Author ORCID Identifier
0009-0007-2529-1130
Document Type
Dissertation
Date of Award
5-31-2025
Degree Name
Doctor of Philosophy in Electrical Engineering - (Ph.D.)
Department
Electrical and Computer Engineering
First Advisor
MengChu Zhou
Second Advisor
Mesut Sahin
Third Advisor
Qing Gary Liu
Fourth Advisor
Xuan Liu
Fifth Advisor
Sergei Adamovich
Sixth Advisor
Xiaobo Li
Abstract
Noninvasive brain stimulation (NIBS) is increasingly utilized in clinical trials for the treatment of neurological disorders. Each NIBS technique offers distinct advantages. Transcranial electrical stimulation (tES) is easy to apply and requires only simple equipment, while transcranial magnetic stimulation (TMS) can penetrate deeper than tES into the brain and it is more focal. Transcranial focused ultrasound stimulation (FUS) is superior to both in terms of penetration and focal stimulation. This study focuses on the modulation of the cerebellum, traditionally believed to be associated with motor coordination but increasingly recognized for its role in cognition and emotion as well. While tES has been extensively applied to other brain regions, cerebellar transcranial alternating current stimulation (ctACS) has only recently garnered interest. FUS is also emerging as a promising method for deep brain modulation.
This dissertation investigates the neuromodulatory effects of ctACS and FUS on cerebellar circuits. The first objective is to elucidate how cerebellar nuclear (CN) cell spiking activity is transsynaptically entrained by AC stimulation in an intensity- and frequency-dependent manner. The second objective is to explore the temporal and steady-state characteristics of PC-CN interactions under clinically relevant stimulation waveforms, such as bursts of AC stimulation at the theta frequencies. Experiments are conducted in anesthetized rats with the electrical stimulations applied to the cerebellar cortex while the spiking activity of PC and CN cells are recorded extracellularly. Results reveal a frequency-dependent modulation, with midrange frequencies (100-150 Hz) being most effective. CN activity generally follows the transient entrainment patterns of projecting PCs but exhibit a suppression during steady-state responses at high frequencies. The third objective is to assess how PC activity is modulated by FUS across varying pulse durations and pulse repetition frequencies. A 500 kHz ultrasound transducer, applied through a coupling cone filled with degassed water, targets the cerebellar cortex from the posterior side. PCs exhibit spike entrainment to the FUS pattern, with spike probability peaking at around 1 ms after stimulus onset, irrespective of pulse duration (0.5, 1, or 2 ms).
In summary, both ctACS and FUS effectively modulate the single cell activity in the cerebellar cortex, and indirectly in the CN by PC projections. The observed CN response patterns provide mechanistic insights that may help explain clinical findings and inform future trials investigating ctACS as a neuromodulation therapy.
Recommended Citation
Kang, Qi, "Modulation of cerebellar cells by transcranial ac stimulation in anesthetized rats" (2025). Dissertations. 1835.
https://digitalcommons.njit.edu/dissertations/1835
