scholarly journals A Study of Brain Neuronal and Functional Complexities Estimated Using Multiscale Entropy in Healthy Young Adults

Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 995
Author(s):  
Sreevalsan S. Menon ◽  
K. Krishnamurthy
Keyword(s):  
Young Adults ◽  
Brain Function ◽  
Fluid Intelligence ◽  
Blood Oxygen Level Dependent ◽  
Multiscale Entropy ◽  
Blood Oxygen Level ◽  
Neurologically Impaired ◽  
Wide Range ◽  
Healthy Control ◽  
Functional Complexity

Brain complexity estimated using sample entropy and multiscale entropy (MSE) has recently gained much attention to compare brain function between diseased or neurologically impaired groups and healthy control groups. Using resting-state functional magnetic resonance imaging (rfMRI) blood oxygen-level dependent (BOLD) signals in a large cohort (n = 967) of healthy young adults, the present study maps neuronal and functional complexities estimated by using MSE of BOLD signals and BOLD phase coherence connectivity, respectively, at various levels of the brain’s organization. The functional complexity explores patterns in a higher dimension than neuronal complexity and may better discern changes in brain functioning. The leave-one-subject-out cross-validation method is used to predict fluid intelligence using neuronal and functional complexity MSE values as features. While a wide range of scales was selected with neuronal complexity, only the first three scales were selected with functional complexity. Fewer scales are advantageous as they preclude the need for long BOLD signals to calculate good estimates of MSE. The presented results corroborate with previous findings and provide a baseline for other studies exploring the use of MSE to examine changes in brain function related to aging, diseases, and clinical disorders.

scholarly journals Recent advances in renal imaging

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1867 ◽  
Author(s):  
Joshua M. Thurman ◽  
Faikah Gueler
Keyword(s):  
Kidney Diseases ◽  
Treatment Strategies ◽  
Blood Oxygen Level Dependent ◽  
Great Promise ◽  
Blood Oxygen Level ◽  
Bold Mri ◽  
Contrast Enhanced ◽  
Radiologic Imaging ◽  
Wide Range ◽  
New Treatment

Kidney diseases can be caused by a wide range of genetic, hemodynamic, toxic, infectious, and autoimmune factors. The diagnosis of kidney disease usually involves the biochemical analysis of serum and blood, but these tests are often insufficiently sensitive or specific to make a definitive diagnosis. Although radiologic imaging currently has a limited role in the evaluation of most kidney diseases, several new imaging methods hold great promise for improving our ability to non-invasively detect structural, functional, and molecular changes within the kidney. New methods, such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and blood oxygen level-dependent (BOLD) MRI, allow functional imaging of the kidney. The use of novel contrast agents, such as microbubbles and nanoparticles, allows the detection of specific molecules in the kidney. These methods could greatly advance our ability to diagnose disease and also to safely monitor patients over time. This could improve the care of individual patients, and it could also facilitate the evaluation of new treatment strategies.

scholarly journals The Significance of Echo Time in fMRI BOLD Contrast: A Clinical Study during Motor and Visual Activation Tasks at 1.5 T

Tomography ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 333-343
Author(s):  
Themistoklis Boursianis ◽  
Georgios Kalaitzakis ◽  
Katerina Nikiforaki ◽  
Emmanouela Kosteletou ◽  
Despina Antypa ◽  
...  
Keyword(s):  
Gray Matter ◽  
Brain Function ◽  
Blood Oxygen Level Dependent ◽  
Small Scale ◽  
Blood Oxygen Level ◽  
Specific Sequence ◽  
Visual Cortices ◽  
Echo Time ◽  
Sequence Parameters ◽  
Larger Sample

Blood Oxygen Level Dependent (BOLD) is a commonly-used MR imaging technique in studying brain function. The BOLD signal can be strongly affected by specific sequence parameters, especially in small field strengths. Previous small-scale studies have investigated the effect of TE on BOLD contrast. This study evaluates the dependence of fMRI results on echo time (TE) during concurrent activation of the visual and motor cortex at 1.5 T in a larger sample of 21 healthy volunteers. The experiment was repeated using two different TE values (50 and 70 ms) in counterbalanced order. Furthermore, T2* measurements of the gray matter were performed. Results indicated that both peak beta value and number of voxels were significantly higher using TE = 70 than TE = 50 ms in primary motor, primary somatosensory and supplementary motor cortices (p < 0.007). In addition, the amplitude of activation in visual cortices and the dorsal premotor area was also higher using TE = 70 ms (p < 0.001). Gray matter T2* of the corresponding areas did not vary significantly. In conclusion, the optimal TE value (among the two studied) for visual and motor activity is 70 ms affecting both the amplitude and extent of regional hemodynamic activation.

scholarly journals Simultaneous mesoscopic Ca2+ imaging and fMRI: Neuroimaging spanning spatiotemporal scales

2018 ◽  
Author(s):  
Evelyn MR Lake ◽  
Xinxin Ge ◽  
Xilin Shen ◽  
Peter Herman ◽  
Fahmeed Hyder ◽  
...  
Keyword(s):  
Brain Function ◽  
Brain Activity ◽  
Blood Oxygen Level Dependent ◽  
Optical Measurements ◽  
Wide Field ◽  
Blood Oxygen Level ◽  
Neural Basis ◽  
Novel Approach ◽  
Transgenic Murine Model ◽  
Spatiotemporal Scales

ABSTRACTTo achieve a more comprehensive understanding of brain function requires simultaneous measurement of activity across a range of spatiotemporal scales. However, the appropriate tools to perform such studies are largely unavailable. Here, we present a novel approach for concurrent wide-field optical and functional magnetic resonance imaging (fMRI). By merging these two modalities, we are for the first time able to simultaneously acquire whole-brain blood-oxygen-level-dependent and whole-cortex calcium-sensitive fluorescent measures of brain activity. We describe the developments that allow us to combine these modalities without compromising the fidelity of either technique. In a transgenic murine model, we examine correspondences between activity measured using these modalities and identify unique and complementary features of each. Our approach links cell-type specific optical measurements of neural activity to the most widely used method for assessing human brain function. These data and approach directly establish the neural basis for the macroscopic connectivity patterns observed with fMRI.

scholarly journals BOLD Responses in Human Auditory Cortex Are More Closely Related to Transient MEG Responses Than to Sustained Ones

2010 ◽  
Vol 103 (4) ◽  
pp. 2015-2026 ◽  
Author(s):  
Alexander Gutschalk ◽  
Matti S. Hämäläinen ◽  
Jennifer R. Melcher
Keyword(s):  
Auditory Cortex ◽  
Blood Oxygen Level Dependent ◽  
Bold Response ◽  
Blood Oxygen Level ◽  
Bold Fmri ◽  
Duty Cycles ◽  
Wide Range ◽  
Bold Responses ◽  
Tightly Coupled ◽  
Click Train

Blood oxygen level dependent–functional magnetic resonance imaging (BOLD–fMRI) and magnetoencephalographic (MEG) signals are both coupled to postsynaptic potentials, although their relationship is incompletely understood. Here, the wide range of BOLD–fMRI and MEG responses produced by auditory cortex was exploited to better understand the BOLD–fMRI/MEG relationship. Measurements of BOLD and MEG responses were made in the same subjects using the same stimuli for both modalities. The stimuli, 24-s sequences of click trains, had duty cycles of 2.5, 25, 72, and 100%. For the 2.5% sequence, the BOLD response was elevated throughout the sequence, whereas for 100%, it peaked after sequence onset and offset and showed a diminished elevation in between. On the finer timescale of MEG, responses at 2.5% consisted of a complex of transients, including N1m, to each click train of the sequence, whereas for 100% the only transients occurred at sequence onset and offset between which there was a sustained elevation in the MEG signal (a sustained field). A model that separately estimated the contributions of transient and sustained MEG signals to the BOLD response best fit BOLD measurements when the transient contribution was weighted 8- to 10-fold more than the sustained one. The findings suggest that BOLD responses in the auditory cortex are tightly coupled to the neural activity underlying transient, not sustained, MEG signals.

scholarly journals Hippocampal function in schizophrenia and bipolar disorder

2009 ◽  
Vol 40 (5) ◽  
pp. 761-770 ◽  
Author(s):  
J. Hall ◽  
H. C. Whalley ◽  
K. Marwick ◽  
J. McKirdy ◽  
J. Sussmann ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Temporal Cortex ◽  
Memory Task ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Blood Oxygen Level ◽  
The Face ◽  
Healthy Control ◽  
Patient Groups ◽  
And Function

BackgroundThe hippocampus plays a central role in memory formation. There is considerable evidence of abnormalities in hippocampal structure and function in schizophrenia, which may differentiate it from bipolar disorder. However, no previous studies have compared hippocampal activation in schizophrenia and bipolar disorder directly.MethodFifteen patients with schizophrenia, 14 patients with bipolar disorder and 14 healthy comparison subjects took part in the study. Subjects performed a face–name pair memory task during functional magnetic resonance imaging (fMRI). Differences in blood oxygen level-dependent (BOLD) activity were determined during encoding and retrieval of the face–name pairs.ResultsThe patient groups showed significant differences in hippocampal and prefrontal cortex (PFC) activation during face–name pair learning. During encoding, patients with schizophrenia showed decreased anterior hippocampal activation relative to subjects with bipolar disorder, whereas patients with bipolar disorder showed decreased dorsal PFC activation relative to patients with schizophrenia. During retrieval, patients with schizophrenia showed greater activation of the dorsal PFC than patients with bipolar disorder. Patients with schizophrenia also differed from healthy control subjects in the activation of several brain regions, showing impaired superior temporal cortex activation during encoding and greater dorsal PFC activation during retrieval. These effects were evident despite matched task performance.ConclusionsPatients with schizophrenia showed deficits in hippocampal activation during a memory task relative to patients with bipolar disorder. The disorders were further distinguished by differences in PFC activation. The results demonstrate that these disorders can distinguished at a group level using non-invasive neuroimaging.

scholarly journals Distinct patterns of brain activity in young carriers of theAPOE-ε4 allele

2009 ◽  
Vol 106 (17) ◽  
pp. 7209-7214 ◽  
Author(s):  
Nicola Filippini ◽  
Bradley J. MacIntosh ◽  
Morgan G. Hough ◽  
Guy M. Goodwin ◽  
Giovanni B. Frisoni ◽  
...  
Keyword(s):  
Brain Function ◽  
Brain Activity ◽  
Memory Performance ◽  
Blood Oxygen Level Dependent ◽  
Brain Morphology ◽  
Blood Oxygen Level ◽  
Prefrontal Cortical ◽  
Ε4 Allele ◽  
Brain Changes ◽  
Age Range

TheAPOEε4 allele is a risk factor for late-life pathological changes that is also associated with anatomical and functional brain changes in middle-aged and elderly healthy subjects. We investigated structural and functional effects of theAPOEpolymorphism in 18 young healthyAPOEε4-carriers and 18 matched noncarriers (age range: 20–35 years). Brain activity was studied both at rest and during an encoding memory paradigm using blood oxygen level-dependent fMRI. Resting fMRI revealed increased “default mode network” (involving retrosplenial, medial temporal, and medial-prefrontal cortical areas) coactivation in ε4-carriers relative to noncarriers. The encoding task produced greater hippocampal activation in ε4-carriers relative to noncarriers. Neither result could be explained by differences in memory performance, brain morphology, or resting cerebral blood flow. TheAPOEε4 allele modulates brain function decades before any clinical or neurophysiological expression of neurodegenerative processes.

scholarly journals Evaluation of Renal Tissue Oxygenation Using Blood Oxygen Level-Dependent Magnetic Resonance Imaging in Chronic Kidney Disease

2021 ◽  
pp. 1-11
Author(s):  
Fen Chen ◽  
Han Yan ◽  
Fan Yang ◽  
Li Cheng ◽  
Siwei Zhang ◽  
...  
Keyword(s):  
Renal Function ◽  
Tissue Oxygenation ◽  
Blood Oxygen Level Dependent ◽  
Renal Tissue ◽  
Selection Method ◽  
Resonance Imaging ◽  
Blood Oxygen Level ◽  
Bold Mri ◽  
Function Group ◽  
Renal Function Group

<b><i>Background:</i></b> Blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) has been widely used to assess renal oxygenation changes in different kidney diseases in recent years. This study was designed to evaluate and compare renal tissue oxygenation using 2 BOLD-MRI analysis methods, namely, the regional and whole-kidney region of interest (ROI) selection methods. <b><i>Methods:</i></b> The study ended up with 10 healthy controls and 40 chronic kidney disease (CKD) patients without dialysis. Their renal BOLD-MRI data were analyzed using whole-kidney ROI selection method and compared with regional ROI selection method. <b><i>Results:</i></b> We found the cortical, medullary, and whole-kidney R2* values were significantly higher in CKD patients than those in controls. Compared with the regional ROI selection method, the whole-kidney ROI selection method yielded higher cortical R2* values in both controls and CKD patients. The whole-kidney R2* values of deteriorating renal function group were significantly higher than those in stable renal function group. <b><i>Conclusions:</i></b> Cortical and medullary oxygenation was decreased significantly in CKD patients compared with the healthy controls, particularly in the medulla. The whole-kidney R2* values were positively correlated with kidney function and inversely correlated with the estimated glomerular filtration rate and effective renal plasma flow. Whole-Kidney R2* value might effectively predict the progression of renal function in patients with CKD.

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