Graduate Student Seminar Series – Bojing Gui

Graduate Student Seminar Series
Please ensure you invite your Principal Investigator by adding their email via the ‘Add Guest’ button and they will also be notified of your presentation.
Location: HS610 – 155 College St, Room 610
Presentation Title: Investigating Cortical Involvement and Spinal Excitability in the Control of Standing Posture
Abstract:
Postural control involves integration of sensory inputs and motor commands within the spinal cord and brain. While studies have investigated the role of descending corticospinal commands and spinal reflexes in maintaining balance using methods such as motor evoked potentials (MEPs) using transcranial magnetic stimulation (TMS) and H-reflexes using peripheral nerve stimulation, the exact pathways involved remain unclear. We aim to contribute to this understanding by exploring the effects of posture on spinal motoneurons by utilizing F-waves as a direct measure of their excitability. Furthermore, we wish to further investigate corticospinal and spinal pathways by isolating the effects of body position and both voluntary and postural muscle activity to understand the specific factors influencing postural control.
Data collection from healthy participants is ongoing. Participants performed four tasks: natural standing, supported standing with voluntary muscle contraction, supported standing, and sitting. Electromyographic signals from the soleus, medial head of gastrocnemius, and tibialis anterior muscles was recorded. Visual feedback was used to ensure consistent muscle activity during voluntary contraction to match natural standing. Soleus F-waves, H-reflexes, and MEPs were measured.
Results from 16 participants (8F) indicate that MEP measures of cortical excitability show modulation of the silent period. A shorter silent period in voluntary activation indicates decreased cortical inhibition, thus increased cortical excitability compared to standing. Meanwhile, F-wave measurements of spinal excitability shows that spinal motoneuron excitability is not modulated by position or activity. This indicates that modulation due to voluntary activation does not originate in the spinal cord. Thus, voluntary activation involves increased cortical control, while postural control has greater involvement of subcortical structures despite matched position, muscle activity, and spinal excitability.
Supervisor Name: Kei Masani
Year of Study: 3
Program of Study: MASc
Powered by Calendly.com