Статті в журналах: "Gradient echo memory"

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Higginbottom, D. B., J. Geng, G. T. Campbell, M. Hosseini, M. T. Cao, B. M. Sparkes, J. Bernu, N. P. Robins, P. K. Lam, and B. C. Buchler. "Dual-rail optical gradient echo memory." Optics Express 23, no. 19 (September 21, 2015): 24937. http://dx.doi.org/10.1364/oe.23.024937.

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BAI Hong-gui, 白洪贵, 黄震 HUANG Zhen, 王明峰 WANG Ming-feng, 王振兴 WANG Zhen-xing, and 郑亦庄 ZHENG Yi-zhuang. "Analysis of Polaritonic in the Quantum Gradient-echo Memory." Acta Sinica Quantum Optica 21, no. 3 (2015): 235–40. http://dx.doi.org/10.3788/asqo20152103.0235.

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Glorieux, Quentin, Jeremy B. Clark, Alberto M. Marino, Zhifan Zhou, and Paul D. Lett. "Temporally multiplexed storage of images in a gradient echo memory." Optics Express 20, no. 11 (May 16, 2012): 12350. http://dx.doi.org/10.1364/oe.20.012350.

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Carreño, F., and M. A. Antón. "Gradient echo memory in a tripod-like dense atomic medium." Optics Communications 283, no. 23 (December 2010): 4787–95. http://dx.doi.org/10.1016/j.optcom.2010.07.024.

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Carreño, F., and M. A. Antón. "Coherent control of light pulses stored in a Gradient Echo Memory." Optics Communications 284, no. 12 (June 2011): 3154–59. http://dx.doi.org/10.1016/j.optcom.2011.02.012.

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Sparkes, B. M., J. Bernu, M. Hosseini, J. Geng, Q. Glorieux, P. A. Altin, P. K. Lam, N. P. Robins, and B. C. Buchler. "Gradient echo memory in an ultra-high optical depth cold atomic ensemble." New Journal of Physics 15, no. 8 (August 23, 2013): 085027. http://dx.doi.org/10.1088/1367-2630/15/8/085027.

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Clark, Jeremy B., Quentin Glorieux, and Paul D. Lett. "Spatially addressable readout and erasure of an image in a gradient echo memory." New Journal of Physics 15, no. 3 (March 6, 2013): 035005. http://dx.doi.org/10.1088/1367-2630/15/3/035005.

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Zhang, Yan, Baoping Wang, Yang Fang, and Zuxun Song. "A Microwave Three-Dimensional Imaging Method Based on Optimal Wave Spectrum Reconstruction." Sensors 20, no. 24 (December 19, 2020): 7306. http://dx.doi.org/10.3390/s20247306.

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Limited by the Shannon–Nyquist sampling law, the number of antenna elements and echo signal data of the traditional microwave three-dimensional (3D) imaging system are extremely high. Compressed sensing imaging methods based on sparse representation of target scene can reduce the data sampling rate, but the dictionary matrix of these methods takes a lot of memory, and the imaging has poor quality for continuously distributed targets. For the above problems, a microwave 3D imaging method based on optimal wave spectrum reconstruction and optimization with target reflectance gradient is proposed in this paper. Based on the analysis of the spatial distribution characteristics of the target echo in the frequency domain, this method constructs an orthogonal projection reconstruction model for the wavefront to realize the optimal reconstruction of the target wave spectrum. Then, the inverse Fourier transform of the optimal target wave spectrum is optimized according to the law of the target reflectance gradient distribution. The proposed method has the advantages of less memory space and less computation time. What is more, the method has a better imaging quality for the continuously distributed target. The computer simulation experiment and microwave anechoic chamber measurement experiment verify the effectiveness of the proposed method.

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Pospisil, Karel, Monika Manychova, Josef Stryk, Marta Korenska, Radek Matula, and Vaclav Svoboda. "Diagnostics of Reinforcement Conditions in Concrete Structures by GPR, Impact-Echo Method and Metal Magnetic Memory Method." Remote Sensing 13, no. 5 (March 3, 2021): 952. http://dx.doi.org/10.3390/rs13050952.

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It is important to use adequately reliable non-destructive methods that would be capable of determining the reinforcement conditions in concrete structures. Three different methods: ground penetrating radar, impact-echo method, and metal magnetic memory method were used for testing laboratory-prepared reinforced concrete beams (with a reinforcing bar of the same diameter along its whole length, reinforcing bar locally impaired, and reinforcing bar interrupted). The ground-penetrating radar proved the correlation of signal parameters with the reinforcing bar condition. An impairment/interruption reinforcing bar appeared in the record from measurements in the transversal and longitudinal direction by changes of the observed depth of the reinforcing bar from the concrete surface and direct wave attenuation. The impact-echo method proved that the shifts of the dominant frequencies from the response signal correspond with the impairment/interruption of the reinforcing bar. Results of diagnostics by the metal magnetic memory method were presented by a magnetogram of the magnetic field strength and field gradient on the measured distance. The changes in the magnetic field strength proved different stress concentration zones due to the reinforcing bar condition. The used non-destructive methods showed that they are capable of indicating the different reinforcement conditions in reinforced concrete beams. This paper indicates in which cases and for what reason it is appropriate to use these three methods and in what way they differ from each other.

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Casey, B. J., Rolf J. Trainor, Jennifer L. Orendi, Anne B. Schubert, Leigh E. Nystrom, Jay N. Giedd, F. Xavier Castellanos, et al. "A Developmental Functional MRI Study of Prefrontal Activation during Performance of a Go-No-Go Task." Journal of Cognitive Neuroscience 9, no. 6 (November 1997): 835–47. http://dx.doi.org/10.1162/jocn.1997.9.6.835.

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This study examines important developmental differences in patterns of activation in the prefrontal cortex during performance of a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned using gradient echo, echo planar imaging during performance of a response inhibition task. The results suggest four general findings. First, the location of activation in the prefrontal cortex was not different between children and adults, which is similar to our earlier pediatric fMRI results of prefrontal activation during a working memory task (Casey et al., 1995). Second, the volume of activation was significantly greater for children relative to adults. These differences in volume of activation were observed predominantly in the dorsal and lateral prefrontal cortices. Third, although inhibitory processes have typically been associated with more ventral or orbital frontal regions, the current study revealed activation that was distributed across both dorsolateral and orbitofrontal cortices. Finally, consistent with animal and human lesion studies, activity in orbital frontal and anterior cingulate cortices correlated with behavioral performance (i.e., number of false alarms). These results further demonstrate the utility of this methodology in studying pediatric populations.

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Di, Sarli, Claudio Gallicchio, and Alessio Micheli. "On the effectiveness of Gated Echo State Networks for data exhibiting long-term dependencies." Computer Science and Information Systems 19, no. 1 (2022): 379–96. http://dx.doi.org/10.2298/csis210218063d.

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In the context of recurrent neural networks, gated architectures such as the GRU have contributed to the development of highly accurate machine learning models that can tackle long-term dependencies in the data. However, the training of such networks is performed by the expensive algorithm of gradient descent with backpropagation through time. On the other hand, reservoir computing approaches such as Echo State Networks (ESNs) can produce models that can be trained efficiently thanks to the use of fixed random parameters, but are not ideal for dealing with data presenting long-term dependencies. We explore the problem of employing gated architectures in ESNs from both theoretical and empirical perspectives. We do so by deriving and evaluating a necessary condition for the non-contractivity of the state transition function, which is important to overcome the fading-memory characterization of conventional ESNs. We find that using pure reservoir computing methodologies is not sufficient for effective gating mechanisms, while instead training even only the gates is highly effective in terms of predictive accuracy.

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Pu, W., Q. Luo, L. Palaniyappan, Z. Xue, S. Yao, J. Feng, and Z. Liu. "Failed cooperative, but not competitive, interaction between large-scale brain networks impairs working memory in schizophrenia." Psychological Medicine 46, no. 6 (January 8, 2016): 1211–24. http://dx.doi.org/10.1017/s0033291715002755.

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BackgroundA large-scale network named the default mode network (DMN) dynamically cooperates and competes with an external attention system (EAS) to facilitate various cognitive functioning that is prominently impaired in schizophrenia. However, it is unclear whether the cognitive deficit in schizophrenia is related to the disrupted competition and/or cooperation between these two networks.MethodA total of 35 schizophrenia patients and 30 healthy controls were scanned using gradient-echo echo-planar imaging during n-back working memory (WM) processing. Brain activities of the DMN and EAS were measured using general linear modelling of the functional magnetic resonance imaging data. Dynamic interaction between the DMN and EAS was decomposed into two directions using Granger causality analysis.ResultsWe observed a significant failure of DMN suppression in patients with schizophrenia, which was significantly related to WM/attentional deficit. Granger causality modelling showed that in healthy controls, while the EAS inhibitorily influenced the DMN, the DMN exerted an ‘excitatory’ or cooperative influence back on the EAS, especially in those with lower WM accuracy. In schizophrenia, this ‘excitatory’ DMN→EAS influence within the reciprocal EAS–DMN loop was significantly reduced, especially in patients with WM/attentional deficit.ConclusionsThe dynamic interaction between the DMN and EAS is likely to be comprised of both competitive and cooperative influences. In healthy controls, both the ‘inhibitory’ EAS→DMN interaction and ‘excitatory’ DMN→EAS interaction are correlated with WM performance. In schizophrenia, reduced ‘cooperative’ influence from the DMN to dorsal nodes of the EAS occurs in the context of non-suppression of the DMN and may form a possible pathophysiological substrate of WM deficit and attention disorder.

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Lim, Seung-Hyun, Jiyoon Lee, Sumin Jung, Bokyung Kim, Hak Young Rhee, Se-Hong Oh, Soonchan Park, Ah Rang Cho, Chang-Woo Ryu, and Geon-Ho Jahng. "Myelin-Weighted Imaging Presents Reduced Apparent Myelin Water in Patients with Alzheimer’s Disease." Diagnostics 12, no. 2 (February 9, 2022): 446. http://dx.doi.org/10.3390/diagnostics12020446.

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The purpose of this study was to investigate myelin loss in both AD and mild cognitive impairment (MCI) patients with a new myelin water mapping technique within reasonable scan time and evaluate the clinical relevance of the apparent myelin water fraction (MWF) values by assessing the relationship between decreases in myelin water and the degree of memory decline or aging. Twenty-nine individuals were assigned to the cognitively normal (CN) elderly group, 32 participants were assigned to the MCI group, and 31 patients were assigned to the AD group. A 3D visualization of the short transverse relaxation time component (ViSTa)-gradient and spin-echo (GraSE) sequence was developed to map apparent MWF. Then, the MWF values were compared between the three participant groups and was evaluated the relationship with the degree of memory loss. The AD group showed a reduced apparent MWF compared to the CN and MCI groups. The largest AUC (area under the curve) value was in the corpus callosum and used to classify the CN and AD groups using the apparent MWF. The ViSTa-GraSE sequence can be a useful tool to map the MWF in a reasonable scan time. Combining the MWF in the corpus callosum with the detection of atrophy in the hippocampus can be valuable for group classification.

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Lee, Jeonghwan, Gawon Ju, Hyemi Park, Seungwon Chung, Jung-Woo Son, Chul-Jin Shin, Sang Ick Lee, and Siekyeong Kim. "Hippocampal Subfields and White Matter Connectivity in Patients with Subclinical Geriatric Depression." Brain Sciences 12, no. 3 (February 28, 2022): 329. http://dx.doi.org/10.3390/brainsci12030329.

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Despite an abundance of research related to the functional and structural changes of the brain in patients with geriatric depression, knowledge related to early alterations such as decreased white matter connectivity and their association with cognitive decline remains lacking. We aimed to investigate early alterations in hippocampal microstructure and identify their associations with memory function in geriatric patients with subclinical depression. Nineteen participants with subclinical geriatric depression and 19 healthy controls aged ≥65 years exhibiting general cognitive function within the normal range were included in the study and underwent assessments of verbal memory. Hippocampal subfield volumes were determined based on T1-weighted magnetization-prepared rapid gradient echo (T1-MPRAGE) images, while group tractography and connectometry analyses were conducted using diffusion tensor images. Our findings indicated that the volumes of whole bilateral hippocampus, cornus ammonis (CA) 1, molecular layer, left subiculum, CA3, hippocampal tail, right CA4, and granule cell/molecular layers of the dentate gyrus (GC-ML-DG) were significantly smaller in the subclinical depression group than in the control group. In the subclinical depression group, verbal learning was positively correlated with the volumes of the CA1, GC-ML-DG, molecular layer, and whole hippocampus in the right hemisphere. The fractional anisotropy of the bilateral fornix was also significantly lower in the subclinical depression group and exhibited a positive correlation with verbal learning and recall in both groups. Our results suggest that hippocampal microstructure is disrupted and associated with memory in patients with subclinical depression.

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Kothapalli, Satya V. V. N., Tammie L. Benzinger, Andrew J. Aschenbrenner, Richard J. Perrin, Charles F. Hildebolt, Manu S. Goyal, Anne M. Fagan, Marcus E. Raichle, John C. Morris, and Dmitriy A. Yablonskiy. "Quantitative Gradient Echo MRI Identifies Dark Matter as a New Imaging Biomarker of Neurodegeneration that Precedes Tisssue Atrophy in Early Alzheimer’s Disease." Journal of Alzheimer's Disease 85, no. 2 (January 18, 2022): 905–24. http://dx.doi.org/10.3233/jad-210503.

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Background: Currently, brain tissue atrophy serves as an in vivo MRI biomarker of neurodegeneration in Alzheimer’s disease (AD). However, postmortem histopathological studies show that neuronal loss in AD exceeds volumetric loss of tissue and that loss of memory in AD begins when neurons and synapses are lost. Therefore, in vivo detection of neuronal loss prior to detectable atrophy in MRI is essential for early AD diagnosis. Objective: To apply a recently developed quantitative Gradient Recalled Echo (qGRE) MRI technique for in vivo evaluation of neuronal loss in human hippocampus. Methods: Seventy participants were recruited from the Knight Alzheimer Disease Research Center, representing three groups: Healthy controls [Clinical Dementia Rating® (CDR®) = 0, amyloid β (Aβ)-negative, n = 34]; Preclinical AD (CDR = 0, Aβ-positive, n = 19); and mild AD (CDR = 0.5 or 1, Aβ-positive, n = 17). Results: In hippocampal tissue, qGRE identified two types of regions: one, practically devoid of neurons, we designate as “Dark Matter”, and the other, with relatively preserved neurons, “Viable Tissue”. Data showed a greater loss of neurons than defined by atrophy in the mild AD group compared with the healthy control group; neuronal loss ranged between 31% and 43%, while volume loss ranged only between 10% and 19%. The concept of Dark Matter was confirmed with histopathological study of one participant who underwent in vivo qGRE 14 months prior to expiration. Conclusion: In vivo qGRE method identifies neuronal loss that is associated with impaired AD-related cognition but is not recognized by MRI measurements of tissue atrophy, therefore providing new biomarkers for early AD detection.

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Bonnier, Guillaume, Alexis Roche, David Romascano, Samanta Simioni, Djalel Eddine Meskaldji, David Rotzinger, Ying-Chia Lin, et al. "Multicontrast MRI Quantification of Focal Inflammation and Degeneration in Multiple Sclerosis." BioMed Research International 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/569123.

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Introduction. Local microstructural pathology in multiple sclerosis patients might influence their clinical performance. This study applied multicontrast MRI to quantify inflammation and neurodegeneration in MS lesions. We explored the impact of MRI-based lesion pathology in cognition and disability.Methods. 36 relapsing-remitting MS subjects and 18 healthy controls underwent neurological, cognitive, behavioural examinations and 3 T MRI including (i) fluid attenuated inversion recovery, double inversion recovery, and magnetization-prepared gradient echo for lesion count; (ii) T1, T2, and T2*relaxometry and magnetisation transfer imaging for lesion tissue characterization. Lesions were classified according to the extent of inflammation/neurodegeneration. A generalized linear model assessed the contribution of lesion groups to clinical performances.Results. Four lesion groups were identified and characterized by (1) absence of significant alterations, (2) prevalent inflammation, (3) concomitant inflammation and microdegeneration, and (4) prevalent tissue loss. Groups 1, 3, 4 correlated with general disability (Adj-R2=0.6;P=0.0005), executive function (Adj-R2=0.5;P=0.004), verbal memory (Adj-R2=0.4;P=0.02), and attention (Adj-R2=0.5;P=0.002).Conclusion. Multicontrast MRI provides a new approach to inferin vivohistopathology of plaques. Our results support evidence that neurodegeneration is the major determinant of patients’ disability and cognitive dysfunction.

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An, Tong, Tao Zhang, Yanzhang Geng, and Haiquan Jiao. "Normalized Combinations of Proportionate Affine Projection Sign Subband Adaptive Filter." Scientific Programming 2021 (August 26, 2021): 1–12. http://dx.doi.org/10.1155/2021/8826868.

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The proportionate affine projection sign subband adaptive filter (PAP-SSAF) has a better performance than the affine projection sign subband adaptive filter (AP-SSAF) when we eliminate the echoes. Still, the robustness of the PAP-SSAF algorithm is insufficient under unknown environmental conditions. Besides, the best balance remains to be found between low steady-state misalignment and fast convergence rate. In order to solve this problem, we propose a normalized combination of PAP-SSAF (NCPAP-SSAF) based on the normalized adaption schema. In this paper, a power normalization adaptive rule for mixing parameters is proposed to further improve the performance of the NCPAP-SSAF algorithm. By using Nesterov’s accelerated gradient (NAG) method, the mixing parameter of the control combination can be obtained with less time consumed when we take the l1-norm of the subband error as the cost function. We also test the algorithmic complexity and memory requirements to illustrate the rationality of our method. In brief, our study contributes a novel adaptive filter algorithm, accelerating the convergence speed, reducing the steady-state error, and improving the robustness. Thus, the proposed method can be utilized to improve the performance of echo cancellation. We will optimize the combination structure and simplify unnecessary calculations to reduce the algorithm’s computational complexity in future research.

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Trufanov, Artem G., Aleksander Yu Efimtsev, and Igor V. Litvinenko. "Alterations in internetwork functional connectivity in patients with post COVID-19 syndrome within the boundaries of the Triple Network Model." Russian Military Medical Academy Reports 41, no. 4 (November 17, 2022): 393–98. http://dx.doi.org/10.17816/rmmar111862.

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AIM: Was to assess the changes in the connections between the three main neural networks using resting-state fMRI in patients with post COVID-19 syndrome with cerebral neurological symptoms, within the boundaries of the triple net-work model. MATERIALS AND METHODS: We examined a total of 15 patients (mean age 36.4 8.3 years; M : W = 10 : 5) with post COVID-19 syndrome who presented with neurological complaints, primarily decreased memory and attention, general weakness, low performance and sleep disturbance. The control group consisted of healthy 15 subjects (mean age, 32.2 6.9 years; M : W = 11 : 4) who had not previously been exposed to COVID-19. All members of the control group were vaccinated with the Sputnik-V vaccine. Magnetic resonance examination was performed on a Siemens Espree magnetic resonance imaging machine with a magnetic field strength of 1.5T. To exclude structural brain lesions, a standard magnetic resonance examination was performed with pulsed T1-WI, T2-WI, and Flair sequences. For postprocessing, T1 gradient echo and resting state echo-planar imaging protocols were performed. Postprocessing was performed using the software package CONN toolbox 20a to obtain clusters of functional connectivity of the studied neural networks using the seed-to-voxel processing protocol. RESULTS: Disruption of connectivity of the standard resting neural network with lingvalis ingual, fusiform, and middle frontal gyrus was detected. The salient resting neural network had a worse ability to form connections in patients with post COVID-19 syndrome with lateral occipital cortex, angular gyrus, superior parietal lobule and supramarginal gyrus in one cluster and frontal cortex, and paracingular gyrus in the second cluster. The resting frontoparietal neural network interacted significantly better in the control group with the cerebellar structures, the middle frontal gyrus, and the cuneus and precuneus. CONCLUSION: Patients with COVID-19 and the presence of post COVID-19 syndrome have reduced functional connectivity of all three basic neural networks with the big number of anatomo-physiological brain structures.

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Kazumata, Ken, Khin Khin Tha, Kikutaro Tokairin, Masaki Ito, Haruto Uchino, Masahito Kawabori, and Taku Sugiyama. "Brain Structure, Connectivity, and Cognitive Changes Following Revascularization Surgery in Adult Moyamoya Disease." Neurosurgery 85, no. 5 (June 3, 2019): E943—E952. http://dx.doi.org/10.1093/neuros/nyz176.

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AbstractBACKGROUNDThe effect of the combined direct/indirect revascularization surgery in Moyamoya disease has not been evaluated sufficiently with regard to cognitive function, brain microstructure, and connectivity.OBJECTIVETo investigate structural and functional changes following revascularization surgery in patients with moyamoya disease (MMD) through a combined analysis of brain morphology, microstructure, connectivity, and neurobehavioral data.METHODSNeurobehavioral and neuroimaging examinations were performed in 25 adults with MMD prior to and >12 mo after revascularization surgery. Cognitive function was investigated using the Wechsler Adult Intelligence Scale-III, Trail-Making Test, Wisconsin Card Sorting Test, Continuous Performance Test, Stroop test, and Wechsler Memory Scale. We assessed white matter integrity using diffusion tensor imaging, brain morphometry using magnetization-prepared rapid gradient-echo sequences, and brain connectivity using resting-state functional magnetic resonance imaging (MRI).RESULTSCognitive examinations revealed significant changes in the full-scale intelligence quotient (IQ), performance IQ (PIQ), perceptual organization (PO), processing speed, and Stroop test scores after surgery (P < .05). Enlargement of the lateral ventricle, volume reductions in the corpus callosum and subcortical nuclei, and cortical thinning in the prefrontal cortex were also observed (P < .05). Fractional anisotropy in the white matter tracts, including the superior longitudinal fasciculus, increased 2 to 4 yr after surgery, relative to that observed in the presurgical state (P < .05). Resting-state brain connectivity was increased predominantly in the fronto-cerebellar circuit and was positively correlated with improvements in PIQ and PO (P < .05).CONCLUSIONRevascularization surgery may improve processing speed and attention in adult patients with MMD. Further, multimodal MRI may be useful for detecting subtle postsurgical brain structural changes, reorganization of white matter tracts, and brain connectivity alterations.

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Elalfy, Mohsen Saleh, Ahmed Smair, Ghada Samir, Hanaa Hussein, Hend Mohammed, and Fatma Soliman Elsayed Ebeid. "Brain Iron Content in Egyptian Patients with Sickle Cell Disease: Impact on Neurocognitive Functions." Blood 136, Supplement 1 (November 5, 2020): 37. http://dx.doi.org/10.1182/blood-2020-139168.

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Background:Children with sickle cell disease (SCD) are at a high risk for neurocognitive impairment which may be due to iron overload in brain tissue or hemoglobin polymerization and endothelial dysfunction.Primary objectivewas measuring brain iron content (using R2* values) in the caudate and thalamic regions through quantitative brain MRI in Egyptian adolescents and young adults with multi-transfused SCD in comparison to beta thalassemia major (BTM) and age- and sex-matched healthy controls.Secondary objectiveswere evaluating the impact of brain iron content on neurocognitive functions of SCD patients and its association with MRI assessment of liver iron concentration (LIC) and cardiac iron (myocardial T2*).Methods: 32 children and young adults with SCD (mean age: 15.3 ± 3.7, 19 males and 13 females), 15 BTM (mean age: 19.4 ± 4.3, 7 males and 8 females) and 11 healthy control age- and gender-matched were recruited. Thorough clinical assessment, hematological and serum ferritin were performed. Brain MRI study using multi-echo fast gradient echo sequence was performed only for 15 patients with SCD, 15 patients with BTM and 11 controls and brain R2* values of both caudate and thalamic regions (right and left sides) were calculated. LIC and myocardial T2 were performed for; 15 with SCD and 15 with BTM. 32 SCD patients were examined for the neurocognitive functions; Wechsler IV Intelligence scale (verbal, perceptual, memory, processing and total IQ), Benton Visual Retention Test and Brief Psychiatric Rating Scale (BPRS).Results:For SCD patients their mean transfusion index was 174.70±63.98ml/kg/year and mean iron overload/day 0.30±0.12 mg/kg. 30 (93.8%) all SCD patients were on regular chelation therapy; 16 were on deferiprone and 16 were on combined chelation over last 5 years. Of those 32 SCD patients; 20 received concomitantly hydroxyurea therapy. Mean total IQ for SCD patients was 86.9±10.7; 68.9% had under- threshold <90 IQ and 27.5% had average (90-109) IQ. 12.5% of SCD patients had moderate to severe anxiety and 60.8% had of SCD patients had depression. No significant differences were found between SCD, BTM as regards LIC (p=0.102) No significant differences were found between SCD, BTM and control group in all regions of interests in brain MRI except that left thalamus R2* higher in BTM patients than both SCD and controls (p=0.032). R2* values of different regions of brain in relation with the studied parameters of SCD patients was not significant except that mean right caudate R2* was higher in female 17.4±0.8 than male 15.6±1.7 (p=0.044). The correlation coefficients showed no significant association between brain R2* and LIC or heart R2* values of SCD patients. There were positive correlation between left caudate R2* and both age and HbS%, negative correlation between transfusion index and right thalamus R2*, negative correlation between HbA% and left caudate R2* among SCD patients.Conclusion:Brain iron content in adolescents and young adults with SCD was not significantly different from either controls or BTM; SCD had high prevalence of neurocognitive dysfunction, which could not be explained by brain iron content or distribution. Figure 1 Disclosures No relevant conflicts of interest to declare.

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Lo, Yu-Chun, Fu-Shan Jaw, Su-Chun Huang, Yu-Yang Yeh, and Wen-Yih Isaac Tseng. "WHITE MATTER TRACTS IN FRONTO-STRIATO-THALAMIC CIRCUIT IN THE HUMAN BRAIN: A DIFFUSION SPECTRUM IMAGING STUDY." Biomedical Engineering: Applications, Basis and Communications 23, no. 03 (June 2011): 215–22. http://dx.doi.org/10.4015/s1016237211002542.

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Gender and handedness differences in cognitive functions and brain structures are well recognized. Recent research has reported different white matter structures between male and female subjects. Yet it is unknown whether the gender and handedness effects on different white matter tracts are comparable or disparate. In this study, we focus on three main tracts in the fronto-striato-thalamic circuit, namely, the cingulum bundles (CG), fornices (FXs) and anterior thalamic radiations (ATR). These are the primary connections among the frontal lobe, the limbic system, and the thalamus, integrating functions of emotion control, memory, and decision-making. A total of 40 healthy adults were recruited in this study. There was no significant difference in demographic variables between males and females. Images were acquired on a 3-T Magnetic resonance imaging (MRI) system with an eight-channel head coil. The diffusion spectrum imaging (DSI) experiment was performed by applying 203 diffusion gradient vectors. DSI maps the angular distribution of water molecule displacement by acquiring diffusion MR signals in a more comprehensive way. The theory of DSI is based on the Fourier transform relationship between diffusion MR signals and the average propagator of water molecule displacement. Isotropic spatial resolution was obtained by setting both in-plane and through-plane resolutions as 2.7 mm. A total of 45 trans-axial slices were acquired encompassing the whole brain. DSI analysis was computed based on the Fourier relationship between diffusion echo signals and the probability density function (PDF). Fiber tracking was used to define the targeted tracts. All fiber orientations of the nearest voxels were used to decide the proceeding orientation for the next step. Tracking stopped if there was no coinciding orientation in the nearest voxels. Mean path analysis, a method that projected the anisotropy of PDF [generalized fractional anisotropy (GFA)] onto a single mean path of the specific white matter tract bundle, was used to analyze subtle changes in microstructure coherence along individual tract bundles. The asymmetric differences of targeted tracts were assessed statistically by calculating GFA values and lateralization indices (LIs). The handedness factor of the LI values in CG and ATR showed a trend for significance. The gender factor of the LI values was investigated in FX also. Different white matter tract bundles manifested different degrees of gender effect on GFA distributions. Our results suggest that the gender and handedness factors should be considered when one evaluates the impairment of the fronto-striato-thalamic circuit.

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Xu, Zhiyuan, Carissa Carlson, John Snell, Matt Eames, Arik Hananel, M. Beatriz Lopes, Prashant Raghavan, et al. "Intracranial inertial cavitation threshold and thermal ablation lesion creation using MRI-guided 220-kHz focused ultrasound surgery: preclinical investigation." Journal of Neurosurgery 122, no. 1 (January 2015): 152–61. http://dx.doi.org/10.3171/2014.9.jns14541.

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OBJECT In biological tissues, it is known that the creation of gas bubbles (cavitation) during ultrasound exposure is more likely to occur at lower rather than higher frequencies. Upon collapsing, such bubbles can induce hemorrhage. Thus, acoustic inertial cavitation secondary to a 220-kHz MRI-guided focused ultrasound (MRgFUS) surgery is a serious safety issue, and animal studies are mandatory for laying the groundwork for the use of low-frequency systems in future clinical trials. The authors investigate here the in vivo potential thresholds of MRgFUS-induced inertial cavitation and MRgFUS-induced thermal coagulation using MRI, acoustic spectroscopy, and histology. METHODS Ten female piglets that had undergone a craniectomy were sonicated using a 220-kHz transcranial MRgFUS system over an acoustic energy range of 5600–14,000 J. For each piglet, a long-duration sonication (40-second duration) was performed on the right thalamus, and a short sonication (20-second duration) was performed on the left thalamus. An acoustic power range of 140–300 W was used for long-duration sonications and 300–700 W for short-duration sonications. Signals collected by 2 passive cavitation detectors were stored in memory during each sonication, and any subsequent cavitation activity was integrated within the bandwidth of the detectors. Real-time 2D MR thermometry was performed during the sonications. T1-weighted, T2-weighted, gradient-recalled echo, and diffusion-weighted imaging MRI was performed after treatment to assess the lesions. The piglets were killed immediately after the last series of posttreatment MR images were obtained. Their brains were harvested, and histological examinations were then performed to further evaluate the lesions. RESULTS Two types of lesions were induced: thermal ablation lesions, as evidenced by an acute ischemic infarction on MRI and histology, and hemorrhagic lesions, associated with inertial cavitation. Passive cavitation signals exhibited 3 main patterns identified as follows: no cavitation, stable cavitation, and inertial cavitation. Low-power and longer sonications induced only thermal lesions, with a peak temperature threshold for lesioning of 53°C. Hemorrhagic lesions occurred only with high-power and shorter sonications. The sizes of the hemorrhages measured on macroscopic histological examinations correlated with the intensity of the cavitation activity (R2 = 0.74). The acoustic cavitation activity detected by the passive cavitation detectors exhibited a threshold of 0.09 V·Hz for the occurrence of hemorrhages. CONCLUSIONS This work demonstrates that 220-kHz ultrasound is capable of inducing a thermal lesion in the brain of living swines without hemorrhage. Although the same acoustic energy can induce either a hemorrhage or a thermal lesion, it seems that low-power, long-duration sonication is less likely to cause hemorrhage and may be safer. Although further study is needed to decrease the likelihood of ischemic infarction associated with the 220-kHz ultrasound, the threshold established in this work may allow for the detection and prevention of deleterious cavitations.

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Tyler, Christopher J., Mauricio Guzman, Luke R. Lundborg, Shaila Yeasmin, Tamara Perez-Jeldres, Andres Yarur, Brian Behm, et al. "Inherent Immune Cell Variation Within Colonic Segments Presents Challenges for Clinical Trial Design." Journal of Crohn's and Colitis 14, no. 10 (April 2, 2020): 1364–77. http://dx.doi.org/10.1093/ecco-jcc/jjaa067.

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Abstract Background and Aims Intestinal biopsy sampling during IBD trials represents a valuable adjunct strategy for understanding drug responses at the tissue level. Given the length and distinctive embryonic origins of the proximal and distal colon, we investigated whether inherent regional differences of immune cell composition could introduce confounders when sampling different disease stages, or pre/post drug administration. Here, we capitalise on novel mass cytometry technology to perform deep immunophenotyping of distinct healthy colonic segments, using the limited numbers of biopsies that can be harvested from patients. Methods Biopsies [2.8 mm] were collected from the caecum, transverse colon, descending colon, and rectum of normal volunteers. Intestinal leukocytes were isolated, stained with a panel of 37 antibodies, and mass cytometry data acquired. Results Site-specific patterns of leukocyte localisation were observed. The proximal colon featured increased CD8+ T cells [particularly resident memory], monocytes, and CD19+ B cells. Conversely, the distal colon and rectum tissues exhibited enrichment for CD4+ T cells and antibody-secreting cells. The transverse colon displayed increased abundance of both γδ T cells and NK cells. Subsets of leukocyte lineages also displayed gradients of expression along the colon length. Conclusions Our results show an inherent regional immune cell variation within colonic segments, indicating that regional mucosal signatures must be considered when assessing disease stages or the prospective effects of trial drugs on leukocyte subsets. Precise protocols for intestinal sampling must be implemented to allow for the proper interpretation of potential differences observed within leukocyte lineages present in the colonic lamina propria.

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Luo, X. W., J. J. Hope, B. Hillman, and T. M. Stace. "Diffusion effects in gradient echo memory." Physical Review A 87, no. 6 (June 24, 2013). http://dx.doi.org/10.1103/physreva.87.062328.

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Pinel, Olivier, Mahdi Hosseini, Ben M. Sparkes, Jesse L. Everett, Daniel Higginbottom, Geoff T. Campbell, Ping Koy Lam, and Ben C. Buchler. "Gradient Echo Quantum Memory in Warm Atomic Vapor." Journal of Visualized Experiments, no. 81 (November 11, 2013). http://dx.doi.org/10.3791/50552.

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Higginbottom, D. B., B. M. Sparkes, M. Rancic, O. Pinel, M. Hosseini, P. K. Lam, and B. C. Buchler. "Spatial-mode storage in a gradient-echo memory." Physical Review A 86, no. 2 (August 1, 2012). http://dx.doi.org/10.1103/physreva.86.023801.

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Sparkes, B. M., M. Hosseini, G. Hétet, P. K. Lam, and B. C. Buchler. "ac Stark gradient echo memory in cold atoms." Physical Review A 82, no. 4 (October 29, 2010). http://dx.doi.org/10.1103/physreva.82.043847.

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Hétet, G., J. J. Longdell, M. J. Sellars, P. K. Lam, and B. C. Buchler. "Multimodal Properties and Dynamics of Gradient Echo Quantum Memory." Physical Review Letters 101, no. 20 (November 13, 2008). http://dx.doi.org/10.1103/physrevlett.101.203601.

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Leung, Anthony C., Mary Ida Melody Kunnel Shine, Aaron D. Tranter, Karun V. Paul, Geoff Campbell, Ping Koy Lam, and Ben Buchler. "Observation of cross phase modulation in cold atom gradient echo memory." New Journal of Physics, August 24, 2022. http://dx.doi.org/10.1088/1367-2630/ac8c64.

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Abstract Strong nonlinear interactions between single photons has important applications in optical quantum information processing. Demonstrations of these interactions in cold atomic ensembles have largely been limited to exploiting slow light generated using electromagnetically induced transparency (EIT). However, these EIT implementations have limited achievable phase shifts [1] due to spontaneous emission.Here, we demonstrate and characterize a scheme free from these limitations using gradient echo memory with inferred single photon phase shifts of 0.07±0.02μrad.

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Fu, Shuangshuang, André R. R. Carvalho, Michael R. Hush, and Matthew R. James. "Cross-phase modulation and entanglement in a compound gradient echo memory." Physical Review A 93, no. 2 (February 4, 2016). http://dx.doi.org/10.1103/physreva.93.023809.

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Clark, James, Khabat Heshami, and Christoph Simon. "Photonic quantum memory in two-level ensembles based on modulating the refractive index in time: Equivalence to gradient echo memory." Physical Review A 86, no. 1 (July 23, 2012). http://dx.doi.org/10.1103/physreva.86.013833.

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Fukuo, Makoto, Koji Kamagata, Mana Kuramochi, Christina Andica, Hiroyuki Tomita, Hidefumi Waki, Hidenori Sugano, et al. "Regional brain gray matter volume in world-class artistic gymnasts." Journal of Physiological Sciences 70, no. 1 (September 18, 2020). http://dx.doi.org/10.1186/s12576-020-00767-w.

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Abstract The relationship between long-term intensive training and brain plasticity in gymnasts has recently been reported. However, the relationship between abilities in different gymnastic events and brain structural changes has not been explored. This study aimed to evaluate the correlation between world-class gymnasts (WCGs)’ specific abilities in different gymnastics events and their gray matter (GM) volume. Ten right-handed Japanese male WCGs and 10 right-handed gender- and age-matched controls with no history of gymnastic training participated in this study. Whole brain three-dimensional T1-weighted images (magnetization-prepared rapid gradient-echo sequence) with 0.90 mm3 voxels were obtained using a 3 T-MRI scanner from each subject. Volume-based morphometry (VolBM) was used to compare GM volume differences between WCGs and controls. We then explored the correlation between specific gymnastic abilities using different gymnastic apparatuses, and GM volume. Significantly higher GM volumes (false discovery rate-corrected p < 0.05) in the inferior parietal lobule, middle temporal gyrus, precentral gyrus, rostral middle frontal gyrus, and superior frontal gyrus were demonstrated in WCGs, compared with controls using VolBM. Moreover, significant positive correlations were observed between brain regions and the difficulty scores for each gymnastic event, for example, rings and inferior parietal lobule and parallel bars and rostral middle frontal gyrus. These results may reflect the neural basis of an outstanding gymnastic ability resulting from brain plasticity in areas associated with spatial perception, vision, working memory, and motor control.

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Elalfy, Mohsen Saleh, Fatma Soliman Elsayed Ebeid, Mohammed Ahmed Samir Ibrahim, and Hanaa Midhat Abdel Gader Hussein. "Evaluation of brain iron content in Egyptian Patients with Sickle cell disease and its impact on Neurocognitive functions." QJM: An International Journal of Medicine 114, Supplement_1 (October 1, 2021). http://dx.doi.org/10.1093/qjmed/hcab113.026.

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Abstract Background Sickle cell disease (SCD) is considered the most prevalent monogenic diseases worldwide. Iron overload is one of the major complications in those patients, especially who in need for frequent transfusion, affecting many organs including the brain. MRI is a valuable, reliable and non-invasive method for quantifying iron concentration in many organs as the liver and heart and it is now used for monitoring of the chelation therapy in SCD patients. Several studies began reporting differences in global cognitive function, particularly for children with SCD, they are at a high risk for neurocognitive impairment they often scored lower on general IQ measures than healthy children which is due to iron overload in brain tissue from the chronic transfusions which can lead to strokes and may be a silent stroke. Objective The current study assessed brain iron content (using R2* values) in the caudate and thalamic regions through quantitative brain MRI study in SCD patients in comparison to age and sex-matched healthy controls. Methods A case-control study recruited 32 patients with SCD and 11 healthy controls. Brain MRI study using multi-echo fast gradient echo sequence was done for all the patients and controls. Brain R2* values of both caudate and thalamic regions (right and left sides) were calculated for only 15 SCD patients and the 11 controls. All recruited SCD patients and controls were examined for the neurocognitive functions by these tests: Wechsler IV Intelligence Scale for Adult shows (Verbal, Perceptual, Memory, Processing and Total IQ), their all normal values between 90 – 110. Benton Visual Retention Test have cut of point at (> 4 or = 4). Those values are the same for the difference between the obtained correct and the expected correct, and the difference between the obtained error and expected error. Results The fifteen patient with SCD who underwent brain MRI were age and sex matched with the eleven healthy control (15 SCD patients: mean-age: 16.93 ± 3.41 years, 40.6% females and 11healthy controls: mean age: 18.73 ± 4.84 years, 54.5% females) were enrolled in the study. As regards the brain MRI, there was no statistically significant differences between SCD and control group in all regions of interests (p > 0.05). Our study showed that 72.7% of our SCD patients had under threshold TIQ scores. Also18% of the patients showed moderate anxiety, 9% mild anxiety and 9% showed severe anxiety. Conclusion The results of our study showed that even in cases of iron overload which affects vital organs as the liver, cardiac and brain iron overload don't occur.

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