Ultrasound has been used to non-invasively manipulate neuronal functions in humans and other animals. However, this approach is limited as it has been challenging to target specific cells within the ...brain or body. Here, we identify human Transient Receptor Potential A1 (hsTRPA1) as a candidate that confers ultrasound sensitivity to mammalian cells. Ultrasound-evoked gating of hsTRPA1 specifically requires its N-terminal tip region and cholesterol interactions; and target cells with an intact actin cytoskeleton, revealing elements of the sonogenetic mechanism. Next, we use calcium imaging and electrophysiology to show that hsTRPA1 potentiates ultrasound-evoked responses in primary neurons. Furthermore, unilateral expression of hsTRPA1 in mouse layer V motor cortical neurons leads to c-fos expression and contralateral limb responses in response to ultrasound delivered through an intact skull. Collectively, we demonstrate that hsTRPA1-based sonogenetics can effectively manipulate neurons within the intact mammalian brain, a method that could be used across species.
Ultrasound has been used to manipulate cells in both humans and animal models. While intramembrane cavitation and lipid clustering have been suggested as likely mechanisms, they lack experimental ...evidence. Here, high‐speed digital holographic microscopy (kiloHertz order) is used to visualize the cellular membrane dynamics. It is shown that neuronal and fibroblast membranes deflect about 150 nm upon ultrasound stimulation. Next, a biomechanical model that predicts changes in membrane voltage after ultrasound exposure is developed. Finally, the model predictions are validated using whole‐cell patch clamp electrophysiology on primary neurons. Collectively, it is shown that ultrasound stimulation directly defects the neuronal membrane leading to a change in membrane voltage and subsequent depolarization. The model is consistent with existing data and provides a mechanism for both ultrasound‐evoked neurostimulation and sonogenetic control.
With the help of a new method for imaging cell membrane motion, high‐speed digital holographic microscopy, membrane deformation responsible for the direct depolarization of membranes that lead to action potential generation in nerve cells is observed. A complete model of the phenomena has been devised, producing voltage spiking and oscillation predictions similar to patch clamp measurements.
Ultrasound neuromodulation has rapidly developed over the past decade, a consequence of the discovery of strain‐sensitive structures in the membrane and organelles of cells extending into the brain, ...heart, and other organs. A key limitation to its use in the brain is the formation of standing waves within the skull. In standing acoustic waves, the maximum ultrasound intensity spatially varies from near zero to double the mean in one‐half of a wavelength, and has led to localized tissue damage and disruption of normal brain function while attempting to evoke a broader response. This phenomenon also produces a large spatial variation in the actual ultrasound exposure in tissue, leading to heterogeneous results. One approach to overcome this limitation is presented here: transducer‐mounted diffusers that result in spatiotemporally incoherent ultrasound. It is shown through experiment and analysis that adding a diffuser to the transducer leads to a twofold increase in ultrasound responsiveness of transient receptor potential ankyrin 1 (TRPA1)‐transfected human embryonic kidney cells. Furthermore, it is shown that the diffuser produces a uniform spatial distribution of pressure within the rodent skull. The approach offers uniform ultrasound delivery into irregular cavities for sonogenetics.
Positioning a microscale diffuser directly on an ultrasound transducer produces spatiotemporally uniform ultrasound within the skull cavity of a mouse, useful for sonogenetics; the actuation of targeted regions of the brain expressing candidate channels using ultrasound in conjunction with transfection of the target tissue to produce ultrasound‐sensitive TRPA1 ion channels.
In this issue of Neuron, Uribe-Arias et al.
show that, in larval zebrafish, astrocyte-like cells exhibit calcium responses to norepinephrine during behavioral-state transitions and alter neuronal ...response properties. Thus, astroglia can sculpt neuronal dynamics in behaviorally meaningful ways.
The interface between two tissues can have very different bioelectrical properties compared to either tissue on its own. Here we show that an interface between non-excitable tissues can be ...electrically excitable because of an interaction between the currents passing through the gap junctions—electrically resistive intercellular connections—and the non-linear current–voltage dependence in the ion channels on either side of the interface. Our theory shows that this topologically robust excitability occurs over a far larger range of ion channel expression levels than can support excitability in the bulk. The corresponding interfacial action potentials can cause local elevations in calcium concentration, possibly providing a bioelectrical mechanism for interface sensing. The observed topological action potentials point to the possibility of other types of topological effect in electrophysiology and at other diffusively coupled interfaces.Interfaces between non-excitable tissues can be electrically excitable, suggesting a possible bioelectrical mechanism for interface sensing.
How the Venus flytrap (Dionaea muscipula) evolved the remarkable ability to sense, capture, and digest animal prey for nutrients has long puzzled the scientific community.
Recent genome and ...transcriptome sequencing studies have provided clues to the genes thought to play a role in these tasks.
However, proving a causal link between these and any aspect of the plant's hunting behavior has been challenging due to the genetic intractability of this non-model organism. Here, we use CRISPR-Cas9 methods to generate targeted modifications in the Venus flytrap genome. The plant detects prey using touch-sensitive trigger hairs located on its bilobed leaves.
Upon bending, these hairs convert mechanical touch signals into changes in the membrane potential of sensory cells, leading to rapid closure of the leaf lobes to ensnare the animal.
Here, we generate mutations in trigger-hair-expressed MscS-like (MSL)-family mechanosensitive ion channel genes FLYCATCHER1 (FLYC1) and FLYCATCHER2 (FLYC2)
and find that double-mutant plants have a reduced leaf-closing response to mechanical ultrasound stimulation. While we cannot exclude off-target effects of the CRISPR-Cas9 system, our genetic analysis is consistent with these and other functionally redundant mechanosensitive ion channels acting together to generate the sensory system necessary for prey detection.
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