Biology subjects

Restrepo, D.

Publications and source records attributed to Restrepo, D..

At least 19 recordsLinked to original sources

bioRxiv2026

Multi-site temporal control of optogenetic stimulation enhances firing frequencies in peripheral nerves

We find that multi-site temporal control of optogenetic photostimulation in peripheral nerves can enhance firing rates by overcoming the intrinsic limitation of opsin photophysics. The benefits of multi-site optogenetic stimulation were demonstrated with three approaches: (1) in silico modeling, (2) ex vivo in the sciatic nerve, and (3) in vivo in the vagus nerve. An in silico model of multi-site optogenetic stimulation was developed in two Hodgkin and Huxley type neuron models, that supported our hypothesis. The ex vivo sciatic nerve showed an increase in firing frequency that is physiologically relevant for functional control. The technique was then applied in vivo for optogenetic vagus nerve stimulation resulting in significant changes in heart rate compared with standard methods of single-site stimulation. Improving the control of optogenetically induced neural firing will have broad impacts for future developments in optical nerve interfaces and brain-machine interfaces.

neuroscience↗

bioRxiv2026

Intranasal HSV 1 Infection Drives Region Specific Interferon Dominant Microglial Remodeling

Background and ObjectivesHerpes simplex virus type 1 (HSV-1) is a neurotropic pathogen capable of invading the central nervous system (CNS) and increasingly associated with chronic neuroinflammation, cognitive impairment, and neurodegenerative disease. While microglia orchestrate the initial immune response to HSV-1, the molecular mechanisms that regulate their sustained neuroinflammatory activity in vivo remain poorly understood. MethodsTo define the transcriptional and epigenetic mechanisms that shape microglial responses during acute HSV-1 infection in vivo, we have, for the first time, integrated single-nucleus RNA sequencing, chromatin accessibility profiling, and spatial transcriptomics in a physiologically relevant intranasal HSV-1 infection model. ResultsSingle-cell multiome analysis of CD11b nuclei identified transcriptionally and epigenetically distinct microglial and macrophage populations. HSV-1 infection redistributed monocyte-lineage states, with a marked overrepresentation of interferon (IFN)-responsive microglia and macrophage-associated populations. These states exhibited amplification of STAT1/2-, IRF1-, and CEBPB-centered regulons, distinguishing IFN-responsive microglia from macrophage-enriched populations rather than reflecting uniform activation. Homeostatic microglial gene signatures (e.g., ApoE, Cst3) were reduced in response to HSV-1 infection. Spatial transcriptomics localized HSV-1 antigen to discrete brainstem regions, which were enriched for predicted STAT-, IRF-, and CEBPB-regulated targets identified through single-nuclei analysis. DiscussionUsing a multiomic framework, we demonstrate that HSV-1 infection drives transcriptional and epigenetic remodeling of microglial populations, characterized by a dominance of IFN-responsive states and a loss of homeostatic signatures. These findings provide mechanistic insight into how localized viral infection can reprogram microglial regulatory landscapes to maintain persistent HSV-1-associated neuroinflammation, contributing to long-term neurological vulnerability and neurodegenerative disease risk.

neuroscience↗

bioRxiv2025

Connexin 36-mediated gap junctions contribute to fine odor discrimination and excitation of mitral cells in the mouse olfactory bulb

Key PointsO_LIThe output MCs of the olfactory bulb (OB) engage in strong electrical coupling via connexin 36 (Cx36)-mediated gap junctions. However, the behavioral and physiological relevance of these gap junctions is not well understood. C_LIO_LIIn studies conducted in Cx36 knock-out (KO) mice, we found that the mice displayed reduced fine odor discrimination capabilities versus wild-type mice in a go/no-go associative learning task. These results provide the first evidence to date of olfactory behavioral deficits in Cx36 KO mice. C_LIO_LIIn OB slices, Cx36 KO reduced excitatory responses in MCs to electrical stimulation of sensory afferents, especially during latter stages of the response. C_LIO_LIWe suggest that KO-induced impairments in fine odor discrimination are linked to reduced late MC excitation due to the longer time that mice require to make difficult odor discriminations. C_LI The output mitral cells (MCs) and tufted cells (TCs) of the mammalian olfactory bulb (OB) are coupled through both chemical mechanisms as well as gap junctions that are mediated by connexin 36 (Cx36). Here we tested both behavioral and physiological effects of eliminating gap junctions in knockout (KO) mice with homozygous deletions of Cx36. In a go/no-go associative learning task, Cx36 KO mice were found to display reduced discrimination capabilities when presented with pairs of stimuli that included a monomolecular odor and mixtures that had the same monomolecular odor and a small amount of a structurally similar odor. The impairments did not occur for less similar odor pairs, suggesting that Cx36 KO mice have olfactory processing deficits that are specific to fine odor discrimination. In physiological recordings in OB slices from Cx36 KO mice, MCs displayed reduced excitation in response to electrical stimulation of sensory afferents, both single stimulus pulses as well as a theta burst pattern designed to mimic sniffing. The reduction in MC excitatory current was most prominent for late portions of their response, 300 ms after single stimulus pulses or following all theta bursts that came after the first. More global local field potentials recorded in OB glomeruli were largely unaffected by Cx36 KO. We suggest that the KO-induced impairments in fine odor discrimination are linked to reduced late MC excitation due to the longer time that mice require to make difficult odor discriminations.

neuroscience↗

bioRxiv2025

Miniaturized widefield microscope for high speed voltage imaging

Functional imaging in freely moving animals with genetically encoded voltage indicators (GEVIs) will open new capabilities for neuroscientists to study the behavioral relevance of neural activity with high spatial and temporal precision. However, miniaturization of an imaging system with sufficient collection efficiency to resolve the small changes in fluorescence yield from voltage spikes, as well as development of efficient image sensors that are sufficiently fast to capture them, has proven challenging. We present a miniaturized microscope designed for voltage imaging, with a numerical aperture of 0.6, 250 m field of view and 1.3 mm working distance that weighs 16.4 g. We show it is capable of imaging in vivo voltage spikes from Voltron2 with a spike peak-to-noise ratio >3 at a framerate of 530 Hz.

neuroscience↗

bioRxiv2025

Voltage Imaging with Periodic Structured Illumination

We utilize periodic structured illumination with pseudo-HiLo (pHiLo) image reconstruction for in vivo voltage imaging. We demonstrate reduced signal from out-of-focus cells, that contaminates voltage activity for in-focus cells of interest, with pHiLo compared to traditional widefield recordings taken with uniform illumination and pseudo-widefield (pWF) reconstructions. We discuss tradeoffs between signal-to-background ratio, signal-to-noise ratio and temporal resolution for pHiLo in the context of high-speed voltage imaging in awake mice.

neuroscience↗

bioRxiv2024

Opto2P-FCM: A MEMS based miniature two-photon microscope with two-photon patterned optogenetic stimulation

Multiphoton microscopy combined with optogenetic photostimulation is a powerful technique in neuroscience enabling precise control of cellular activity to determine the neural basis of behavior in a live animal. Two-photon patterned photostimulation has taken this further by allowing interrogation at the individual neuron level. However, it remains a challenge to implement imaging of neural activity with spatially patterned two-photon photostimulation in a freely moving animal. We developed a miniature microscope for high resolution two-photon fluorescence imaging with patterned two-photon optogenetic stimulation. The design incorporates a MEMS scanner for two-photon imaging and a second beam path for patterned two-photon excitation in a compact and lightweight design that can be head-attached to a freely moving animal. We demonstrate cell-specific optogenetics and high resolution MEMS based two-photon imaging in a freely moving mouse. The new capabilities of this miniature microscope design can enable cell-specific studies of behavior that can only be done in freely moving animals.

neuroscience↗

bioRxiv2024

Olfactory and Trigeminal Routes of HSV-1 CNS Infection with Regional Microglial Heterogeneity

Herpes simplex virus type 1 (HSV-1) primarily targets the oral and nasal epithelia before establishing latency in the trigeminal and other peripheral ganglia (TG). HSV-1 can also infect and go latent in the central nervous system (CNS) independent of latency in the TGs. Recent studies suggest entry to the CNS via two distinct routes: the TG-brainstem connection and olfactory nerve; however, to date, there is no characterization of brain regions targeted during HSV-1 primary infection. Furthermore, the immune response by microglia may also contribute to the heterogeneity between different brain regions. However, the response to HSV-1 by microglia has not been characterized in a region-specific manner. This study investigated the time course of HSV-1 spread within the olfactory epithelium (OE) and CNS following intranasal inoculation and the corresponding macrophage/microglial response in a C57BL/6 mouse model. We found an apical to basal spread of HSV-1 within the OE and underlying tissue accompanied by an inflammatory response of macrophages. OE Infection was followed by infection of a small subset of brain regions targeted by the TG in the brainstem, as well as other cranial nerve nuclei, including the vagus and hypoglossal nerve. Furthermore, other brain regions were positive for HSV-1 antigens, such as the locus coeruleus (LC), raphe nucleus (RaN), and hypothalamus, while sparing the hippocampus and cortex. Within each brain region, microglia activation also varied widely. These findings provide critical insights into the region-specific dissemination of HSV-1 within the CNS, elucidating potential mechanisms linking viral infection to neurological and neurodegenerative diseases. ImportanceThis study sheds light on how herpes simplex virus type 1 (HSV-1) spreads within the brain after infecting the nasal passages. Our data reveals the distinct pattern of HSV-1 through the brain during a non-encephalitic infection. Furthermore, microglial activation was also temporally and spatially specific, with some regions of the brain having sustained microglial activation even in the absence of viral antigen. Previous reports have identified specific regions of the brain found to be positive for HSV-1 infection; however, to date, there has not been a concise investigation of the anatomical spread of HSV-1 and the regions of the brain consistently vulnerable to viral entry and spread. Understanding these region-specific differences in infection and immune response is crucial because it links HSV-1 infection to potential triggers for neurological and neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Miniscope Recording Calcium Signals at Hippocampus of Mice Navigating an Odor Plume

Mice navigate an odor plume with a complex spatiotemporal structure in the dark to find the source of odorants. This article describes a protocol to monitor behavior and record Ca2+ transients in dorsal CA1 stratum pyramidale neurons in hippocampus (dCA1) in mice navigating an odor plume in a 50 cm x 50 cm x 25 cm odor arena. An epifluorescence miniscope focused through a GRIN lens imaged Ca2+ transients in dCA1 neurons expressing the calcium sensor GCaMP6f in Thy1-GCaMP6f mice. The paper describes the behavioral protocol to train the mice to perform this odor plume navigation task in an automated odor arena. The methods include a step-by-step procedure for the surgery for GRIN lens implantation and baseplate placement for imaging GCaMP6f in CA1. The article provides information on real-time tracking of the mouse position to automate the start of the trials and delivery of a sugar water reward. In addition, the protocol includes information on using of an interface board to synchronize metadata describing the automation of the odor navigation task and frame times for the miniscope and a digital camera tracking mouse position. Moreover, the methods delineate the pipeline used to process GCaMP6f fluorescence movies by motion correction using NorMCorre followed by identification of regions of interest with EXTRACT. Finally, the paper describes an artificial neural network approach to decode spatial paths from CA1 neural ensemble activity to predict mouse navigation of the odor plume. SUMMARYThis protocol describes how to investigate the brain-behavior relationship in hippocampal CA1 in mice navigating an odor plume. This article provides a step-by-step protocol, including the surgery to access imaging of the hippocampus, behavioral training, miniscope GCaMP6f recording and processing of the brain and behavioral data to decode the mouse position from ROI neural activity.

neuroscience↗

bioRxiv2024

Airway succinate chemosensing induces CFTR-dependent anion secretion and mucus clearance which is impaired in cystic fibrosis.

The respiratory tract possesses a highly regulated innate defense system which includes efficient cilia-mediated mucus transport or mucociliary clearance (MCC). This essential process relies on appropriate hydration of airway surfaces which is controlled by a blend of transepithelial sodium and liquid absorption via the epithelial sodium channel (ENaC), and anion and liquid secretion, primarily regulated by the cystic fibrosis transmembrane conductance regulator (CFTR) channel. MCC is tightly regulated by second messenger signalling pathways. Succinate is derived from parasites, microorganisms and inflammatory cells, and its concentration increases in the airway surface liquid (ASL) during infections. Increases in ASL succinate activates the G-protein coupled succinate receptor (SUCNR1), which acts as a succinate sensor. Here, we tested the hypothesis that succinate signalling was linked to CFTR activity, ASL hydration and increased MCC. We observed that SUCNR1 activation stimulated anion secretion, increased mucus transport and induced bronchoconstriction in mouse airways. In parallel, stimulation of human bronchial epithelial cells (HBEC) with succinate activated anion secretion and increased ASL height. All functions activated by succinate/SUCNR1 were impeded when working with tissues and cells isolated from animal models or individuals affected cystic fibrosis (CF) or when CFTR was inhibited. Moreover, when HBECs derived from {Delta}F508 individuals were incubated with the triple drug combination of elexacaftor/tezacaftor/ivacaftor (ETI), succinate-induced anion secretion was restored, confirming the tight relationship between SUCNR1 signalling and CFTR function. Our results identify a novel activation pathway for CFTR that participates in the defence response of the airways, which is defective in CF. We propose that succinate acts as a danger molecule that alerts the airways to the presence of pathogens leading to a flushing out of the airways.

physiology↗

bioRxiv2023

Long-term in vivo three-photon imaging reveals region-specific differences in healthy and regenerative oligodendrogenesis

The generation of new myelin-forming oligodendrocytes in the adult CNS is critical for cognitive function and regeneration following injury. Oligodendrogenesis varies between gray and white matter regions suggesting that local cues drive regional differences in myelination and the capacity for regeneration. Yet, the determination of regional variability in oligodendrocyte cell behavior is limited by the inability to monitor the dynamics of oligodendrocytes and their transcriptional subpopulations in white matter of the living brain. Here, we harnessed the superior imaging depth of three-photon microscopy to permit long-term, longitudinal in vivo three-photon imaging of an entire cortical column and underlying subcortical white matter without cellular damage or reactivity. Using this approach, we found that the white matter generated substantially more new oligodendrocytes per volume compared to the gray matter, yet the rate of population growth was proportionally higher in the gray matter. Following demyelination, the white matter had an enhanced population growth that resulted in higher oligodendrocyte replacement compared to the gray matter. Finally, deep cortical layers had pronounced deficits in regenerative oligodendrogenesis and restoration of the MOL5/6-positive oligodendrocyte subpopulation following demyelinating injury. Together, our findings demonstrate that regional microenvironments regulate oligodendrocyte population dynamics and heterogeneity in the healthy and diseased brain.

neuroscience↗

bioRxiv2023

Time Tiling of Learned Stimulus-Based Decision Making in Dorsal CA1 in the Hippocampus

Sequential neural dynamics encoded by "time cells" play a crucial role in hippocampal function. However, the role of hippocampal sequential neural dynamics in associative learning is an open question. In this manuscript, we used two-photon Ca2+ imaging of dorsal CA1 pyramidal neurons in head-fixed mice performing a go-no-go associative learning task. We found that pyramidal cells responded differentially to the rewarded or unrewarded stimuli. The stimuli were decoded accurately from the activity of the neuronal ensemble, and accuracy increased substantially as the animal learned to differentiate the stimuli. Decoding the stimulus from individual pyramidal cells that responded differentially revealed that decision-making took place at discrete times after stimulus presentation. Lick prediction decoded from the ensemble activity of cells in dCA1 correlated linearly with lick behavior indicating that sequential activity of pyramidal cells in dCA1 constitutes a temporal memory map used for decision-making in associative learning.

neuroscience↗

bioRxiv2022

Signatures for Viral Infection and Inflammation in the Proximal Olfactory System in Familial Alzheimer's Disease

ObjectiveAlzheimers disease (AD) is characterized by loss of smell and olfactory system pathology that precedes the diagnosis of dementia. Understanding these early processes can potentially identify diagnostic and therapeutic targets to slow AD progression. Here we analyzed differential gene and protein expression in the olfactory bulb (OB) and olfactory tract (OT) of familial AD (FAD) individuals carrying the autosomal dominant presenilin 1 E280A paisa mutation and age-matched controls. MethodsFormalin-fixed, paraffin-embedded sections containing both the OB and OT from 6 FAD individuals and 6 age-matched controls were obtained. Tissue morphology and composition were characterized by immunohistochemistry using antibodies against the myelin marker proteolipid protein (PLP), amyloid-beta (A{beta}), and microglia/macrophage markers Iba1 and CD68, respectively. OB and OT were analyzed separately by targeted RNA sequencing of the whole human transcriptome (BioSpyder TempO-Seq); ingenuity pathway analysis and R-computational program were used to identify differentially expressed genes and pathways between groups. The nanoString spatial proteomics assay for 88 proteins, including markers for AD and immune responses, was used to complement gene expression findings. ResultsCompared to control OT, FAD OT had significantly increased immunostaining for A{beta} and CD68 in the high and low myelinated regions, as well as increased immunostaining for Iba1 in the high myelinated region only; both control and FAD OT samples had similar total area of high and low myelinated regions. In FAD samples, RNA sequencing showed a transcription profile consistent with: (1) viral infection in the OB; (2) inflammation in the OT that carries information via entorhinal cortex from the OB to hippocampus, a brain region essential for learning and memory; and (3) decreased oligodendrocyte deconvolved transcripts, indicating dysregulation of myelination. Interestingly, spatial proteomic analysis confirmed altered myelination in the OT of FAD individuals, implying dysfunction of communication between the OB and hippocampus. ConclusionsThese findings raise the possibility that viral infection and associated inflammation and dysregulation of myelination of the olfactory system may disrupt downstream hippocampal function, contributing to acceleration of FAD progression.

neuroscience↗

bioRxiv2022

GRINtrode: A neural implant for simultaneous two-photon imaging and extracellular electrophysiology in freely moving animals

SignificanceIn vivo imaging and electrophysiology are powerful tools to explore neuronal function that each offer unique complementary information with advantages and limitations. Capturing both data types from the same neural population in the freely moving animal would allow researchers to take advantage of the capabilities of both modalities and further understand how they relate to each other. AimHere we present a head-mounted neural implant suitable for in vivo two-photon imaging of neuronal activity with simultaneous extracellular electrical recording in head-fixed or freely moving animals. ApproachA GRIN lens-based head-mounted neural implant with extracellular electrical recording provided by tetrodes on the periphery of the GRIN lens was chronically implanted. The design of the neural implant allows for recording from head-fixed animals, as well as freely moving animals by coupling the imaging system to a coherent imaging fiber bundle. ResultsWe demonstrate simultaneous two-photon imaging of GCaMP and extracellular electrophysiology of neural activity in awake head-fixed, and freely moving mice. Using the collected information, we perform correlation analysis to reveal positive correlation between optical and local field potential recordings. ConclusionSimultaneously recording neural activity using both optical and electrical methods provides complementary information from each modality. Designs that can provide such bimodal recording in freely moving animals allow for the investigation of neural activity underlying a broader range of behavioral paradigms.

neuroscience↗

bioRxiv2021

Miniature Structured Illumination Microscope for in vivo 3D Imaging of Brain Structures with Optical Sectioning

We present a high-resolution miniature, light-weight fluorescence microscope with electrowetting lens and onboard CMOS for high resolution volumetric imaging and structured illumination for rejection of out-of-focus and scattered light. The miniature microscope (SIMscope3D) delivers structured light using a coherent fiber bundle to obtain optical sectioning with an axial resolution of 18 m. Volumetric imaging of eGFP labeled cells in fixed mouse brain tissue at depths up to 220 m is demonstrated. The functionality of SIMscope3D to provide background free 3D imaging is shown by recording time series of microglia dynamics in awake mice at depths up to 120 m in the brain.

bioengineering↗

bioRxiv2021

Characterization of red fluorescent reporters for dual-color in vivo three-photon microscopy

SignificanceThree-photon (3P) microscopy significantly increases the depth and resolution of in vivo imaging due to decreased scattering and nonlinear optical sectioning. Simultaneous excitation of multiple fluorescent proteins is essential to study multicellular interactions and dynamics in the intact brain. AimWe characterized the excitation laser pulses at a range of wavelengths for 3P microscopy, and then explored the application of tdTomato or mScarlet and EGFP for dual-color single-excitation structural 3P imaging deep in the living mouse brain. ApproachWe used frequency-resolved optical gating to measure the spectral intensity, phase, and retrieved pulse widths at a range of wavelengths. Then, we performed in vivo single wavelength-excitation 3P imaging in the 1225 - 1360 nm range deep in the mouse cerebral cortex to evaluate the performance of tdTomato or mScarlet in combination with EGFP. ResultsWe find that tdTomato and mScarlet, expressed in oligodendrocytes and neurons respectively, have high signal-to-background in the 1300-1360 nm range, consistent with enhanced 3P cross sections. ConclusionsThese results suggest that a single excitation wavelength source is advantageous for multiple applications of dual-color brain imaging and highlight the importance of empirical characterization of individual fluorophores for 3P microscopy.

neuroscience↗

bioRxiv2021

Hippocampal-prefrontal theta coupling develops as mice become proficient in associative odorant discrimination learning

Learning and memory requires coordinated activity between different regions of the brain. Here we studied the interaction between infralimbic medial prefrontal cortex (mPFC) and hippocampal dorsal CA1 during associative odorant discrimination learning in the male mouse. We found that as the animal learns to discriminate odorants in a go- no go task the coupling of high frequency neural oscillations to the phase of theta oscillations (theta-referenced phase-amplitude coupling or tPAC) changes in a manner that results in divergence between rewarded and unrewarded odorant-elicited changes in the theta-phase referenced power (tPRP) for beta and gamma oscillations. In addition, in the proficient animal there was a decrease in the coordinated oscillatory activity between CA1 and mPFC in the presence of the unrewarded odorant. Furthermore, the changes in tPAC resulted in a marked increase in the accuracy for decoding contextual odorant identity from tPRP when the animal became proficient. Finally, we studied the role of Ca2+/calmodulin-dependent protein kinase II (CaMKII), a protein involved in learning and memory, in oscillatory neural processing in this task. We find that the accuracy for decoding the contextual odorant identity from tPRP decreases in CaMKII knockout mice and that this accuracy correlates with behavioral performance. These results implicate a role for tPAC and CaMKII genotype in olfactory go-no go associative learning in the hippocampal-prefrontal circuit. Significance statementCoupling of neural oscillations between hippocampal CA1 and medial prefrontal cortex (mPFC) is involved in spatial learning and memory, but the role of oscillation coupling for other learning tasks is not well understood. Here we performed local field potential recording in CA1 and mPFC in mice learning to differentiate rewarded from unrewarded odorants in an associative learning task. We find that odorant-elicited changes in the power of bursts of gamma oscillations at distinct phases of theta oscillations become divergent as the animal becomes proficient allowing decoding of contextual odorant identity. Finally, we find that the accuracy to decode contextual odorant identity decreases in mice deficient for the expression of Ca2+/calmodulin-dependent protein kinase II , a protein involved in synaptic plasticity.

neuroscience↗

bioRxiv2021

Excitable axonal domains adapt to sensory deprivation in the olfactory system

The axon initial segment, nodes of Ranvier, and the oligodendrocyte-derived myelin sheath have significant influence on the firing patterns of neurons and the faithful, coordinated transmission of action potentials to downstream brain regions. In the olfactory bulb, olfactory discrimination tasks lead to adaptive changes in cell firing patterns, and the output signals must reliably travel large distances to other brain regions along highly myelinated tracts. Whether myelinated axons adapt to facilitate olfactory sensory processing is unknown. Here, we investigate the morphology and physiology of mitral cell axons in the adult olfactory system, and show that unilateral sensory deprivation causes system-wide adaptations in axons. Mitral cell spiking patterns and action potentials also adapted to sensory deprivation. Strikingly, both axonal morphology and mitral cell physiology were altered on both the deprived and non-deprived sides, indicating system level adaptations to reduced sensory input. Our work demonstrates a previously unstudied mechanism of plasticity in the olfactory system.

neuroscience↗

bioRxiv2020

Selective Modulation of Heart and Respiration by Optical Control of Vagus Nerve Axons Innervating the Heart

Targeting specifics subsets of peripheral pathways of the autonomic nervous system will enable new avenues to study organ control and develop new disease therapies. Vagus nerve stimulation (VNS) has shown many therapeutic benefits but current approaches involve imprecise electrical stimulation that gives rise to adverse effects, and the functionally relevant pathways are poorly understood. One method to overcome these limitations is the use of optogenetic techniques, which facilitate highly specific neural communication with light-sensitive actuators (opsins). Opsins can be targeted to cell populations of interest based on the location of viral delivery and genetic control of expression. Here, we tested whether holographic photostimulation of subsets of axons of the cervical vagus nerve that innervate the heart can be used to modulate cardiac function. Viral injection of retrograde adeno-associated virus (rAAV2-retro) in the heart resulted in robust, primarily afferent, opsin reporter expression in the vagus nerve, nodose ganglion, and brainstem. Selective holographic photostimulation of axons resulted in changes in heart rate, surface cardiac electrogram, and respiratory responses that were different from responses elicited by whole nerve photostimulation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

bioengineering↗