scholarly journals Inception in visual cortex: in vivo-silico loops reveal most exciting images

2018 ◽  
Author(s):  
Edgar Y. Walker ◽  
Fabian H. Sinz ◽  
Emmanouil Froudarakis ◽  
Paul G. Fahey ◽  
Taliah Muhammad ◽  
...  
Keyword(s):  
Linear Models ◽  
Sensory Information ◽  
Target Cells ◽  
New Approach ◽  
Spatial Features ◽  
Sensory Information Processing ◽  
Response Modeling ◽  
The Brain ◽  
Better Than

Much of our knowledge about sensory processing in the brain is based on quasi-linear models and the stimuli that optimally drive them. However, sensory information processing is nonlinear, even in primary sensory areas, and optimizing sensory input is difficult due to the high-dimensional input space. We developed inception loops, a closed-loop experimental paradigm that combines in vivo recordings with in silico nonlinear response modeling to identify the Most Exciting Images (MEIs) for neurons in mouse V1. When presented back to the brain, MEIs indeed drove their target cells significantly better than the best stimuli identified by linear models. The MEIs exhibited complex spatial features that deviated from the textbook ideal of V1 as a bank of Gabor filters. Inception loops represent a widely applicable new approach to dissect the neural mechanisms of sensation.

scholarly journals Widespread inhibition, antagonism, and synergy in mouse olfactory sensory neurons in vivo

2019 ◽  
Author(s):  
Shigenori Inagaki ◽  
Ryo Iwata ◽  
Masakazu Iwamoto ◽  
Takeshi Imai
Keyword(s):  
Sensory Neurons ◽  
Calcium Imaging ◽  
Odorant Receptor ◽  
Sensory Information ◽  
Olfactory Sensory Neurons ◽  
Axon Terminals ◽  
Two Photon ◽  
Odor Mixtures ◽  
The Brain

SUMMARYSensory information is selectively or non-selectively inhibited and enhanced in the brain, but it remains unclear whether this occurs commonly at the peripheral stage. Here, we performed two-photon calcium imaging of mouse olfactory sensory neurons (OSNs) in vivo and found that odors produce not only excitatory but also inhibitory responses at their axon terminals. The inhibitory responses remained in mutant mice, in which all possible sources of presynaptic lateral inhibition were eliminated. Direct imaging of the olfactory epithelium revealed widespread inhibitory responses at OSN somata. The inhibition was in part due to inverse agonism toward the odorant receptor. We also found that responses to odor mixtures are often suppressed or enhanced in OSNs: Antagonism was dominant at higher odor concentrations, whereas synergy was more prominent at lower odor concentrations. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy, at the early peripheral stage, contributing to robust odor representations.

Low-dimensional versus high-dimensional chaos in brain function – is it an and/or issue?

2001 ◽  
Vol 24 (5) ◽  
pp. 823-824 ◽  
Author(s):  
Márk Molnár
Keyword(s):  
Brain Function ◽  
Sensory Information ◽  
Event Related Potentials ◽  
Cognitive Effort ◽  
Neural Systems ◽  
Sensory Information Processing ◽  
Related Potentials ◽  
Dimensional Complexity ◽  
Low Dimensional ◽  
The Brain

We discuss whether low-dimensional chaos and even nonlinear processes can be traced in the electrical activity of the brain. Experimental data show that the dimensional complexity of the EEG decreases during event-related potentials associated with cognitive effort. This probably represents increased nonlinear cooperation between different neural systems during sensory information processing.

scholarly journals TheEscherichia coli-Derived Thymosinβ4 Concatemer Promotes Cell Proliferation and Healing Wound in Mice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaolei Wang ◽  
Guihua Yang ◽  
Shanshuang Li ◽  
Meifeng Gao ◽  
Pangfeng Zhao ◽  
...  
Keyword(s):  
Spleen Cells ◽  
New Approach ◽  
E Coli ◽  
Sds Page ◽  
Strain Bl21 ◽  
Healing Wound ◽  
Production Strategy ◽  
Better Than

Thymosinβ4 (Tβ4) is one of the most promising thymosins for future clinical applications, and it is anticipated that commercial demand for Tβ4 will increase. In order to develop a new approach to produce recombinant Tβ4, a 168 bp DNA (termedTβ4) was designed based on the Tβ4 protein sequence and used to express a 4 ×Tβ4 concatemer (four tandem copies of Tβ4, termed 4 ×Tβ4) together with a histidine tag (6 × His) inE. coli(strain BL21). SDS-PAGE and western blot analysis were used to confirm that a recombinant 4 × Tβ4 protein of the expected size (30.87 kDa) was produced following the induction of the bacterial cultures with isopropylβ-D-thiogalactoside (IPTG). TheE. coli-derived 4 ×Tβ4 was purified by Ni-NTA resin, and its activities were examined with regard to both stimulating proliferation of the mice spleen cellsin vitroandin vivowound healing. The results demonstrate that these activities of theE. coli-derived recombinant 4 × Tβ4 were similar or even better than existing commercially obtained Tβ4. This production strategy therefore represents a potentially valuable approach for future commercial production of recombinant Tβ4.

Effects of Propofol on the Dynamic Properties of Sensory Information Processing in the Mouse Cerebellar Cortical Molecular Layer in vivo

Pharmacology ◽  
2015 ◽  
Vol 96 (5-6) ◽  
pp. 271-277 ◽  
Author(s):  
Wen-Zhe Jin ◽  
Jin-Di Shi ◽  
Heng Liu ◽  
Yan Lan ◽  
Chun-Ping Chu ◽  
...  
Keyword(s):  
Information Processing ◽  
Dynamic Properties ◽  
Molecular Layer ◽  
Sensory Information ◽  
Sensory Information Processing

scholarly journals Central vestibular tuning arises from patterned convergence of otolith afferents

2020 ◽  
Author(s):  
Zhikai Liu ◽  
Yukiko Kimura ◽  
Shin-ichi Higashijima ◽  
David G. Hildebrand ◽  
Joshua L. Morgan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Sensory Information ◽  
Vestibular Neurons ◽  
Section Electron ◽  
Afferent Inputs ◽  
Sensory Responses ◽  
Serial Section Electron Microscopy ◽  
The Brain ◽  
Section Electron Microscopy

AbstractAs sensory information moves through the brain, higher-order areas exhibit more complex tuning than lower areas. Though models predict this complexity is due to convergent inputs from neurons with diverse response properties, in most vertebrate systems convergence has only been inferred rather than tested directly. Here we measure sensory computations in zebrafish vestibular neurons across multiple axes in vivo. We establish that whole-cell physiological recordings reveal tuning of individual vestibular afferent inputs and their postsynaptic targets. An independent approach, serial section electron microscopy, supports the inferred connectivity. We find that afferents with similar or differing preferred directions converge on central vestibular neurons, conferring more simple or complex tuning, respectively. Our data also resolve a long-standing contradiction between anatomical and physiological analyses by revealing that sensory responses are produced by sparse but powerful inputs from vestibular afferents. Together these results provide a direct, quantifiable demonstration of feedforward input convergence in vivo.

scholarly journals JC Polyomavirus Uses Extracellular Vesicles To Infect Target Cells

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Jenna Morris-Love ◽  
Gretchen V. Gee ◽  
Bethany A. O’Hara ◽  
Benedetta Assetta ◽  
Abigail L. Atkinson ◽  
...  
Keyword(s):  
Progressive Multifocal Leukoencephalopathy ◽  
Extracellular Vesicles ◽  
Critical Role ◽  
Outer Side ◽  
Target Cells ◽  
Alternative Mechanism ◽  
Jc Polyomavirus ◽  
Virus Receptors ◽  
The Brain

ABSTRACTThe endemic human JC polyomavirus (JCPyV) causes progressive multifocal leukoencephalopathy in immune-suppressed patients. The mechanisms of virus infectionin vivoare not understood because the major target cells for virus in the brain do not express virus receptors and do not bind virus. We found that JCPyV associates with extracellular vesicles (EVs) and can infect target cells independently of virus receptors. Virus particles were found packaged inside extracellular vesicles and attached to the outer side of vesicles. Anti-JCPyV antisera reduced infection by purified virus but had no effect on infection by EV-associated virus. Treatment of cells with the receptor-destroying enzyme neuraminidase inhibited infection with purified virus but did not inhibit infection by EV-associated virus. Mutant pseudoviruses defective in sialic acid receptor binding could not transduce cells as purified pseudovirions but could do so when associated with EVs. This alternative mechanism of infection likely plays a critical role in the dissemination and spread of JCPyV both to and within the central nervous system.IMPORTANCEJC polyomavirus (JCPyV) is a ubiquitous human pathogen that causes progressive multifocal leukoencephalopathy (PML), a severe and often fatal neurodegenerative disease in immunocompromised or immunomodulated patients. The mechanisms responsible for initiating infection in susceptible cells are not completely known. The major attachment receptor for the virus, lactoseries tetrasaccharide c (LSTc), is paradoxically not expressed on oligodendrocytes or astrocytes in human brain, and virus does not bind to these cells. Because these are the major cell types targeted by the virus in the brain, we hypothesized that alternative mechanisms of infection must be responsible. Here we provide evidence that JCPyV is packaged in extracellular vesicles from infected cells. Infection of target cells by vesicle-associated virus is not dependent on LSTc and is not neutralized by antisera directed against the virus. This is the first demonstration of a polyomavirus using extracellular vesicles as a means of transmission.

Sensorimotor integration in the whisker somatosensory brain stem trigeminal loop

2019 ◽  
Vol 122 (5) ◽  
pp. 2061-2075
Author(s):  
Omer Tsur ◽  
Yana Khrapunsky ◽  
Rony Azouz
Keyword(s):  
Brain Stem ◽  
Tactile Stimulus ◽  
Sensorimotor Integration ◽  
Somatosensory System ◽  
Sensory Information ◽  
Stem Loop ◽  
The Brain ◽  
The Way

The rodent’s vibrissal system is a useful model system for studying sensorimotor integration in perception. This integration determines the way in which sensory information is acquired by sensory organs and the motor commands that control them. The initial instance of sensorimotor integration in the whisker somatosensory system is implemented in the brain stem loop and may be essential to the way rodents explore and sense their environment. To examine the nature of these sensorimotor interactions, we recorded from lightly anesthetized rats in vivo and brain stem slices in vitro and isolated specific parts of this loop. We found that motor feedback to the vibrissal pad serves as a dynamic gain controller that controls the response of first-order sensory neurons by increasing and decreasing sensitivity to lower and higher tactile stimulus magnitudes, respectively. This delicate mechanism is mediated through tactile stimulus magnitude-dependent motor feedback. Conversely, tactile inputs affect the motor whisking output through influences on the rhythmic whisking circuitry, thus changing whisking kinetics. Similarly, tactile influences also modify the whisking amplitude through synaptic and intrinsic neuronal interaction in the facial nucleus, resulting in facilitation or suppression of whisking amplitude. These results point to the vast range of mechanisms underlying sensorimotor integration in the brain stem loop. NEW & NOTEWORTHY Sensorimotor integration is a process in which sensory and motor information is combined to control the flow of sensory information, as well as to adjust the motor system output. We found in the rodent’s whisker somatosensory system mutual influences between tactile inputs and motor output, in which motor neurons control the flow of sensory information depending on their magnitude. Conversely, sensory information can control the magnitude and kinetics of whisker movement.

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