5,568 research outputs found
Deep learning long-range information in undirected graphs with wave networks
Graph algorithms are key tools in many fields of science and technology. Some
of these algorithms depend on propagating information between distant nodes in
a graph. Recently, there have been a number of deep learning architectures
proposed to learn on undirected graphs. However, most of these architectures
aggregate information in the local neighborhood of a node, and therefore they
may not be capable of efficiently propagating long-range information. To solve
this problem we examine a recently proposed architecture, wave, which
propagates information back and forth across an undirected graph in waves of
nonlinear computation. We compare wave to graph convolution, an architecture
based on local aggregation, and find that wave learns three different
graph-based tasks with greater efficiency and accuracy. These three tasks
include (1) labeling a path connecting two nodes in a graph, (2) solving a maze
presented as an image, and (3) computing voltages in a circuit. These tasks
range from trivial to very difficult, but wave can extrapolate from small
training examples to much larger testing examples. These results show that wave
may be able to efficiently solve a wide range of problems that require
long-range information propagation across undirected graphs. An implementation
of the wave network, and example code for the maze problem are included in the
tflon deep learning toolkit (https://bitbucket.org/mkmatlock/tflon)
Structure-based control of complex networks with nonlinear dynamics
What can we learn about controlling a system solely from its underlying
network structure? Here we adapt a recently developed framework for control of
networks governed by a broad class of nonlinear dynamics that includes the
major dynamic models of biological, technological, and social processes. This
feedback-based framework provides realizable node overrides that steer a system
towards any of its natural long term dynamic behaviors, regardless of the
specific functional forms and system parameters. We use this framework on
several real networks, identify the topological characteristics that underlie
the predicted node overrides, and compare its predictions to those of
structural controllability in control theory. Finally, we demonstrate this
framework's applicability in dynamic models of gene regulatory networks and
identify nodes whose override is necessary for control in the general case, but
not in specific model instances.Comment: Includes main text and supporting informatio
Convolutional neural networks automate detection for tracking of submicron scale particles in 2D and 3D
Particle tracking is a powerful biophysical tool that requires conversion of
large video files into position time series, i.e. traces of the species of
interest for data analysis. Current tracking methods, based on a limited set of
input parameters to identify bright objects, are ill-equipped to handle the
spectrum of spatiotemporal heterogeneity and poor signal-to-noise ratios
typically presented by submicron species in complex biological environments.
Extensive user involvement is frequently necessary to optimize and execute
tracking methods, which is not only inefficient but introduces user bias. To
develop a fully automated tracking method, we developed a convolutional neural
network for particle localization from image data, comprised of over 6,000
parameters, and employed machine learning techniques to train the network on a
diverse portfolio of video conditions. The neural network tracker provides
unprecedented automation and accuracy, with exceptionally low false positive
and false negative rates on both 2D and 3D simulated videos and 2D experimental
videos of difficult-to-track species
Recommended from our members
Exosomes regulate neurogenesis and circuit assembly.
Exosomes are thought to be released by all cells in the body and to be involved in intercellular communication. We tested whether neural exosomes can regulate the development of neural circuits. We show that exosome treatment increases proliferation in developing neural cultures and in vivo in dentate gyrus of P4 mouse brain. We compared the protein cargo and signaling bioactivity of exosomes released by hiPSC-derived neural cultures lacking MECP2, a model of the neurodevelopmental disorder Rett syndrome, with exosomes released by isogenic rescue control neural cultures. Quantitative proteomic analysis indicates that control exosomes contain multiple functional signaling networks known to be important for neuronal circuit development. Treating MECP2-knockdown human primary neural cultures with control exosomes rescues deficits in neuronal proliferation, differentiation, synaptogenesis, and synchronized firing, whereas exosomes from MECP2-deficient hiPSC neural cultures lack this capability. These data indicate that exosomes carry signaling information required to regulate neural circuit development
Cell identification in whole-brain multiview images of neural activation
We present a scalable method for brain cell identification in multiview
confocal light sheet microscopy images. Our algorithmic pipeline includes a
hierarchical registration approach and a novel multiview version of semantic
deconvolution that simultaneously enhance visibility of fluorescent cell
bodies, equalize their contrast, and fuses adjacent views into a single 3D
images on which cell identification is performed with mean shift.
We present empirical results on a whole-brain image of an adult Arc-dVenus
mouse acquired at 4micron resolution. Based on an annotated test volume
containing 3278 cells, our algorithm achieves an measure of 0.89
Recommended from our members
Differentiation and Characterization of Excitatory and Inhibitory Synapses by Cryo-electron Tomography and Correlative Microscopy.
As key functional units in neural circuits, different types of neuronal synapses play distinct roles in brain information processing, learning, and memory. Synaptic abnormalities are believed to underlie various neurological and psychiatric disorders. Here, by combining cryo-electron tomography and cryo-correlative light and electron microscopy, we distinguished intact excitatory and inhibitory synapses of cultured hippocampal neurons, and visualized the in situ 3D organization of synaptic organelles and macromolecules in their native state. Quantitative analyses of >100 synaptic tomograms reveal that excitatory synapses contain a mesh-like postsynaptic density (PSD) with thickness ranging from 20 to 50 nm. In contrast, the PSD in inhibitory synapses assumes a thin sheet-like structure โผ12 nm from the postsynaptic membrane. On the presynaptic side, spherical synaptic vesicles (SVs) of 25-60 nm diameter and discus-shaped ellipsoidal SVs of various sizes coexist in both synaptic types, with more ellipsoidal ones in inhibitory synapses. High-resolution tomograms obtained using a Volta phase plate and electron filtering and counting reveal glutamate receptor-like and GABAA receptor-like structures that interact with putative scaffolding and adhesion molecules, reflecting details of receptor anchoring and PSD organization. These results provide an updated view of the ultrastructure of excitatory and inhibitory synapses, and demonstrate the potential of our approach to gain insight into the organizational principles of cellular architecture underlying distinct synaptic functions.SIGNIFICANCE STATEMENT To understand functional properties of neuronal synapses, it is desirable to analyze their structure at molecular resolution. We have developed an integrative approach combining cryo-electron tomography and correlative fluorescence microscopy to visualize 3D ultrastructural features of intact excitatory and inhibitory synapses in their native state. Our approach shows that inhibitory synapses contain uniform thin sheet-like postsynaptic densities (PSDs), while excitatory synapses contain previously known mesh-like PSDs. We discovered "discus-shaped" ellipsoidal synaptic vesicles, and their distributions along with regular spherical vesicles in synaptic types are characterized. High-resolution tomograms further allowed identification of putative neurotransmitter receptors and their heterogeneous interaction with synaptic scaffolding proteins. The specificity and resolution of our approach enables precise in situ analysis of ultrastructural organization underlying distinct synaptic functions
A deep convolutional neural network approach for astrocyte detection
Astrocytes are involved in various brain pathologies including trauma, stroke, neurodegenerative disorders such as Alzheimer's and Parkinson's diseases, or chronic pain. Determining cell density in a complex tissue environment in microscopy images and elucidating the temporal characteristics of morphological and biochemical changes is essential to understand the role of astrocytes in physiological and pathological conditions. Nowadays, manual stereological cell counting or semi-automatic segmentation techniques are widely used for the quantitative analysis of microscopy images. Detecting astrocytes automatically is a highly challenging computational task, for which we currently lack efficient image analysis tools. We have developed a fast and fully automated software that assesses the number of astrocytes using Deep Convolutional Neural Networks (DCNN). The method highly outperforms state-of-the-art image analysis and machine learning methods and provides precision comparable to those of human experts. Additionally, the runtime of cell detection is significantly less than that of other three computational methods analysed, and it is faster than human observers by orders of magnitude. We applied our DCNN-based method to examine the number of astrocytes in different brain regions of rats with opioid-induced hyperalgesia/tolerance (OIH/OIT), as morphine tolerance is believed to activate glia. We have demonstrated a strong positive correlation between manual and DCNN-based quantification of astrocytes in rat brain.Peer reviewe
AI Solutions for MDS: Artificial Intelligence Techniques for Misuse Detection and Localisation in Telecommunication Environments
This report considers the application of Articial Intelligence (AI) techniques to
the problem of misuse detection and misuse localisation within telecommunications
environments. A broad survey of techniques is provided, that covers inter alia
rule based systems, model-based systems, case based reasoning, pattern matching,
clustering and feature extraction, articial neural networks, genetic algorithms, arti
cial immune systems, agent based systems, data mining and a variety of hybrid
approaches. The report then considers the central issue of event correlation, that
is at the heart of many misuse detection and localisation systems. The notion of
being able to infer misuse by the correlation of individual temporally distributed
events within a multiple data stream environment is explored, and a range of techniques,
covering model based approaches, `programmed' AI and machine learning
paradigms. It is found that, in general, correlation is best achieved via rule based approaches,
but that these suffer from a number of drawbacks, such as the difculty of
developing and maintaining an appropriate knowledge base, and the lack of ability
to generalise from known misuses to new unseen misuses. Two distinct approaches
are evident. One attempts to encode knowledge of known misuses, typically within
rules, and use this to screen events. This approach cannot generally detect misuses
for which it has not been programmed, i.e. it is prone to issuing false negatives.
The other attempts to `learn' the features of event patterns that constitute normal
behaviour, and, by observing patterns that do not match expected behaviour, detect
when a misuse has occurred. This approach is prone to issuing false positives,
i.e. inferring misuse from innocent patterns of behaviour that the system was not
trained to recognise. Contemporary approaches are seen to favour hybridisation,
often combining detection or localisation mechanisms for both abnormal and normal
behaviour, the former to capture known cases of misuse, the latter to capture
unknown cases. In some systems, these mechanisms even work together to update
each other to increase detection rates and lower false positive rates. It is concluded
that hybridisation offers the most promising future direction, but that a rule or state
based component is likely to remain, being the most natural approach to the correlation
of complex events. The challenge, then, is to mitigate the weaknesses of
canonical programmed systems such that learning, generalisation and adaptation
are more readily facilitated
์ด์์๋ ๋ด๋ฐ๊ณผ ๋๋ฌผ์์ mRNA ๊ด์ฐฐ์ ๋ํ ์ฐ๊ตฌ
ํ์๋
ผ๋ฌธ(๋ฐ์ฌ) -- ์์ธ๋ํ๊ต๋ํ์ : ์์ฐ๊ณผํ๋ํ ๋ฌผ๋ฆฌยท์ฒ๋ฌธํ๋ถ(๋ฌผ๋ฆฌํ์ ๊ณต), 2021.8. ์ด๋ณํ.mRNA๋ ์ ์ ์ ๋ฐํ์ ์ฒซ๋ฒ์งธ ์ฐ๋ฌผ์ด๋ฉด์, ๋ฆฌ๋ณด์๊ณผ ํจ๊ป ๋จ๋ฐฑ์ง์ ํฉ์ฑํ๋ค. ํนํ ๋ด๋ฐ์์, ๋ช๋ช RNA๋ค์ ์๊ทน์ ์ํด ๋ง๋ค์ด์ง๊ณ , ๋ด๋ฐ์ ํน์ ๋ถ๋ถ์ผ๋ก ์์ก๋์ด ๊ตญ์์ ์ผ๋ก ๋จ๋ฐฑ์ง ์์ ์กฐ์ ํ ์ ์๊ฒ ํ๋ค. ์ต๊ทผ mRNA ํ์ง ๊ธฐ์ ์ ๋ฐ์ ์ผ๋ก ์ด์์๋ ์ธํฌ์์ ๋จ์ผ mRNA๋ฅผ ๊ด์ฐฐํ๋ ๊ฒ์ด ๊ฐ๋ฅํด์ก๋ค. ์ด ์ฐ๊ตฌ์์, ์ฐ๋ฆฌ๋ RNA ์ด๋ฏธ์ง ๊ธฐ์ ์ ์ด์ฉํด, ๊ธฐ์ต ํ์ฑ๊ณผ ์๊ธฐํ ๋ ํ์ฑํ๋ ๋ด๋ฐ์ ์งํฉ์ ์ฐพ๋ ๊ฒ ๋ฟ ์๋๋ผ, ๋ด๋ฐ์ ์ถ์ญ๋๊ธฐ์์ mRNA๊ฐ ์ด๋ป๊ฒ ์์ก๋๋์ง๋ฅผ ๊ด์ฐฐํ๋ค.
์ด ๋
ผ๋ฌธ์ ์ฒซ ๋ถ๋ถ์์ ์ฐ๋ฆฌ๋ ์ ๊ฒฝ ์๊ทน์ ๋ฐ์ํด์ ๋ง๋ค์ด์ง๋ ๊ฒ์ผ๋ก ์๋ ค์ง, Arc ์ ์ ์์ ์ ์ฌ๋ฅผ ๊ด์ฐฐํ์๋ค. ๊ธฐ์ต์ engram ํน์ ๊ธฐ์ต ํ์ (memory trace)๋ผ๊ณ ๋ถ๋ฆฌ๋ ๋ด๋ฐ๋ค์ ์งํฉ์ ์ ์ฅ๋์ด ์๋ค๊ณ ์๊ฐ๋๋ค. ๊ทธ๋ฌ๋, ์๊ฐ์ ๋ฐ๋ผ์ ์ด๋ฐ ๊ธฐ์ต ํ์ ์ธํฌ๋ค์ ์งํฉ์ด ์ด๋ป๊ฒ ๋ณํ๊ณ , ๋ณํํ๋ฉด์๋ ์ด๋ป๊ฒ ์ ๋ณด๋ฅผ ์ ์งํ ์ ์๋์ง ์ ์๋ ค์ ธ ์์ง ์๋ค. ๋ํ, ์ด์์๋ ๋๋ฌผ์์, ๊ธฐ์ต ํ์ ์ธํฌ๋ฅผ ๊ธด ์๊ฐ ๋์ ์ฌ๋ฌ ๋ฒ ์ฐพ์๋ด๋ ๊ฒ์ ์ด๋ ค์ด ์ผ์ด์๋ค. ์ด ์ฐ๊ตฌ์์๋ genetically-encoded RNA indicator (GERI) ๊ธฐ์ ์ ์ฌ์ฉํด, ๊ธฐ์ต ํ์ ์ธํฌ์ ํ์์ผ๋ก ๋๋ฆฌ ์ฌ์ฉ๋๋ Arc mRNA์ ์ ์ฌ๊ณผ์ ์ ์ด์์๋ ์ฅ์์ ๊ด์ฐฐํ์๋ค. GERI๋ฅผ ์ด์ฉํจ์ผ๋ก์จ, ๊ธฐ์กด ๋ฐฉ๋ฒ๋ค์ ํ๊ณ์ ์ด์๋ ์๊ฐ ์ ์ฝ ์์ด, ์ค์๊ฐ์ผ๋ก Arc๋ฅผ ๋ฐํํ๋ ๋ด๋ฐ๋ค์ ์ฐพ์๋ผ ์ ์์๋ค. ์ฅ์๊ฒ ๊ณต๊ฐ ๊ณตํฌ ๊ธฐ์ต์ ์ฃผ๊ณ ๋์ ์ฌ๋ฌ ๋ฒ ๊ธฐ์ต์ ์๊ธฐ์ํค๋ ํ๋์คํ ํ์ Arc๋ฅผ ๋ฐํํ๋ ์ธํฌ๋ฅผ ์๋ณํ์ ๋, CA1์์๋ Arc๋ฅผ ๋ฐํํ๋ ์ธํฌ๊ฐ ์ดํ ํ์๋ ๋ ์ด์ ํ์ฑํ๋์ง ์์์ผ๋, RSC์ ๊ฒฝ์ฐ 4ํผ์ผํธ์ ๋ด๋ฐ๋ค์ด ๊ณ์ํด์ ํ์ฑํํ๋ ๊ฒ์ ๊ด์ฐฐํ๋ค. ์ ๊ฒฝํ๋๊ณผ ์ ์ ์ ๋ฐํ์ ๊ฐ์ด ์กฐ์ฌํ๊ธฐ ์ํด, ์ฅ๊ฐ ๊ฐ์ ํ๊ฒฝ์ ํํํ๊ณ ์์ ๋ GERI์ ์นผ์ ์ด๋ฏธ์ง์ ๋์์ ์งํํ์๋ค. ๊ทธ ๊ฒฐ๊ณผ, ๊ธฐ์ต์ ํ์ฑํ ๋์ ์๊ธฐ์ํฌ ๋ Arc๋ฅผ ๋ฐํํ๋ ๋ด๋ฐ๋ค์ด ๊ธฐ์ต์ ํ์ํ๋ ๊ฒ์ ์์๋ผ ์ ์์๋ค. ์ด์ฒ๋ผ GERI ๊ธฐ์ ์ ์ด์ฉํด ์ด์์๋ ๋๋ฌผ์์ ์ ์ ์ ๋ฐํ๋ ์ธํฌ๋ฅผ ์ฐพ์๋ด๋ ๋ฐฉ์์ ๋ค์ํ ํ์ต ๋ฐ ๊ธฐ์ต ๊ณผ์ ์์ ๊ธฐ์ต ํ์ ์ธํฌ์ dynamics์ ๋ํด ์์๋ผ ์ ์์ ๊ฒ์ผ๋ก ๊ธฐ๋๋๋ค.
์ด ๋
ผ๋ฌธ์ ๋๋ฒ์งธ ๋ถ๋ถ์์, ์ฐ๋ฆฌ๋ ์ธํฌ ๊ณจ๊ฒฉ์ ๊ธฐ๋ณธ ๊ตฌ์ฑ ๋จ์๊ฐ ๋๋ ฮฒ-actin์ mRNA๋ฅผ ์ถ์ญ๋๊ธฐ์์ ๊ด์ฐฐํ์๋ค. mRNA์ ๊ตญ์ํ (localization)๋ฅผ ํตํ ๊ตญ์ ๋จ๋ฐฑ์ง ํฉ์ฑ์ ์ถ์ญ๋๊ธฐ (axon)์ ์ฑ์ฅ๊ณผ ์ฌ์์ ์ค์ํ ์ญํ ์ด ์๋ค๊ณ ์๋ ค์ ธ ์๋ค. ํ์ง๋ง, ์์ง mRNA์ ๊ตญ์ํ๊ฐ ์ถ์ญ๋๊ธฐ์์ ์ด๋ป๊ฒ ์กฐ์ ๋๊ณ ์๋์ง ์ ์๋ ค์ ธ ์์ง ์๋ค. ์ด ๋ฌธ์ ๋ฅผ ํด๊ฒฐํ๊ธฐ ์ํด์, ์ฐ๋ฆฌ๋ ๋ชจ๋ ฮฒ-actin mRNA๊ฐ ํ๊ด์ผ๋ก ํ์ง๋ ์ ์ ์ ๋ณํ ์ฅ๋ฅผ ์ด์ฉํด, ์ด์์๋ ์ถ์ญ๋๊ธฐ์์ ฮฒ-actin mRNA๋ฅผ ๊ด์ฐฐํ์๋ค. ์ด ์ฅ์ ๋ด๋ฐ์ ์ถ์ญ์ ๊ตฌ๋ถํด ์ค ์ ์๋ ๋ฏธ์ธ์ ์ฒด ์ฅ์น (microfluidic device)์ ๋ฐฐ์ํ ๋ค์, ฮฒ-actin mRNA๋ฅผ ๊ด์ฐฐํ๊ณ ์ถ์ ์ ์งํํ๋ค. ์ถ์ญ์ ์ธํฌ ๋ชธํต์ผ๋ก๋ถํฐ ๊ธธ๊ฒ ์๋ผ๊ธฐ ๋๋ฌธ์ mRNA๊ฐ ๋จผ ๊ฑฐ๋ฆฌ๋ฅผ ์์ก๋์ด์ผ ํจ์๋ ๋ถ๊ตฌํ๊ณ , ๋๋ถ๋ถ์ mRNA๊ฐ ์์๋๊ธฐ์ ๋นํด ๋ ์์ง์ด๊ณ ์์ ์์ญ์์ ์์ง์ด๋ ๊ฒ์ ๋ณด์๋ค. ์ฐ๋ฆฌ๋ ฮฒ-actin mRNA๊ฐ ์ฃผ๋ก ์ถ์ญ๋๊ธฐ์ ๊ฐ์ง๊ฐ ๋ ์ ์๋ filopodia ๊ทผ์ฒ์, ์๋
์ค๊ฐ ๋ง๋ค์ด์ง๋ bouton ๊ทผ์ฒ์ ๊ตญ์ํ๋๋ ๊ฒ์ ๊ด์ฐฐํ๋ค. Filopodia์ bouton์ด actin์ด ํ๋ถํ ๋ถ๋ถ์ผ๋ก ์๋ ค์ ธ ์๊ธฐ ๋๋ฌธ์, ์ฐ๋ฆฌ๋ ์กํด ํ๋ผ๋ฉํธ์ ฮฒ-actin mRNA์ ์์ง์๊ฐ์ ์ฐ๊ด์ฑ์ ์กฐ์ฌํ๋ค. ํฅ๋ฏธ๋กญ๊ฒ๋, ์ฐ๋ฆฌ๋ ฮฒ-actin mRNA๊ฐ ์กํด ํ๋ผ๋ฉํธ์ ๊ฐ์ด ๊ตญ์ํ ๋๊ณ , ฮฒ-actin mRNA๊ฐ ์กํด ํ๋ผ๋ฉํธ ์์์ sub-diffusiveํ ์์ง์์ ๋ณด์์ผ๋ฉฐ, ๋จผ ๊ฑฐ๋ฆฌ๋ฅผ ์์ง์ด๋ mRNA๋ ์กํด ํ๋ผ๋ฉํธ์ ๊ณ ์ ๋๋ ๋ชจ์ต๋ ํ์ธํ ์ ์์๋ค. ์ถ์ญ์์ ฮฒ-actin mRNA ์์ง์์ ๋ณธ ์ด๋ฒ ๊ด์ฐฐ์ mRNA ์์ก ๋ฐ ๊ตญ์ํ์ ๋ํ ์๋ฌผ๋ฌผ๋ฆฌํ ์ ๋ฉ์ปค๋์ฆ์ ๊ธฐ๋ฐ์ด ๋ ์ ์์ ๊ฒ์ด๋ค.mRNA is the first product of the gene expression and facilitates the protein synthesis. Especially in neurons, some RNAs are transcribed in response to stimuli and transported to the specific region, altering local proteome for neurons to function normally. Recent advances of mRNA labeling techniques allowed us to observe the single mRNAs in live cells. In this thesis, we applied RNA imaging technique not only to identify the neuronal ensemble that activated during memory formation and retrieval, but also to traffic mRNAs transported to the axon.
In the first part of the thesis, we observed the transcription site of Arc gene, one of the immediate-early gene, which is rapidly transcribed upon the neural stimuli. Because of the characteristic of expressing in response to stimuli, Arc is widely used as a marker for memory trace cells thought to store memories. However, little is known about the ensemble dynamics of these cells because it has been challenging to observe them repeatedly over long periods of time in vivo. To overcome this limitation, we present a genetically-encoded RNA indicator (GERI) technique for intravital chronic imaging of endogenous Arc mRNA. We used our GERI to identify Arc-positive neurons in real time without the time lag associated with reporter protein expression in conventional approaches. We found that Arc-positive neuronal populations rapidly turned over within two days in CA1, whereas ~4% of neurons in the retrosplenial cortex consistently expressed Arc upon contextual fear conditioning and repeated memory retrievals. Dual imaging of GERI and calcium indicator in CA1 of mice navigating a virtual reality environment revealed that only the overlapping population of neurons expressing Arc during encoding and retrieval exhibited relatively high calcium activity in a context-specific manner. This in vivo RNA imaging approach has potential to unravel the dynamics of engram cells underlying various learning and memory processes.
In the second part of this thesis, we imaged ฮฒ-actin mRNAs, which can generate a cytoskeletal protein, ฮฒ-actin, through translation. Local protein synthesis has a critical role in axonal guidance and regeneration. Yet it is not clearly understood how the mRNA localization is regulated in axons. To address these questions, we investigated mRNA motion in live axons using a transgenic mouse that expresses fluorescently labeled endogenous ฮฒ-actin mRNA. By culturing hippocampal neurons in a microfluidic device that allows separation of axons from dendrites, we performed single particle tracking of ฮฒ-actin mRNA selectively in axons. Although axonal mRNAs need to travel a long distance, we observed that most axonal mRNAs show much less directed motion than dendritic mRNAs. We found that ฮฒ-actin mRNAs frequently localize at the neck of filopodia which can grow as axon collateral branches and at varicosities where synapses typically occur. Since both filopodia and varicosities are known as actin-rich areas, we investigated the dynamics of actin filaments and ฮฒ-actin mRNAs simultaneously by using high-speed dual-color imaging. We found that axonal mRNAs colocalize with actin filaments and show sub-diffusive motion within the actin-rich regions. The novel findings on the dynamics of ฮฒ-actin mRNA will shed important light on the biophysical mechanisms of mRNA transport and localization in axons.1. INTRODUCTION, 1
1.1. Neuronal ensemble, 1
1.2. Immediate-early Gene (IEG), 3
1.3. Methods for IEG-positive neurons, 3
1.4. Two-photon microscope, 5
1.5. References, 7
2. IMAGING ARC mRNA TRANSCRIPTION SITES IN LIVE MICE, 9
2.1. Introduction, 9
2.2. Materials and Methods, 10
2.3. Results and Discussion, 18
2.4. References, 26
3. NEURONS EXPRESSING ARC mRNA DURING REPEATED MEMORY RETRIEVALS, 28
3.1. Introduction, 28
3.2. Results and Discussion, 28
3.3. References, 35
4. NEURAL ACTIVITIES OF ARC+ NEURONS, 36
4.1. Introduction, 36
4.2. Materials and Methods, 37
4.3. Results and Discussion, 38
4.4. References, 52
5. AXONAL mRNA DYNAMICS IN LIVE NEURONS, 54
5.1. Introduction, 54
5.2. Materials and Methods, 55
5.3. Results and Discussion, 59
5.4. References, 70
6. CONCLUSION AND OUTLOOK, 72
ABSTRACT IN KOREAN (๊ตญ๋ฌธ์ด๋ก), 76๋ฐ
Biomedical applications of threeโdimensional bioprinted craniofacial tissue engineering
Abstract Anatomical complications of the craniofacial regions often present considerable challenges to the surgical repair or replacement of the damaged tissues. Surgical repair has its own set of limitations, including scarcity of the donor tissues, immune rejection, use of immune suppressors followed by the surgery, and restriction in restoring the natural aesthetic appeal. Rapid advancement in the field of biomaterials, cell biology, and engineering has helped scientists to create cellularized skeletal muscleโlike structures. However, the existing method still has limitations in building large, highly vascular tissue with clinical application. With the advance in the threeโdimensional (3D) bioprinting technique, scientists and clinicians now can produce the functional implants of skeletal muscles and bones that are more patientโspecific with the perfect match to the architecture of their craniofacial defects. Craniofacial tissue regeneration using 3D bioprinting can manage and eliminate the restrictions of the surgical transplant from the donor site. The concept of creating the new functional tissue, exactly mimicking the anatomical and physiological function of the damaged tissue, looks highly attractive. This is crucial to reduce the donor site morbidity and retain the esthetics. 3D bioprinting can integrate all three essential components of tissue engineering, that is, rehabilitation, reconstruction, and regeneration of the lost craniofacial tissues. Such integration essentially helps to develop the patientโspecific treatment plans and damage siteโdriven creation of the functional implants for the craniofacial defects. This article is the bird's eye view on the latest development and application of 3D bioprinting in the regeneration of the skeletal muscle tissues and their application in restoring the functional abilities of the damaged craniofacial tissue. We also discussed current challenges in craniofacial bone vascularization and gave our view on the future direction, including establishing the interactions between tissueโengineered skeletal muscle and the peripheral nervous system
- โฆ