John T. Johnson, PhD

Atlanta, Ga

I am currently a Machine Learning Engineer at Neurogram, Inc., where I develop systems for automated sleep staging, respiratory event detection, and real-time identification of epileptiform phenomena in the ICU. These systems aim to shorten the time from data acquisition to diagnosis and clinical intervention, improving outcomes for both patients and clinical staff.

I completed my PhD in 2022. My doctoral work examined the neural and behavioral effects of sensory changes on reach-to-grasp actions, with relevance to individuals with limb difference and to conditions such as stroke or diabetic neuropathy. My research experience includes designing and building custom instrumentation for human-subjects studies, collecting and analyzing EEG, fMRI, and motion-capture data, and producing scientific visualizations, presentations, and publications.

My earlier background in electronics, programming, and field engineering has enabled me to design and build research equipment for multimodal data collection and to mentor graduate students in developing their own experimental systems. I have created tools that allow for the co-registration of EEG, motion capture, and eye-tracking data, supporting the generation of high-quality datasets for both scientific and clinical applications.

posts

selected publications

Patent

Prosthesis Simulator Devices and Methods

Alterman, Bennett Leonard, Hendrix, William D, Johnson, John T, Lee, Perry J, and Wheaton, Lewis A

2025

Abs

Prosthesis simulator devices including a first restraint configured to restrain one or more fingers of a wearer of the simulator, a second restraint configured to restrain a thumb of the wearer, and a plurality of artificial digits configured to move in a manner to simulate one or more prosthetic fingers and a prosthetic thumb of a prosthesis. The first restraint can be attached to a roof plate connected to a base plate and defining a dorsal side of the prosthesis simulator. The second restraint can be attached to a holster connected to the base plate on a palmar side of the prosthesis simulator. Also disclosed herein are methods of using the same.
Article

Alpha-Band Activity in Parietofrontal Cortex Predicts Future Availability of Vibrotactile Feedback in Prosthesis Use

Johnson, John T., de Mari, Daniele, Doherty, Harper, Hammond, Frank L., and Wheaton, Lewis A.

Experimental Brain Research Mar 2022

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Prosthesis disuse and abandonment is an ongoing issue in upper-limb amputation. In addition to lost structural and motor function, amputation also results in decreased task-specific sensory information. One proposed remedy is augmenting somatosensory information using vibrotactile feedback to provide tactile feedback of grasping objects. While the role of frontal and parietal areas in motor tasks is well established, the neural and kinematic effects of this augmented vibrotactile feedback remain in question. In this study, we sought to understand the neurobehavioral effects of providing augmented feedback during a reach-grasp-transport task. Ten persons with sound limbs performed a motor task while wearing a prosthesis simulator with and without vibrotactile feedback. We hypothesized that providing vibrotactile feedback during prosthesis use would increase activity in frontal and parietal areas and improve grasp-related behavior. Results show that anticipation of upcoming vibrotactile feedback may be encoded in motor and parietal areas during the reach-to-grasp phase of the task. While grasp aperture is unaffected by vibrotactile feedback, the availability of vibrotactile feedback does lead to a reduction in velocity during object transport. These results help shed light on how engineered feedback is utilized by prostheses users and provide methodologies for further assessment in advanced prosthetics research.
Dissertation

The Neurobehavioral Effects of Sensorimotor Dissonance During Observation and Execution with Upper-Extremity Prostheses

Johnson, John Terry

Mar 2022

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The human ability to perform powerful, complex, and intricate actions using our hands is made possible by the hand’s 27 degrees of freedom, its rich sensory feedback, and our ability to observe and understand the actions of others. In the event of an upper-extremity amputation, not only are articulated biological structures lost, but also their available sensory feedback. While great advances have been made in prosthesis engineering, the rate of prosthesis use in upper-extremity amputees remains low. Those who choose to use a prosthesis only do so an average of 50% of the time they could use them. One proposed strategy to improve prosthesis use and acceptance is the provision of task-salient vibrotactile feedback. Studies have been conducted on the efficacy of vibrotactile feedback, but have largely focused on kinematics, leaving a dearth of knowledge regarding the neural effects of vibrotactile feedback. In …
Article

Neurorehabilitation in Adults With Traumatic Upper Extremity Amputation: A Scoping Review

Rydland, Jake, Spiegel, Stephanie, Wolfe, Olivia, Alterman, Bennett, Johnson, John T, and Wheaton, Lewis A

Neurorehabilitation and Neural Repair Dec 2021

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Background Most of the current literature around amputation focuses on lower extremity amputation or engineering aspects of prosthetic devices. There is a need to more clearly understand neurobehavioral mechanisms related to upper extremity amputation and how such mechanisms might influence recovery and utilization of prostheses. Objective This scoping review aims to identify and summarize the current literature on adult traumatic upper limb amputation in regard to recovery and functional outcomes and how neuroplasticity might influence these findings. Methods We identified appropriate articles using Academic Search Complete EBSCO, OVID Medline, and Cochrane databases. The resulting articles were then exported, screened, and reviewed based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) guidelines. Results Eleven (11) studies met the study criteria. Of these studies, 7 focused on sensory involvement, 3 focused on neuroplastic changes post-amputation related to functional impact, and 1 study focused on motor control and learning post-amputation. Overall, these studies revealed an incomplete understanding of the neural mechanisms involved in motor rehabilitation in the central and peripheral nervous systems, while also demonstrating the value of an individualized approach to neurorehabilitation in upper limb loss. Conclusions There is a gap in our understanding of the role of neurorehabilitation following amputation. Overall, focused rehabilitation parameters, demographic information, and clarity around central and peripheral neural mechanisms are needed in future research to address neurobehavioral mechanisms to promote functional recovery following traumatic upper extremity amputation.