Patricia Shewokis
Drexel University, Biomedical Engineering, Faculty Member
Research Interests:
Background / Purpose: Recent evidence suggests that deficits in frontally-mediated executive skills occur in up to 50% of individuals with Amyotrophic Lateral Sclerosis (ALS). Functional Near Infrared Spectroscopy (fNIR) is a safe,... more
Background / Purpose: Recent evidence suggests that deficits in frontally-mediated executive skills occur in up to 50% of individuals with Amyotrophic Lateral Sclerosis (ALS). Functional Near Infrared Spectroscopy (fNIR) is a safe, noninvasive, affordable, and portable neuroimaging technology that may be useful in detecting pathophysiologic changes in the frontal lobe that may correlate with cognitive involvement. The objective of this study was to examine and compare hemodynamic changes detected by fNIR during challenging cognitive tasks in individuals with ALS and healthy controls. Main conclusion: Differences in oxygen utilization between ALS and healthy controls were noted despite the lack of gross cognitive impairment in the ALS group, implying that fNIR may be more sensitive to early cognitive changes than neuropsychological testing alone. Correlations between fNIR measures and respiratory, executive, and behavioral subscales also imply that fNIR is sensitive to changes in the...
When Licklider published Man-Computer Symbiosis in 1960, he stated that ldquoIt seems entirely possible that, in due course, electronic or chemical ldquomachinesrdquo will outdo the human brain in most of the functions we now consider... more
When Licklider published Man-Computer Symbiosis in 1960, he stated that ldquoIt seems entirely possible that, in due course, electronic or chemical ldquomachinesrdquo will outdo the human brain in most of the functions we now consider exclusively within its province. (p.2)rdquo The brain-machine interface Licklider envisioned has been extended beyond his initial conceptions by noninvasive and portable technologies, such as EEG
Research Interests:
Brain-computer interface (BCI) provides patients suffering from severe neuromuscular disorders an alternative way of interacting with the outside world. The P300-based BCI is among the most popular paradigms in the field and most current... more
Brain-computer interface (BCI) provides patients suffering from severe neuromuscular disorders an alternative way of interacting with the outside world. The P300-based BCI is among the most popular paradigms in the field and most current versions operate in synchronous mode and assume participant engagement throughout operation. In this study, we demonstrate a new approach for assessment of user engagement through a hybrid classification of ERP and band power features of EEG signals that could allow building asynchronous BCIs. EEG signals from nine electrode locations were recorded from nine participants during controlled engagement conditions when subjects were either engaged with the P3speller task or not attending. Statistical analysis of band power showed that there were significant contrasts of attending only for the delta and beta bands as indicators of features for user attendance classification. A hybrid classifier using ERP scores and band power features yielded the best ov...
Research Interests:
In this study, a Brain Computer Interface (BCI) based on the P300 oddball paradigm has been developed for spatial navigation control in virtual environments. Functionality and efficacy of the system were analyzed with results from nine... more
In this study, a Brain Computer Interface (BCI) based on the P300 oddball paradigm has been developed for spatial navigation control in virtual environments. Functionality and efficacy of the system were analyzed with results from nine healthy volunteers. Each participant was asked to gaze at an individual target in a 3×3 P300 matrix containing different symbolic navigational icons while EEG signals were collected. Resulting ERPs were processed online and classification commands were executed to control spatial movements within the MazeSuite virtual environment and presented to the user online during an experiment. Subjects demonstrated on average, ∼89% online accuracy for simple mazes and ∼82% online accuracy in longer more complex mazes. Results suggest that this BCI setup enables guided free-form navigation in virtual 3D environments.
Research Interests:
Research Interests: Psychophysiology, Brain Imaging, Working Memory, Understanding, Aviation, and 10 moreHuman Factors in Aviation, Aviation Psychology, Air traffic control, Physiological Measurements, Near Infrared Spectroscopy, Cerebral Oxygenation, Mental workload measures, Task Difficulty, Optical brain imaging, and Human Factors In Design
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To examine the role of reflex activity in spasticity and the relationship between peak passive torque, Ashworth Scale (AS), and Spasm Frequency Scale (SFS) of the knee flexors and extensors during the measurement of spasticity using an... more
To examine the role of reflex activity in spasticity and the relationship between peak passive torque, Ashworth Scale (AS), and Spasm Frequency Scale (SFS) of the knee flexors and extensors during the measurement of spasticity using an isokinetic dynamometer in children with spinal cord injury (SCI). Eighteen children with chronic SCI and 10 children of typical development (TD) participated. One set of 10 passive movements was completed using an isokinetic dynamometer at 15, 90, and 180 degrees per second (deg/s) while surface electromyographic data were collected from the vastus lateralis (VL) and medial hamstrings (MH). Spasticity was clinically assessed using the AS and SFS. There were no significant differences in peak passive torque of the knee flexors and extensors at any velocity for children with SCI compared to children with TD. Children with TD demonstrated significantly more reflex activity of the MH during the assessment of knee flexor spasticity at all movement velociti...
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Research Interests:
To harness the increased dexterity and sensing capabilities in advanced prosthetic device designs, amputees will require interfaces supported by novel forms of sensory feedback and novel control paradigms. We are using a motorized elbow... more
To harness the increased dexterity and sensing capabilities in advanced prosthetic device designs, amputees will require interfaces supported by novel forms of sensory feedback and novel control paradigms. We are using a motorized elbow brace to feed back grasp forces to the user in the form of extension torques about the elbow. This force display complements myoelectric control of grip closure in which EMG signals are drawn from the biceps muscle. We expect that the action/reaction coupling experienced by the biceps muscle will produce an intuitive paradigm for object manipulation, and we hope to uncover neural correlates to support this hypothesis. In this paper we present results from an experiment in which 7 able-bodied persons attempted to distinguish three objects by stiffness while grasping them under myoelectric control and feeling reaction forces displayed to their elbow. In four conditions (with and without force display, and using biceps myoelectric signals ipsilateral an...
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Research Interests: Brain Imaging, Situation awareness, Spectroscopy, Functional Near Infrared Spectroscopy, Prefrontal Cortex, and 11 moreOptical Imaging, Biomedical Optics, Infrared spectroscopy, Near Infrared Spectroscopy, Brain Computer Interfaces, SITUATIONAL AWARENESS, Cost effectiveness, Task Performance, Mental Workload, Unmanned Aerial Vehicle, and Cognitive overload
Research Interests:
... amputees with tactile and hand position feedback--moving closer to the bionic arm." Technol Health ... the gripper while the elbow exoskeleton is based on a commercial elbow brace. ... a functional muscle (biceps shown)... more
... amputees with tactile and hand position feedback--moving closer to the bionic arm." Technol Health ... the gripper while the elbow exoskeleton is based on a commercial elbow brace. ... a functional muscle (biceps shown) and uses an exoskeleton to backdrive the joint spanned by ...
Research Interests:
We investigated the paradox of the contented working woman among middle and first-line intercollegiate athletics administrators. In this paradox, women report lower salaries than men but express comparable job satisfaction. The sample... more
We investigated the paradox of the contented working woman among middle and first-line intercollegiate athletics administrators. In this paradox, women report lower salaries than men but express comparable job satisfaction. The sample comprised 143 women and 371 men in 106 National Collegiate Athletic Association (NCAA) Division I-A institutions. Job satisfaction was measured with the Job Descriptive Index (Smith, Kendall & Hulin, 1969) and Job in General (Ironson, Smith, Brannick, Gibson & Paul, 1989) scales. Analyses revealed the existence of the paradox: Women were paid significantly less, but were equally satisfied with their jobs. Neither gender was satisfied with promotion opportunities or pay, but both were highly satisfied with their jobs in general--another apparent paradox. The disproportionate number of male respondents raised questions about gender equity in athletics administration.
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Research Interests: Health Behavior, Child health, Obesity, Quality of life, Childhood Obesity, and 21 moreMultidisciplinary, Intention, Motivation, Overweight, Humans, Child, African American, Female, Male, STEM (short form), Body Mass Index, Health Status, African Americans, Middle Aged, Parents, Self Concept, Questionnaires, Adult, Health surveys, Indexation, and Parent‐child Relations
The development of rehabilitation engineering technologies such as the design of smart prosthetics necessitates a deep understanding of brain mechanisms engaged in ecological situations when human interact with new tools and/or... more
The development of rehabilitation engineering technologies such as the design of smart prosthetics necessitates a deep understanding of brain mechanisms engaged in ecological situations when human interact with new tools and/or environments. Thus, we aimed to investigate potential hemodynamic signatures reflecting the level of cognitive-motor performance and/or the internal or mental states of individuals when learning a novel tool with unknown properties. These markers were derived from functional Near Infrared Spectroscopy (fNIR) signals. Our results indicate an increased level of oxy-hemoglobin in prefrontal sensors associated with enhanced kinematics during early compared with late learning. This is consistent with previous neuroimaging studies that revealed a higher contribution of prefrontal areas during early compare to late adaptation learning. These non-invasive functional hemodynamic markers may play a role in bioengineering applications such as smart neuroprosthesis and b...
Research Interests:
Functional Near-Infrared Spectroscopy (fNIR) is an optical brain monitoring technology that tracks changes in hemodynamic responses within the cortex. fNIR uses specific wavelengths of light, introduced at the scalp, to enable the... more
Functional Near-Infrared Spectroscopy (fNIR) is an optical brain monitoring technology that tracks changes in hemodynamic responses within the cortex. fNIR uses specific wavelengths of light, introduced at the scalp, to enable the noninvasive measurement of changes in the relative ratios of deoxygenated hemoglobin (deoxy-Hb) and oxygenated hemoglobin (oxy-Hb) during brain activity. This technology allows the design of portable, safe, affordable,
Research Interests:
MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments. MazeSuite can be used to design and edit adapted virtual 3D environments, track a participants' behavioral performance within the... more
MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments. MazeSuite can be used to design and edit adapted virtual 3D environments, track a participants' behavioral performance within the virtual environment and synchronize with external devices for physiological and neuroimaging measures, including electroencephalogram and eye tracking. Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables continuous, noninvasive, and portable monitoring of changes in cerebral blood oxygenation related to human brain functions. Over the last decade fNIR is used to effectively monitor cognitive tasks such as attention, working memory and problem solving. fNIR can be implemented in the form of a wearable and minimally intrusive device; it has the capacity to monitor brain activity in ecologically valid environments. Cognitive functions assessed through task performance involve patterns of brain activation of th...
Research Interests: Neuroscience, Brain Imaging, Eye tracking, Imaging, Working Memory, and 30 moreFunctional Near Infrared Spectroscopy, Protocol Design, Positron Emission Tomography, Prefrontal Cortex, Cognitive, Space perception, Software, Navigation, Brain, Humans, Virtual Environment, Near Infrared Spectroscopy, Female, Optical, Data acquisition, Spatial, Male, Electroencephalogram, Human Brain, Task Performance, Ecological Validity, Computer User Interface Design, Adult, Cognitive Function, Regional Cerebral Blood Flow, Spatial navigation, Monitoring System, Maze Learning, Frontal Lobe, and Right Handed
A brain computer interface (BCI) is a system that translates neurophysiological signals detected from the brain to supply input to a computer or to control a device. Volitional control of neural activity and its real-time detection... more
A brain computer interface (BCI) is a system that translates neurophysiological signals detected from the brain to supply input to a computer or to control a device. Volitional control of neural activity and its real-time detection through neuroimaging modalities are key constituents of BCI systems. The purpose of this study was to develop and test a new BCI design that utilizes intention-related cognitive activity within the dorsolateral prefrontal cortex using functional near infrared (fNIR) spectroscopy. fNIR is a noninvasive, safe, portable and affordable optical technique with which to monitor hemodynamic changes, in the brain's cerebral cortex. Because of its portability and ease of use, fNIR is amenable to deployment in ecologically valid natural working environments. We integrated a control paradigm in a computerized 3D virtual environment to augment interactivity. Ten healthy participants volunteered for a two day study in which they navigated a virtual environment wit...