classifying ischemic stroke brain tissue in around 1 min.</p><p><strong>Conclusions: </strong>The high-sensitivity and label-free circular polarimetric method based on the multiplexed optical fiber meta-tip renders its potential for rapid digital pathology of various diseases. It will empower the application of digital pathology in future disease diagnosis by quantitatively introducing a new reliable data modality without altering currently established processes.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015012"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11888776/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143588121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced spectral resolution and reduced acquisition time in fiber-based wavelength-swept source Raman spectroscopy.","authors":"Elahe Parham, Maxime Tousignant-Tremblay, Mireille Quémener, Martin Parent, Daniel C Côté","doi":"10.1117/1.NPh.12.1.015014","DOIUrl":"10.1117/1.NPh.12.1.015014","url":null,"abstract":"<p><strong>Significance: </strong>We introduce a fast Raman spectroscopy (SSRS) system that reduces acquisition time and enhances data quality, providing a breakthrough in SSRS for real-time applications. We demonstrate its utility in differentiating brain tissue regions based on lipid and protein content.</p><p><strong>Aim: </strong>Our primary goal was to develop a fast SSRS system that enables rapid data acquisition for <i>in vivo</i> applications. We aimed to investigate its effectiveness in differentiating brain tissue types by analyzing lipid and protein content, ultimately enhancing classification accuracy and supporting advancements in medical diagnostics.</p><p><strong>Approach: </strong>We implemented an optimized circuit and signal processing technique to reduce high-frequency noise and improve signal-to-noise ratio. Brain tissue measurements were validated against staining models, and classification accuracy was tested with principal component analysis (PCA) and support vector machine (SVM).</p><p><strong>Results: </strong>Our SSRS system captures spectra in 1 s which is significantly faster than similar systems. This rapid method enables real-time monitoring and accurate classification of brain regions based on lipid-protein content, confirmed by neurofilament and Nissl staining correlations ( <math> <mrow> <msup><mrow><mi>R</mi></mrow> <mrow><mn>2</mn></mrow> </msup> <mo>=</mo> <mn>0.75</mn></mrow> </math> and 0.55, respectively). Tissue classification showed 80.20% accuracy using spectral intensity at the wavenumbers associated with C-H, <math> <mrow><msub><mi>CH</mi> <mn>3</mn></msub> </mrow> </math> , and <math> <mrow><msub><mi>CH</mi> <mn>2</mn></msub> </mrow> </math> vibrations and 81.23% accuracy using PCA-derived features (PC1, PC2, and PC3).</p><p><strong>Conclusions: </strong>The fast-SSRS system marks a significant advance in Raman spectroscopy, improving speed and data quality. Our setup captures finer spectral details, facilitating reliable differentiation of tissue types, as verified by staining methods and PCA. This method shows promise for real-time tissue analysis and medical diagnostics, outperforming traditional Raman techniques in speed and data throughput.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015014"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11905921/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143626098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarization optical coherence tomography optoretinography: verifying light-induced photoreceptor outer segment shrinkage and subretinal space expansion.","authors":"Shaiban Ahmed, Taeyoon Son, Guangying Ma, Xincheng Yao","doi":"10.1117/1.NPh.12.1.015005","DOIUrl":"10.1117/1.NPh.12.1.015005","url":null,"abstract":"<p><strong>Significance: </strong>Stimulus-evoked intrinsic optical signal (IOS) changes in retinal photoreceptors are critical for functional optoretinography (ORG). Optical coherence tomography (OCT), with its depth-resolved imaging capability, has been actively explored for IOS imaging of retinal photoreceptors. However, recent OCT studies have reported conflicting results regarding light-induced changes in the photoreceptor outer segments (OSs), with both elongation and shrinkage being observed. These discrepancies may stem from the difficulty in reliably identifying OS boundaries, particularly the inner segment/outer segment (IS/OS) junction and OS tip, as well as potential confusion with subretinal space dynamics. Gaining a better understanding of these light-induced OS changes is essential for accurate interpretation of ORG measurements and for optimizing IOS imaging systems to enhance sensitivity.</p><p><strong>Aim: </strong>We aim to develop a method for the reliable identification of OS boundaries and to verify light-induced photoreceptor OS shrinkage and subretinal space expansion.</p><p><strong>Approach: </strong>We employed a polarization-resolved full-field swept-source optical coherence tomography system capable of sequentially capturing parallel-polarization and cross-polarization OCT signals. The parallel-polarization mode is optimized to detect ballistically reflected photons from well-defined retinal boundaries, such as the IS/OS junction and the photoreceptor tips, whereas cross-polarization primarily captures multiply scattered photons. This differentiation enables parallel-polarization OCT to minimize the interference from scattered photons, enhancing the precision of OCT band quantification.</p><p><strong>Results: </strong>Parallel-polarization OCT revealed photoreceptor OS shrinkage and subretinal space expansion in light conditions compared with dark conditions. Moreover, the overall outer retinal length appeared to swell under light. These observations were consistently confirmed in four healthy adult human subjects.</p><p><strong>Conclusions: </strong>Parallel-polarization OCT provides a reliable method for identifying the IS/OS junction and OS tip, confirming light-induced photoreceptor OS shrinkage and subretinal space expansion.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 1","pages":"015005"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11770343/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143054150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Semi-automated analysis of cerebral capillary red blood cell velocities allows modeling of transit time distribution after experimental subarachnoid hemorrhage in mice.","authors":"Kévin Chalard, Yan Chastagnier, Julie Perroy, Vivien Szabo","doi":"10.1117/1.NPh.12.S1.S14612","DOIUrl":"10.1117/1.NPh.12.S1.S14612","url":null,"abstract":"<p><strong>Significance: </strong>Microvascular dysfunction stems from the origin of various neurological diseases. Among these, delayed cerebral ischemia following subarachnoid hemorrhage (SAH) is a major complication. Even though pathogenesis remains poorly understood, hypotheses converge toward early and persistent microvascular dysfunction. In this context, mathematical models have been developed to study oxygen delivery using theoretical distributions of capillary flux. However, these distributions lack experimental validation.</p><p><strong>Aim: </strong>We propose experimental recording of capillary red blood cell (RBC) velocities in a superficial cortical microvascular network in a mouse model of SAH, testing theoretical transit time distributions and their implications on tissue oxygenation.</p><p><strong>Approach: </strong>We performed optical recording of RBC velocities. We propose a complete software, available on GitHub, for velocity semi-automated measurement. Experimental data were fitted with Gamma and Cauchy probability distribution functions (PDFs). Corresponding maximal oxygen metabolic rates ( <math> <mrow><msubsup><mi>CMRO</mi> <mn>2</mn> <mi>max</mi></msubsup> </mrow> </math> ) were computed.</p><p><strong>Results: </strong>Data showed that transit time distributions changed after SAH, such that they followed a Cauchy distribution. Corresponding <math> <mrow><msubsup><mi>CMRO</mi> <mn>2</mn> <mi>max</mi></msubsup> </mrow> </math> maps showed a malignant capillary heterogeneity state.</p><p><strong>Conclusions: </strong>We provide distributions of transit times in an SAH mouse model, allowing us to discuss PDF implications for maximal oxygen consumption.</p>","PeriodicalId":54335,"journal":{"name":"Neurophotonics","volume":"12 Suppl 1","pages":"S14612"},"PeriodicalIF":4.8,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12081204/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144095857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}