The neural correlates of executive functioning of adults with different language profiles
Executive functioning is critical for goal-directed problem solving and attention, and is a foundational tenet for learning throughout the lifespan. Robust empirical evidence in the field of linguistics and cognitive psychology show that bilingualism can significantly enhance executive functioning. However, bilingualism is not monolithic, and proficiency levels can vary greatly in the United States where linguistic assimilation to English is the norm. Thus, it is still an empirical question of what proficiency 'threshold' might be necessary in order to reap the benefits of bilingualism. Heritage speakers, e.g. those who acquired Spanish as their first language but are more dominant and comfortable in English, are a growing demographic in the United States. Research is needed on these types of bilinguals in addition to fully productive bilinguals as compared to monolingual adults.
Here in the ANS lab, we are conducting the first study to compare executive functioning of monolinguals, bilinguals, and heritage speakers. Executive functioning is being measured by two standardized, validated assessments. We are simultaneously examining the neural recruitment of executive functioning via functional Near-Infrared Spectroscopy (fNIRS). With this research project, we aim to shed light on the neural correlates of executive functioning in young adults with different language profiles.
This study is funded by the Ronald E. McNair Undergraduate Post-Baccalaureate Achievement Program (PI: Valentina Dargam), as well as Robert Wood Johnson Foundation.
A Naturalistic Investigation of Brain Neuroplasticity in Children Born Prematurely
Prematurity is a risk factor for cognitive impairment including deficits in executive functioning. Executive functioning is responsible for a child's cognitive and adaptive functioning, goal-directed behavior, social interaction, and emotional control. Deficits in executive functioning may be the underlying mechanism of the well-documented poorer academic achievement in children born preterm. The disparity in preterm children's cognitive abilities calls for identifying ways to minimize their impairments. Bilingualism may offer an important direction for this search. For example, it is well established that bilingual children significantly outperform monolingual children on tests of executive functioning. The brain mechanisms associated with the bilingual advantage are plastic; they can be developed. No prior work, however, has involved children born prematurely, who arguably could benefit from brain changes associated with environmental stimuli such as that provided by bilingualism. Here in the ANS lab, we are examining preterm children's linguistic environment, exploring the possibility that bilingualism positively moderates this population's executive functioning, as it does for term children.
This study is funded by the Robert Wood Johnson Foundation.
Dr. Ashley Darcy Mahoney (Baptist Children's Hospital), Dr. Melissa Baralt, Valentina Dargam, Anil Thota, Dr. Liliana Rincón González, Victoria Leon, Caitlyn Myland, Dr. Ranu Jung (Florida International University)
Neural Enabled Prosthesis for Upper Limb Amputees
As we use a hand to manipulate an object, high quality control is enabled by multi-modal, distributed, and graded sensations from somatosensory receptors. Today's motorized upper limb prostheses do not afford amputees with high quality control due to the lack of critical information such as contact force and hand opening, which results in an increased reliance on visual feedback and high attentional demands. It follows that there is a large population of amputees whose needs are not being fully met by current prosthetic hand technology, which results in reduced quality of life.
To address this problem, we, at the Adaptive Neural Systems lab, in collaboration with commercial and clinical partners have developed an Adaptive Neural Systems-Neural-Enabled Prosthetic Hand (ANS-NEPH) system intended to provide the sense of touch, grasp force and hand opening to the user by sending electrical stimulation pulses to nerves of the residual limb. The system includes a neural stimulation device and an instrumented prosthetic hand. It uses signals derived from sensors on the instrumented prosthetic hand to elicit sensations by delivering stimulation via fine-wire longitudinal intrafascicular electrodes (LIFEs) implanted in peripheral nerves of the residual limb.
The technology has received approval from the US Food and Drug Administration as an investigational device and is being evaluated in a clinical trial supported by a grant from the HAPTIX program under the Defense Advanced Research Projects Agency (DARPA).
Neural Enabled Prostheses with Sensorimotor Integration
There are more than 1.7 million individuals living with amputations in the United States alone and this number is projected to reach 3.6 million by 2050. Even though prosthetic technology continues to advance, adequate replacement of the human hand and arm remains one of the most difficult problems facing medical technology. The current “state of the art” upper limb prosthetics remain inadequate as replacements for the lost limb, despite significant advancements in technology. Hence, patient satisfaction, use, and compliance remain less than ideal. A truly advanced prosthetic system will require seamless integration of the intact sensory-motor living system with advanced highly capable artificial limbs. We have developed an advanced prosthetic system that will provide sensory feedback to an upper extremity amputee using sensors embedded in the prosthetic hand to determine fingertip forces and hand opening to control an implanted electrical stimulation device. In turn, the stimulation device elicits sensation by delivering weak electrical pulses via electrodes implanted in the fascicles of the peripheral nerve in the residual arm. The National Institute of Biomedical Imaging & Bioengineering (NIBIB) and National Institute of Child & Human Development (NICHD) fund this endeavor.
Computation-Enabled Adaptive Ventilatory Control System (CENAVEX)
Thousands of people have a spinal cord injury that severely impairs or completely paralyzes the respiratory musculature. This project will develop a smart adaptive ventilatory control system that activates paralyzed muscles by a personalized electrical stimulation pattern that meets the ventilatory needs of the individual. It will overcome drawbacks of mechanical ventilation or prefixed stimulation by utilizing neuromorphic spiking neural networks. Supported by National Institute of Neurological Disorders and Stroke.
Sensory Perception and Motor Control in Adults
With more than 1 million individuals living with amputations in the United States, the development of advanced prostheses is imperative. However, adequate replacement of the human hand and arm remains problematic. In other projects, we developed an advanced prosthetic system that will be capable of providing sensory feedback to upper extremity amputees using sensors embedded in the prosthetic hand. To test how well the amputee is able to control the advanced prosthesis, we have developed a variety of measurement devices and sensorimotor assessment protocols and we have purchased a validated instrument (SHAP: Southampton Hand Assessment Procedure, a clinically validated hand function test developed to assess the effectiveness of upper limb prostheses). However, to characterize the benefits of the prosthetic system fully, we need to know the capabilities of able-bodied (control) subjects on the testing procedures that we have developed or adopted from the literature. Therefore, the goals of this research study are to investigate sensation, perception, and motor control in healthy adults.
Non-invasive Electrical Neurostimulation for Sensory Feedback
People rely on sensory feedback for everyday function, including planning and control of even simple movements, such as reaching for an object. Loss of sensory function due to disease or limb amputation can be a devastating, life-changing event.
About 185,000 Americans suffer from limb loss every year. Despite the recent advances in myoelectric prostheses, they remain limited in their ability to provide sensory feedback to the users, which increases reliance on visual cues and attentional demands, resulting in substantial functional deficits and negative impact on their quality of life.
Recent efforts to incorporate sensory feedback into prosthetic systems include invasive approaches through the use of implanted electrodes for direct sensory nerve activation; while non-invasive approaches have relied on the activation of sensory receptors through mechanical or electrical tactile input. Although implantable neural stimulators have shown potential for providing naturalistic referred sensations, they require invasive surgical procedures not acceptable to all. Transcutaneous electrical stimulation (TES) has been explored as a non-invasive alternative for delivering sensory feedback more effectively than mechanical stimulation methods. However, traditional TES approaches for sensory feedback using single-channel stimulation are hampered by large charge requirements, low selectivity, distracting local sensations, and limited stability.
The purpose of this study is to develop a non-invasive multichannel neurostimulation platform capable of evoking distally referred sensations to deliver graded multimodal feedback more comfortably, efficiently and consistently than traditional TES approaches. In this study we will evaluate the perceptions elicited by the stimulation and quantify enhancements in functional discrimination of sensory information and closed-loop prosthesis control capabilities.
CRCNS: Improving Bioelectronic Selectivity with Intrafascicular Stimulation
The network of peripheral nerves offers extraordinary potential for modulating and/or monitoring the functioning of internal organs or the brain. To influence neural activity for desired outcomes, neural interface technology must access the appropriate peripheral nerve tissue, activate it in a focal targeted manner, and alter the patterns of activity. The anatomical organization of peripheral nerves, which consists of multiple nerve fibers clustered into one or more fascicles, presents opportunities and challenges for precise control of spatiotemporal patterns. This US-French collaborative project will utilize computational models pf peripheral nerves to develop and analyze new strategies for selective stimulation of nerve fibers within individual fascicles, and develop and utilize a hardware platform to enable real-time implementation and evaluation of the strategies with a set of longitudinal intrafascicular electrodes in in vivo studies in anesthetized rabbits. The work is supported by a grant from the National Institute of Biomedical Imaging and Bioengineering, USA and Agence nationale de la recherché, France.