Non-invasive modulation of brain activity and behavior by transcranial radio frequency stimulation.

Abstract

BACKGROUND: Achieving non-invasive, targeted modulation of deep brain tissue remains a major challenge in neurotechnology. Current non-invasive brain stimulation methods-such as transcranial electrical (TES), magnetic (TMS), and focused ultrasound (TFUS) stimulation-suffer from limitations in spatial focality, penetration depth, or skull-related distortions. Radio frequency (RF) energy, which penetrates biological tissue effectively, offers an alternative avenue for neural modulation. This study introduces Transcranial Radio Frequency Stimulation (TRFS) as a novel, non-invasive neuromodulation technique that leverages RF-induced thermal effects to modulate neural activity in vivo. METHODS: We developed a custom RF stimulation system using 945 MHz stub antennas optimized for localized brain heating in mice. Using our unique experimental setup, we developed and tested two operational modes of TRFS:Pristine mode: RF stimulation applied to intact brain tissue.RF-genetics mode: RF stimulation applied to brain regions virally transduced to overexpress the thermosensitive TRPV1 ion channel. Neural activity was recorded using metal-free one-photon fiber photometry with GCaMP calcium indicators. Behavioral effects were assessed through a rotational test in freely moving mice after MK-801-induced hyperlocomotion. Local temperature changes were monitored by optical thermometry. RESULTS: In pristine mode, RF exposure induced temperature rises leading to dose-dependent suppression of cortical parvalbumin (PV) interneuron activity. This neural suppression translated behaviorally into a unilateral rotational bias ipsilateral to the stimulated hemisphere in hyperlocomotive freely moving mice.In RF-genetics mode, RF stimulation of TRPV1-overexpressing regions produced temperature-dependent excitation of neural activity once local change in temperatures exceeded ΔT ≈ 1.5 °C. Behaviorally, this excitation reversed the direction of rotation in hyperlocomotive freely moving mice, yielding a contralateral bias. CONCLUSIONS: TRFS represents a conceptual advance in neuromodulation, uniting the inherent capability of RF energy to target deep brain tissue with the biophysical reliability of thermal modulation. TRFS applications are bimodal, capable of influencing the pristine brain by suppressing the activity of specific neuronal populations in targeted regions, or of exciting selectively transfected neural ensembles expressing thermosensitive TRPV1 ion channels. The latter modality, first introduced here, represents a novel concept termed "RF-genetics." TRFS represents a promising platform for next-generation non-invasive brain stimulation with potential translational applications in treating various neurological and psychiatric disorders.

AI evidence extraction

Main findings

A custom 945 MHz TRFS system produced localized brain heating in mice. In pristine mode, RF-induced temperature rises caused dose-dependent suppression of cortical PV interneuron activity and an ipsilateral rotational bias. In RF-genetics mode (TRPV1 overexpression), RF stimulation produced temperature-dependent excitation once local temperature change exceeded approximately 1.5°C and reversed rotational bias to contralateral.

Outcomes measured

• Local brain temperature change (optical thermometry)
• Neural activity (GCaMP calcium signals via metal-free one-photon fiber photometry)
• Cortical parvalbumin (PV) interneuron activity
• Behavior (rotational bias in freely moving mice after MK-801-induced hyperlocomotion)

Limitations

• Sample size not reported in abstract
• Exposure metrics beyond frequency (e.g., SAR, power density) not reported in abstract
• Duration/timing of RF exposures not reported in abstract
• Animal model; translational relevance to humans not established in abstract

Suggested hubs

• rf-neuromodulation (0.9)
  Introduces and tests transcranial radio frequency stimulation as a neuromodulation technique in vivo.

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    "exposure": {
        "band": "RF",
        "source": "transcranial radio frequency stimulation (stub antennas)",
        "frequency_mhz": 945,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Mice (in vivo); includes virally transduced TRPV1 overexpression in some experiments",
    "sample_size": null,
    "outcomes": [
        "Local brain temperature change (optical thermometry)",
        "Neural activity (GCaMP calcium signals via metal-free one-photon fiber photometry)",
        "Cortical parvalbumin (PV) interneuron activity",
        "Behavior (rotational bias in freely moving mice after MK-801-induced hyperlocomotion)"
    ],
    "main_findings": "A custom 945 MHz TRFS system produced localized brain heating in mice. In pristine mode, RF-induced temperature rises caused dose-dependent suppression of cortical PV interneuron activity and an ipsilateral rotational bias. In RF-genetics mode (TRPV1 overexpression), RF stimulation produced temperature-dependent excitation once local temperature change exceeded approximately 1.5°C and reversed rotational bias to contralateral.",
    "effect_direction": "mixed",
    "limitations": [
        "Sample size not reported in abstract",
        "Exposure metrics beyond frequency (e.g., SAR, power density) not reported in abstract",
        "Duration/timing of RF exposures not reported in abstract",
        "Animal model; translational relevance to humans not established in abstract"
    ],
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    "peer_reviewed_likely": "yes",
    "keywords": [
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        "TRFS",
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        "945 MHz",
        "thermal neuromodulation",
        "brain stimulation",
        "mice",
        "TRPV1",
        "RF-genetics",
        "parvalbumin interneurons",
        "GCaMP",
        "fiber photometry",
        "behavior",
        "rotational test",
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    ],
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