Graduation Semester and Year




Document Type


Degree Name

Master of Science in Biomedical Engineering



First Advisor

Hanli Liu


Transcranial near infrared stimulation or Low Level Laser Therapy (LLLT) is an innovative technique shown to control neuronal function in cell cultures, animal models and clinical conditions. The aim of this study was to use near infrared spectroscopy (NIRS) to evaluate the physiological and functional effects of LLLT on prefrontal cognitive functions in young healthy adults. This study was divided into two parts: the first part investigated the physiological effects of LLLT and the second investigated the functional effects.The aim of the first part of this study was to explore how a single session of LLLT altered the hemodynamic status of the prefrontal cortex. Two experiments were designed to irradiate the therapeutic laser at 1) the centre and 2) the right side of the frontal lobe, while monitoring the changes in hemoglobin concentrations in both hemispheres. The results obtained showed significant hemodynamic changes in responses to the laser stimulation in both the experiments (p<0.01). The objective of the second part of this study was to evaluate whether a single session of LLLT could induce any beneficial effects on the functioning of prefrontal cortex in attention and short-term memory domains. This was achieved by instructing participants to perform two neurocognitive tasks, namely, Psychomotor Vigilance Task (PVT) and Delayed Match-to-Sample (DMS) memory task, before and after LLLT. PVT was used to evaluate individual’s sustained attention, while DMS memory task was used to examine short-term memory. Functional near infrared spectroscopy (FNIRS) was used to record the hemodynamic responses of the brain while the subjects were performing these tasks. Pre- and post- treatment results were compared to evaluate the effects of LLLT. Results in this part of study showed insignificant improvement in the performance of PVT after LLLT (p > 0.05), but significant improvement in the performance of the DMS task (p < 0.05). The results in this study indicate that LLLT could lead to the development of non-invasive, performance-enhancing interventions in healthy humans, which in future might be applicable on those in need of neurorehabilitation.


Biomedical Engineering and Bioengineering | Engineering


Degree granted by The University of Texas at Arlington