Optogenetic control of nerve growth

Due to the limited regenerative ability of neural tissue, a diverse set of biochemical and biophysical cues for increasing nerve growth has been investigated, including neurotrophic factors, topography, and electrical stimulation. In this report, we explore optogenetic control of neurite growth as a cell-specific alternative to electrical stimulation. By investigating a broad range of optical stimulation parameters on dorsal root ganglia (DRGs) expressing channelrhodopsin 2 (ChR2), we identified conditions that enhance neurite outgrowth by three-fold as compared to unstimulated or wild-type (WT) controls. Furthermore, optogenetic stimulation of ChR2 expressing DRGs induces directional outgrowth in WT DRGs co-cultured within a 10 mm vicinity of the optically sensitive ganglia. This observed enhancement and polarization of neurite growth was accompanied by an increased expression of neural growth and brain derived neurotrophic factors (NGF, BDNF). This work highlights the potential for implementing optogenetics to drive nerve growth in specific cell populations.Charles Stark Draper Laboratory (University Research and Development Grant)National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (Award DMR-0819762)National Science Foundation (U.S.) (CAREER Award CBET-1253890)Simons FoundationKorean Government Scholarship Program for Study Oversea

Polymer Fiber Probes Enable Optical Control of Spinal Cord and Muscle Function In Vivo

Restoration of motor and sensory functions in paralyzed patients requires the development of tools for simultaneous recording and stimulation of neural activity in the spinal cord. In addition to its complex neurophysiology, the spinal cord presents technical challenges stemming from its flexible fibrous structure and repeated elastic deformation during normal motion. To address these engineering constraints, we developed highly flexible fiber probes, consisting entirely of polymers, for combined optical stimulation and recording of neural activity. The fabricated fiber probes exhibit low-loss light transmission even under repeated extreme bending deformations. Using our fiber probes, we demonstrate simultaneous recording and optogenetic stimulation of neural activity in the spinal cord of transgenic mice expressing the light sensitive protein channelrhodopsin 2 (ChR2). Furthermore, optical stimulation of the spinal cord with the polymer fiber probes induces on-demand limb movements that correlate with electromyographical (EMG) activity.National Science Foundation (U.S.) (EEC-1028725)National Science Foundation (U.S.) (Career Award)National Science Foundation (U.S.) (DMR-0819762)McGovern Institute for Brain Research at MIT (Neurotechnology Grant)Massachusetts Institute of Technology. Simons Center for the Social Brai

Flexible high density active neural implants combining a distributed multiplexing transceiver architecture with biocompatible technology

Precise localization of brain tissue causing severe neurological conditions requires subdural recording arrays with high electrode density and low mechanical stiffness compliant with the brain tissue. However, most arrays currently used − such as clinical ECoG grids − are rather stiff and limited in spatial resolution. To overcome these constrains a novel architecture is proposed using delocalized electronic (de)multiplexer grains. Here, their functional units are described in both hard‐ and software, and tested in simulations and experimentally. The results show that in case of a 100 × 100 mm ECoG array with lower mechanical stiffness, inter‐electrode distances <1 mm can be achieved. Taking parasitic capacitances into account, a signal resolution of 100 μV is reached with an inter‐channel timing resolution of 200 ns, which in our model corresponds to tissue localization as precise as 1.2 mm. For clinical application of envisaged 5000 electrodes, a preselection mechanism and routes for adoption of this technology toward cochlear implants and brain computer interfaces are presented