John T. Johnson

Georgia Tech

555 14th St NW

Atlanta, Ga 30318

My doctoral research was related to the neural and behavioral effects of sensory changes on the way we understand and execute reach to grasp actions. This research is applicable to people with limb difference as well as other types of sensory loss, such as stroke or diabetic neuropathy. My research experience runs the gamut from building research equipment for human subjects research, to collecting EEG, fMRI, and motion capture data, analyzing those data, and preparing visualizations, and presenting and publishing results. My previous background in electronics, programming, and field engineering has allowed me to build research equipment for our lab and mentor and assist other grad students in developing their own research equipment. I have also developed equipment that has allowed our lab to collect rich datasets of co-registered data from disparate systems, such as EEG, motion capture, and eye tracking systems.

Having finished my PhD, I am looking for an employer for which I can apply my broad range of research, scientific, and engineering skills to help them address their most interesting and challenging problems.

posts

Thoughts on Information Transmission Through Space and Time

selected publications

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

Abs

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.
Partial-Hand Prosthesis Users Show Improved Reach-to-Grasp Behaviour Compared to Transradial Prosthesis Users with Increased Task Complexity

Alterman, Bennett L., Keeton, Emily, Ali, Saif, Binkley, Katrina, Hendrix, William, Lee, Perry J., Wang, Shuo, Kling, James, Johnson, John T., and Wheaton, Lewis A.

Journal of Motor Behavior Apr 2022

Abs

Approaches to improve outcomes after upperextremity amputation remain poorly understood. Examining prosthesis-use at different levels of loss elucidates motor control challenges. Non-amputated participants completed simple and complex reach-to-grasp actions using a body-powered transradial or partial-hand prosthesis simulator. We hypothesised that increased task complexity and participants using a partial-hand device would show greater functional adaptation compared to participants using a transradial device. Partialhand users demonstrated variable grasp postures and higher reach peak velocities in the complex, but not simple, task. All groups showed decreases in movement duration in the complex task, but only partial-hand users improved in the simple task. These behavioural changes suggest how device level and task may influence prosthesis-use, with relevance to amputation rehabilitation.
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

Abs

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.