Optical Tools Research Articles

Urban-Rural Disparities in Community Participation after Spinal Cord Injury in Ontario.

Personal, social, and environmental factors may influence self-efficacy and social reintegration among people living with spinal cord injury or disease (SCI/D) in urban and rural areas. Novel data collection methods have the potential to characterize community participation (CP) in diverse settings. The objectives were (1) to describe and compare self-reported community participation (Reintegration to Normal Living Index (RNLI) and Moorong Self-Efficacy Scale (MSES)) levels of individuals with SCI/D living in urban or rural Ontario, Canada; and (2) to determine the accuracy of an artificial intelligence (AI) optical mark recognition tool for extracting data from CP surveys conducted among participants after transitioning from inpatient rehabilitation to home and residing in the community. We partnered with SCI Ontario staff to collect MSES and RNLI survey data from adults with motor complete (e.g., AIS A-B) and incomplete (AIS C-D) SCI/D living in urban or rural Ontario, Canada, between January and October 2022. The Rurality Index of Ontario (RIO) from the postal code determined urban or rural residency. Optical mark recognition (OMR) software was used for survey data extraction. A Research Associate validated the extracted survey responses. Descriptive statistics, correlation analysis, and non-parametric statistics were used to describe the participants, their impairments, and their reported CP levels across urban and rural settings. Eighty-five individuals with SCI/D (mean age 53.7 years, 36.5% female) completed the survey. Most of the participants resided in major urban areas (69.4%) and had traumatic injuries (64.7%). The mean total MSES score for Ontarians with SCI/D was 87.96 (95% confidence interval [CI]: 84.45, 91.47), while the mean total RNLI score for the same individuals was 75.61 (95% CI: 71.85, 79.37). Among the MSES domains, the lowest score was observed in response to sexual satisfaction (mean: 4.012, 95% CI: 3.527, 4.497), while the lowest RNLI domain item score was associated with the ability to travel out of town (mean: 5.965, 95% CI: 5.252, 6.678). Individuals with incomplete injuries in rural areas reported lower MSES and RNLI scores than those with complete motor injuries, whereas no significant differences were found in MSES and RNLI scores among urban residents based on impairment. These findings suggest that, depending on the environmental context (e.g., rural vs. urban areas), AIS categories may influence the perception of CP among people living with SCI/D. The OMR tool had 97.4% accuracy in extracting data from the surveys. The CP (MSES and RNLI) scores reported by individuals with SCI/D differ based on their living setting. In rural Ontario, individuals with greater functional ability reported lower CP than their counterparts living in urban settings. Although CP remains a challenge, the needs of individuals with motor incomplete SCI/D and heterogeneous levels of mobility residing in rural areas require exploration and targeted interventions. The OMR tool facilitates accurate data extraction from surveys across settings.

Development of a 3D Printed Flow Cell for Application as an In-line Optical Particle Analysis Tool

Development of a 3D Printed Flow Cell for Application as an In-line Optical Particle Analysis Tool

In vivo volumetric analysis of retinal vascular hemodynamics in mice with spatio-temporal optical coherence tomography.

Microcirculation and neurovascular coupling are important parameters to study in neurological and neuro-ophthalmic conditions. As the retina shares many similarities with the cerebral cortex and is optically accessible, a special focus is directed to assessing the chorioretinal structure, microvasculature, and hemodynamics of mice, a vital animal model for vision and neuroscience research. We aim to introduce an optical imaging tool enabling in vivo volumetric mouse retinal monitoring of vascular hemodynamics with high temporal resolution. We translated the spatio-temporal optical coherence tomography (STOC-T) technique into the field of small animal imaging by designing a new optical system that could compensate for the mouse eye refractive error. We also developed post-processing algorithms, notably for the assessment of (i) localized hemodynamics from the analysis of pulse wave-induced Doppler artifact modulation and (ii) retinal tissue displacement from phase-sensitive measurements. We acquired high-quality, in vivo volumetric mouse retina images at a rate of 113Hz over a lateral field of view of . We presented high-resolution en face images of the retinal and choroidal structure and microvasculature from various layers, after digital aberration correction. We were able to measure the pulse wave velocity in capillaries of the outer plexiform layer with a mean speed of 0.35mm/s and identified venous and arterial pulsation frequency and phase delay. We quantified the modulation amplitudes of tissue displacement near major vessels (with peaks of 150nm), potentially carrying information about the biomechanical properties of the retinal layers involved. Last, we identified the delays between retinal displacements due to the passing of venous and arterial pulse waves. The developed STOC-T system provides insights into the hemodynamics of the mouse retina and choroid that could be beneficial in the study of neurovascular coupling and vasculature and flow speed anomalies in neurological and neuro-ophthalmic conditions.

Technical Strategies and Learning Curve in Robotic-assisted Peripheral Nerve Surgery.

Robotic-assisted peripheral nerve surgery (RASPN) has emerged as a promising advancement in microsurgery, offering enhanced precision and tremor reduction for nerve coaptations. This study investigated the largest published patient collective in RASPN and provided specific technical aspects, operative setups, and a learning curve. Data collection involved creating a prospective database that recorded surgical details such as surgery type, duration, nerve coaptation time, and number of stitches. The experienced surgeon first underwent a 12-hour training program utilizing the Symani robot system in combination with optical magnification tools before using the system clinically. The study included 19 patients who underwent robot-assisted peripheral nerve reconstruction. The cohort included six men (31.6%) and 13 women (68.4%), with an average age of 53.8 ± 18.4 years. The procedures included nerve transfers, targeted muscle reinnervation, neurotized free flaps, and autologous nerve grafts. Learning curve analysis revealed no significant reduction in time per stitch over the initial nine coaptations (4.9 ± 0.5 min) compared with the last 10 coaptations (5.5 ± 1.5 min). The learning curve for RASPN was compared with early experiences with other surgical robots, emphasizing the importance of surgical proficiency and assistant training. Obstacles such as instrument grip strength and blood clot formation were highlighted, and suggestions for future advancements were proposed. RASPN presents an exciting opportunity to enhance precision; however, ongoing research and optimization are necessary to fully harness its benefits.

All-Optical Trapping and Programmable Transport of Gold Nanorods with Simultaneous Orientation and Spinning Control.

Gold nanorods (GNRs) are of special interest in nanotechnology and biomedical applications due to their biocompatibility, anisotropic shape, enhanced surface area, and tunable optical properties. The use of GNRs, for example, as sensors and mechanical actuators, relies on the ability to remotely control their orientation as well as their translational and rotational motion, whether individually or in groups. Achieving such particle control by using optical tools is challenging and exceeds the capabilities of conventional laser tweezers. We present a tool that addresses this complex manipulation problem by using a curve-shaped laser trap, enabling the optical capture and programmable transport of single and multiple GNRs along any trajectory. This type of laser trap combines confinement and propulsion optical forces with optical torque to transport the GNRs while simultaneously controlling their rotation (spinning) and orientation. The proposed system facilitates the light-driven control of GNRs and the quantitative characterization of their motion dynamics including transport speed, spinning frequency, orientation, and confinement strength. We experimentally demonstrate that remote control of the GNRs can be achieved both near a substrate surface (2D trapping) and deep within the sample (3D all-optical trapping). The motion dynamics of two sets of off-resonant GNRs, possessing similar aspect ratios but different resonance wavelengths, are analyzed to highlight the role played by their optical and mechanical properties in the optical manipulation process. The experimental results are supported by a theoretical model describing the observed motion dynamics of the GNRs. This optical manipulation tool can significantly facilitate applications of light-driven nanorods.

Glycoconjugate coumarins exploiting metabolism-enhanced fluorescence and preferential uptake: New optical tools for tumor cell staining

The possibility to visually discriminate cells based on their metabolism and capability to uptake exogenous molecules is an important topic with exciting fallback on translational and precision medicine. To this end, probes that combine several complementary features are necessary. The ideal probe is selectively uptaken and activated in tumor cells compared with control ones and is not fluorescent in the extracellular medium. Fluorogenic compounds that combine enzyme-activated pH sensitivity and good cell uptake can be an ideal solution, provided that the sensed enzymes are dysregulated in tumor cells. Here, we present synthesis and in vitro evaluation of a new class of glyco-coumarin based probes that merge all these features. These probes show uptake ratio in tumor vs. control cells up to 3:1, with a cell to background ratio upon administration of the probe up to 5:1. These features make this new family of fluorogenic targeted probes a promising tool in life science.

Optical fiber SPR probe platform combined with oriented antibody optimized modification for ultrasensitive and portable detection of human thyroglobulin

Thyroglobulin (Tg) is an essential indicator for monitoring differentiated thyroid cancer. However, there are still significant challenges in achieving fast, accurate, and efficient point-of-care testing (POCT). This paper presented an optical fiber bioprobe platform technology based on the ultrasensitive sensing principle of surface plasmon resonance (SPR), aiming to achieve an efficient and precise immunoassay of Tg. The fiber probes were modified with Tg antibodies to form fiber Tg probes. After optimization of the oriented antibody modification, the detection sensitivity of fiber Tg probes increased by 3 times, facilitating one-step direct detection of μg-level sample concentrations such as thyroid tissue fluid samples. For ng-level sample concentrations such as blood samples, a two-step measurement method was used to amplify the surface load signal. Through Tg detection studies in different concentration ranges and background environments, our fiber Tg probes exhibited a sensitivity of 81.99 pm / (ng / mL) and a limit of detection of 1.4 ng / mL, and were able to complete ng-level detection in serum backgrounds. The fiber Tg probe holds immense potential in the diagnosis and postoperative monitoring of thyroid cancer. Additionally, being a miniature, disposable, reliable, and portable quantitative optical immunoassay tool, it can serve as a rapid detection instrument for various target proteins and pathogens by simply altering the modified antibody.

A novel super-resolution microscopy platform for cutaneous alpha-synuclein detection in Parkinson's disease.

Alpha-synuclein (aSyn) aggregates in the central nervous system are the main pathological hallmark of Parkinson's disease (PD). ASyn aggregates have also been detected in many peripheral tissues, including the skin, thus providing a novel and accessible target tissue for the detection of PD pathology. Still, a well-established validated quantitative biomarker for early diagnosis of PD that also allows for tracking of disease progression remains lacking. The main goal of this research was to characterize aSyn aggregates in skin biopsies as a comparative and quantitative measure for PD pathology. Using direct stochastic optical reconstruction microscopy (dSTORM) and computational tools, we imaged total and phosphorylated-aSyn at the single molecule level in sweat glands and nerve bundles of skin biopsies from healthy controls (HCs) and PD patients. We developed a user-friendly analysis platform that offers a comprehensive toolkit for researchers that combines analysis algorithms and applies a series of cluster analysis algorithms (i.e., DBSCAN and FOCAL) onto dSTORM images. Using this platform, we found a significant decrease in the ratio of the numbers of neuronal marker molecules to phosphorylated-aSyn molecules, suggesting the existence of damaged nerve cells in fibers highly enriched with phosphorylated-aSyn molecules. Furthermore, our analysis found a higher number of aSyn aggregates in PD subjects than in HC subjects, with differences in aggregate size, density, and number of molecules per aggregate. On average, aSyn aggregate radii ranged between 40 and 200 nm and presented an average density of 0.001-0.1 molecules/nm2. Our dSTORM analysis thus highlights the potential of our platform for identifying quantitative characteristics of aSyn distribution in skin biopsies not previously described for PD patients while offering valuable insight into PD pathology by elucidating patient aSyn aggregation status.

Thermographic study of freezing water drops: An insight on Mpemba effect

Despite decades of research, the Mpemba Effect challenges scientists, prompting further investigation and refinement of existing hypotheses. This work uses optical tools such as thermography to analyze and study the Mpemba effect on drops. We analyze times and contact angle changes with temperature with an easily controlled experiment. This work contributes to the ongoing discourse surrounding the Mpemba Effect, emphasizing the need for interdisciplinary collaboration and experimental rigor to unravel the complexities of this intriguing phenomenon. A deeper understanding of the Mpemba Effect enhances our knowledge of thermodynamics and fluid dynamics and opens avenues for practical applications in fields such as cryopreservation, meteorology, and materials science.

Development of a hybrid rhodamine-hydrazine NIR fluorescent probe for sensitive detection and imaging of peroxynitrite in necrotizing enterocolitis model

This study describes the synthesis and characterization of a novel near-infrared (NIR) fluorescent probe RBNE based on a hybrid rhodamine dye, which shows excellent optical capability for detecting and imaging ONOO− in necrotizing enterocolitis (NEC) mouse model. The probe RBNE undergoes hydrazine redox-process, and subsequently the spirocyclic structure’s opening, resulting in a turn-on fluorescence emission with the presence of ONOO−, which exhibits several excellent features, including a significant Stokes shift of 108 nm, near-infrared emission at 668 nm, a lower detection limit of 56 nM, low cytotoxicity, and excellent imaging ability for ONOO− both in vitro and in vivo. The presented study introduces a novel optical tool that has the potential to significantly advance our understanding of peroxynitrite (ONOO−) behaviors in necrotizing enterocolitis (NEC).

(Nanocarbons Division Poster Award, Third Place) Development of an Optical Probe for the Detection of Steroid Hormones

Hormones play major roles in several biological processes. Steroid hormones are crucial for reproductive maturation in women. Abnormal steroid hormones (e.g., estrogen) levels have several pathological conditions, including ovarian failure, bone loss, or increased risk for breast cancer. Thus, accurate and precise detection of steroid hormone levels is crucial for timely health interventions. The current gold standard for steroid hormone detection is immunoassays. Optical measurement technologies are promising alternatives to traditional immunoassays. Optical tools could provide a novel platform for direct, sensitive, and specific measurements of target analytes. Due to their non-photobleaching near-infrared fluorescence, high optical sensitivity, high stability, and sizes within the nanoscale, photoluminescent single-walled carbon nanotubes have great potential for a rapid, sensitive, and specific detection. Here, we investigate an optical biosensor fabricated with SWCNT for hormone detection in biofluids.

Near Infrared Nanosensors Enable Optical Imaging of Oxytocin with Selectivity over Vasopressin in Acute Mouse Brain Slices

Oxytocin plays a critical role in regulating social behaviors, yet our understanding of its function in both neurological health and disease remains incomplete. Real-time oxytocin imaging probes with spatiotemporal resolution relevant to its endogenous signaling are required to fully elucidate oxytocin’s role in the brain. Herein, we describe a near-infrared oxytocin nanosensor (nIROXT), a synthetic probe capable of imaging oxytocin in the brain without interference from its structural analogue, vasopressin. nIROXT leverages the inherent tissue-transparent fluorescence of single-walled carbon nanotubes (SWCNT) and the molecular recognition capacity of an oxytocin receptor peptide fragment (OXTp) to selectively and reversibly image oxytocin. We employ these nanosensors to monitor electrically stimulated oxytocin release in brain tissue, revealing oxytocin release sites with a median size of 3 µm in the paraventricular nucleus (PVN) of C57BL/6 mice, which putatively represents the spatial diffusion of oxytocin from its point of release. These data demonstrate that covalent SWCNT constructs, such as nIROXT, are powerful optical tools that can be leveraged to measure neuropeptide release in brain tissue.

Anisotropic Third Harmonic Generation in 2D Tin Sulfide

AbstractThe in‐plane anisotropic properties of 2D group IV monochalcogenides offer an additional degree of freedom which can be advantageous in optoelectronic applications. Here, it is demonstrated that the third harmonic generation (THG) produced by ultrathin tin (II) sulfide (SnS) is in‐plane anisotropic with respect to the direction of the excitation linear polarization. The polarization‐resolved THG (P‐THG) measurements are described with a nonlinear optics model, which accounts for the orthorhombic crystal structure of the 2D SnS. The relative magnitudes of the χ(3) tensor components are calculated by recording and simultaneously fitting two orthogonal polarization components of the P‐THG signals. Furthermore, the “THG anisotropy ratio” is introduced, which compares the THG intensity produced when the excitation linear polarization is along the armchair crystallographic direction, with the case when it is along the zigzag direction. The experimental findings provide quantitative information on the anisotropic nature of the THG process in various SnS flakes. Nonlinear anisotropic 2D materials can be used in future optoelectronic devices, where anisotropic polarization sensitivity is required. Having an optical tool that quantitatively probes the effect of the in‐plane anisotropy among different 2D materials, could be of considerable importance for evaluating the performance of such materials and devices.

Imaging of developing human brains with ex vivo PSOCT and dMRI.

The human brain undergoes substantial developmental changes in the first five years of life. Particularly in the white matter, myelination of axons occurs near birth and continues at a rapid pace during the first 2 to 3 years. Diffusion MRI (dMRI) has revolutionized our understanding of developmental trajectories in white matter. However, the mm-resolution of in vivo techniques bears significant limitation in revealing the microstructure of the developing brain. Polarization sensitive optical coherence tomography (PSOCT) is a three-dimensional (3D) optical imaging technique that uses polarized light interferometry to target myelinated fiber tracts with micrometer resolution. Previous studies have shown that PSOCT contributes significantly to the elucidation of myelin content and quantification of fiber orientation in adult human brains. In this study, we utilized the PSOCT technique to study developing brains during the first 5 years of life in combination with ex vivo dMRI. The results showed that the optical properties of PSOCT quantitatively reveal the myelination process in young children. The imaging contrast of the optic axis orientation is a sensitive measure of fiber orientations in largely unmyelinated brains as young as 3-months-old. The micrometer resolution of PSOCT provides substantially enriched information about complex fiber networks and complements submillimeter dMRI. This new optical tool offers great potential to reveal the white matter structures in normal neurodevelopment and developmental disorders in unprecedented detail.

Tailored detection efficiency for linear variable filter-based sensors: applying simulation models of spectral characteristics in optical design

To accurately model the specific detection characteristics of spectral sensors based on linear variable filters (LVFs) within an optical design tool, it is essential to consider crucial position-variable spectral properties, such as peak transmittance, central wavelength, half width, or slope steepness. In this context, we propose a straightforward approach, integrating a dynamic link library (DLL) containing all position-dependent spectral properties of the LVF into a commercial optical design software. Exemplary investigations are conducted for an LVF with a detection range of 450–850 nm. For ease of use, the measured position-, wavelength-, and angle-dependent transmission properties of the LVF have been described through a simple yet highly accurate model system. Moreover, to highlight the essential value of this simulation for specific applications, an efficiency-enhancing spectral module is simulated, which is an LVF-mirror arrangement characterized by a multiple-reflected beam path. The introduced optical design tool demonstrates its particular strength by enabling the optimization of the highest detection efficiency for either the short- or long-wavelength range.

Advancing DIEP Flap Monitoring with Optical Imaging Techniques: A Narrative Review.

This review aims to explore recent advancements in optical imaging techniques for monitoring the viability of Deep Inferior Epigastric Perforator (DIEP) flap reconstruction. The objectives include highlighting the principles, applications, and clinical utility of optical imaging modalities such as near-infrared spectroscopy (NIRS), indocyanine green (ICG) fluorescence angiography, laser speckle contrast imaging (LSCI), hyperspectral imaging (HSI), dynamic infrared thermography (DIRT), and short-wave infrared thermography (SWIR) in assessing tissue perfusion and oxygenation. Additionally, this review aims to discuss the potential of these techniques in enhancing surgical outcomes by enabling timely intervention in cases of compromised flap perfusion. A comprehensive literature review was conducted to identify studies focusing on optical imaging techniques for monitoring DIEP flap viability. We searched PubMed, MEDLINE, and relevant databases, including Google Scholar, Web of Science, Scopus, PsycINFO, IEEE Xplore, and ProQuest Dissertations & Theses, among others, using specific keywords related to optical imaging, DIEP flap reconstruction, tissue perfusion, and surgical outcomes. This extensive search ensured we gathered comprehensive data for our analysis. Articles discussing the principles, applications, and clinical use of NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR in DIEP flap monitoring were selected for inclusion. Data regarding the techniques' effectiveness, advantages, limitations, and potential impact on surgical decision-making were extracted and synthesized. Optical imaging modalities, including NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation in DIEP flap reconstruction. These techniques provide objective and quantitative data, enabling surgeons to monitor flap viability accurately. Studies have demonstrated the effectiveness of optical imaging in detecting compromised perfusion and facilitating timely intervention, thereby reducing the risk of flap complications such as partial or total loss. Furthermore, optical imaging modalities have shown promise in improving surgical outcomes by guiding intraoperative decision-making and optimizing patient care. Recent advancements in optical imaging techniques present valuable tools for monitoring the viability of DIEP flap reconstruction. NIRS, ICG fluorescence angiography, LSCI, HSI, DIRT, and SWIR offer a non- or minimal-invasive, real-time assessment of tissue perfusion and oxygenation, enabling accurate evaluation of flap viability. These modalities have the potential to enhance surgical outcomes by facilitating timely intervention in cases of compromised perfusion, thereby reducing the risk of flap complications. Incorporating optical imaging into clinical practice can provide surgeons with objective and quantitative data, assisting in informed decision-making for optimal patient care in DIEP flap reconstruction surgeries.

Modeling quantum optical phenomena using transition currents

Spontaneous light emission is central to a vast range of physical systems and is a founding pillar for the theory of light–matter interactions. In the presence of complex photonic media, the description of spontaneous light emission usually requires advanced theoretical quantum optics tools such as macroscopic quantum electrodynamics, involving quantized electromagnetic fields. Although rigorous and comprehensive, the complexity of such models can obscure the intuitive understanding of many quantum-optical phenomena. Here, we review a method for calculating spontaneous emission and other quantum-optical processes without making explicit use of quantized electromagnetic fields. Instead, we introduce the concept of transition currents, comprising charges in matter that undergo transitions between initial and final quantum states. We show how predictions that usually demand advanced methods in quantum electrodynamics or quantum optics can be reproduced by feeding these transition currents as sources to the classical Maxwell equations. One then obtains the relevant quantum observables from the resulting classical field amplitudes, without washing out quantum optical effects. We show that this procedure allows for a straightforward description of quantum phenomena, even when going beyond the dipole approximation and single emitters. As illustrative examples, we calculate emission patterns and Purcell-enhanced emission rates in both bound-electron and free-electron systems. For the latter, we derive cathodoluminescence emission and energy-loss probabilities of free electrons interacting with nanostructured samples. In addition, we calculate quantum-beat phenomena in bound-electron systems and wave function-dependent optical coherence in free-electron systems. Remarkably, the transition-current formalism captures more complex phenomena, such as many-body interference effects and super-radiance of both bound- and free-electron systems, second-order processes such as two-photon emission, and quantum recoil corrections to free-electron radiation. We review a variety of light–matter interactions in fields ranging from electron microscopy to nanophotonics and quantum optics, for which the transition-current theoretical formalism facilitates practical simulations and a deeper understanding of novel applications.

Enhancing optical modulator and link performance through modulation instability: design, simulation and implementation

In future optical communication applications, broadband tools and technologies are essential for increasing transfer and processing speeds. Conventional microwave tools are too slow and inflexible to meet these demands. Photonic microwave technology offers that most current solution to this issue, utilizing modulation tools to convert microwave signals to the optical domain. However, these modulation tools face significant challenges, including low bandwidth and high voltage requirements. Although various methods have been proposed in recent decades to address these issues, most increase structural complexity and cost without significantly improving modulator performance and bandwidth. In this article, by using a modulation instability in optical fibers, without manipulating and complicating the structure of the modulator and only by using common modulators, their bandwidth was multiplied and the required voltage was significantly reduced. Finally, a special fiber channel was designed, which showed a much better performance.

A Region-Monitoring-Type Slitless Imaging Spectrometer.

In modern scientific practice, it is necessary to consistently observe predetermined zones, with the expectation of detecting and identifying emerging targets or events inside such areas. This research presents an innovative imaging spectrometer system for the continuous monitoring of specific areas. This study begins by providing detailed information on the features and optical structure of the constructed instrument. This is then followed by simulations using optical design tools. The device has an F-number of 5, a focal length of 100 mm, a field of view of 3 × 7, and a wavelength range spanning from 400 nm to 600 nm. The optical path diagram demonstrates that the system's dispersion and imaging pictures can be distinguished, hence fulfilling the system's specifications. Furthermore, the utilization of a Modulation Transfer Function (MTF) graph has substantiated that the image quality indeed satisfies the specified criteria. To evaluate the instrument's performance in the spectrum observation of fixed regions, a region-monitoring-type slitless imaging spectrometer was built. The equipment has the capability to identify a specific region and rapidly capture the spectra of objects or events that are present inside that region. The spectral data were collected effectively by the implementation of image processing techniques on the captured photos. The correlation coefficient between these data and the reference data was 0.9226, showing that the device successfully measured the target's spectrum. Therefore, the instrument that was created successfully demonstrated its ability to capture images of the observed areas and collect spectral data from the targets located within those regions.

Effect of Optogenetic Stimulation Parameters on Firing Rate of Basal Ganglia Neurons in Parkinsonian State BG and RT Networks

Purpose: Parkinson's disease is a neurodegenerative disorder that affects the basal ganglia of the brain, which plays an important role in movement. Basal Ganglia-Thalamic network model including Subthalamic nucleus, Globus Pallidus externa, Globus Pallidus interna and Thalamus neurons. Optogenetics is a combination of optical and genetic tools used to stimulate basal ganglia neurons by light-sensitive ion channels (opsins) to eliminate the pathological effects of Parkinson's disease. Materials and Methods: To analyze the effect of optogenetic stimulation on Parkinsonian nervous systems, two complete models of BG and RT (including STN, GPe, Gpi, and TH neurons) have been selected and developed for Parkinson’s disease and to apply three and four-state optogenetic stimulation. For this purpose, ChETA, ChRwt, and NpHR opsins have been selected in three-state and four-state stimulations and different stimulation conditions according to different parameters in both models have been investigated. Results: To evaluate the performance of two models for each gene in three- and four-state stimulation conditions with different values of basic parameters, the value of error index is calculated and stimulation conditions that created an error index equal to zero have been introduced as optimal conditions. Based on the results, frequencies of 20 and 200 Hz in the four-state ChRwt model and frequency of 80 Hz in the three-state ChETA model have been introduced as optimal genes, frequencies, and models. To verify the developed model, the obtained results have been compared with the results of experimental studies. Conclusion: In optimal conditions, STN provides excitatory input and GPe provide appropriate inhibitory input to GPi, and GPi can provide appropriate inhibitory input to TH, and as a result, its function improves and pathological effects of Parkinson's disease disappear. The response of GPe neurons is consistent with the experimental results and the response of other neurons is also similar to the response of GPe neurons.