A Wireless Head-mountable Device with Tapered Optical Fiber-coupled Laser Diode for Light Delivery in Deep Brain Regions

A Review: Research Progress of Neural Probes for Brain Research and Brain-Computer Interface

Neural probes, as an invasive physiological tool at the mesoscopic scale, can decipher the code of brain connections and communications from the cellular or even molecular level, and realize information fusion between the human body and external machines. In addition to traditional electrodes, two new types of neural probes have been developed in recent years: optoprobes based on optogenetics and magnetrodes that record neural magnetic signals. In this review, we give a comprehensive overview of these three kinds of neural probes. We firstly discuss the development of microelectrodes and strategies for their flexibility, which is mainly represented by the selection of flexible substrates and new electrode materials. Subsequently, the concept of optogenetics is introduced, followed by the review of several novel structures of optoprobes, which are divided into multifunctional optoprobes integrated with microfluidic channels, artifact-free optoprobes, three-dimensional drivable optoprobes, and flexible optoprobes. At last, we introduce the fundamental perspectives of magnetoresistive (MR) sensors and then review the research progress of magnetrodes based on it.

Biodegradable Optical Fiber in a Soft Optoelectronic Device for Wireless Optogenetic Applications

Optogenetics is a new neuroscience technology that uses light-responsive proteins to stimulate neurons with light and control the emotions and/or behavior of animals. There are a few approaches to deliver light to neurons in vivo, including a using an optical fiber that can send light from an external source to a target neuron, directly inserting a light-emitting device, and shooting light to penetrate tissue from the outside. Among these methods, inserting a wireless light-emitting device that is capable of being used for an experiment while leaving an animal completely free is a method that has been studied in recent years. At the same time, the possibility of causing mechanical and thermal damage to neural tissues has been highlighted as an issue due to the stiffness of robust injection tools and the photoelectric efficiency of light-emitting diodes (LEDs). In this study, we developed a device that can send light from a wireless light-emitting device to a target neuron without mechanical and thermal effects and analyzed the optical and thermal characteristics of the device to be used for optogenetic studies.

Integrated Neurophotonics: Toward Dense Volumetric Interrogation of Brain Circuit Activity-at Depth and in Real Time

We propose a new paradigm for dense functional imaging of brain activity to surmount the limitations of present methodologies. We term this approach "integrated neurophotonics"; it combines recent advances in microchip-based integrated photonic and electronic circuitry with those from optogenetics. This approach has the potential to enable lens-less functional imaging from within the brain itself to achieve dense, large-scale stimulation and recording of brain activity with cellular resolution at arbitrary depths. We perform a computational study of several prototype 3D architectures for implantable probe-array modules that are designed to provide fast and dense single-cell resolution (e.g., within a 1-mm3 volume of mouse cortex comprising ∼100,000 neurons). We describe progress toward realizing integrated neurophotonic imaging modules, which can be produced en masse with current semiconductor foundry protocols for chip manufacturing. Implantation of multiple modules can cover extended brain regions.

Wireless Optogenetic Stimulation of Oxytocin Neurons in a Semi-natural Setup Dynamically Elevates Both Pro-social and Agonistic Behaviors

Complex behavioral phenotyping techniques are becoming more prevalent in the field of behavioral neuroscience, and thus methods for manipulating neuronal activity must be adapted to fit into such paradigms. Here, we present a head-mounted, magnetically activated device for wireless optogenetic manipulation that is compact, simple to construct, and suitable for use in group-living mice in an enriched semi-natural arena over several days. Using this device, we demonstrate that repeated activation of oxytocin neurons in male mice can have different effects on pro-social and agonistic behaviors, depending on the social context. Our findings support the social salience hypothesis of oxytocin and emphasize the importance of the environment in the study of social neuromodulators. Our wireless optogenetic device can be easily adapted for use in a variety of behavioral paradigms, which are normally hindered by tethered light delivery or a limited environment.

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A small, wireless device is used for optogenetic activation in a complex environment

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PVN oxytocin neurons were activated repeatedly over 2 days in a group setting

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Repeated activation in a group setting elicited both pro-social and agonistic behavior

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Findings support the social salience hypothesis of oxytocin neuro-modulation

Optogenetics in Brain Research: From a Strategy to Investigate Physiological Function to a Therapeutic Tool

Dissecting the functional roles of neuronal circuits and their interaction is a crucial step in basic neuroscience and in all the biomedical field. Optogenetics is well-suited to this purpose since it allows us to study the functionality of neuronal networks on multiple scales in living organisms. This tool was recently used in a plethora of studies to investigate physiological neuronal circuit function in addition to dysfunctional or pathological conditions. Moreover, optogenetics is emerging as a crucial technique to develop new rehabilitative and therapeutic strategies for many neurodegenerative diseases in pre-clinical models. In this review, we discuss recent applications of optogenetics, starting from fundamental research to pre-clinical applications. Firstly, we described the fundamental components of optogenetics, from light-activated proteins to light delivery systems. Secondly, we showed its applications to study neuronal circuits in physiological or pathological conditions at the cortical and subcortical level, in vivo. Furthermore, the interesting findings achieved using optogenetics as a therapeutic and rehabilitative tool highlighted the potential of this technique for understanding and treating neurological diseases in pre-clinical models. Finally, we showed encouraging results recently obtained by applying optogenetics in human neuronal cells in-vitro.