Graduate Studies


First Advisor

Gregory R. Bashford

Date of this Version


Document Type



Hage, Benjamin. “Hemodynamics during Pneumotactile Somatosensory Stimulation Measured by Transcranial Doppler Ultrasound.’” Master’s thesis, University of Nebraska-Lincoln, 2017.


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agricultural and Biological Systems Engineering, Under the Supervision of Professor Gregory R. Bashford. Lincoln, Nebraska: December, 2017

Copyright 2017 Benjamin D. Hage


Stroke is the fourth leading cause of death in the United States, and causes tremendous burden due to disability worldwide. Ischemic stroke occurs when blood flow to the brain is blocked, leading to neural cell death if the flow is not re-established. Transcranial Doppler ultrasound (TCD) is a medical imaging modality that measures blood flow in the brain with high temporal resolution. We used TCD to study hemodynamic changes evoked by a pneumotactile somatosensory stimulus applied to the palmar skin of the right hand. The stimulus was generated by a Galileo device and consisted of very short pressures pulses travelling across the hand at traverse velocities ranging from 5 to 65 cm/s. This stimulus shows potential for preventing damage due to ischemic strokes and for rehabilitation of stroke survivors. The goal of this work was to understand how pneumotactile stimulation with the Galileo device affects cerebral blood flow in healthy adults, which will provide a reference for how pneumotactile stimulation with the Galileo will affect cerebral blood flow in adults with chronic and acute stroke.

This work first looked at how time length of stimulus affects the maximum percent change in cerebral blood flow velocity (CBFV) and the lateralization of CBFV during pneumotactile somatosensory stimulation using the Galileo device. Three time lengths were used: 10, 20, and 30 s. It was found that the 20 s stimulus length had the largest increase in CBFV and the most lateralized response.

We next looked at the hemodynamic output for a particular stimulus velocity and time length to characterize the hemodynamic response function (HRF) for healthy adults. This involved: (1) measuring characteristics of the hemodynamic response function (HRF), (2) comparing percent change over time in the right and left middle cerebral arteries (MCAs) to determine if the response was lateralized, and (3) observing the time course of the transient response to stimulation to see how long it takes for the transient response to return to steady state. It was found that the response did show lateralization, and did return to steady state within 1 minute of stimulus removal.

Advisor: Gregory R. Bashford