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Optetrode: A multichannel readout for optogenetic control in freely moving mice
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Recent advances in optogenetics have improved the precision with which defined circuit elements can be controlled optically in freely moving mammals; in particular, recombinase-dependent opsin viruses, used with a growing pool of transgenic mice expressing recombinases, allow manipulation of specific cell types. However, although optogenetic control has allowed neural circuits to be manipulated in increasingly powerful ways, combining optogenetic stimulation with simultaneous multichannel electrophysiological readout of isolated units in freely moving mice remains a challenge. We designed and validated the optetrode, a device that allows for colocalized multi-tetrode electrophysiological recording and optical stimulation in freely moving mice. Optetrode manufacture employs a unique optical fiber-centric coaxial design approach that yields a lightweight (2 g), compact and robust device that is suitable for behaving mice. This low-cost device is easy to construct (2.5 h to build without specialized equipment). We found that the drive design produced stable high-quality recordings and continued to do so for at least 6 weeks following implantation. We validated the optetrode by quantifying, for the first time, the response of cells in the medial prefrontal cortex to local optical excitation and inhibition, probing multiple different genetically defined classes of cells in the mouse during open field exploration.
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... Furthermore, they result in unintended superficial layer neuron activation and even heating damage at the higher intensities required to reach deep layers 9,24 . In contrast, penetrating optical fibers, integrated with single 25,26 or multiple 27 recording probes, allow photoactivation at depths >1 mm, but only of a volume a few hundred microns in diameter, and, due to their size and shape, can cause significant superficial layer damage. ...
... We have developed and validated a novel device, the UOA, which has the potential to further optogenetic research in NHPs. Current optogenetic approaches in NHPs permit light delivery either over a large superficial area 9,23 , or to deeper tissue over a small area [25][26][27]38 . Multi-site probes for larger volume stimulation have also been developed, and combined with single 45 or multisite 46,47 electrical recordings, but these approaches are typically cumbersome to assemble and don't easily scale to precisely target multiple small tissue volumes. ...
Optogenetics has transformed studies of neural circuit function, but remains challenging to apply to non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally-precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback circuits. To address this need, we have developed the Utah Optrode Array (UOA), a 10×10 glass needle waveguide array fabricated atop a novel opaque optical interposer, and bonded to an electrically addressable µLED array. In vivo experiments with the UOA demonstrated large-scale, spatiotemporally precise, activation of deep circuits in NHP cortex. Specifically, the UOA permitted both focal (confined to single layers/columns), and widespread (multiple layers/columns) optogenetic activation of deep layer neurons, as assessed with multi-channel laminar electrode arrays, simply by varying the number of activated µLEDs and/or the irradiance. Thus, the UOA represents a powerful optoelectronic device for targeted manipulation of deep-layer circuits in NHP models.
... Laying on seabed, a ber cable can distributedly monitor the sea oor earthquakes and tsunamis while ful ll the duty of data transmission 20,21 . Deployed into brain, optogenetics orchestrates the optical stimulation and electrophysiological readout using a single ber probe 22,23 . Likewise, the integration of diagnostic and therapeutic capabilities in a uni ed optical ber not only sticks to the development path of optical ber technology, but also enable practical implications. ...
Efficient delivery of photons to visceral organs is critical for the treatment of deep-seated tumors taking advantage of photo-theranostics. Optical fiber can be regarded as a direct and facile photon pathway for targeting tumor lesion with negligible body invasion. However, current fiber theranostic strategies rely on the spatially separated optical fibers to realize diagnosis and therapy independently, resulting in low compactness, poor continuity of medical process, and incompatibility with current medical technologies. Herein, we develop an integrated fiber-optic theranostic (iFOT) probe that merges tumor microenvironment (TME) sensing and photothermal therapy (PTT) by functionalizing the fiber with graphene/gold nanostar hybrid materials and hypoxic-responsive fluorophores. The iFOT probe can quickly detect the hypoxia of xenograft tumors of mice with high sensitivity. The tumors can be photothermally killed on-site through the same fiber probe tightly followed by detection, which presents a high cure rate without the risk of recurrence. More importantly, the iFOT is highly adaptable to the conventional medical imaging and endoscopic techniques, such as laparoscope, magnetic resonance imaging, and ultrasound imaging, which facilitates the imaging-assisted navigation and manipulation by use of the interventional trocar. The proposed integrated fiber-optic theranostic strategy can be used as an effective endoscopic and interventional tool for tackling deep-situated tumor and may open a revolutionized pathway to bridge the separate diagnosis and therapy process in the current stage.
... Comprehensive understanding of the sophisticated and intricate interplays among distinct neural populations in the brain requires innovative, implantable neural interfaces capable of manipulating and interrogating target neurons across multiple locations with high spatiotemporal resolutions 14 . Thus, the development of micro-neural implant electronics (μ-NIE) based on microelectromechanical systems has led to their extensive use in various applications for pathological research on neurological disorders over the past few decades by incorporating advanced optogenetic techniques [15][16][17][18][19] . Despite the potential of neural implants as promising tools in neurosciences, the μ-NIE are manufactured using commercially available inorganic materials, resulting in significant mechanical mismatches between the device and brain tissue. ...
Bioresorbable neural implants based on emerging classes of biodegradable materials offer a promising solution to the challenges of secondary surgeries for removal of implanted devices required for existing neural implants. In this study, we introduce a fully bioresorbable flexible hybrid opto-electronic system for simultaneous electrophysiological recording and optogenetic stimulation. The flexible and soft device, composed of biodegradable materials, has a direct optical and electrical interface with the curved cerebral cortex surface while exhibiting excellent biocompatibility. Optimized to minimize light transmission losses and photoelectric artifact interference, the device was chronically implanted in the brain of transgenic mice and performed to photo-stimulate the somatosensory area while recording local field potentials. Thus, the presented hybrid neural implant system, comprising biodegradable materials, promises to provide monitoring and therapy modalities for versatile applications in biomedicine.
... The core of an optogenetic system is a light source for optical stimulation of neurons. Traditional optogenetics employs optical fibers to direct light to the target brain regions [18][19][20][21][22][23][24] New methods such as using microscale injectable needles with integrated microscale inorganic light-emitting diodes (μ-LEDs) have been proposed in literature. [25,26] Nevertheless, using tethered technologies for animal studies hinder the natural mobility of freely moving animals, for example, mice, and may cause micrometer-scale movements between probes and soft tissues during movements, which potentially can damage brain tissues, create artefacts, and degrade long-term signal quality, especially in neural interfaces with multiple channels. ...
Body implants play a crucial role in clinical applications, encompassing data acquisition, diagnosis, and disease treatment. However, challenges in size, power consumption, and biocompatibility, particularly in brain applications requiring small, battery‐free devices for deep areas, hinder their development. Despite potential advances through simplified, single‐purpose devices, such as recording or stimulation, overcoming the power and biocompatibility issues remains a hurdle. Addressing this, the article introduces an ultrasonically powered light delivery implant (LDI) utilizing lead‐free piezoelectric material (Li 0.08 K 0.46 Na 0.46 ) NbO 3 to harvest energy from external ultrasonic waves. The prototype includes a piezoelectric cube, a chip fabricated in 180 nm CMOS technology, and a microscale light‐emitting diode ( μ ‐LED) for optogenetics. Achieving an end‐to‐end efficiency of 0.75%, the LDI holds promise for various optogenetic studies, particularly in animal studies targeting specific brain areas for treating Parkinson's disease. The delivered optical power on the μ ‐LED surface, at 14.1 mW mm ⁻² , presents applicability to diverse studies involving specific opsins.
Essential tremor (ET) is the most prevalent movement disorder, characterized primarily by action tremor, an involuntary rhythmic movement with a specific frequency. However, the neuronal mechanism underlying the coding of tremor frequency remains unexplored. Here, we used in vivo electrophysiology, optogenetics, and simultaneous motion tracking in the Grid2 dupE3 mouse model to investigate whether and how neuronal activity in the olivocerebellum determines the frequency of essential tremor. We report that tremor frequency was encoded by the temporal coherence of population neuronal firing within the olivocerebellums of these mice, leading to frequency-dependent cerebellar oscillations and tremors. This mechanism was precise and generalizable, enabling us to use optogenetic stimulation of the deep cerebellar nuclei to induce frequency-specific tremors in wild-type mice or alter tremor frequencies in tremor mice. In patients with ET, we showed that deep brain stimulation of the thalamus suppressed tremor symptoms but did not eliminate cerebellar oscillations measured by electroencephalgraphy, indicating that tremor-related oscillations in the cerebellum do not require the reciprocal interactions with the thalamus. Frequency-disrupting transcranial alternating current stimulation of the cerebellum could suppress tremor amplitudes, confirming the frequency modulatory role of the cerebellum in patients with ET. These findings offer a neurodynamic basis for the frequency-dependent stimulation of the cerebellum to treat essential tremor.
Multimaterial fibers, as a new generation and rapidly developed fiber materials, have been widely used in advanced photonic and optoelectronic devices, energy conversion, optogenetics, smart fabrics, artificial muscles, micro/nano fabrications, 3D printing fields, etc. The great success of multimaterial fibers are mainly benefited from their multifunctionality, outstanding performance, and scalable manufacturing capability. In this review, we gave a comprehensive review on the novel sensing principles, advanced manufacture techniques, and multifunctional sensing applications of multimaterial fibers. The development history of multimaterial fibers are introduced, and the importance of the appearance of multimaterial fibers are also evaluated. In addition, the commonly used fabrication techniques of multimaterial fibers with excellent scalability are summarized, and the general design strategies and working principles of multimaterial fibers are also highlighted. Furthermore, the recent advances of multimaterial fibers in diverse meaningful applications such as optical sensing, thermal sensing, chemical sensing, deformation sensing, microfluidic sensing, acoustic sensing, physiological sensing, neural sensing, radiation detection, and magnetic sensing are summarized. The future developments and challenges of multimaterial fibers are also indicated. In summary, this review is envisioned to not only provide fabrication methods and working principles of multimaterial fibers, but also demonstrate its great potentials in practical applications.
Existing methods for studying neural circuits and treating neurological disorders are typically based on physical and chemical cues to manipulate and record neural activities. These approaches often involve predefined, rigid, and unchangeable signal patterns, which cannot be adjusted in real time according to the patient's condition or neural activities. With the continuous development of neural interfaces, conducting in vivo research on adaptive and modifiable treatments for neurological diseases and neural circuits is now possible. In this review, we summarize current and potential integration of various modalities to achieve precise, closed‐loop modulation and sensing in neural systems. We highlight advanced materials, devices, or systems that generate or detect electrical, magnetic, optical, acoustic, or chemical signals and utilize them to interact with neural cells, tissues, and networks for closed‐loop interrogation. Further, we elaborate on the significance of developing closed‐loop techniques for diagnostics and treatment of neurological disorders such as epilepsy, depression, rehabilitation of spinal cord injury patients, and exploration of brain neural circuit functionality.
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The neural circuits underlying sleep-wakefulness and general anesthesia have not been fully investigated. The GABAergic neurons in the bed nucleus of the stria terminalis (BNST) play a critical role in stress and fear that relied on heightened arousal. Nevertheless, it remains unclear whether BNST GABAergic neurons are involved in the regulation of sleep-wakefulness and anesthesia. Here, using in vivo fiber photometry combined with electroencephalography, electromyography, and video recordings, we found that BNST GABAergic neurons exhibited arousal-state-dependent alterations, with high activities in both wakefulness and rapid-eye movement sleep, but suppressed during anesthesia. Optogenetic activation of these neurons could initiate and maintain wakefulness, and even induce arousal from anesthesia. However, chronic lesion of BNST GABAergic neurons altered spontaneous sleep-wakefulness architecture during the dark phase, but not induction and emergence from anesthesia. Furthermore, we also discovered that the BNST-ventral tegmental area pathway might participate in promoting wakefulness and reanimation from steady-state anesthesia. Collectively, our study explores new elements in neural circuit mechanisms underlying sleep-wakefulness and anesthesia, which may contribute to a more comprehensive understanding of consciousness and the development of innovative anesthetics.
The accumulation of metabolic waste is a leading cause of numerous neurological disorders, yet we still have only limited knowledge of how the brain performs self-cleansing. Here we demonstrate that neural networks synchronize individual action potentials to create large-amplitude, rhythmic and self-perpetuating ionic waves in the interstitial fluid of the brain. These waves are a plausible mechanism to explain the correlated potentiation of the glymphatic flow1,2 through the brain parenchyma. Chemogenetic flattening of these high-energy ionic waves largely impeded cerebrospinal fluid infiltration into and clearance of molecules from the brain parenchyma. Notably, synthesized waves generated through transcranial optogenetic stimulation substantially potentiated cerebrospinal fluid-to-interstitial fluid perfusion. Our study demonstrates that neurons serve as master organizers for brain clearance. This fundamental principle introduces a new theoretical framework for the functioning of macroscopic brain waves.
Severe behavioural deficits in psychiatric diseases such as autism and schizophrenia have been hypothesized to arise from elevations in the cellular balance of excitation and inhibition (E/I balance) within neural microcircuitry. This hypothesis could unify diverse streams of pathophysiological and genetic evidence, but has not been susceptible to direct testing. Here we design and use several novel optogenetic tools to causally investigate the cellular E/I balance hypothesis in freely moving mammals, and explore the associated circuit physiology. Elevation, but not reduction, of cellular E/I balance within the mouse medial prefrontal cortex was found to elicit a profound impairment in cellular information processing, associated with specific behavioural impairments and increased high-frequency power in the 30-80 Hz range, which have both been observed in clinical conditions in humans. Consistent with the E/I balance hypothesis, compensatory elevation of inhibitory cell excitability partially rescued social deficits caused by E/I balance elevation. These results provide support for the elevated cellular E/I balance hypothesis of severe neuropsychiatric disease-related symptoms.
The thalamic reticular nucleus (TRN) is hypothesized to regulate neocortical rhythms and behavioral states. Using optogenetics and multi-electrode recording in behaving mice, we found that brief selective drive of TRN switched the thalamocortical firing mode from tonic to bursting and generated state-dependent neocortical spindles. These findings provide causal support for the involvement of the TRN in state regulation in vivo and introduce a new model for addressing the role of this structure in behavior.
Placing a patient in a state of general anesthesia is crucial for safely and humanely performing most surgical and many nonsurgical procedures. How anesthetic drugs create the state of general anesthesia is considered a major mystery of modern medicine. Unconsciousness, induced by altered arousal and/or cognition, is perhaps the most fascinating behavioral state of general anesthesia. We perform a systems neuroscience analysis of the altered arousal states induced by five classes of intravenous anesthetics by relating their behavioral and physiological features to the molecular targets and neural circuits at which these drugs are purported to act. The altered states of arousal are sedation-unconsciousness, sedation-analgesia, dissociative anesthesia, pharmacologic non-REM sleep, and neuroleptic anesthesia. Each altered arousal state results from the anesthetic drugs acting at multiple targets in the central nervous system. Our analysis shows that general anesthesia is less mysterious than currently believed.
Optogenetics is a technique for controlling subpopulations of neurons in the intact brain using light. This technique has the potential to enhance basic systems neuroscience research and to inform the mechanisms and treatment of brain injury and disease. Before launching large-scale primate studies, the method needs to be further characterized and adapted for use in the primate brain. We assessed the safety and efficiency of two viral vector systems (lentivirus and adeno-associated virus), two human promoters (human synapsin (hSyn) and human thymocyte-1 (hThy-1)) and three excitatory and inhibitory mammalian codon-optimized opsins (channelrhodopsin-2, enhanced Natronomonas pharaonis halorhodopsin and the step-function opsin), which we characterized electrophysiologically, histologically and behaviorally in rhesus monkeys (Macaca mulatta). We also introduced a new device for measuring in vivo fluorescence over time, allowing minimally invasive assessment of construct expression in the intact brain. We present a set of optogenetic tools designed for optogenetic experiments in the non-human primate brain.
Ensemble recordings of 73 to 148 rat hippocampal neurons were used to predict accurately the animals' movement through their environment, which confirms that the hippocampus transmits an ensemble code for location. In a novel space, the ensemble code was initially less robust but improved rapidly with exploration. During this period, the activity of many inhibitory cells was suppressed, which suggests that new spatial information creates conditions in the hippocampal circuitry that are conducive to the synaptic modification presumed to be involved in learning. Development of a new population code for a novel environment did not substantially alter the code for a familiar one, which suggests that the interference between the two spatial representations was very small. The parallel recording methods outlined here make possible the study of the dynamics of neuronal interactions during unique behavioral events.
A new method is described for the recording and discrimination of extracellular action potentials in CNS regions with high cellular packing density or where there is intrinsic variation in action potential amplitude during burst discharge. The method is based on the principle that cells with different ratios of distances from two electrode tips will have different spike-amplitude ratios when recorded on two channels. The two channel amplitude ratio will remain constant regardless of intrinsic variation in the absolute amplitude of the signals. The method has been applied to the rat hippocampal formation, from which up to 5 units have been simultaneously isolated. The construction of the electrodes is simple, relatively fast, and reliable, and their low tip impedances result in excellent signal to noise characteristics.
Anxiolytic drugs including diazepam (DZP), chlordiazepoxide (CDX), pentabarbitol (PB) and ethanol (EtOH) produce specific alterations in the behavior of fasted rats given access to a single food pellet secured in the center of a novel open field environment. These drugs increase the total amount of food eaten in a 15 mind test and the mean amount eaten per approach to the fast food pedestal. This latter appears to be the more sensitive index of anxiolytic drug action and occurs at doses which have no effect on rearing or grooming. DZP was effective following either acute or chronic (15 day) treatment at doses which had no effect on the food consumption by fasted rats tested in their home cages. The effects of the sedative benzodiazepine, flurazepam, were similar to those of DZP but were not statistically significant. Behavioral effects similar to those of DZP were seen in animals received additional handling prior to testing or in animals habituated to the open field. Neither the anti-psychotic haloperidol nor morphine mimicked the actions of DZP.