scholarly journals Exploiting modal demultiplexing properties of tapered optical fibers for tailored optogenetic stimulation

2017 ◽  
Author(s):  
Marco Pisanello ◽  
Filippo Pisano ◽  
Leonardo Sileo ◽  
Emanuela Maglie ◽  
Elisa Bellistri ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Neural Activity ◽  
Propagation Constant ◽  
Numerical Aperture ◽  
Brain Regions ◽  
Brain Volumes ◽  
Light Delivery ◽  
Multiple Wavelengths ◽  
Active Segment ◽  
Site Selective

AbstractOptogenetic control of neural activity in deep brain regions requires precise and flexible light delivery with non-invasive devices. To this end, Tapered Optical Fibers (TFs) represent a minimally-invasive tool that can deliver light over either large brain volumes or spatially confined subregions. This work links the emission properties of TFs with the modal content injected into the fiber, finding that the maximum transversal propagation constant (kt) and the total number of guided modes sustained by the waveguide are key parameters for engineering the mode demultiplexing properties of TFs. Intrinsic features of the optical fiber (numerical aperture and core/cladding diameter) define the optically active segment of the taper (up to ∼3mm), along which a linear relation between the propagating set of kt values and the emission position exists. These site-selective light-delivery properties are preserved at multiple wavelengths, further extending the range of applications expected for tapered fibers for optical control of neural activity.

scholarly journals Dynamically controlled light delivery over large brain volumes through tapered optical fibers

2016 ◽  
Author(s):  
Ferruccio Pisanello ◽  
Gil Mandelbaum ◽  
Marco Pisanello ◽  
Ian A. Oldenburg ◽  
Leonardo Sileo ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Light Emission ◽  
Motor Behavior ◽  
Numerical Aperture ◽  
Brain Volumes ◽  
Light Emitting ◽  
Precise Control ◽  
Neural Processes ◽  
Large Brain

ABSTRACTOptogenetics promises spatiotemporal precise control of neural processes using light. However, the spatial extent of illumination within the brain is difficult to control and cannot be adjusted using standard fiber optics. We demonstrate that optical fibers with tapered tips can be used to illuminate either large brain volumes or dynamically selectable subregions. Remotely adjusting the light input angle to the fiber varies the light-emitting portion of the taper over several millimeters without movement of the implant. We use this mode to activate dorsal versus ventral striatum of individual mice and reveal different effects of each manipulation on motor behavior. Conversely injecting light over the full numerical aperture of the fiber results in light emission from the entire taper surface, achieving broader and more efficient optogenetic activation of neurons when compared to the standard flat-faced fiber stimulation. Thus, tapered fibers permit focal or broad illumination that can be precisely and dynamically matched to experimental needs.

scholarly journals Deep brain fluorescence imaging with minimally invasive ultra-thin optical fibers

2017 ◽  
Author(s):  
Shay Ohayon ◽  
Antonio M. Caravaca-Aguirre ◽  
Rafael Piestun ◽  
James J. DiCarlo
Keyword(s):  
Optical Fibers ◽  
Neural Activity ◽  
Brain Regions ◽  
Volumetric Imaging ◽  
Non Invasive ◽  
Cellular Resolution ◽  
Calcium Indicator ◽  
Acquisition Speed ◽  
Resolution Imaging

AbstractA major open challenge in neuroscience is the ability to measure and perturb neural activity in vivo from well-defined neural sub-populations at cellular resolution anywhere in the brain. However, limitations posed by scattering and absorption prohibit non-invasive (surface) multiphoton approaches1,2 for deep (>2mm) structures, while Gradient Refreactive Index (GRIN) endoscopes2–4 are thick and cause significant damage upon insertion. Here, we demonstrate a novel microendoscope to image neural activity at arbitrary depths via an ultrathin multimode optical fiber (MMF) probe that is 5-10X thinner than commercially available microendoscopes. We demonstrate micron-scale resolution, multispectral and volumetric imaging. In contrast to previous approaches1,5–8 we show that this method has an improved acquisition speed that is sufficient to capture rapid neuronal dynamics in-vivo in rodents expressing a genetically encoded calcium indicator. Our results emphasize the potential of this technology in neuroscience applications and open up possibilities for cellular resolution imaging in previously unreachable brain regions.

scholarly journals Neural substrates of propranolol-induced impairments in the reconsolidation of nicotine-associated memories in smokers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiao Lin ◽  
Jiahui Deng ◽  
Kai Yuan ◽  
Qiandong Wang ◽  
Lin Liu ◽  
...  
Keyword(s):  
Neural Activity ◽  
Neural Substrates ◽  
Brain Regions ◽  
Reward Processing ◽  
Memory Reconsolidation ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Postcentral Gyrus ◽  
Propranolol Group ◽  
Propranolol Administration

AbstractThe majority of smokers relapse even after successfully quitting because of the craving to smoking after unexpectedly re-exposed to smoking-related cues. This conditioned craving is mediated by reward memories that are frequently experienced and stubbornly resistant to treatment. Reconsolidation theory posits that well-consolidated memories are destabilized after retrieval, and this process renders memories labile and vulnerable to amnestic intervention. This study tests the retrieval reconsolidation procedure to decrease nicotine craving among people who smoke. In this study, 52 male smokers received a single dose of propranolol (n = 27) or placebo (n = 25) before the reactivation of nicotine-associated memories to impair the reconsolidation process. Craving for smoking and neural activity in response to smoking-related cues served as primary outcomes. Functional magnetic resonance imaging was performed during the memory reconsolidation process. The disruption of reconsolidation by propranolol decreased craving for smoking. Reactivity of the postcentral gyrus in response to smoking-related cues also decreased in the propranolol group after the reconsolidation manipulation. Functional connectivity between the hippocampus and striatum was higher during memory reconsolidation in the propranolol group. Furthermore, the increase in coupling between the hippocampus and striatum positively correlated with the decrease in craving after the reconsolidation manipulation in the propranolol group. Propranolol administration before memory reactivation disrupted the reconsolidation of smoking-related memories in smokers by mediating brain regions that are involved in memory and reward processing. These findings demonstrate the noradrenergic regulation of memory reconsolidation in humans and suggest that adjunct propranolol administration can facilitate the treatment of nicotine dependence. The present study was pre-registered at ClinicalTrials.gov (registration no. ChiCTR1900024412).

scholarly journals Shaping Beam Profiles Using Plastic Optical Fiber Tapers with Application to Ice Sensors

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2503
Author(s):  
Kostas Amoiropoulos ◽  
Georgia Kioselaki ◽  
Nikolaos Kourkoumelis ◽  
Aris Ikiades
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Laser Cooling ◽  
Detection Efficiency ◽  
Numerical Aperture ◽  
Beam Profile ◽  
Hollow Beam ◽  
Enhanced Sensitivity ◽  
Surface Irregularities ◽  
Plastic Optical Fibers

Using either bulk or fiber optics the profile of laser beams can be altered from Gaussian to top-hat or hollow beams allowing enhanced performance in applications like laser cooling, optical trapping, and fiber sensing. Here, we report a method based on multimode Plastic Optical Fibers (POF) long-tapers, to tweak the beam profile from near Gaussian to a hollow beam, by generating surface irregularities on the conical sections of the taper with a heat-and-pull technique. Furthermore, a cutback technique applied on long tapers expanded the output beam profile by more than twice the numerical aperture (NA) of the fiber. The enhanced sensitivity and detection efficiency of the extended profile was tested on a fiber optical ice sensor related to aviation safety.

Fabrication of Lensed Plastic Optical Fiber Array Using Electrostatic Force

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Yih-Tun Tseng ◽  
Jhong-Bin Huang ◽  
Che-Hsin Lin ◽  
Chin-Lung Chen ◽  
Wood-Hi Cheng
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Electrostatic Force ◽  
Coupling Efficiency ◽  
Numerical Aperture ◽  
Uv Curing ◽  
Power Budget ◽  
Fiber Array ◽  
Plastic Optical Fibers ◽  
Efficient Coupling

The GI (graded-index) POFs (Plastic optical fibers), which has been proven to reach distances as long as 1 km at 1.25 Gb/s has a relatively low numerical aperture . Therefore, the efficient coupling of GI POFs to the light source has become critical to the power budget in the system. Efficient coupling for a POFs system normally involves either a separate lens or the direct formation of the lens at the end of the fiber. Forming the lens-like structure directly on the fiber end is preferred for simplicity of fabrication and packaging, such as polishing and fusion, combine different fibers with the cascaded fiber method and hydroflouride (HF) chemical etching. These approaches are well established, but applicable only to glass. Optical assembly architecture for multichannel fibers and optical devices is critical to optical fiber interconnections. Multichannel fiber-pigtail laser diode (LD) modules have potential for supporting higher data throughput and longer transmission distances. However, to be of practical use, these modules must be more precise. This work proposes and manufactures lensed plastic optical fibers (LPOF) array. This novel manipulation can be utilized to fabricate an aspherical lens on a fiber array after the UV curing of the photo-sensitive polymer; the coupling efficiency (CE) is increased and exceeds 47% between the LD array and the fiber array.

scholarly journals Reported Hearing Loss in Alzheimer’s Disease Is Associated With Loss of Brainstem and Cerebellar Volume

2021 ◽  
Vol 15 ◽  
Author(s):  
Daniel A. Llano ◽  
Susanna S. Kwok ◽  
Viswanath Devanarayan ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Hearing Loss ◽  
Normal Subjects ◽  
Neural Substrates ◽  
Epidemiological Studies ◽  
Brain Regions ◽  
Pathological State ◽  
Brain Volumes ◽  
The Relationship

Multiple epidemiological studies have revealed an association between presbycusis and Alzheimer’s Disease (AD). Unfortunately, the neurobiological underpinnings of this relationship are not clear. It is possible that the two disorders share a common, as yet unidentified, risk factor, or that hearing loss may independently accelerate AD pathology. Here, we examined the relationship between reported hearing loss and brain volumes in normal, mild cognitive impairment (MCI) and AD subjects using a publicly available database. We found that among subjects with AD, individuals that reported hearing loss had smaller brainstem and cerebellar volumes in both hemispheres than individuals without hearing loss. In addition, we found that these brain volumes diminish in size more rapidly among normal subjects with reported hearing loss and that there was a significant interaction between cognitive diagnosis and the relationship between reported hearing loss and these brain volumes. These data suggest that hearing loss is linked to brainstem and cerebellar pathology, but only in the context of the pathological state of AD. We hypothesize that the presence of AD-related pathology in both the brainstem and cerebellum creates vulnerabilities in these brain regions to auditory deafferentation-related atrophy. These data have implications for our understanding of the potential neural substrates for interactions between hearing loss and AD.

scholarly journals Dissociable oscillatory networks support gain and loss processing in human orbitofrontal cortex

2021 ◽  
Author(s):  
Ignacio Saez ◽  
Jack Lin ◽  
Edward Chang ◽  
Josef Parvizi ◽  
Robert T. Knight ◽  
...  
Keyword(s):  
Neural Activity ◽  
Orbitofrontal Cortex ◽  
Low Frequency ◽  
Brain Regions ◽  
Reward Processing ◽  
Neural Oscillations ◽  
Beta Band ◽  
Neuronal Ensembles ◽  
Gain And Loss

AbstractHuman neuroimaging and animal studies have linked neural activity in orbitofrontal cortex (OFC) to valuation of positive and negative outcomes. Additional evidence shows that neural oscillations, representing the coordinated activity of neuronal ensembles, support information processing in both animal and human prefrontal regions. However, the role of OFC neural oscillations in reward-processing in humans remains unknown, partly due to the difficulty of recording oscillatory neural activity from deep brain regions. Here, we examined the role of OFC neural oscillations (<30Hz) in reward processing by combining intracranial OFC recordings with a gambling task in which patients made economic decisions under uncertainty. Our results show that power in different oscillatory bands are associated with distinct components of reward evaluation. Specifically, we observed a double dissociation, with a selective theta band oscillation increase in response to monetary gains and a beta band increase in response to losses. These effects were interleaved across OFC in overlapping networks and were accompanied by increases in oscillatory coherence between OFC electrode sites in theta and beta band during gain and loss processing, respectively. These results provide evidence that gain and loss processing in human OFC are supported by distinct low-frequency oscillations in networks, and provide evidence that participating neuronal ensembles are organized functionally through oscillatory coherence, rather than local anatomical segregation.

scholarly journals Locus Coeruleus to Paraventricular Thalamus Projections Facilitate Emergence From Isoflurane Anesthesia in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Yawen Ao ◽  
Bo Yang ◽  
Caiju Zhang ◽  
Bo Wu ◽  
Xuefen Zhang ◽  
...  
Keyword(s):  
Locus Coeruleus ◽  
Neural Activity ◽  
Brain Regions ◽  
Cortical Arousal ◽  
Emergence Time ◽  
General Anesthetic ◽  
Common Pathway ◽  
Isoflurane Anesthesia ◽  
New Strategy ◽  
Paraventricular Thalamus

Locus coeruleus (LC) sends widespread outputs to many brain regions to modulate diverse functions, including sleep/wake states, attention, and the general anesthetic state. The paraventricular thalamus (PVT) is a critical thalamic area for arousal and receives dense tyrosine-hydroxylase (TH) inputs from the LC. Although anesthesia and sleep may share a common pathway, it is important to understand the processes underlying emergence from anesthesia. In this study, we hypothesize that LC TH neurons and the TH:LC-PVT circuit may be involved in regulating emergence from anesthesia. Only male mice are used in this study. Here, using c-Fos as a marker of neural activity, we identify LC TH expressing neurons are active during anesthesia emergence. Remarkably, chemogenetic activation of LC TH neurons shortens emergence time from anesthesia and promotes cortical arousal. Moreover, enhanced c-Fos expression is observed in the PVT after LC TH neurons activation. Optogenetic activation of the TH:LC-PVT projections accelerates emergence from anesthesia, whereas, chemogenetic inhibition of the TH:LC-PVT circuit prolongs time to wakefulness. Furthermore, optogenetic activation of the TH:LC-PVT projections produces electrophysiological evidence of arousal. Together, these results demonstrate that activation of the TH:LC-PVT projections is helpful in facilitating the transition from isoflurane anesthesia to an arousal state, which may provide a new strategy in shortening the emergence time after general anesthesia.

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