Partial correlation analysis for functional connectivity studies in cortical networks

AbstractAmblyopia is a prevalent developmental visual disorder of childhood that typically persists in adults. Due to altered visual experience during critical periods of youth, the structure and function of adult visual cortex is abnormal. In addition to substantial deficits shown with task-based fMRI, previous studies have used resting state measures to demonstrate altered long-range connectivity in amblyopia. This is the first study in amblyopia to analyze connectivity between regions of interest that are smaller than a single cortical area and to apply partial correlation analysis to reduce network effects. We specifically assess short-range connectivity between retinotopically defined regions of interest within the occipital lobe of 8 subjects with amblyopia and 7 subjects with normal vision (aged 19-45). The representations of visual areas V1, V2, and V3 within each of the four quadrants of visual space were further subdivided into three regions based on maps of visual field eccentricity. Connectivity between pairs of all nine regions of interest in each quadrant was tested via correlation and partial correlation for both groups. Only the tests of partial correlation, i.e., correlation between time courses of two regions following the regression of time courses from all other regions, yielded significant differences between resting state functional connectivity in amblyopic and normal subjects. Subjects with amblyopia showed significantly higher partial correlation between para-foveal and more eccentric representations within V1, and this effect associated with poor acuity of the worse eye. In addition, we observed reduced correlation in amblyopic subjects between isoeccentricity regions in V1 and V2, and separately, between such regions in V2 and V3. We conclude that partial correlation-based connectivity is altered in an eccentricity-dependent pattern in visual field maps of amblyopic patients. Moreover, results are consistent with known clinical and psychophysical vision loss. More broadly, this provides evidence that abnormal cortical adaptations to disease may be better isolated with tests of partial correlation connectivity than with the regular correlation techniques that are currently widely used.

Download Full-text

Correlating Capsaicinoid Levels and Physicochemical Proper-ties of Kimchi and Its Perceived Spiciness

Foods ◽

10.3390/foods10010086 ◽

2021 ◽

Vol 10 (1) ◽

pp. 86

Author(s):

So-Ra Yoon ◽

Yun-Mi Dang ◽

Su-Yeon Kim ◽

Su-Yeon You ◽

Mina K. Kim ◽

...

Keyword(s):

Correlation Analysis ◽

Physicochemical Properties ◽

Correlation Coefficient ◽

Partial Correlation ◽

Sugar Content ◽

Amino Acid Content ◽

Titratable Acidity ◽

Free Sugar ◽

Partial Correlation Analysis ◽

The Relationship

Capsaicinoid content, among other factors, affects the perception of spiciness of commercial kimchi. Here, we investigated whether the physicochemical properties of kimchi affect the spicy taste of capsaicinoids perceived by the tasting. High-performance liquid chromatography (HPLC) was used to evaluate the capsaicinoid content (mg/kg) of thirteen types of commercial kimchi. The physicochemical properties such as pH, titratable acidity, salinity, free sugar content, and free amino acid content were evaluated, and the spicy strength grade was determined by selected panel to analyze the correlation between these properties. Panels were trained for 48 h prior to actual evaluation by panel leaders trained for over 1000 h according to the SpectrumTM method. Partial correlation analysis was performed to examine other candidate parameters that interfere with the sensory evaluation of spiciness and capsaicinoid content. To express the specific variance after eliminating the effects of other variables, partial correlations were used to estimate the relationships between two variables. We observed a strong correlation between spiciness intensity ratings and capsaicinoid content, with a Pearson’s correlation coefficient of 0.78 at p ≤ 0.001. However, other specific variables may have influenced the relationship between spiciness intensity and total capsaicinoid content. Partial correlation analysis indicated that the free sugar content most strongly affected the relationship between spiciness intensity and capsaicinoid content, showing the largest first-order partial correlation coefficient (rxy/z: 0.091, p ≤ 0.01).

Download Full-text

Temperature Extreme May Exaggerate the Mortality Risk of COVID-19 in the Low- and Middle-income Countries: A Global Analysis

10.20944/preprints202006.0369.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Mizanur Rahman ◽

Mahmuda Islam ◽

Mehedi Hasan Shimanto ◽

Jannatul Ferdous ◽

Abdullah Al-Nur Shanto Rahman ◽

...

Keyword(s):

Correlation Analysis ◽

Partial Correlation ◽

Global Analysis ◽

Temperature Extreme ◽

Spread Rate ◽

Partial Correlation Analysis ◽

Mixed Effect ◽

Middle Income ◽

Middle Income Countries ◽

Low And Middle Income

We performed a global analysis with data from 149 countries to test whether temperature can explain the spatial variability of the spread rate and mortality of COVID-19 at the global scale. We performed partial correlation analysis and linear mixed effect modelling to evaluate the association of the spread rate and motility of COVID-19 with maximum, minimum, average temperatures and temperature extreme (difference between maximum and minimum temperature) and other environmental and socioeconomic parameters. After controlling the effect of the duration after the first positive case, partial correlation analysis revealed that temperature was not related with the spatial variability of the spread rate of COVID-19. Mortality was negatively related with temperature in the countries with high-income economies. In contrast, temperature extreme was significantly and positively correlated with mortality in the low-and middle-income countries. Taking the country heterogeneity into account, mixed effect modelling revealed that inclusion of temperature as a fixed effect in the model significantly improved model skill predicting mortality in the low-and middle-income countries. Our analysis suggest that warm climate may reduce the mortality rate in high-income economies but in low and middle-income countries temperature extreme may increase the mortality risk.

Download Full-text

Use of element-mineral correlations to investigate fractionation of rare earth elements in fine-grained sediments

Mineralogical Magazine ◽

10.1180/minmag.1994.058.393.01 ◽

1994 ◽

Vol 58 (393) ◽

pp. 533-541 ◽

Cited By ~ 1

Author(s):

J. T. Temple ◽

J. N. Walsh

Keyword(s):

Rare Earth ◽

Correlation Analysis ◽

Rare Earth Elements ◽

Partial Correlation ◽

Correlation Coefficients ◽

Partial Correlation Analysis ◽

Middle Ordovician ◽

Fine Grained ◽

South Wales

AbstractRelative concentrations of elements in the minerals of fine-grained sediments can be inferred from element-mineral correlation coefficients. The technique is applied to the distribution of REE in Middle Ordovician shales from South Wales analysed by ICPAES, Leco C/S125 and XRD. Phosphate and chlorite show mid-REE enrichment; muscovite + biotite shows mid-REE depletion. The complementarity of the chlorite and muscovite + biotite patterns may be due to fractionation during diagenetic recrystallisation. Partial correlation analysis is used to infer the presence of zircon.

Download Full-text

0761 Independent Components Analysis And Graph Theoretical Analysis In Patients With Narcolepsy

SLEEP ◽

10.1093/sleep/zsaa056.757 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A289-A289

Author(s):

F Xiao ◽

L Zhao ◽

F Han

Keyword(s):

Functional Connectivity ◽

Partial Correlation ◽

Sleep Latency ◽

Small World ◽

Anterior Cingulate ◽

Healthy Controls ◽

Topological Properties ◽

Partial Correlation Analysis ◽

Brain Areas ◽

Independent Components

Abstract Introduction To evaluate resting state functional connectivity and topological properties of brain network in narcolepsy compared with healthy controls. Methods Resting state fMRI was performed in 26 adult narcolepsy patients and 30 matched healthy controls. MRI data was first analyzed by group independent component analysis, then a graph theoretical method was applied to evaluate topological properties within whole brain. Small-world network parameters and nodal topological properties were measured. Altered topological properties in brain areas between groups were selected as ROI-seeds, then functional connectivity among these ROI-seeds were compared between groups. Partial correlation analysis was performed to evaluate the relationship between sleepiness severity and functional connectivity or topological properties in the narcolepsy. Results 21 independent components out of 48 components were obtained. Compared with healthy controls, narcolepsy exhibited a significant decreased functional connectivity within the executive and salience network, while increased functional connectivity in bilateral frontal lobe within executive network can be detected in narcolepsy. There were no differences in small-world network properties between narcolepsy and healthy controls. The altered brain areas in nodal topological properties were mainly located in inferior frontal cortex, basal ganglia, anterior cingulate, sensory cortex, supplementary motor cortex and visual cortex between groups. In the partial correlation analysis, nodal topological properties in putamen, anterior cingulate and sensory cortex as well as functional connectivity between these brain regions were correlated with the severity of sleepiness (sleep latency, REM sleep latency and ESS) among narcolepsy. Conclusion Altered connectivity within executive network and salience network were found in narcolepsy. Functional connection changes between left frontal cortex and left caudate nucleus may be one of the parameters describing the severity of narcolepsy. Nodal topological properties alterations in left putamen and left posterior cingulate, changes in functional connectivity between left supplementary motor area and right occipital as well as changes in functional connectivity between left anterior cingulate gyrus and bilateral postcentral gyrus can be considered to be a specific indicator for evaluating the severity of narcolepsy. Support National Natural Science Foundation of China (81700088)National Program on Key Basic Research Project of China (973 Program, 2015CB856405)

Download Full-text

Detection of Model Parameter Mismatch Using Simplified Partial Correlation Analysis for Closed-Loop System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.625.398 ◽

2014 ◽

Vol 625 ◽

pp. 398-401

Author(s):

Nur Hidayah Kamal Iqbal ◽

Nooryusmiza Yusoff ◽

Lemma Dendena Tufa

Keyword(s):

Correlation Analysis ◽

Partial Correlation ◽

Closed Loop ◽

Loop System ◽

Model Structure ◽

Closed Loop System ◽

Partial Correlation Analysis ◽

Parameter Mismatch ◽

Arx Model ◽

Model Parameter

Partial correlation analysis is used in detecting the model-plant mismatch as it will give accurate location of mismatched submodel. In this work of model parameter mismatch detection in closed-loop system, a simplified method of partial correlation analysis is proposed. In this method, the identification step for input sensitivities relating setpoints and manipulated variables,Sru, is omitted due the ability of ARX model structure to capture the dynamic of the input-output data even though in the presence of unmeasured disturbance in closed-loop system. The ARX model structure is implemented in decorrelating the observed data from the correlated inputs. By using the ARX model, the mismatch is detected at the precise location compared to the detection using FIR decorrelation model.

Download Full-text