Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science


Health and Rehabilitation Sciences


Peters, Sue

2nd Supervisor

Hunter, Susan


The purpose of this exploratory study is to evaluate prefrontal cortex (PFC) activation patterns linked to active and passive paretic ankle dorsiflexion and plantarflexion and somatosensory stimulation (SS) using a reformed paperclip in people with subacute stroke. By using a neuroimaging tool called functional near-infrared spectroscopy (fNIRS) over the PFC, oxygenated and deoxygenated hemoglobin levels were collected in 9 participants. Objectives, including between-condition differences in PFC activation, interhemispheric asymmetry during conditions, and the relationship between interhemispheric asymmetry and clinical outcome measurement (Fugl-Meyer Lower Extremity Assessment, or FMLE), were evaluated using the fNIRS plots and Laterality Index (LI). Results showed that the active condition demonstrated the highest PFC activation, followed by the SS condition, then the passive condition. Two methods (LI and fNIRS plots) investigated interhemispheric asymmetry and divergent findings were found. Moreover, participants who have a higher score on the FMLE demonstrated bilateral PFC activation during active and SS conditions but contralesional activation during the passive condition. Overall, our study provided exploratory results that assist in understanding the role of PFC in ankle sensorimotor functions in people with subacute stroke.

Summary for Lay Audience

Walking is an essential part of people’s lives. In order to walk, the ability to move the ankle up and down and to feel the contact with the ground is important. However, these functions can be impacted after a stroke. Stroke damages the brain. Many people experience challenges regarding movement and sensation in one of their ankles after a stroke. Recent research has highlighted the relationship between brain activity and its role in arm and hand rehabilitation after a stroke. However, the role of brain activity in ankle functions is less well understood. Hence, this study intended to clarify the role of the prefrontal cortex (PFC) during ankle movement and sensory conditions. To measure brain activation, functional near-infrared spectroscopy (fNIRS) was placed on the forehead of 9 participants with subacute stroke during three conditions: 1) the active condition: participants moved their ankle up and down on their own; 2) the passive condition: the researcher moved their ankle up and down for them; 3) the SS condition: ankle stimulation using a reformed paperclip. We investigated the differences between conditions, the asymmetrical activation between the affected and unaffected sides of the brain and if there is a relationship between the activation patterns in the brain and their leg functions. Our results indicated that the active condition has the strongest relationship with the PFC, followed by the SS condition and then the passive condition. Two methods that we used to examine the brain activation asymmetry showed us contrary findings. Furthermore, participants who have better functions in the ankle demonstrated a similar amount of PFC activation on both affected and unaffected sides of the brain during the active and the SS condition, but the unaffected side of the brain was more activated during the passive condition. Ultimately, this study can help us understand how the PFC connects with ankle movements and sensation to inform future stroke rehabilitation and better interpretation of recovery outcomes for individuals who have experienced a stroke.