Mechanical stimulation and electrophysiological monitoring at subcellular resolution reveals differential mechanosensation of neurons within networks.

A growing consensus that the brain is a mechanosensitive organ is driving the need for tools that mechanically stimulate and simultaneously record the electrophysiological response of neurons within neuronal networks. Here we introduce a synchronized combination of atomic force microscopy, high-density microelectrode array and fluorescence microscopy to monitor neuronal networks and to mechanically characterize and stimulate individual neurons at piconewton force sensitivity and nanometre precision while monitoring their electrophysiological activity at subcellular spatial and millisecond temporal resolution. No correlation is found between mechanical stiffness and electrophysiological activity of neuronal compartments.

Highly specific and non-invasive imaging of Piezo1-dependent activity across scales using GenEPi.

Mechanosensing is a ubiquitous process to translate external mechanical stimuli into biological responses. Piezo1 ion channels are directly gated by mechanical forces and play an essential role in cellular mechanotransduction. However, readouts of Piezo1 activity are mainly examined by invasive or indirect techniques, such as electrophysiological analyses and cytosolic calcium imaging.

Neurons differentiate magnitude and location of mechanical stimuli.

Neuronal activity can be modulated by mechanical stimuli. To study this phenomenon quantitatively, we mechanically stimulated rat cortical neurons by shear stress and local indentation. Neurons show 2 distinct responses, classified as transient and sustained.

Restoration of high-sensitivity and adapting vision with a cone opsin.

Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to blindness, but spare downstream retinal neurons, which can be targeted for optogenetic therapy. However, optogenetic approaches have been limited by either low light sensitivity or slow kinetics, and lack adaptation to changes in ambient light, and not been shown to restore object vision. We find that the vertebrate medium wavelength cone opsin (MW-opsin) overcomes these limitations and supports vision in dim light.

Author Correction: Restoration of patterned vision with an engineered photoactivatable G protein-coupled receptor.

Kevin J. Cao and Richard H. Kramer, who developed extended release with beta cyclodextrin, were inadvertently omitted from the author list and author contributions section of this Article.

Restoration of patterned vision with an engineered photoactivatable G protein-coupled receptor.

Retinitis pigmentosa results in blindness due to degeneration of photoreceptors, but spares other retinal cells, leading to the hope that expression of light-activated signaling proteins in the surviving cells could restore vision. We used a retinal G protein-coupled receptor, mGluR2, which we chemically engineered to respond to light. In retinal ganglion cells (RGCs) of blind rd1 mice, photoswitch-charged mGluR2 ("SNAG-mGluR2") evoked robust OFF responses to light, but not in wild-type retinas, revealing selectivity for RGCs that have lost photoreceptor input.

Optogenetic Retinal Gene Therapy with the Light Gated GPCR Vertebrate Rhodopsin.

In retinal disease, despite the loss of light sensitivity as photoreceptors die, many retinal interneurons survive in a physiologically and metabolically functional state for long periods. This provides an opportunity for treatment by genetically adding a light sensitive function to these cells. Optogenetic therapies are in development, but, to date, they have suffered from low light sensitivity and narrow dynamic response range of microbial opsins.

Inertial picobalance reveals fast mass fluctuations in mammalian cells.

The regulation of size, volume and mass in living cells is physiologically important, and dysregulation of these parameters gives rise to many diseases. Cell mass is largely determined by the amount of water, proteins, lipids, carbohydrates and nucleic acids present in a cell, and is tightly linked to metabolism, proliferation and gene expression. Technologies have emerged in recent years that make it possible to track the masses of single suspended cells and adherent cells.

Mechanical Stimulation of Piezo1 Receptors Depends on Extracellular Matrix Proteins and Directionality of Force.

Piezo receptors convert mechanical forces into electrical signals. In mammals, they play important roles in basic physiological functions including proprioception, sensation of touch, and vascular development. However, basic receptor properties like the gating mechanism, the interaction with extracellular matrix (ECM) proteins, and the response to mechanical stimulation, remain poorly understood.

Optogenetic Vision Restoration Using Rhodopsin for Enhanced Sensitivity.

Retinal disease is one of the most active areas of gene therapy, with clinical trials ongoing in the United States for five diseases. There are currently no treatments for patients with late-stage disease in which photoreceptors have been lost. Optogenetic gene therapies are in development, but, to date, have suffered from the low light sensitivity of microbial opsins, such as channelrhodopsin and halorhodopsin, and azobenzene-based photoswitches.

A Device for Human Ultrasonic Echolocation.

Objective: We present a device that combines principles of ultrasonic echolocation and spatial hearing to provide human users with environmental cues that are 1) not otherwise available to the human auditory system, and 2) richer in object and spatial information than the more heavily processed sonar cues of other assistive devices. The device consists of a wearable headset with an ultrasonic emitter and stereo microphones with affixed artificial pinnae. The goal of this study is to describe the device and evaluate the utility of the echoic information it provides.

Restoration of visual function by expression of a light-gated mammalian ion channel in retinal ganglion cells or ON-bipolar cells.

Most inherited forms of blindness are caused by mutations that lead to photoreceptor cell death but spare second- and third-order retinal neurons. Expression of the light-gated excitatory mammalian ion channel light-gated ionotropic glutamate receptor (LiGluR) in retinal ganglion cells (RGCs) of the retina degeneration (rd1) mouse model of blindness was previously shown to restore some visual functions when stimulated by UV light. Here, we report restored retinal function in visible light in rodent and canine models of blindness through the use of a second-generation photoswitch for LiGluR, maleimide-azobenzene-glutamate 0 with peak efficiency at 460 nm (MAG0(460)).

Optical control of metabotropic glutamate receptors.

G protein-coupled receptors (GPCRs), the largest family of membrane signaling proteins, respond to neurotransmitters, hormones and small environmental molecules. The neuronal function of many GPCRs has been difficult to resolve because of an inability to gate them with subtype specificity, spatial precision, speed and reversibility. To address this, we developed an approach for opto-chemical engineering of native GPCRs.

Optochemical control of genetically engineered neuronal nicotinic acetylcholine receptors.

Advances in synthetic chemistry, structural biology, molecular modelling and molecular cloning have enabled the systematic functional manipulation of transmembrane proteins. By combining genetically manipulated proteins with light-sensitive ligands, innately 'blind' neurobiological receptors can be converted into photoreceptors, which allows them to be photoregulated with high spatiotemporal precision. Here, we present the optochemical control of neuronal nicotinic acetylcholine receptors (nAChRs) with photoswitchable tethered agonists and antagonists.

Robust coding of ego-motion in descending neurons of the fly.

In many species, motion-sensitive neurons responding to optic flow at higher processing stages are well characterized; however, less is known how this representation of ego-motion is further transformed into an appropriate motor response. Here, we analyzed in the blowfly Calliphora vicina the visuomotor transformation from motion-sensitive neurons in the lobula plate [V2 and vertical system (VS) cells] onto premotor descending neurons [descending neurons of the ocellar and vertical system (DNOVS) cells] feeding into the motor circuit of the fly thoracic ganglion. We found that each of these cells is tuned to rotation of the fly around a particular body axis.

Switching the mechanics of dsDNA by Cu salicylic aldehyde complexation.

DNA is increasingly employed as a programmable building block for nanoscale structures. Self-assembly via specific DNA base-pair recognition allows an unparalleled variety of structures to be formed. Subsequent stabilization of such structures may be desirable and can be accomplished by metal coordination bonds to substituted bases.