Next Generation fNIRS System Development and Evaluation
fNIRS is an emerging, safe, noninvasive, affordable and portable neuroimaging modality. There are various forms of commercially available fNIRS system and sensor designs, from wireless to desktop versions. The primary objective of this research study is to design a fully wireless, miniaturized, app operable, cost efficient and easily processable fNIRS system that can be used in the field, at home or in classroom settings. This device is aimed to be smaller, lighter and comfortable than existing solutions, and able to transmit the data wirelessly from the sensor itself so that it can be worn on the head for a prolonged time while transmit ting brain oxygenation signals during everyday activities to any presentation device, personal computers, tablets and phones.
A prototype design has been achieved in Villanova University’s Electrical and Computer Engineering Department, by a group of undergraduate students during the Harris Summer Innovation Program. This initial fully wireless and app-operable prototype forms the basis of further development and testing on laboratory models and humans to achieve a flexible, reliable and durable designs.
Phantom Development and Testing
Human head mimicking laboratory models (phantoms) play an important role in the calibration, testing and evaluation of fNIRS-based optical brain imaging systems. Phantoms reported in the literature are generally of solid nature mimicking optical properties of the overall human head within one layer. Solid phantoms can further be constructed as multilayered to mimic superficial layers of the head or with disks to mimic lesions within the brain layer. However, solid phantoms are of static nature and hence changing characteristics within the brain layer, such as in oxygen saturation cannot be modeled. Liquid phantoms can be used to model dynamic changes within the brain, however, existing liquid phantoms are of one layer only and cannot mimic the superficial layers of the head.
In this research study, together with colleagues from Drexel University’s School of Biomedical Engineering and Infrascan, Inc. we are working on the design and development of a multi-layer human head mimicking phantoms that are a mixture of solid compartments modeling the superficial layers of the head and a liquid section mimicking the brain layer which provides a realistic and dynamic design. This hybrid, multi-layer phantom can further be used in the design and evaluation of fNIRS-based brain imaging systems.
Cerebral Hematoma Detection and Edema Monitoring & Cerebral and Body Oximetry
The two leading causes of death on the battlefield are brain injury and hemorrhage. In civilian populations, each year in the U.S. alone about 1.5 million people incur a head injury requiring medical care and over 5.3 million people suffer severe disabilities due to past traumatic brain injury (TBI). Resuscitation and triage of casualties of brain injury and hemorrhagic shock remains one of the most challenging aspects of trauma care. One of the most common effects of head trauma, in addition to intracranial hematomas, is brain edema. A critical obstacle to improving survival is the lack of methods and systems to measure, monitor, and trend physiologic parameters. Noninvasive devices to be applied in the field to detect tissue oxygen to assess vital organ perfusion are desperately needed. Such technology would provide critical baselines for monitoring and assessment of trauma victims during triage and resuscitation efforts.
This research study aims to develop a portable near infrared (NIR) based device for field triage and resuscitation of trauma victims at the site of injury. The proposed integrated system will capitalize on the Infrascanner, a hand-held point-of-care medical device (Infrascan, Inc). The main objective is to develop and translate an integrated hand-held point-of-care system, the next generation of Infrascanner for effective triage and resuscitation to aid head trauma and hemorrhagic shock victims in settings where timely decisions are critical. To achieve the overall objective, the specific aims are to:
- Design and develop prototypes, i.e., hardware, software and signal processing algorithms, to reliably detect and monitor changes in the brain blood and water content for cerebral hematoma and edema detection and oxygen saturation measurements within the brain and extremities
- Evaluate and validate accurate, non-invasive detection and monitoring of brain hematoma, edema and oxygenation saturation changes in the brain and extremities through laboratory phantom and animal testing and human experimentation.
This project has been ongoing for several years with funds from the U.S. Army, Marines, and Coulter Foundation as a joint effort of engineers and clinicians from Drexel University’s School of Biomedical Engineering, Infrascan, Inc. and University of Pennsylvania Hospital.
Establishment of Cognitive Abilities in Aging Populations
Evidence suggests that gait is influenced by higher-order cognitive and cortical control mechanisms. However, less is known about the functional correlates of cortical control of gait. Previously, we evaluated whether increased activations in the Pre-Frontal Cortex (PFC) were detected in Walking While Talking (WWT) compared to Normal Pace Walking (NW) in young and old participants using fNIRS. This study provided the first evidence in the literature that oxygenation levels are increased in the PFC in WWT compared to NW in young and old individuals. This effect was modified by age suggesting that older adults may underutilize the PFC in attention demanding locomotion tasks. In a follow up NIH funded research study, together with collaborators from Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, ~500 elderly subjects have been enrolled and monitored with fNIRS over five consecutive years where co-registration with fMRI and fNIRS were also performed. We have been studying not only cognitive control of mobility in aged populations but also effects of gender, stress and fatigue in the general group, and also in subgroups having Parkinsonian, diabetes, neurological gait abnormalities, and MS syndromes. The capability of cognitive activity-based biomarkers in the prediction of falls in elderly have also been studied. We are continuing this research for the study of neurophysiological underpinnings of MS in elderly with collaborators from Einstein College of Medicine and University of Illinois at Urbana Champaign. In addition, we are exploring the effects of various fNIRS processing methods and parameters in the hemodynamic signal extraction and artifact removal.
Studies on Semantic Memory and Attentional Control
Together with colleagues from Villanova University’s Department of Psychology, we are working on two separate cognitive activity monitoring studies for:
- Semantic retrieval and selection using a picture naming task
- Attentional control and distraction using fNIRS
In the first study, we are first aiming to replicate prior fMRI findings using fNIRS measurements on healthy young adults. Next, our aim is to extend the study findings to elderly populations during the same semantic task and further testing of the results under imposed conditions with postural differences and external sound noise.
In the second study, we aim to study attentional control and distractibility on healthy young adults using a picture-based task of shapes with and without distractors that subjects have to identify the targets under these two conditions. Behavioral and cognitive next step in this study is to extend the findings in individuals with mild brain injury, concussion.
Assessment and Enhancement in Reading Comprehension and Mathematics
Reading is a complex cognitive process, which requires the coordination, implementation and integration of different cognitive domains via the information processing system within a short period of time. The actual spatial, temporal and flow mechanisms in the brain during different forms of reading, oral and silent has not yet been established. Furthermore, effectiveness of the existing reading assessment and enhancement techniques in the improvement of reading performance in the long term and their impact on brain mechanism is still not fully known. Even though there are established reading assessment tools for younger students in elementary school, there are few reading assessments for older students in middle and high schools. Those assessments usually assess reading fluency. Teachers of secondary education students find it difficult to assess reading comprehension. With the introduction of the new Common Core Career and College Readiness standards, teachers will be expected to have students reading on higher lexile levels and teachers will need to know if text is too easy or difficult for students based on quantitative, qualitative and reader and task measures.
With collaborators from the School of Education at Drexel University, we have been working on the development and evaluation of the app-based Adolescent Reading Evaluation (ACE) tool. ACE will allow teachers to determine appropriate levels of text for each student and provide the information necessary to show growth in reading lexile levels, which can easily be used in the classroom independently by students where multiple students can be assessed at the same time. Furthermore, brain mechanisms involved in reading comprehension in different subject groups at various grades with (dyslexia) and without reading disabilities. Similar concepts can also be explored for subject groups having disabilities in mathematics (dyscalculia) to pinpoint the differences in brain mechanisms of dyscalculics and the effects of enhancement procedures on their performance.
Anesthesia Awareness Monitoring
Awareness is an unintended mental state during general anesthesia. An accurate, objective measure of return to consciousness would provide an important safeguard for patients and physicians alike. In a former study funded by Coulter Foundation, together with colleagues from Drexel University’s School of Biomedical Engineering, we have examined hemodynamic changes during deep and light anesthesia as measured by fNIRS. The results of this former study suggested that the rate of deoxygenated hemoglobin change can be used as a descriptive neuromarker to differentiate between deep and light anesthesia stages. We have then verified this marker in a follow up study carried out in Seville, Spain, where similar results were found. Machine learning algorithms for the automatic and real time separation of anesthesia stages based on fNIRS features which can help in translation of the technology from bench to bedside are developed and studied. These general anesthesia monitoring studies are further extended to a related study where outpatients were monitored under light sedation during colonoscopic procedures. The results of these studies are summarized in various publications and in two issued and one pending patents. Currently, we are extending this research for the monitoring of anesthesia in one of the most vulnerable groups, children.
As a prevalent childbirth complication, post-partum depression (PPD), which occurs among 10-15% of all childbearing women, has numerous adverse effects on maternal health and functioning, and poses a significant risk factor for impaired infant development. Among the proposed pathways explaining how PPD affects child development, neurophysiologic processes have been under-studied. Cortical hemodynamic response (CHR), which reflects changes in cognitive activity indicative of executive function, attention, and social engagement during emotionally salient tasks in the prefrontal regions, may be a neurophysiological correlate of impaired mother infant interaction (MII). fNIRS has significant advantages over traditional methods, including the ability to assess CHR in infants and mothers simultaneously during MII, greater acceptability, less movement restriction and distress, portability and less expense. With collaborators from College of Nursing and Department of Psychology at Drexel University we are working on the assessment of the difference in CHR between mothers with and without PPD and their infants during MII. In a related study, we are working on the relationship between PPD and eating habits and their neurophysiological underpinnings.
Development and Monitoring of Cognitive Indices in Learning and Training
The primary objective of this study is to establish an individual’s cognitive baseline by administering neurocognitive tasks, and to assess cognitive workload and capacities with the fNIRS technology. Based on the obtained cognitive baseline index, reliable and dynamic performance indices during training and on the task will be developed. This idea of baseline, training and on-task indices can be applied to different subject groups in different professions to evaluate their intrinsic capabilities, their levels of expertise and performance on the job from military to medical personnel, from students to employees. In collaboration with colleagues from Drexel University’s School of Biomedical Engineering, under a former grant from the U.S. Army, these indices were studied in military personnel training to objectively evaluate if they have transitioned from novice to expert levels and to evaluate their performance and level of overload in the theatre when they are deployed.
Similarly, baseline, training and performance indices can be used for medical personnel training and performance evaluation. In the medical field, there is a need for objective metrics for the assessment of simulation programs in moving the novice trainees to expert levels which can be achieved by the utilization of baseline and training indices. Once the medical personnel are trained their cognitive overload can be evaluated under challenging working conditions during and after 12-hour night shifts using the deployment index. In a former study with collaborators from Children’s Hospital of Philadelphia, similar concepts were tested on the evaluation of individual cognitive processes from nursing students to residents to expert clinicians in a team simulation learning environment. Recently, with a group of researchers at Drexel University, College of Nursing and Health Professions, School of Education and Westphal College of Media Arts and Design, a research study on learning in virtual and augmented reality (AR/VR) environments and its effects on cognitive load has been initiated.