Degree

Doctor of Philosophy (PhD)

Department

Kinesiology

Document Type

Dissertation

Abstract

Abstract

In this dissertation, we examined the effects of single and multiple sessions of anodal high-definition transcranial direct current stimulation (HD tDCS) on the left dorsolateral prefrontal cortex (LDLPFC) to mitigate the effect of cognitive fatigue, specifically focusing on Stroop response time(s) (RSPT), and accuracy percentages related to incongruent and congruent stimuli responses. A simple motor task was also designed to evaluate movement time (MT) and reaction time (RT). We designed a 20-minute Stroop color-naming task to induce cognitive fatigue while the participants engaged in one of three tDCS stimulation conditions: a single 20-minute HD tDCS session (ST20); two 10-minute HD tDCS sessions separated by a 5-minute break (STB1 & STB2); and a sham stimulation (SH). Motor performance (MT & RT) was assessed directly after tDCS and the Stroop task using a discrete, simple arm-movement task on a digitized tablet.

The motor task results revealed that movement time (MT) was significantly faster in the ST20 group than in the SH group. Additionally, Stroop data indicated that participants exhibited significantly faster response times (RSPT) during stimulation following the break (STB2) than in the SH protocol. We found no differences in the proportion of incorrect incongruent responses across the three conditions. However, we found that participants in the STB2 group responded more quickly to incongruent stimuli. The results show that short, repeated anodal HD tDCS bouts can significantly modulate the effects of cognitive fatigue on RSPT and the processing of incongruent stimuli. Results also show that a single 20-minute session of HD tDCS over the LDLPFC may improve MT in a simple motor task.

The results of this experiment will provide valuable insights into how short anodal HD tDCS sessions over the LDLPFC can affect neuronal behavior, even when cortical resources are reduced by fatigue. Moreover, given the current limited understanding of tDCS’s effectiveness in alleviating cognitive fatigue, these findings advance our knowledge of brain stimulation and its cognitive-motor outcomes. In the future, researchers should continue to focus on enhancing our understanding of the differences between single- and repeated-session tDCS and cognitive fatigue. If single or multiple sessions of tDCS can safely reduce some of the effects of cognitive fatigue, it may significantly help professionals across various fields overcome the challenges posed by cognitively demanding situations.

Date

5-25-2026

Committee Chair

Arend Van Gemmert

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Wednesday, May 26, 2027

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Motor Control Commons

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