Figure 4 - uploaded by Dennis R Sparta
Content may be subject to copyright.
Interfacing implantable optical fibers with in vivo electrophysiological arrays.(a) An optical fiber mount that is constructed out of stainless steel tubing is epoxied to the multiunit electrode array. (b) The implantable optical fiber is mounted and secured to the optical fiber mount located on the array. (c) The finished optrode is connected to the stereotaxic adapter and is ready for implantation.
Source publication
In vivo optogenetic strategies have redefined our ability to assay how neural circuits govern behavior. Although acutely implanted optical fibers have previously been used in such studies, long-term control over neuronal activity has been largely unachievable. Here we describe a method to construct implantable optical fibers to readily manipulate n...
Contexts in source publication
Context 1
... crItIcal step Steps 37-59 describe the procedure for standard implantation of optical fibers for in vivo behavior experiments. To interface the implantable optical fiber with in vivo electrophysiological arrays, follow the procedure outlined in Box 2 and Figure 4. ...
Context 2
... Under a stereomicroscope, place one drop of 5-min epoxy on the Omnetics connector of the MEA and glue the two pieces of stainless steel tubing to the MEA with the flattened ends pointing toward the electrodes; let the glue dry (Fig. 4a). crItIcal step This will allow for the positioning of the optical fiber within 1 mm of the MEA tips as well as creating an angle of ~20° between the MEA and the optical fiber; this allows sufficient spacing between the MEA and the optical fiber and enables the connection of the headstage and patch cable. 4. Place one drop of 5-min ...
Context 3
... fiber; this allows sufficient spacing between the MEA and the optical fiber and enables the connection of the headstage and patch cable. 4. Place one drop of 5-min epoxy on the two stainless steel tubes attached to the MEA and position the optical fiber portion of the implantable optical fiber so that it rests between the stainless steel tubes (Fig. 4b). Use forceps to gently position the optical fiber so that the optical fiber tip terminates ~500 µm above the MEA tips. crItIcal step This is important to allow the diffusion of light in the tissue surrounding the tips of the electrodes and to minimize photoelectric artifacts during recording. See Cardin et al. 22 for additional ...
Context 4
... min to allow the Titan Bond to dry completely. ? trouBlesHootInG 13. Mount the optrode on the stereotactic arm by connecting it to an Omnetics connector that has been epoxied to a 4-cm piece of 20-gauge stainless steel tubing that is held by the stereotactic arm. Gently position the optrode so that the MEA wires are perpendicular to the skull (Fig. 4c). 14. Remove the sponge piece from the craniotomy. 15. Lower the optrode through the craniotomy to the desired depth. crItIcal step This should be done very slowly, (e.g., do not lower the optrode at rate of more than 500 µm min − 1 ). 16. Wrap the ground wire connected to the MEA around each skull screw twice using fine forceps. ...
Similar publications
The transition from childhood to adulthood represents the developmental time frame in which the majority of psychiatric disorders emerge. Recent efforts to identify risk factors mediating the susceptibility to psychopathology have led to a heightened focus on both typical and atypical trajectories of neural circuit maturation. Mounting evidence has...
Background:
Childhood adversity is strongly linked to negative mental health outcomes, including depression and anxiety. Leveraging cognitive neuroscience to identify mechanisms that contribute to resilience in children with a history of maltreatment may provide viable intervention targets for the treatment or prevention of psychopathology. We pre...
Citations
... Other interfaces of recent interest are concerned with integrating multiple functions, such as electrical stimulation and photometric recording [30][31][32]. Through innovation in the constructional design and manufacturing processes, a minimally invasive interface is able to transmit two or more separate signals simultaneously. ...
Implantable bioelectronics hold tremendous potential in the field of healthcare, yet the performance of these systems heavily relies on the interfaces between artificial machines and living tissues. In this paper, we discuss the recent developments of tethered interfaces, as well as those of non-tethered interfaces. Among them, systems that study neural activity receive significant attention due to their innovative developments and high relevance in contemporary research, but other functional types of interface systems are also explored to provide a comprehensive overview of the field. We also analyze the key considerations, including perforation site selection, fixing strategies, long-term retention, and wireless communication, highlighting the challenges and opportunities with stable, effective, and biocompatible interfaces. Furthermore, we propose a primitive model of biocompatible electrical and optical interfaces for implantable systems, which simultaneously possesses biocompatibility, stability, and convenience. Finally, we point out the future directions of interfacing strategies.
... Fiber optic implants for photostimulation were fabricated as previously described using 200 μm glass fibers and implanted midline over SuM (Norris et al., 2021;Sparta et al., 2011). For implantation, the skull was cleaned and etched with OptiBond (Kerr) and the fiber was cemented to the skull with Tetric N-Flow (Ivoclar Vivadent). ...
Threat-response neural circuits are conserved across species and play roles in normal behavior and psychiatric diseases. Maladaptive changes in these neural circuits contribute to stress, mood, and anxiety disorders. Active coping in response to stressors is a psychosocial factor associated with resilience against stress-induced mood and anxiety disorders. The neural circuitry underlying active coping is poorly understood, but the functioning of these circuits could be key for overcoming anxiety and related disorders. The supramammillary nucleus (SuM) has been suggested to be engaged by threat. SuM has many projections and a poorly understood diversity of neural populations. In studies using mice, we identified a unique population of glutamatergic SuM neurons (SuM VGLUT2+ ::POA) based on projection to the preoptic area of the hypothalamus (POA) and found SuM VGLUT2+ ::POA neurons have extensive arborizations. SuM VGLUT2+ ::POA neurons project to brain areas that mediate features of the stress and threat responses including the paraventricular nucleus thalamus (PVT), periaqueductal gray (PAG), and habenula (Hb). Thus, SuM VGLUT2+ ::POA neurons are positioned as a hub, connecting to areas implicated in regulating stress responses. Here we report SuM VGLUT2+ ::POA neurons are recruited by diverse threatening stressors, and recruitment correlated with active coping behaviors. We found that selective photoactivation of the SuM VGLUT2+ ::POA population drove aversion but not anxiety like behaviors. Activation of SuM VGLUT2+ ::POA neurons in the absence of acute stressors evoked active coping like behaviors and drove instrumental behavior. Also, activation of SuM VGLUT2+ ::POA neurons was sufficient to convert passive coping strategies to active behaviors during acute stress. In contrast, we found activation of GABAergic (VGAT+) SuM neurons (SuM VGAT+ ) neurons did not alter drive aversion or active coping, but termination of photostimulation was followed by increased mobility in the forced swim test. These findings establish a new node in stress response circuitry that has projections to many brain areas and evokes flexible active coping behaviors.
... /2024 Once the animals exhibited no response to foot pinching, indicating successful anesthesia, a craniotomy was performed above each olfactory bulb (OB), precisely 4.3 mm anterior from bregma. Fiber optic pins were then implanted on the dorsal surface of each OB (Figure 1a), as previously described (Li et al., 2014;Sparta et al., 2012;Ung and Arenkiel, 2012). Post-surgery, mice received a Ketoprofen injection (5 mg/kg) for pain management. ...
The integration of optogenetic techniques with traditional behavioral paradigms has provided novel insights into the neural mechanisms underlying olfactory-based fear conditioning. Olfactory cues are potent triggers for fear responses, and understanding the intricate neural dynamics involved in olfactory fear learning is crucial for unraveling the complexities of aversive memory formation. In this study, a robust method is presented that combines optogenetic stimulation of olfactory bulb glomeruli with foot shock fear conditioning to investigate olfactory-based fear learning in mice. By merging optogenetic manipulation with behavioral assays, a comprehensive framework for studying the mechanisms of olfactory fear conditioning is provided. This method offers new avenues for exploring the neural dynamics of adaptive responses to olfactory threats and may have implications for understanding fear-related disorders.
... 11 Course of Applied Science, Graduate School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan. e-mail: tn@nips.ac.jp magnification and a high numerical aperture (NA) [17][18][19][20] , optic devices [21][22][23][24] , multiplexing of laser pathways 17,20,[25][26][27][28] . To perform high-resolution imaging in a living mouse brain, maximizing the capabilities of two-photon microscopy, a cranial window is typically created by removing a portion of the skull (craniectomy) and sealing the hole with a glass coverslip 29,30 . ...
Two-photon microscopy enables in vivo imaging of neuronal activity in mammalian brains at high resolution. However, two-photon imaging tools for stable, long-term, and simultaneous study of multiple brain regions in same mice are lacking. Here, we propose a method to create large cranial windows covering such as the whole parietal cortex and cerebellum in mice using fluoropolymer nanosheets covered with light-curable resin (termed the ‘Nanosheet Incorporated into light-curable REsin’ or NIRE method). NIRE method can produce cranial windows conforming the curved cortical and cerebellar surfaces, without motion artifacts in awake mice, and maintain transparency for >5 months. In addition, we demonstrate that NIRE method can be used for in vivo two-photon imaging of neuronal ensembles, individual neurons and subcellular structures such as dendritic spines. The NIRE method can facilitate in vivo large-scale analysis of heretofore inaccessible neural processes, such as the neuroplastic changes associated with maturation, learning and neural pathogenesis.
... Adenoassociated virus (AAV) injections are widely used for expressing GCaMP in target brain regions 11,12 . Following an AAV injection, a second surgical step is required for implantation of an optical device, most commonly a gradient refractive index (GRIN) lens, for monitoring fluorescence deep in the brain 5,13,14 . This two-step procedure results in reduced experimental success rates due to an increased incidence of tissue damage and difficulties in targeting both the virus and the optical lens to the same site within the brain (Fig. 1a, SI Fig. 1a,b). ...
Optical methods for studying the brain offer powerful approaches for understanding how neural activity underlies complex behavior. These methods typically rely on genetically encoded sensors and actuators to monitor and control neural activity. For microendoscopic calcium imaging, injection of a virus followed by implantation of a lens probe is required to express a calcium sensor and enable optical access to the target brain region. This two-step process poses several challenges, chief among them being the risks associated with mistargeting and/or misalignment between virus expression zone, lens probe and target brain region. Here, we engineer an adeno-associated virus (AAV)-eluting polymer coating for gradient refractive index (GRIN) lenses enabling expression of a genetically encoded calcium indicator (GCaMP) directly within the brain region of interest upon implantation of the lens. This approach requires only one surgical step and guarantees alignment between GCaMP expression and lens in the brain. Additionally, the slow virus release from these coatings increases the working time for surgical implantation, expanding the brain regions and species amenable to this approach. These enhanced capabilities should accelerate neuroscience research utilizing optical methods and advance our understanding of the neural circuit mechanisms underlying brain function and behavior in health and disease.
Significance Statement
We engineered a polymer coating for gradient refractive index (GRIN) lenses that provides controlled release of adeno-associated viruses (AAVs). This technology enables expression of a genetically encoded calcium indicator (GCaMP) directly at the brain region of interest upon implantation of the lens. Compared to current methods, our coating offers two important improvements. First, it simplifies surgery by combining GCaMP expression and lens placement in one step, saving time and ensuring alignment. Second, controlled release of AAV from these coatings extends the time available for surgery, making it possible to implant lenses in deeper parts of the brain and in more species. These advances accelerate neuroscience research and deepen our understanding of how neural circuits impact both health and disease.
... Also worth consideration are the effects of an implant within the tissue of a freely moving animal. The fiber employed for this type of imaging is typically stiffer than the surrounding tissue with few notable exceptions 12,13 . This resistance of the fiber to movement of the surrounding tissue can introduce disruptive forces to local vasculature, affecting both the blood brain barrier and parenchyma 12,14 . ...
... The fiber employed for this type of imaging is typically stiffer than the surrounding tissue with few notable exceptions 12,13 . This resistance of the fiber to movement of the surrounding tissue can introduce disruptive forces to local vasculature, affecting both the blood brain barrier and parenchyma 12,14 . In freely behaving animals, this can introduce damage that cannot be accounted for until the end of the experimental period, especially for animals used for repeated recordings over time. ...
Optical imaging of activity has provided valuable insight into brain function and accelerated the field of neuroscience in recent years. Genetically encoded fluorescent activity sensors of calcium, neurotransmitters and voltage have been tools of choice for optical recording of neuronal activity. However, photon scattering and absorbance limits fluorescence imaging to superficial regions for in vivo activity imaging. This limitation prevents recording of population level activity in lower brain regions of experimental animals without implanted hardware. Single and multiphoton methods find maximal use in the cortex and experience loss of signal at greater depths. Successful efforts have been made to increase the depth of fluorescence imaging using fiber photometry and gradient reflective index lenses. However, these methods are highly invasive, requiring an implant within the brain. Bioluminescence imaging offers a promising alternative to achieve activity imaging in deeper brain regions without hardware implanted within the brain. Bioluminescent reporters can be genetically encoded and produce photons without external excitation. The use of enzymatic photon production also enables prolonged imaging sessions without the risk of photobleaching or phototoxicity. These characteristics render bioluminescence suitable to non-invasive imaging of deep neuronal populations. To facilitate the adoption of bioluminescent activity imaging, we sought to develop a low cost, simple in vitro method to optimize imaging parameters for determining optimal exposure times and optical hardware configurations to determine what frame rates can be captured with an individual labs imaging hardware with sufficient signal-to-noise ratios without the use of animals prior to starting an in vivo experiment. To achieve this, we developed an assay for modeling in vivo optical conditions with a brain tissue phantom paired with engineered cells that produce bioluminescence. We then used this assay to limit-test the detection depth vs maximum frame rate for bioluminescence imaging at experimentally relevant tissue depths using off the shelf imaging hardware. With this method, we demonstrate an effective means for increasing the utility of bioluminescent tools and lowering the barrier to adoption of bioluminescence activity imaging with bioluminescent sensors.
... This technique substantially advanced our understanding of the nervous system by providing an unprecedented level of resolution for manipulating and monitoring the activity of specific target neural circuits and presented potential therapeutic applications for brain disorders and neurodegenerative diseases (3)(4)(5)(6). Overcoming the limitations of conventional optogenetic approaches like tethered and wired light delivery (3,7,8) is crucial to effectively study brain circuits under undisturbed naturalistic behavior. These tethered systems with bulky optical wires substantially restrict animals' movement, impede their natural behavior, and limit the scope of experimental paradigms that can be used, such as complex behavior tests, social interactions, prolonged tasks, and multiple animals' in vivo experiments. ...
Numerous wireless optogenetic systems have been reported for practical tether-free optogenetics in freely moving animals. However, most devices rely on battery-powered or coil-powered systems requiring periodic battery replacement or bulky, high-cost charging equipment with delicate antenna design. This leads to spatiotemporal constraints, such as limited experimental duration due to battery life or animals’ restricted movement within specific areas to maintain wireless power transmission. In this study, we present a wireless, solar-powered, flexible optoelectronic device for neuromodulation of the complete freely behaving subject. This device provides chronic operation without battery replacement or other external settings including impedance matching technique and radio frequency generators. Our device uses high-efficiency, thin InGaP/GaAs tandem flexible photovoltaics to harvest energy from various light sources, which powers Bluetooth system to facilitate long-term, on-demand use. Observation of sustained locomotion behaviors for a month in mice via secondary motor cortex area stimulation demonstrates the notable capabilities of our device, highlighting its potential for space-free neuromodulating applications.
... On the second front -effective and safe delivery of light into large primate brains -there have also been many exciting developments ranging from optical fiber based technologies (Pisanello et al., 2014;Sileo et al., 2015;Sparta et al., 2012;Tsakas et al., 2021), to direct optical targeting (Ruiz et al., 2013;Yazdan-Shahmorad et al., 2016;Shewcraft et al., 2019) and chronically implantable LED arrays (Kwon et al., 2015;Steude et al., 2016;Rajalingham et al., 2021). This challenge, covering large physical areas, is not limited to light delivery, as mentioned earlier, virus delivery is also subject to the same limitations. ...
Optogenetics has been a promising and developing technology in systems neuroscience throughout the past decade. It has been difficult though to reliably establish the potential behavioral effects of optogenetic perturbation of the neural activity in nonhuman primates. This poses a challenge on the future of optogenetics in humans as the concepts and technology need to be developed in nonhuman primates first. Here, I briefly summarize the viable approaches taken to improve nonhuman primate behavioral optogenetics, then focus on one approach: improvements in the measurement of behavior. I bring examples from visual behavior and show how the choice of method of measurement might conceal large behavioral effects. I will then discuss the “cortical perturbation detection” task in detail as an example of a sensitive task that can record the behavioral effects of optogenetic cortical stimulation with high fidelity. Finally, encouraged by the rich scientific landscape ahead of behavioral optogenetics, I invite technology developers to improve the chronically implantable devices designed for simultaneous neural recording and optogenetic intervention in nonhuman primates.
... Integrated with endoscopes, or guided by magnetic resonance imaging, optical fiber devices could be minimally invasively placed at desired locations, for targeted illumination in applications including laser-induced thermotherapy, optogenetics, temperature and pressure sensing, etc [27][28][29] . For deep targets, optical fibers need to be inserted into the tissues, which is associated with risks of impairing tissue functions [30][31][32] . Through the ...
... Integrated with endoscopes, or guided by magnetic resonance imaging, optical fiber devices could be minimally invasively placed at desired locations, for targeted illumination in applications including laser-induced thermotherapy, optogenetics, temperature and pressure sensing, etc [27][28][29] . For deep targets, optical fibers need to be inserted into the tissues, which is associated with risks of impairing tissue functions [30][31][32] structural design of the optical fiber-based photonic devices, optical energy distribution can be manipulated to some extent 25,[33][34][35] . The tips of regular optical fibers are flat, therefore light leaving the fiber tips transmits in forward direction, only illuminates a small piece of tissue in front of the fiber tip 30,34 . ...
Diagnostic and therapeutic illumination on internal organs and tissues with high controllability and adaptability in terms of spectrum, area, depth, and intensity remains a major challenge. Here, we present a flexible, biodegradable photonic device called iCarP with a micrometer scale air gap between a refractive polyester patch and the embedded removable tapered optical fiber. ICarP combines the advantages of light diffraction by the tapered optical fiber, dual refractions in the air gap, and reflection inside the patch to obtain a bulb-like illumination, guiding light towards target tissue. We show that iCarP achieves large area, high intensity, wide spectrum, continuous or pulsatile, deeply penetrating illumination without puncturing the target tissues and demonstrate that it supports phototherapies with different photosensitizers. We find that the photonic device is compatible with thoracoscopy-based minimally invasive implantation onto beating hearts. These initial results show that iCarP could be a safe, precise and widely applicable device suitable for internal organs and tissue illumination and associated diagnosis and therapy.
... Optic fiber implants for in-vivo optogenetic experiments (Figures 1 and 5) were custom-made from a 200 μm core / 0.39 NA / 230 μm outer diameter optic fiber (FT200EMT; Thorlabs Inc, Newton, NJ, USA) glued inside 1.25 mm diameter ceramic ferrules (CFLC230; Thorlabs) as described in (Sparta et al., 2012). During surgery, the implantable part (230 μm diameter optic fiber) was slowly advanced until the tip reached a position 500 μm above the injection site. ...
During fear learning, associations between an aversive stimulus (the US), and a sensory cue (CS) are formed at specific brain synapses. Nevertheless, how US information is transmitted to brain areas involved in value processing, like the amygdala, is still elusive. Using optogenetics, in-vivo Ca ²⁺ imaging, and circuit tracing, we investigate the role of the posterior insular cortex (pInsCx) and relevant output pathways of this cortical area in fear learning. Optogenetic suppression of US-signaling in pInsCx principal neurons compromises auditory-cued fear learning. The pInsCx makes a robust glutamatergic synapse in the lateral amygdala (LA), which undergoes long-term potentiation after fear learning, and transmits US-information to a sub-population of LA neurons. Suppressing US-signaling in LA-projectors recapitulates the fear learning deficits observed after silencing pInsCx principal neurons. Thus, the pInsCx, via a plastic output synapse, transmits US-information to the LA and critically contributes to the formation of auditory-cued fear memories.
