Biology subjects

Alon, L.

Publications and source records attributed to Alon, L..

4 recordsLinked to original sources

bioRxiv2025

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

STRUCTURED ABSTRACTO_ST_ABSBackgroundC_ST_ABSAchieving 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, contactless neuromodulation technique that leverages RF-induced thermal effects to modulate neural activity in vivo. MethodsWe 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. ResultsIn 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 {Delta}T {approx} 1.5 {degrees}C. Behaviorally, this excitation reversed the direction of rotation in hyperlocomotive freely moving mice, yielding a contralateral bias. ConclusionsTRFS 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.

neuroscience↗

bioRxiv2022

Open-source versatile 3D-print animal conditioning platform design for in-vivo preclinical brain imaging in awake mice and anesthetized mice and rats

Proper animal conditioning is a key factor in the quality and success of preclinical neuroimaging applications. We introduce an open-source easy-to-modify multi-modal 3D printable design for rodent conditioning for magnetic resonance imaging (MRI) or other imaging modalities. Our design can be used for brain imaging in anesthetized or awake mice and anesthetized rats. We show ease-of-use and reproducibility of subject conditioning with anatomical T2-weighted imaging for both mice and rats. We also demonstrate application of our design for awake fMRI in mice using both visual evoked potential and olfactory stimulation paradigms. In addition, we demonstrate that our proposed cradle design can be extended to multiple imaging modalities combining MRI, Positron emission tomography and X-ray computed tomography.

neuroscience↗

bioRxiv2022

In-vivo Measurement of Radio Frequency Electric Fields in Mice Brain

With development of novel technologies, radio frequency (RF) energy exposure is expanding at various wavelengths and power levels. These developments necessitate updated approaches of RF measurements in complex environments, particularly in live biological tissue. In this study, we introduce a technique for direct in-vivo measurement of electric fields in living tissue. Proof of principle in-vivo electric field measurements were conducted in rodent brains using Bismuth Silicon Oxide (BSO) crystals exposed to varying levels of RF energy. Electric field measurements were calibrated and verified using in-vivo temperature measurements using optical temperature fibers alongside electromagnetic field simulations of a transverse electromagnetic (TEM) cell. SIGNIFICANCEAccurate dosimetry of the absorbed radio frequency (RF) electric fields (E-Fields) by the live tissue is the keystone of environmental health considerations for this type of ever-growing non-ionizing radiation energy. The complexity of biological tissue and technical difficulties have made direct measurement of E-fields in live tissue challenging leading to application of ex-vivo and in-silico approaches. Here, we present a novel method for in-vivo direct measurement of RF E-fields in anesthetized mice brain using electro-optic sensors.

biophysics↗

bioRxiv2022

Brain-implanted conductors amplify radiofrequency fields in rodents: advantages and risks

Over the past few decades, daily exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. Under extreme circumstances, exposure to very strong RF energy can lead to heating of body tissue, even resulting in tissue injury. The presence of implanted devices, moreover, can amplify RF effects on surrounding tissue. Therefore, it is important to understand the interactions of RF fields with tissue in the presence of implants, in order to establish appropriate wireless safety protocols, and also to extend the benefits of medical imaging to increasing numbers of people with implanted medical devices. This study explored the neurological effects of RF exposure in rodents implanted with neuronal recording electrodes. We exposed freely moving and anesthetized rats and mice to 950 MHz RF energy while monitoring their brain activity, temperature, and behavior. We found that RF exposure could induce fast onset firing of single neurons without heat injury. In addition, brain implants enhanced the effect of RF stimulation resulting in reversible behavioral changes. Using an optical temperature measurement system, we found greater than tenfold increase in brain temperature in the vicinity of the implant. On the one hand, our results underline the importance of careful safety assessment for brain implanted devices, but on the other hand, we also show that metal implants may be used for neurostimulation if brain temperature can be kept within safe limits.

neuroscience↗