This PDF file contains the front matter associated with SPIE Proceedings Volume 11226 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

We here report an optical system for live 3D microscopy that we call the Multifocus 25-camera microscope (M25). M25 is a new design for aberration-corrected multifocus microscopy (MFM) that employs the latest generation of small, fast and sensitive CMOS cameras. Each of the 25 focal planes is captured on one of the individual cameras, enabling truly simultaneous 3D recording at >100Hz. M25 is built from a combination of custom manufactured diffractive Fourier optics elements and off-the-shelf components. We are employing M25 to study neural circuit function in small model organisms including C. elegans, Drosophila, and fish.

Neuroscience research is propelled by advance imaging tools, which ideally could provide high spatial and temporal resolution imaging. However, available fast 3-dimensional optical sectioning approaches applicable to deep tissue and large scale in-vivo imaging are still limited. We develop a novel two-photon Bessel beam scanning light sheet microscope, which has two distinct imaging modes: 1) The light-sheet imaging mode enables sub-micron 3D imaging over hundreds of microns field of view, which is well adapted to the neural tissue with complex structure; 2) The projection imaging mode aims to capture fast neural activities at up to 100 volumes per second. Imaging results of various neural specimens will be presented.

Although it is well known that zebrafish display the behavioural signature of sleep, the neuronal correlates of this state are not yet completely understood, due to the complexity of the measurements required. For example, when performed with visible excitation light, functional imaging can disrupt the day/night cycle due to the induced visual stimulation. To address this issue, we developed a custom-made two-photon light-sheet microscope optimized for high-speed volumetric imaging. By employing infra-red light (not visible to the larva) for excitation, we are able to record wholebrain neuronal activity with high temporal- and spatial-resolution without affecting the sleep state. In two-photon light-sheet microscopy the maximum achievable frame rate is limited by the signal-to-noise ratio. To maximize this parameter, we optimized our setup for high peak power of excitation light, while finely controlling its polarisation, and we implemented remote scanning of the focal plane to record without disturbing the sample. Using this setup, as a preliminary result, we characterized the intensity spectra of neuronal calcium traces of 4 days post fertilisation larvae during the day/night phases. We aim to extend these results to multiple brain regions and frequency bands.

Two-photon microscopy has become the method of choice for in vivo brain imaging in neuroscience research during the past decades owing to its inherent sectioning capability and large penetration depth in scattering tissues. By integrating with a gradient refractive index (GRIN) lens that implanted into the brain, two-photon microendoscopy further extends the imaging depth down to subcortical regions. However, the imaging resolution and field of view (FOV) are compromised due to the intrinsic aberrations of the inserted GRIN lens. Here, we developed an adaptive optics (AO) two-photon microendoscopy based on direct wavefront sensing that can measure and correct the aberrations of GRIN lens during in vivo brain imaging. Using our system, the diffraction-limited resolution was restored and the fine structures such as dendritic spines of hippocampal CA1 neurons can be clearly resolved over a much extended FOV.

We introduce a novel method to enhance the sensitivity of near-infrared spectroscopy (NIRS) to deep tissue (i.e. brain cortex, skeletal muscle, etc.) in non-invasive diffuse optical measurements. Our method relies on the collection of the phase of photon-density waves, launched by intensity-modulated light in frequency-domain NIRS, from two paired sets of multi-distance data. The two sets of data are combined into a phase dual-slope, which features a stronger sensitivity to deeper vs. superficial tissue. For typical conditions of functional NIRS, the maximum sensitivity of phase dual-slopes is at a depth of ~11 mm, which approaches the depth of cortical tissue.

Current gold standard neuroimaging tools lack either necessary temporal resolution (PET) or optimal safety due to contraindications (fMRI) for measuring the neural mechanisms underlying the effects of deep brain stimulation of the subthalamic nucleus (STN DBS) in Parkinson disease (PD). In this study, we validate the feasibility of High-Density Diffuse Optical Tomography (HD-DOT) for mapping the cortical activity of the PD patients with their STN DBS ON and OFF during auditory and visual tasks and during resting state.

We still lack a detailed map of the anatomical disposition of neurons in the human brain. A complete map would be an important step for deeply understanding the brain function, providing anatomical information useful to decipher the neuronal pattern in healthy and diseased conditions. Here, we present several important advances towards this goal, obtained by combining a new clearing method, advanced Light Sheet Microscopy and automated machine-learning based image analysis. We perform volumetric imaging of large sequentially stained human brain slices, labelled for two different neuronal markers NeuN and GAD67, discriminating the inhibitory population and reconstructing the brain connectivity.

In this study, functional near-infrared spectroscopy (fNIRS) was used to examine the brain activation patterns in the occipitotemporal cortex (OTC) associated with Chinese character recognition (CCR). Eighteen healthy participants were recruited to perform a well-designed task involving three types of stimuli including real characters, pseudo characters and checkerboards. By inspecting the brain activation difference and its relationship with behavioral data, we discovered that the left hemisphere is responsible for the orthographical information processing. Meanwhile, we found that the bilateral superior temporal gyrus (STG), bilateral Brodmann's area (BA) 19 and left fusiform gyrus were involved in high-level lexical information processing such as semantic and phonological ones, indicating that the brain activities in these regions were associated with enhanced CCR performance. In addition, by examining functional brain networks, it was discovered that increased brain connectivity in the right BA 19 exhibited significant correlation with the performance of CCR. Consequently, the combination of fNIRS technique with functional network analysis paves a new avenue for an improved understanding the cognitive mechanism underlying CCR.

Working memory (WM) is part of the short-term memory storage in human brain. N-back is a WM task to assess mental workload on the prefrontal cortex (PFC). In this work, we studied how mental workload changes in an N-back task over the length of the experiment. We focused on two task levels of two- and three-back. Examining both hemodynamics and behavioral data (correct answers), we found a significant difference between 2-back and 3-back tasks and a significant difference between the beginning and end of the 3-back task.

High density diffuse optical tomography (HD-DOT) combines logistical advantages of fNIRS with enhanced image quality, validated extensively against fMRI in adults and neonates. However, HD-DOT is yet to be evaluated in preschool-age children. Here we present an HD-DOT system optimized for preschoolers, including a 128-source by 125-detector console, light-weight fiber optics, and an expanded field-of-view. We validated the system by mapping cortical activations during visual, auditory, and motor tasks in adults. We then imaged children while they watched movies, finding reproducible patterns of brain activity and showing that feature regressors can map functionally specific regions from movie-viewing data in preschoolers.

The advent of genetically-encoded calcium indicators, along with surgical preparations such as thinned skulls or refractive index matched skulls, have enabled mesoscale cortical activity imaging in headfixed mice. Such imaging studies have revealed complex patterns of coordinated activity across the cortical surface during a variety of behaviors. However, neural activity during free, unrestrained behavior significantly differs from that observed in headfixed animals. The ability to perform mesoscale imaging of the cortex in freely behaving mice may launch new avenues of scientific enquiry. Here we present the ‘Mesoscope’, a miniature, head-mountable imaging device compatible with transparent polymer skulls recently developed by our group. With an 8x10 mm field of view, the Mesoscope can image most of the mouse dorsal cortex and weighs only 3.7 grams. Here, we show preliminary behavioral experiments and mesoscale imaging in anesthetized mice.

We developed an all-optical system that couples large-scale cortical imaging with chronic light-based motor mapping in awake mice. By AAV-mediated cortical transfection, we induced the co-expression of the red-shifted genetically encoded calcium indicator and a light-sensitive optogenetic actuator ChR2 over both the rostral and caudal forelimb areas, which was stable over several months. No evidence of cross-talk was detected during illumination of ChR2+ neurons with the light source used for RCaMP1a excitation. Light-based motor mapping coupled with wide-field imaging of neuronal activation in awake mice revealed spatiotemporal patterns of cortical activation specific for movement category.

It is still unclear how neuronal metabolism is affected by opioids. We developed a multimodal nonlinear optical imaging platform that can resolve single neurons while monitoring endogenous metabolic molecules in a label-free manner. These capabilities enable investigation of morphine-induced metabolic changes in neurons. Additionally, mouse brain slices were used to study the effects of morphine on metabolism in the brain. We found that after morphine exposure, the nucleus accumbens area showed increased metabolic activity compared to the cerebral cortex. Further studies will reveal how opioids alter the metabolism of the brain and individual neurons at the sub-cellular level.

Automatic serial sectioning polarization sensitive optical coherence tomography (as-PSOCT) enables volumetric reconstruction of human brain samples with unprecedented resolution and volume coverage. Here we show the laminar structures and the optical properties in human cerebellar cortex using as-PSOCT. The cerebellum cortex was segmented based on the retardance images. The scattering coefficient maps were created, and the thickness maps were generated for the molecular and granular layers, respectively. The relationship between the optical property and the geometry was investigated. The optical property indicated a homogenous cell density despite great variations in the thickness due to the folding patterns in the cerebellum.

Optical neuroimaging technologies aim to observe neural tissue structure and function by detecting changes in optical signals (scatter, absorption, etc…) that accompany a range of anatomical and functional properties of brain tissue. At present, there is a tradeoff between spatial and temporal resolution that is not currently optimized in a single imaging modality. We have developed a coherent optical imaging approach that begins to remove this trade-off and have demonstrated high spatiotemporal (<100µm and >100Hz) in-vivo recordings of neural activity over large 20mm2 areas.

We demonstrate imaging of amyloid-beta plaques in ex-vivo Alzheimer’s disease brain tissue using a 1060 nm swept source optical coherence tomography setup. This instrument enabled a global investigation of the brain tissue with a large field of view of 8 mm x 8 mm as well as sequential high resolution imaging. Amyloid-beta (A-β) plaques were identified as highly scattering features. Results were in good agreement with immunohistochemically stained images gained by histology.

Optical coherence tomography (OCT) is a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. We sought to examine non-vascular depth-dependent optical changes directly related to neural activity in the brain using OCT. Results of this study show a significant temporal correlation between non-vascular decrease in attenuation in ex vivo and in vivo seizure models and increased electrical activity during seizure. This study allows for a more thorough and biologically relevant analysis of the optical signature of seizure activity ex vivo and in vivo using OCT.

Deficits in the medial prefrontal cortex (mPFC) function play a crucial role in promoting compulsive cocaine use. This dysfunction might result from cocaine’s effects on neurons possibly including modification of the expression of the dopamine type 2 receptors (D2r). However, studies on D2r function have been hindered by relatively low receptor expression in mPFC and low detection sensitivity. To tackle this problem, we developed a workflow to optically image D2r through enhancing visualization of GFP fluorescence in a D2r-expressing transgenic mouse model. Two groups of animals were used: group 1 was treated daily by saline (0.1cc/100g, i.p.) and group 2 received cocaine (30mg/kg, i.p.) for 2 weeks. Following 1-day withdrawal, their brains were fixed and processed. The brain sections underwent immunostaining and ex vivo imaging using a confocal fluorescence microscope to capture co-registered fluorescence labeling of both neurons (NeuN) and D2r-expressing neurons (GFP). These images were montaged to cover a large field of view of the mPFC to quantify the changes in the count of neurons and D2r-expressing neurons. Our results show that chronic cocaine exposure results in 34.7%±5.7% decrease in neurons but a 44.7%±13.2% increase of D2r expressing neurons in the mPFC compared to saline treated group. Additionally, in-vivo Ca²⁺ imaging of D2r-expressing neurons in the mPFC revealed cocaine’s effects on the prefrontal response to the stimulation at the VTA. These changes might underlie the hypofrontality observed in human studies and exacerbate the loss of control associated with chronic cocaine use

Diffuse correlation spectroscopy (DCS) is an increasingly widespread non-invasive technology to measure tissue perfusion. Extending this technique into adult brain monitoring to assess real-time cerebral blood flow (CBF) requires addressing the influence of extracerebral contributions on DCS measurements. We compare several Monte Carlo based forward simulation models on the efficacy of CBF isolation, including ones generated directly from individual subject MRI scans. We conclude that a multi-layer curved surface representation is beneficial, and that the traditional single-layer homogenous model is insufficient; however, detailed structural information such as cortical folding represented in an individualized tissue-specific model may not be needed.

Cerebrovascular Autoregulation failure is known to allow drastic changes in cerebral blood flow in cases of extreme Cerebral Perfusion Pressure (CPP) or Intracranial Pressure (ICP). Brain pathologies (such as traumatic brain injury, hydrocephalus, stroke, etc.) which alter CPP and ICP are also known to show impaired neurovascular coupling. We analyzed these characteristic changes in neurovascular coupling in a model to develop a non-invasive diagnostic marker of autoregulation failure using EEG, Near-Infrared Spectroscopy and Diffuse Correlation Spectroscopy.

Vascular impedance is a frequency dependent quantity relating a vascular compartment's flow dynamics to pressure changes. Although vascular impedance has been investigated in larger arteries, probing smaller arterioles using similar techniques has been difficult due to their small cross-sectional area. Here we show how vascular impedance can be quantified based on pulsatile data from cerebral measurements using diffuse correlation spectroscopy (DCS) as well as near-infrared spectroscopy (NIRS). Results from head of bed tilting in healthy volunteers will be presented, showing that quantification of vascular impedance is possible. Applications and the relationship to cerebral autoregulation will be discussed.

Quantitative 3D analysis of brain vasculature is a fundamental problem with important applications, for which vessel segmentation is a first step. Traditional segmentation methods based on parametric models have limited accuracy. More recent techniques based on machine learning have promising results but limited generalization capability. We present a deep-learning based segmentation method that overcomes limitations of existing systems and demonstrates the ability to generalize to various imaging setups, samples including both in-vivo/ex-vivo data, with state-of-the-art results. We achieve so by exploiting several novel methods in deep learning, such as semi-supervised learning. We believe that our work will be another step forward towards improved large-scale neurovascular analysis.

We have evaluated in vitro and in vivo the efficiency and practicability of reversible optical clearing of the skull for minimally invasive, longitudinal imaging of the rodent brain. Firstly, in vitro experiments have been conducted on resected mice skulls to evaluate the efficiency of the optical clarification process using different optical clearing agents. On the basis of recent literature, we have evaluated in vitro different optical clearing processes: (i) the direct application of PEG400; (ii) sequential EDTA and glycerol application and (iii) application of a solution of urea dissolved in ethanol. First, the time course of the clarification of the skull has been monitored quantitatively. We have carried out photometry experiments at 633 nm using a two integrating spheres system to characterize the total transmittance and reflectance of the mice skull samples. The evaluation of the optical transmission coefficient at 1300 nm was also obtained at different time points of the clearing process using sequential optical coherent tomography (OCT) imaging of the skull samples during the clearing process. Second, in vivo evaluation was carried out for repeated transcranial mapping of brain blood flow after optical clarification of the skull. Relative blood flow maps were obtained from multiple exposure laser speckle imaging. Third, post-mortem analysis of the toxicity of the chemicalstopical application was evaluated using immunohistochemistry to asses eventual cells death and inflammation. Overall our results show that in vivo brain imaging in mice could benefit from in vivo optical clearing. Yet, the use of optical clearing agents in vivo requires a proper evaluation of their efficiency, practicability of their use and potential toxicity to the tissues, especially for long term longitudinal studies.

Light in the range of 700-1100 nm has many proven diagnostics and therapeutic medical applications. In this study, we demonstrate another potential application of light. We implemented a testbed to transmit data wirelessly through a human skull and biological phantoms mimicking skin tissues properties using near-infrared (NIR) light. Currently, radio frequency (RF) is widely used to transmit data wirelessly through biological tissues, example includes implants communications. However, RF communications contain interference and security challenges. In this study, we present a novel use of NIR light for wireless data transfer, for which a phantom is exposed to an externally modulated light source and the transmitted light through phantom is captured with a receiver. Initially, a high-resolution picture is successfully transmitted through skin phantom of 2 cm in depth. In the second phase, we successfully communicated through a human skull. Due to hardware limitations, we are able to achieve data rates in tens of kilobits per second. The minimum power applied to the phantoms measured during the data transmission from 810 nm light-emitting-diode (LED) is 0.098 W/cm². The measured optical power values are within the safe limit set by ANSI.Z136.1-2007 standard on laser safety, which is 2 W/cm² for 1 sec exposure of 830 nm wavelength. Initial results are encouraging and there are many possible applications for a system using light to transmit data wirelessly through biological tissues, including communication with brain implants and performing brain therapies.

As transient intracellular Ca²⁺ changes play an important role in many essential processes including neuronal and astrocytic plasticity, tracking brain activity via Ca²⁺ is crucial. Unlike hemodynamics, Ca²⁺ change must be measured optically using an ionic fluorescent Ca²⁺ indicator. Here, we combine our highly sensitive multimodality optical imaging platform with genetically encoded Ca²⁺ indicator (GCaMP6f) expressed in neurons or astrocytes in somatosensory cortex, which enables simultaneous tracking of single-stimulation-evoked neuronal, astrocytic Ca²⁺ transients along with the corresponding hemodynamic responses at high spatiotemporal resolutions. We imaged neuronal and astrocytic Ca²⁺ transients from mouse cortex in response to a single electrical pulse (3mA, 0.3ms). Our results show that the neuronal Ca²⁺ responses were strong (ΔF/F_N=6.4±0.29%), fast (latency τ_N=6±2.7ms) and of short duration (Δt_N=537±34ms) whereas the astrocyte responses were weak, slow and long-lasting (i.e., ΔF/F_A=1.7±0.1%, τ_A=313±65ms, Δt_A =993±48ms). The synchronized activities among astrocytes were temporally less correlated than those among neurons. These results demonstrate the capability of optical detection of cell-specific Ca²⁺ activities from synchronized neuronal, astrocyte ensembles concurrently with the hemodynamic responses within the neuro-glio-vascular network, which can facilitate the study of the roles of astrocytes in the neurovascular coupling process. We also report time-lapse image results to analyze the interactions between stimuli-evoked neurovascular response versus the spontaneous cortical slow oscillations for brain functional studies

Neurovascular coupling, the close spatial and temporal relationship between neural activity and hemodynamics, is disrupted in pathological brain states. To understand the altered neurovascular relationship in abnormal brain states, longitudinal, simultaneous mapping of neural activity and hemodynamics is highly desired but challenging to achieve. Here, we report the development of a multimodal neural platform that realize long-term, spatially-resolved tracking of intracortical neural activity and cerebral blood flow in the same brain regions. We demonstrate the powerful application of this multimodal platform in a mouse model of microinfarcts and reveal a pronounced, long-lasting neurovascular dissociation that depends on the ischemic severity.

Quick and accurate parcellation of neural networks has been a goal spanning multiple decades of research in the functional MRI world in order to organize and understand the overwhelmingly complex human brain with high statistical rigor. The same mathematical development in the mouse brain, which is frequently studied to understand human conditions, has been lagging. To this end, we perform high-throughput fluorescence imaging (GCaMP6f) in healthy mice in a cell-specific and non-invasive manner during rest and sensorimotor tasks in order to map healthy networks and understand patterns due to disease processes.

Sensory perception involves the coordinated effort of thousands of intermingled neurons that act together in groups to amplify and strengthen perceptions. We developed a new approach to edit neural population codes in the cortex during behavior using spatiotemporally precise multiphoton optogenetics. These tools allow us to manipulate individual or groups of cells selected by their functional properties with the precision to write in particular trains of action potentials. We are using these tools to probe how different patterns of activity added to the mouse visual cortex change the overall firing patterns in the cortex, recruiting inhibition, and altering sensory representations.

There is current demand for pattern programmable devices that can deliver light to deep brain structures for use in optogenetic experiments. Here we introduce a microLED optrode device with 181 individually addressable sites, each with the capability to optogenetically excite thousands of neurons in vivo. The device consists of a 10 x 10 glass microneedle array directly integrated with a custom fabricated microLED device. 100 microLEDs couple to the needle tips for intra-cortical light delivery and 81 microLEDs sit at interstitial points for surface illumination. Light delivery and thermal properties are comprehensively evaluated.

The changes in cell metabolism can affect the epigenome-modifying enzymes activity during iPSCs differentiation and thus control the functional potential of the final cell. Therefore, for therapeutic applications, the restoration of a fully functional mitochondrial network specific for the cell types derived from iPSCs will be required to support the energy and other mitochondrial factors. Recently, FLIM method allows to study the metabolic changes that accompanying cell differentiation noninvasively and without additional labels. In this study, we investigated the metabolic changes in iPSCs during neural differentiation using two-photon fluorescence microscopy and FLIM. Cellular metabolism was examined by monitoring the optical redox ratio (FAD/NAD(P)H), the fluorescence lifetime contributions of the free and bound forms of NADH and NADPH. Given that neural differentiation is also accompanied by synthetic processes and oxidative stress, this process was included in the scope of this work. We demonstrated an increased contribution of protein-bound NADH and NADPH in neuron associated with metabolic switch to oxidative phosphorylation and the biosynthetic processes or oxidative stress, respectively. We also found that the optical redox ratio FAD/NAD(P)H decreased during neural differentiation, and this was likely to be explained by the intensive lipid membrane synthesis or ROS generating and the enhanced NADPH production associated with them. The biochemical analysis was carried out to verify the metabolic status of iPSCs and their neural derivatives. Based on the data on glucose consumption, lactate and ATP amount we registered the trend to the metabolic pathways redistribution towards the oxidative phosphorylation in neuron.

Maximal safe resection is of utmost importance when operating on intracranial tumors. However, the discrimination between physiological and malignant tissue is challenging. A solution is 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX (PPIX) fluorescence of malignant cells, which has evolved as powerful intraoperative tool for tumor identification. We investigated 43 samples obtained during 5-ALA guided surgery using a combined optical coherence microscopy (OCM) and fluorescence imaging system and compared results to cell density maps utilizing digital pathology. Based on fluorescence intensity, attenuation coefficients, and cell density, tumor core was differentiated from tumor-associated brain parenchyma with high sensitivity and specificity.

We report mesoscopic physics based nanoscale sensitive partial wave spectroscopy (PWS) study of the structural changes in brain hippocampal region due to chronic stress induced by a stress hormone in a mouse model. Our results show that the change in the average degree of structural disorder in hippocampal tissues from stressed hormone induced mice brains has a higher structural disorder value relative to that of controlled mice, and the change is in correlation with the duration of the stress. Furthermore, the structural changes are peaked around the mid hippocampal regions, both sides of the hippocampal tissues centering around the ventricle.

Intracranial pressure (ICP) is an important metric in the management of severe head injury. We show alternatives to today’s standard of highly invasive measurement devices using near-infrared spectroscopy and diffuse correlation spectroscopy to create a real-time ICP monitor. The algorithms were developed and tested in an animal model. First results of a clinical validation will be presented.

In vivo rat brain imaging was demonstrated using the FF OCM (full field optical coherence microscopy) with SMMF (short multimode fiber) of a diameter of 125 μm and a length of 7.33 mm. The spatial resolution was measured to be 2.0 μm. The influences of motions for OCM images and methods to detect motions were investigated using image processing. Measurements were combinations of 3D OCM imaging (M1) with measurement time 10min and en face imaging (M2) at fixed depth with 17.9 fps and the interval time of 1 min during 30 min. For Rat 1 measured point was at the prim somatosens cortex, and the insertion length (IL) was 3.2 mm, the motions were not remarkable. En face OCM images with the region of X 56.3 μm, Y 56.3 μm, and Z 110 μm were measured. For Rat 2 measured point was at med parietal association cortex, and IL was 3.1 mm. Difference images and those intensity profiles showed the lateral motion of 5 µm between two sequent en face OCM images. For both cases, 3D images similarly showed the spatial arrangement of nerve fibers. The feasibility that the motions of tissues could be detected under the SMMF using sequential difference images was shown. This might be applicable to detect the motions in deep areas in measurements such as the optical intrinsic imaging

We present a high spatiotemporal resolution system for neuroimaging using functional near-infrared spectroscopy (fNIRS). The system is configured as bundled optodes with a single photodiode (PD) and 128 dual-wavelength LEDs in a module. This system is developed using a modular approach where a single module can cover approximately 7 cm × 7 cm, while multiple modules can be used to a broader area. The system has the capacity to measure concentration changes of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) at different brain depths ranging from 2 cm to 3.5 cm. The system also provides the superficial layer information by measuring the short-separation channels. The short-separation channels allow removal of noise and enhancement of signals. The drive circuit of LEDs is carefully designed to switch the light with appropriate intensity, which provides a stable reception for each channel. MOSFET based switching is implemented that allows sharp current switching for high-speed data acquisition. The system can display the acquired HbO and HbR signals as well as activation maps in real-time on a lab-developed Windows-based software. The hardware connects to the software using Wi-Fi. Phantom model with known optical properties and a human subject were used for testing the functionality and efficacy of the device. A complete 128 channel fNIRS sample was recorded in 25 ms. The phantom results showed reduced signal intensity when the channel separation was increased that provides the HbO and HbR. The activation was seen using HbO in the human subject while performing hand tapping task.

This study aims to create a neurofeedback system and observe whether wearing this system assists participants in consciously changing their state of mind. Brainwaves are produced by synchronized electrical pulses from masses of neurons communicating with each other. Through the use of a Neurosky Electroencephalogram (EEG) biosensor, we can detect the brainwaves that result from neuron activity. Attention and meditation levels are two significant examples of brain activity that are reflected by the human body. Our neurofeedback system can monitor attention and meditation levels that humans are normally unable to sense. The Arduino-medium-developed program records brainwaves as attention and meditation values (eSense meter value). In addition, we constructed a vibration system that provided realtime notification to notify participants when their state of relaxation or concentration changed. With appropriate training, users of the neurofeedback system can develop strategies to control their state of mind successfully. [4]