Nil Z. Gurel

Nil Z. Gurel
Reality Labs

Ph.D. in Electrical and Computer Engineering

About

68
Publications
8,001
Reads
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224
Citations
Education
September 2016 - August 2020
Georgia Institute of Technology
Field of study
  • Electrical and Computer Engineering
September 2014 - June 2016
University of Maryland, College Park
Field of study
  • Electrical and Computer Engineering
September 2010 - January 2014
Bogazici University
Field of study
  • Electrical and Electronics Engineering

Publications

Publications (68)
Article
Human-computer interaction (HCI) technology, and the automatic classification of a person’s mental state, are of interest to multiple industries. In this work, the fusion of sensing modalities that monitor the oxygenation of the human prefrontal cortex (PFC) and cardiovascular physiology was evaluated to differentiate between rest, mental arithmeti...
Article
Full-text available
Background: The autonomic response to acute emotional stress can be highly variable, and pathological responses are associated with increased risk of adverse cardiovascular events. We evaluated the autonomic response to stress reactivity of young healthy subjects and aging subjects with coronary artery disease to understand how the autonomic stress...
Article
Background Stress is associated with activation of the sympathetic nervous system, and can lead to lasting alterations in autonomic function and in extreme cases symptoms of posttraumatic stress disorder (PTSD). Vagal nerve stimulation (VNS) is a potentially useful tool as a modulator of autonomic nervous system function, however currently availabl...
Article
Transcutaneous cervical vagal nerve stimulation (tcVNS) devices are attractive alternatives to surgical implants, and can be applied for a number of conditions in ambulatory settings, including stress-related neuropsychiatric disorders. Transferring tcVNS technologies to at-home settings brings challenges associated with the assessment of therapy r...
Article
Pre‐ejection period (PEP), an indicator of sympathetic nervous system activity, is useful in psychophysiology and cardiovascular studies. Accurate PEP measurement is challenging and relies on robust identification of the timing of aortic valve opening, marked as the B point on impedance cardiogram (ICG) signals. The ICG sensitivity to noise and its...
Article
Full-text available
Neural control of the heart involves continuous modulation of cardiac mechanical and electrical activity to meet the organism’s demand for blood flow. The closed-loop control scheme consists of interconnected neural networks with central and peripheral components working cooperatively with each other. These components have evolved to cooperate cont...
Article
Pre-ejection period (PEP) is an index of sympathetic nervous system activity that can be computed from electrocardiogram (ECG) and impedance cardiogram (ICG) signals, but sensitive to speech/motion artifact. We sought to validate an ICG noise removal method, three-stage ensemble-average algorithm (TEA), in data acquired from a clinical trial compar...
Article
Cardiovascular and psychiatric disorders are among the most commonly treated conditions worldwide. Research in neurocardiology, psychiatry, and epidemiology have defined bidirectional relationships between psychiatric disorders and heart disease, affirming the role of impaired autonomic nervous system, or dysautonomia in the prognosis and developme...
Article
Maladaptation of the sympathetic nervous system contributes to the progression of cardiovascular disease and risk for sudden cardiac death, the leading cause of mortality worldwide. Axonal modulation therapy (AMT) directed at the paravertebral chain blocks sympathetic efferent outflow to the heart, and may be a promising strategy to mitigate excess...
Conference Paper
Full-text available
Research has shown that transcutaneous cervical vagus nerve stimulation (tcVNS) yields downstream changes in peripheral physiology in individuals afflicted with posttraumatic stress disorder (PTSD). While the cardiovascular effects of tcVNS have been studied broadly in prior work, the specific effects of tcVNS on the reciprocal of the pulse transit...
Preprint
Full-text available
Neural control of the heart involves dynamic adaptation of mechanical and electrical indices to meet blood flow demands. The control system receives centrally-derived inputs to coordinate cardiac function on a beat-by-beat basis, producing 'functional' outputs such as the blood pressure waveform. Bilateral stellate ganglia (SG) are responsible for...
Article
Full-text available
Objective: Variations in respiration patterns are a characteristic response to distress due to underlying neurorespiratory couplings. Yet, no work to date has quantified respiration pattern variability (RPV) in the context of traumatic stress and studied its functional neural correlates this analysis aims to address this gap. Methods: Fifty huma...
Conference Paper
Full-text available
Transcutaneous electrical stimulation of the vagus nerve is believed to deliver afferent signaling to the brain that, in turn, yields downstream changes in peripheral physiology, including cardiovascular and respiratory parameters. While the effects of transcutaneous cervical vagus nerve stimulation (tcVNS) on these parameters have been studied bro...
Article
Objective: Posttraumatic stress disorder (PTSD) is a disabling condition affecting a large segment of the population, however current treatment options have limitations. New interventions that target the neurobiological alterations underlying symptoms of PTSD could be highly beneficial. Transcutaneous cervical (neck) vagal nerve stimulation (tcVNS...
Article
Full-text available
Background: Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory and sympathetic function, responsible for maintenance of symptoms. Treatment options including medications and psychotherapies have limitations. We previously showed t...
Article
Full-text available
Objective Exacerbated autonomic responses to acute stress are prevalent in posttraumatic stress disorder (PTSD). The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on autonomic responses to acute stress in patients with PTSD. The authors hypothesized tcVNS would reduce the sympathetic response to stress compa...
Article
Full-text available
Pituitary adenylate cyclase-activating peptide (PACAP) is a neuropeptide that plays a key role in the neurobiology of the stress response, and prior studies suggest that its function is dysregulated in post-traumatic stress disorder (PTSD). Transcutaneous cervical vagus nerve stimulation (tcVNS) acts through PACAP and other neurobiological systems...
Article
Full-text available
Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory function. Vagus nerve stimulation (VNS) decreases inflammation, however few studies have examined the effects of non-invasive VNS on physiology in human subjects, and no studies in...
Article
Full-text available
Background: Transcutaneous cervical vagus nerve stimulation (tcVNS) is a promising alternative to implantable stimulation of the vagus nerve. With demonstrated potential in myriad applications, ranging from systemic inflammation reduction to traumatic stress attenuation, closed-loop tcVNS during periods of risk could improve treatment efficacy and...
Article
Full-text available
Background: Vagal Nerve Stimulation (VNS) has been shown to be efficacious for the treatment of depression, but to date, VNS devices have required surgical implantation, which has limited widespread implementation. Methods: New noninvasive VNS (nVNS) devices have been developed which allow external stimulation of the vagus nerve, and their effec...
Article
Full-text available
Background Traumatic stress can have lasting effects on neurobiology and result in psychiatric conditions such as posttraumatic stress disorder (PTSD). We hypothesize that non-invasive cervical vagal nerve stimulation (nVNS) may alleviate trauma symptoms by reducing stress sympathetic reactivity. This study examined how nVNS alters neural responses...
Preprint
BACKGROUND Transcutaneous cervical vagus nerve stimulation (tcVNS) is a promising alternative to implantable stimulation of the vagus nerve. With demonstrated potential in myriad applications, ranging from systemic inflammation reduction to traumatic stress attenuation, closed-loop tcVNS during periods of risk could improve treatment efficacy and r...
Article
Full-text available
Noninvasive vagal nerve stimulation (n-VNS) devices have the potential for widespread applicability in improving the well-being of patients with stress-related psychiatric disorders. n-VNS devices are known to affect physiological signals, and, recently, they have been employed in various protocols involving both acute and longitudinal applications...
Article
Da Costa originally described Soldier's Heart in the 19th Century as a syndrome that occurred on the battlefield in soldiers of the American Civil War. Soldier's Heart involved symptoms similar to modern day posttraumatic stress disorder (PTSD) as well as exaggerated cardiovascular reactivity felt to be related to an abnormality of the heart. Inter...
Preprint
Full-text available
Objective Exacerbated autonomic responses to acute stress are prevalent in posttraumatic stress disorder (PTSD). The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on autonomic responses to acute stress in patients with PTSD. The authors hypothesized tcVNS would reduce the sympathetic response to stress compa...
Preprint
Full-text available
Transcutaneous cervical vagal nerve stimulation (tcVNS) devices are attractive alternatives to surgical implants, and can be applied for a number of conditions in ambulatory settings, including stress-related neuropsychiatric disorders. Transferring tcVNS technologies to at-home settings brings challenges associated with the assessment of therapy r...
Conference Paper
Full-text available
Noninvasive vagal nerve stimulation (n-VNS) devices have the potential for widespread applicability in improving the well-being of patients with stress-related psychiatric disorders. n-VNS devices are known to affect physiological signals, and, recently, they have been employed in various protocols involving both acute and longitudinal applications...
Conference Paper
Full-text available
Non-invasive vagus nerve stimulation (n-VNS) devices offer non-surgical alternatives to implantable VNS therapy for possible treatment of autonomic nervous system disorders. In this work, we investigate the patient outcomes for n-VNS devices applied in tandem with traumatic stress. A total of 25 human subjects participated in a double-blind study,...
Conference Paper
Full-text available
With the advent of non-invasive vagus nerve stimulation (n-VNS) devices, numerous studies have explored the viability of n-VNS as an alternative to implantable VNS. In recent work exploring biomarkers, the amplitude of the peripheral photoplethysmogram (PPG) was shown to increase due to n-VNS application; however, with results based on time average...
Data
Effects of a behavioral intervention using biofeedback on myocardial blood flow changes during mental stress in patients with coronary artery disease. Protocol document provides detailed description of each intervention applied to patients with CAD. (PDF)
Data
R-squared values and 95% CI for stress reactivity and Gensini scores. R-squared values and 95% CI (lower bound, upper bound) values from the linear models derived from the change in each physiological measure and the corresponding Gensini score. The changes were assessed as the difference between stress and rest values for each physiological measur...
Data
Consolidated Standards of Reporting Trials (CONSORT) checklist of the manuscript. (DOC)
Data
Lists the physiological outcomes for each young, heathy and aging subject with CAD, each are in separate sheets. (XLSX)
Data
Statistical analyses on the CAD group’s baseline, first minute of stress, and overall stress on HR, SBP, DBP, PP. Baseline, first minute of stress, overall stress values represent mean (SD). P-values were calculated from ANOVA (for normal data) or Kruskal-Wallis (for non-normal data) on the three intervals (baseline, first minute of stress, overall...
Conference Paper
A non-invasive, soft, thermal modulation system was designed and evaluated for use in physiological experiments to assess neuro-vascular health. The system stimulates biomechanisms involved in thermoregulation by varying the temperature of the skin with a soft, fluidically-controlled thermal pad. The silicone-based thermal pad was strategically emb...
Conference Paper
Full-text available
The evaluation of cardiovascular autonomic function plays an essential role in explaining autonomic nervous system activity in diverse conditions for clinical and preclinical research. Long-term analysis of heart dynamics, widely studied as heart rate variability, require long-term (>24 hours) obtrusive electrocardiography (ECG) recordings, potenti...
Conference Paper
Full-text available
This live demonstration presents a wearable system for neuro-vascular health assessment. The system is comprised of three key subcomponents: 1) a soft, fluid-driven thermal modulation pad, 2) a portable case containing electrical and mechanical hardware, and 3) off-board biosignal processing and power units. The soft thermal modulation pad (the onl...
Conference Paper
Full-text available
Introduction: Non-invasive Vagal Nerve Stimulation (nVNS) shows promise as a new form of neuromodulation that could have applications to patients with mental health disorders. The anterior cingulate plays an important role in modulation of emotion and response to stress, and alterations in function in this region have been associated with stress-re...
Conference Paper
Full-text available
Unobtrusive monitoring of physio-behavioral variables from animals can minimize variability in preclinical research and thereby maximize the potential for clinical translation. In this paper, we present the design, implementation, and validation of an instrumented nest providing continuous recordings of seismocardiogram (SCG) signals and skin tempe...
Conference Paper
Full-text available
Introduction: Autonomic nervous system imbalance with elevated sympathetic activity is the hallmark of many mental disorders, and vagus nerve stimulation (VNS) using an implantable device is a proven treatment method to address such imbalance. Non-invasive cervical VNS (n-VNS) offers an inexpensive and low-risk alternative to implantable VNS devic...
Conference Paper
Full-text available
Transcutaneous vagus nerve stimulation (t-VNS) is a promising technology for modulating brain function and possibly treating disorders of the central nervous system. While handheld devices are available for t-VNS, stimulation efficacy can only be quantified using expensive imaging or blood biomarker analyses. Additionally, the parameters and "dosag...
Article
Sympathetic nervous system (SNS) activity plays a significant role in cardiovascular control. Pre-ejection period (PEP) is a non-invasive biomarker that reflects SNS activity. In this paper, unobtrusive estimation of PEP of the heart using ballistocardiogram (BCG) and electrocardiogram (ECG) signals is investigated. Although previous work has shown...
Technical Report
Full-text available
The structure of an animal's eye is determined by the tasks it must perform. While vertebrates rely on their 2 eyes for all visual functions, insects have evolved a wide range of specialized visual organs to support behaviors such as prey capture, predator evasion, mate pursuit, flight stabilization, and navigation. Compound eyes and ocelli constit...
Thesis
The structure of an animal’s eye is determined by the tasks it must perform. While vertebrates rely on their two eyes for all visual functions, insects have evolved a wide range of specialized visual organs to support behaviors such as prey capture, predator evasion, mate pursuit, flight stabilization, and navigation. Compound eyes and ocelli const...

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Projects

Projects (7)
Project
The autonomic response to acute emotional stress can be highly variable, and pathological responses are associated with increased risk of adverse cardiovascular events. We evaluated the autonomic response to stress reactivity of young healthy subjects and aging subjects with coronary artery disease to understand how the autonomic stress response differs with aging
Project
Local heating and cooling of the skin are employed in scientific experiments to evaluate the physiological responses to temperature modulation. Conventional procedures include open-loop approaches in which a body part is placed in sudden contact with stimuli, such as a cold-pack, or immersion in cold or hot water. We designed a soft thermal modulation system with embedded fluid channels for neuro-vascular assessment to change the local temperature of skin in a closed-loop fashion. This system would eliminate the unintended physiological stimuli due to sudden, painful modulation used in conventional methods.
Archived project
Non-Invasive Physiological Monitoring