scholarly journals Measuring single neuron visual receptive field sizes by fMRI

2018 ◽  
Author(s):  
Georgios A. Keliris ◽  
Qinglin Li ◽  
Amalia Papanikolaou ◽  
Nikos K. Logothetis ◽  
Stelios M. Smirnakis
Keyword(s):  
Receptive Field ◽  
Single Neuron ◽  
Current Knowledge ◽  
Brain Organization ◽  
New Approach ◽  
Non Invasive ◽  
Visual Receptive Field ◽  
Large Populations ◽  
First Time

AbstractThe non-invasive measurements of neuronal receptive field (RF) properties in-vivo allow a detailed understanding of brain organization as well as its plasticity by longitudinal following of potential changes. Visual RFs measured invasively by electrophysiology in animal models have traditionally provided a great extent of our current knowledge about the visual brain and its disorders. Voxel based estimates of population RF (pRF) by functional magnetic resonance imaging (fMRI) in humans revolutionized the field and have been used extensively in numerous studies. However, current methods cannot estimate single-neuron RF sizes as they reflect large populations of neurons with individual RF scatter. Here, we introduce a new approach to estimate RF size using spatial frequency selectivity to checkerboard patterns. This method allowed us to obtain non-invasive, single-unit, RF estimates in human V1 for the first time. These estimates were significantly smaller compared to prior pRF methods. Further, fMRI and electrophysiological experiments in non-human primates demonstrated an exceptional match validating the approach.

scholarly journals Estimating average single-neuron visual receptive field sizes by fMRI

2019 ◽  
Vol 116 (13) ◽  
pp. 6425-6434 ◽  
Author(s):  
Georgios A. Keliris ◽  
Qinglin Li ◽  
Amalia Papanikolaou ◽  
Nikos K. Logothetis ◽  
Stelios M. Smirnakis
Keyword(s):  
Receptive Field ◽  
Nonhuman Primates ◽  
Single Neuron ◽  
Current Knowledge ◽  
Brain Organization ◽  
Visual Receptive Field ◽  
Noninvasive Estimation ◽  
Large Populations ◽  
Early Visual Cortex

The noninvasive estimation of neuronal receptive field (RF) properties in vivo allows a detailed understanding of brain organization as well as its plasticity by longitudinal following of potential changes. Visual RFs measured invasively by electrophysiology in animal models have traditionally provided a great extent of our current knowledge about the visual brain and its disorders. Voxel-based estimates of population RF (pRF) by functional magnetic resonance imaging (fMRI) in humans revolutionized the field and have been used extensively in numerous studies. However, current methods cannot estimate single-neuron RF sizes as they reflect large populations of neurons with individual RF scatter. Here, we introduce an approach to estimate RF size using spatial frequency selectivity to checkerboard patterns. This method allowed us to obtain noninvasive, average single-neuron RF estimates over a large portion of human early visual cortex. These estimates were significantly smaller compared with prior pRF methods. Furthermore, fMRI and electrophysiology experiments in nonhuman primates demonstrated an exceptionally good match, validating the approach.

A new approach to non-invasive quantitative study of hepatic haemodynamics using radiocolloids in vivo

1985 ◽  
Vol 6 (3) ◽  
pp. 179-204 ◽  
Author(s):  
A Magrini ◽  
G Izzo ◽  
M Guerrisi ◽  
A Favella ◽  
R Picardi ◽  
...  
Keyword(s):  
Quantitative Study ◽  
New Approach ◽  
Non Invasive

scholarly journals Comparison of Different Polarization Sensitive Second Harmonic Generation Imaging Techniques

2019 ◽  
Vol 2 (2) ◽  
pp. 49 ◽  
Author(s):  
Mehdi Alizadeh ◽  
Masood Ghotbi ◽  
Pablo Loza-Alvarez ◽  
David Merino
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Imaging Techniques ◽  
Image Plane ◽  
Excitation Beam ◽  
Non Invasive ◽  
Second Harmonic Generation Imaging ◽  
First Time

Polarization sensitive second harmonic generation (pSHG) microscopy is an imaging technique able to provide, in a non-invasive manner, information related to the molecular structure of second harmonic generation (SHG) active structures, many of which are commonly found in biological tissue. The process of acquiring this information by means of pSHG microscopy requires a scan of the sample using different polarizations of the excitation beam. This process can take considerable time in comparison with the dynamics of in vivo processes. Fortunately, single scan polarization sensitive second harmonic generation (SS-pSHG) microscopy has also been reported, and is able to generate the same information at a faster speed compared to pSHG. In this paper, the orientation of second harmonic active supramolecular assemblies in starch granules is obtained on by means of pSHG and SS-pSHG. These results are compared in the forward and backward directions, showing a good agreement in both techniques. This paper shows for the first time, to the best of the authors’ knowledge, data acquired using both techniques over the exact same sample and image plane, so that they can be compared pixel-to-pixel.

Targeting 5α-reductase with 99mTc labeled dutasteride derivatives for prostate imaging

2020 ◽  
Vol 108 (4) ◽  
pp. 305-313
Author(s):  
◽  
Syed Qaiser Shah
Keyword(s):  
Room Temperature ◽  
Target Tissue ◽  
Prostate Imaging ◽  
Non Invasive ◽  
Good Target ◽  
Target Ratio ◽  
First Time ◽  
Analogous Behavior

AbstractTo assess the suitability of 99mTc labeled 5α-reductase (5α-Rds) inhibitors for non-invasive targeting of prostate cancer (PCa) using Male Sprague Dawely Rat (MSDR) model. In this work, dutasteride (Cpd-1) a 5α-Rds inhibitor was derivatized to its dithiocarbamate analogue (Cpd-2) for subsequent synthesis of 99mTc(CO)3-dutasteride dithiocarbamate (Cpd-3) using tricarbonyl technique. To determine the structure of Cpd-3, for the first time a reference Re(CO)3-dutasteride dithiocarbamate (Cpd-4) was synthesized and characterized with NMR, ESIMS, HPLC and elemental analysis. HPLC was used to establish the identity of Cpd-3 using Cpd-4 as a reference standard. The suitability of Cpd-3 as a new 5α-Rds targeting agent was investigated, both in vitro and vivo. The Cpd-3 has shown ≥98 % in vitro stability at room temperature and was remained ≥90 % stable up to 6 h. In serum Cpd-3 has revealed an analogous behavior with a small decrease in stability after 16 h. High uptake (26.25 ± 1.10 %, after 4 h of i.v.) of Cpd-3 was observed in the prostate (target tissue) of MSDR model with reasonably good target to non-target ratio. Blocking the target site with excess Cpd-2 considerably decreased the uptake of Cpd-3 to 4.10 ± 0.75 % in PCa. High in vitro stability in saline and serum and in vivo uptake in prostate of MSDR model plausibly attracts the opportunity of using Cpd-3 as a novel radiopharmaceutical for non invasive targeting of prostate.

Morphology and morphogenesis of Strongylidium pseudocrassum Wang and Nie, 1935, with redefinition of Strongylidium Sterki, 1878  (Protista: Ciliophora: Stichotrichia)

Zootaxa ◽  
2007 ◽  
Vol 1559 (1) ◽  
pp. 31-57 ◽  
Author(s):  
THIAGO DA SILVA PAIVA ◽  
INÁCIO DOMINGOS DA SILVA-NETO
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Division ◽  
Rare Species ◽  
De Novo ◽  
Current Knowledge ◽  
Northern Region ◽  
First Time ◽  
Scanning Electron

A population of the rare species Strongylidium pseudocrassum Wang and Nie, 1935, was discovered from a lagoon in the northern region of Rio de Janeiro, Brazil, and its morphology was investigated through protargol-impregnation, scanning electron microscopy and in vivo observations. Morphogenetic events of cell division and physiological reorganization were described for the first time to this species. It was found that S. pseudocrassum has the ventral cirral rows organized in the same manner as Pseudouroleptus caudatus Hemberger, 1985. However two independent primordia VI, one for the proter and other for the opisthe, are generated intrakinetally from the rightmost ventral cirral row. In addition, dorsal kineties replicate entirely “de novo” and do not fragment. Based on the data obtained, the genus Strongylidium was redefined and the species currently assigned to it were classified into five groups according to current knowledge on their ciliature and the combination S. lentum (Biernacka, 1963) nov. comb. is proposed.

scholarly journals In vivo detection of tau fibrils and amyloid β aggregates with luminescent conjugated oligothiophenes and multiphoton microscopy

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Maria Calvo-Rodriguez ◽  
Steven S. Hou ◽  
Austin C. Snyder ◽  
Simon Dujardin ◽  
Hamid Shirani ◽  
...  
Keyword(s):  
Amyloid Beta ◽  
In Vivo Imaging ◽  
Multiphoton Microscopy ◽  
Amyloid Β ◽  
New Approach ◽  
Cerebral Amyloidosis ◽  
In Vivo Detection ◽  
Longitudinal Imaging ◽  
First Time

Summary The detection of amyloid beta deposits and neurofibrillary tangles, both hallmarks of Alzheimer’s disease (AD), is key to understanding the mechanisms underlying these pathologies. Luminescent conjugated oligothiophenes (LCOs) enable fluorescence imaging of these protein aggregates. Using LCOs and multiphoton microscopy, individual tangles and amyloid beta deposits were labeled in vivo and imaged longitudinally in a mouse model of tauopathy and cerebral amyloidosis, respectively. Importantly, LCO HS-84, whose emission falls in the green region of the spectrum, allowed for the first time longitudinal imaging of tangle dynamics following a single intravenous injection. In addition, LCO HS-169, whose emission falls in the red region of the spectrum, successfully labeled amyloid beta deposits, allowing multiplexing with other reporters whose emission falls in the green region of the spectrum. In conclusion, this method can provide a new approach for longitudinal in vivo imaging using multiphoton microscopy of AD pathologies as well as other neurodegenerative diseases associated with protein aggregation in mouse models.

scholarly journals Deep Learning Analysis of in Vivo Hyperspectral Images for Automated Intraoperative Nerves Detection

2021 ◽  
Author(s):  
Manuel Barberio ◽  
Toby Collins ◽  
Valentin Bencteux ◽  
Richard Nkusi ◽  
Eric Felli ◽  
...  
Keyword(s):  
Deep Learning ◽  
Cross Validation ◽  
State Of The Art ◽  
Invasive Technique ◽  
Midline Incision ◽  
Average Sensitivity ◽  
Non Invasive ◽  
First Time ◽  
Learning Analysis

Abstract Nerves are difficult to recognize during surgery and inadvertent injuries may occur, bringing catastrophic consequences for the patient. Hyperspectral imaging (HSI) is a non-invasive technique combining photography with spectroscopy, allowing biological tissue property quantification. We show for the first time that HSI combined with deep learning allows nerves and other tissue types to be automatically recognized in-vivo at the pixel level. An animal model is used comprising eight anesthetized pigs with a neck midline incision, exposing several structures (nerve, artery, vein, muscle, fat, skin). State-of-the-art machine learning models have been trained to recognize these tissue types in HSI data. The best model is a Convolutional Neural Network (CNN), achieving an overall average sensitivity of 0.91 and specificity of 0.99, validated with leave-one-patient-out cross-validation. For the nerve, the CNN achieves an average sensitivity of 0.76 and specificity of 1.0. In conclusion, HSI combined with a CNN model is suitable for in vivo nerve recognition.

scholarly journals Apoptosis-reactivating agents for targeted anticancer therapy

2013 ◽  
Vol 59 (2) ◽  
pp. 119-143 ◽  
Author(s):  
A.A. Philchenkov
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Death Receptor ◽  
Mitochondrial Pathway ◽  
Chemotherapeutic Drugs ◽  
Promising Candidate ◽  
Non Invasive ◽  
Key Factor ◽  
Apoptotic Pathways

The current knowledge on molecular mechanisms of apoptosis is presented focusing on the key elements of the extrinsic death receptor pathway as well as the intrinsic mitochondrial pathway. Disregulation of apoptotic pathways is considered as a key factor in the survival of cancer cells in response to conventional chemotherapeutic drugs or radiation therapy. Substances that selectively reactivate apoptosis in malignant cells are the promising candidate anticancer drugs, which have now entered various phases of clinical trials. The up-to-date techniques allowing for non-invasive in vivo visualization of apoptotic cells with special reference to therapy-induced cell death are briefly surveyed.

Notizen: In vivo Metabolism of [4-13C]Phenacetin in an Isolated Perfused Rat Liver Measured by Continuous Flow 13C NMR Spectroscopy

1984 ◽  
Vol 39 (7-8) ◽  
pp. 859-862 ◽  
Author(s):  
Klaus Albert ◽  
Gerd Kruppa ◽  
Klaus-Peter Zeller ◽  
Ernst Bayer ◽  
Franz Hartmann
Keyword(s):  
Nmr Spectroscopy ◽  
Continuous Flow ◽  
13C Nmr Spectroscopy ◽  
Point Of View ◽  
Isolated Perfused Rat Liver ◽  
Metabolite Formation ◽  
Non Invasive ◽  
First Time ◽  
C Nmr

Abstract Metabolism, [4-13C]Phenacetin, Continuous Flow 13C NMR Continuous flow 13C NMR spectroscopy has been used for the first time to monitor the metabolism of a 13C labeled drug in an isolated liver. Continuous and almost immediate information on the metabolite formation could be obtained using 13C labeled phenacetin without alteration of the biological system. The data are consistent with those observed by conventional techniques (HPLC, aliquot 13C NMR measurements). From the biological point of view the sensitivity of continuous flow 13C NMR spectroscopy is still low (10-3 ᴍ). The results presented demonstrate however that non-invasive and non-radio-active real time monitoring of drug metabolism in intact organs is possible.

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