tES Induces Frequency Dependent Patterns of Neuronal Activation

Publication Date

July 2026

Document Type

Abstract

Start Date

24-7-2026 9:00 AM

End Date

24-7-2026 3:00 PM

Description

Transcranial electrical stimulation (tES) is an emerging non-invasive technique for modulating neural circuit activity and behavior. We previously demonstrated that 6 Hz tES reduces fear memory retention and enhances fear extinction. To better understand the cellular mechanisms underlying these behavioral effects, we examined frequency-dependent neuronal activation across the cerebellar cortex following stimulation. Adult male wild-type mice received either sham stimulation or tES at 6 Hz or 40 Hz. Ninety minutes after stimulation, brains were collected, fixed, cryoprotected, sectioned, and processed for immunohistochemistry. Sections containing cerebellar vermis lobules V–VI were stained for c-Fos, calbindin, and neuronal nitric oxide synthase (nNOS), counterstained with DAPI, and imaged using confocal microscopy. Quantitative fluorescence analysis was used to compare neuronal activity across the granule cell layer, Purkinje cell layer, and molecular layer. Compared with sham controls, 6 Hz stimulation significantly increased c-Fos immunoreactivity throughout the granule cell layer, Purkinje cell layer, and molecular layer. In contrast, 40 Hz stimulation produced a more restricted pattern of activation, with increased cFos expression primarily in the outer molecular layer. Direct comparisons between stimulation frequencies showed that 6 Hz elicited significantly greater c-Fos activity in the outer molecular layer and Purkinje cell layer than 40 Hz stimulation, while only a trend toward greater activation was observed in the granule cell layer. Notably, these frequency-dependent activation patterns were not confined to lobules V–VI, suggesting that different stimulation frequencies recruit distinct neuronal populations throughout the cerebellar cortex. Together, these findings demonstrate that tES frequency shapes the spatial pattern of neuronal activation within the cerebellar cortex. We propose that these differences are driven primarily by the biophysical properties of brain tissue, with lower-frequency stimulation penetrating more effectively into deeper cerebellar layers and higher-frequency stimulation preferentially influencing more superficial regions. Ongoing analyses will identify the specific neuronal populations recruited by each stimulation frequency and further define how these circuit-level effects contribute to the modulation of fear memory.

Comments

Mentor: Dr. Siqiong "June" Liu, Cell Biology and Anatomy

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Jul 24th, 9:00 AM Jul 24th, 3:00 PM

tES Induces Frequency Dependent Patterns of Neuronal Activation

Transcranial electrical stimulation (tES) is an emerging non-invasive technique for modulating neural circuit activity and behavior. We previously demonstrated that 6 Hz tES reduces fear memory retention and enhances fear extinction. To better understand the cellular mechanisms underlying these behavioral effects, we examined frequency-dependent neuronal activation across the cerebellar cortex following stimulation. Adult male wild-type mice received either sham stimulation or tES at 6 Hz or 40 Hz. Ninety minutes after stimulation, brains were collected, fixed, cryoprotected, sectioned, and processed for immunohistochemistry. Sections containing cerebellar vermis lobules V–VI were stained for c-Fos, calbindin, and neuronal nitric oxide synthase (nNOS), counterstained with DAPI, and imaged using confocal microscopy. Quantitative fluorescence analysis was used to compare neuronal activity across the granule cell layer, Purkinje cell layer, and molecular layer. Compared with sham controls, 6 Hz stimulation significantly increased c-Fos immunoreactivity throughout the granule cell layer, Purkinje cell layer, and molecular layer. In contrast, 40 Hz stimulation produced a more restricted pattern of activation, with increased cFos expression primarily in the outer molecular layer. Direct comparisons between stimulation frequencies showed that 6 Hz elicited significantly greater c-Fos activity in the outer molecular layer and Purkinje cell layer than 40 Hz stimulation, while only a trend toward greater activation was observed in the granule cell layer. Notably, these frequency-dependent activation patterns were not confined to lobules V–VI, suggesting that different stimulation frequencies recruit distinct neuronal populations throughout the cerebellar cortex. Together, these findings demonstrate that tES frequency shapes the spatial pattern of neuronal activation within the cerebellar cortex. We propose that these differences are driven primarily by the biophysical properties of brain tissue, with lower-frequency stimulation penetrating more effectively into deeper cerebellar layers and higher-frequency stimulation preferentially influencing more superficial regions. Ongoing analyses will identify the specific neuronal populations recruited by each stimulation frequency and further define how these circuit-level effects contribute to the modulation of fear memory.