Ultrasonic Modulation of Astrocytic and Neuronal Calcium Dynamics in Mouse Cortex
Yu Yong, Hao Jiang, Chaofeng Qiao, Zhuoyan Liu, Xiaohan Zhou, Yufeng Zhou, Fenfang Li
2025 · 10.1101/2025.03.03.641164
Abstract
Background Astrocytes are abundant in the brain and their calcium signaling is reported to have an important effect on neuronal activity in both physiological and pathological conditions. Low-frequency focused ultrasound (FUS) has recently emerged as a powerful noninvasive neuromodulation approach, yet its impact on astrocyte calcium dynamics in different brain states in vivo is poorly understood. Objective This study aimed to elucidate the effects of non-thermal FUS on astrocyte calcium dynamic with in vivo cellular-resolution and cell-type-specific recording and identify whether the influences of FUS on cortical astrocytes and neurons are distinctive and state dependent. Methods Here we combined a customized 0.521MHz FUS transducer with two-photon microscopy, allowing simultaneous single-cell resoultion imaging and FUS stimulation at intensities of 0.91 or 1.5 W/cm 2 to examine astrocyte and neuronal calcium responses in somatosensory cortex of both awake and lightly anesthetized mice. Functional clustering analysis was performed to identify calcium response activated or inhibited subpopulations. Results In awake mice, FUS significantly enhanced the amplitude, frequency, and temporal integral of astrocyte calcium transients, while suppressing neuronal calcium activity and reducing the proportion of activated neuronal subpopulations. In contrast, lightly anesthetized mice displayed a blunted yet increased astrocyte response and negligible neuronal modulation under FUS, suggesting that baseline suppression from anesthesia partially masks FUS effects. Conclusions Our study demonstrated that FUS elicited distinctive, state-dependent effects on cortical astrocytes and neurons, highlighting astrocytes as previously underappreciated targets of ultrasound neuromodulation. These findings will pave the way for FUS-based therapies targeting astrocyte–neuron interactions in conditions involving abnormal brain excitability. Highlights Low duty cycle low frequency focused ultrasound induced negligible heat effects. Ultrasound markedly enhanced astrocyte calcium transients in awake mice. Ultrasound suppressed neuronal calcium activity in awake mice. The effects of ultrasound on both cell types were reduced under light anesthesia.
Abstract via europepmc.
Exposures
Exposure 1: FUS to S1 cortex, 0.91 W/cm2 at 5% DC and 1.5 W/cm2 at 10% DC
Target: primary somatosensory cortex — “somatosensory cortex of both awake and lightly anesthetized mice”
Device: not reported · customized 0.521 MHz ring-shaped transducer
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 521 | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | not reported | ⚑ |
| Duty cycle (%) | 5, 10swept | ✓✓✓ |
| Sonication duration (s) | 60 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 0.91, 1.5swept | ✓✓✓ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
1 min of FUS at 5% duty cycle, 0.91 W/cm2 Isppa or 10% duty cycle, 1.5 W/cm2 Isppa, within a 3 min imaging recording (1 min before, during, after).
Flags from extraction
n_subjects— Only per-cohort counts given (7 awake and 5 anaesthetised mice for astrocytes; 10 awake and 13 anaesthetised for neurons); animals may overlap, total not stated.exposures[0].unspecified_domain.isppa_w_cm2— Isppa quoted for the transducer measured by hydrophone beneath the coverslip in a water tank; domain not explicitly stated per value. Two intensities paired with 5% and 10% duty cycle.exposures[0].timing.pulse_repetition_frequency_hz— PRF and pulse duration not stated in the main text.sham_type— 'No FUS' condition recorded with imaging; paper does not say whether transducer was in place.auditory_control— Authors say pulsed and smoothed waveforms were used to eliminate auditory confound; they cannot exclude auditory contributions.exposures[0].device.family— Transducer described as customized/ring-shaped; maker or builder not stated.