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The effects of aging on the brain activation pattern during a speech perception task: an fMRI study

Manan HA, Franz EA, Yusoff AN, Mukari SZ

Aging Clin Exp Res, 2015 Feb;27(1):27-36.
PMID: 24906677 DOI: 10.1007/s40520-014-0240-0

In the present study, brain activation associated with speech perception processing was examined across four groups of adult participants with age ranges between 20 and 65 years, using functional MRI (fMRI). Cognitive performance demonstrates that performance accuracy declines with age. fMRI results reveal that all four groups of participants activated the same brain areas. The same brain activation pattern was found in all activated areas (except for the right superior temporal gyrus and right middle temporal gyrus); brain activity was increased from group 1 (20-29 years) to group 2 (30-39 years). However, it decreased in group 3 (40-49 years) with further decreases in group 4 participants (50-65 years). Result also reveals that three brain areas (superior temporal gyrus, Heschl's gyrus and cerebellum) showed changes in brain laterality in the older participants, akin to a shift from left-lateralized to right-lateralized activity. The onset of this change was different across brain areas. Based on these findings we suggest that, whereas all four groups of participants used the same areas in processing, the engagement and recruitment of those areas differ with age as the brain grows older. Findings are discussed in the context of corroborating evidence of neural changes with age.
Fulltext Effective connectivity between superior temporal gyrus and Heschl's gyrus during white noise listening: linear versus non-linear models

Hamid K, Yusoff A, Rahman M, Mohamad M, Hamid A

Biomed Imaging Interv J, 2012 Apr;8(2):e13.
PMID: 22970069 MyJurnal DOI: 10.2349/biij.8.2.e13

This fMRI study is about modelling the effective connectivity between Heschl's gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. MATERIALS #ENTITYSTARTX00026;
Fulltext Early and Late Shift of Brain Laterality in STG, HG, and Cerebellum with Normal Aging during a Short-Term Memory Task

Abdul Manan H, Yusoff AN, Franz EA, Sarah Mukari SZ

ISRN Neurol, 2013;2013:892072.
PMID: 23533806 DOI: 10.1155/2013/892072

Evidence suggests that cognitive performance deteriorates in noisy backgrounds and the problems are more pronounced in older people due to brain deficits and changes. The present study used functional MRI (fMRI) to investigate the neural correlates of this phenomenon during short-term memory using a forward repeat task performed in quiet (STMQ) and in noise: 5-dB SNR (STMN) on four groups of participants of different ages. The performance of short-term memory tasks was measured behaviourally. No significant difference was found across age groups in STMQ. However, older adults (50-65 year olds) performed relatively poorly on the STMN. fMRI results on the laterality index indicate changes in hemispheric laterality in the superior temporal gyrus (STG), Heschl's gyrus (HG), and cerebellum, and a leftward asymmetry in younger participants which changes to a more rightward asymmetry in older participants. The results also indicate that the onset of the laterality shift varies from one brain region to another. STG and HG show a late shift while the cerebellum shows an earlier shift. The results also reveal that noise influences this shifting. Finally, the results support the hypothesis that functional networks that underlie STG, HG, and cerebellum undergo reorganization to compensate for the neural deficit/cognitive decline.
Hemispheric Lateralization of Auditory Working Memory Regions During Stochastic Resonance: An fMRI Study

Othman EA, Yusoff AN, Mohamad M, Abdul Manan H, Abd Hamid AI, Giampietro V

J Magn Reson Imaging, 2020 06;51(6):1821-1828.
PMID: 31794119 DOI: 10.1002/jmri.27016

BACKGROUND: The auditory and prefrontal cortex supports auditory working memory processing. Many neuroimaging studies have shown hemispheric lateralization of auditory working memory brain regions in the presence of background noise, but few studies have focused on the lateralization of these regions during stochastic resonance.
PURPOSE: To investigate the effects of stochastic resonance on lateralization of auditory working memory regions, and also to examine the brain-behavior relationship during stochastic resonance.
STUDY TYPE: Cross-sectional.
POPULATION/SUBJECTS: Forty healthy young adults (18-24 years old).
FIELD STRENGTH/SEQUENCE: 3.0T, T1 , and T2 *-weighted imaging.
ASSESSMENT: The auditory working memory performance was assessed using a backward recall task. Functional magnetic resonance imaging (fMRI) was used to measure brain activity during task performance. Functional MRI data were analyzed using SPM12 and WFU PickAtlas.
STATISTICAL TESTS: One-way independent analyses of variance (ANOVA) were conducted on the behavioral and functional data to examine the main effect of noise level on performance (P
Effects of white noise on word recall performance and brain activity in healthy adolescents with normal and low auditory working memory

Othman E, Yusoff AN, Mohamad M, Abdul Manan H, Abd Hamid AI, Giampietro V

Exp Brain Res, 2020 Apr;238(4):945-956.
PMID: 32179941 DOI: 10.1007/s00221-020-05765-3

The present study examined the impact of white noise on word recall performance and brain activity in 40 healthy adolescents, split in two groups (normal and low) depending on their auditory working memory capacity (AWMC). Using functional magnetic resonance imaging, participants performed a backward recall task under four different signal-to-noise ratio (SNR) conditions: 15, 10, 5, and 0-dB SNR. Behaviorally, normal AWMC individuals scored significantly higher than low AWMC individuals across noise levels. Whole-brain analyses showed brain activation not to be statistically different between groups across noise levels. In the normal group, a significant positive relationship was found between performance and number of activated voxels in the right superior frontal gyrus. In the low group, significant positive correlations were found between performance and number of activated voxels in left superior frontal gyrus, left inferior frontal gyrus, and left anterior cingulate cortex. These findings suggest that the strategic structure involved in the enhancement of AWM performance may differ in normal and low AWMC individuals.
Is Diagnostic Performance of Quantitative 2D-Shear Wave Elastography Optimal for Clinical Classification of Benign and Malignant Thyroid Nodules?: A Systematic Review and Meta-analysis

Nattabi HA, Sharif NM, Yahya N, Ahmad R, Mohamad M, Zaki FM, et al.

Acad Radiol, 2017 Oct 18.
PMID: 29054676 DOI: 10.1016/j.acra.2017.09.002

RATIONALE AND OBJECTIVE: This study is a dedicated 2D-shear wave elastography (2D-SWE) review aimed at systematically eliciting up-to-date evidence of its clinical value in differential diagnosis of benign and malignant thyroid nodules.
METHODS: PubMed, Web of Science, and Scopus databases were searched for studies assessing the diagnostic value of 2D-SWE for thyroid malignancy risk stratification published until December 2016. The retrieved titles and abstracts were screened and evaluated according to the predefined inclusion and exclusion criteria. Methodological quality of the studies was assessed using the Quality Assessment of Studies of Diagnostic Accuracy included in Systematic Review 2 (QUADAS-2) tool. Extracted 2D-SWE diagnostic performance data were meta-analyzed to assess the summary sensitivity, specificity, and area under the receiver operating characteristic curve.
RESULTS: After stepwise review, 14 studies in which 2D-SWE was used to evaluate 2851 thyroid nodules (1092 malignant, 1759 benign) from 2139 patients were selected for the current study. Study quality on QUADAS-2 assessment was moderate to high. The summary sensitivity, specificity and area under the receiver operating characteristic curve of 2D-SWE for differential diagnosis of benign and malignant thyroid nodules were 0.66 (95% confidence interval [CI]: 0.64-0.69), 0.78 (CI: 0.76-0.80), and 0.851 (Q* = 0.85), respectively. The pooled diagnostic odds ratio, negative likelihood ratio, and positive likelihood ratio were 12.73 (CI: 8.80-18.43), 0.31 (CI: 0.22-0.44), and 3.87 (CI: 2.83-5.29), respectively.
CONCLUSION: Diagnostic performance of quantitative 2D-SWE for malignancy risk stratification of thyroid nodules is suboptimal with mediocre sensitivity and specificity, contrary to earlier reports of excellence.
Fulltext Brain Activation during Addition and Subtraction Tasks In-Noise and In-Quiet

Abd Hamid AI, Yusoff AN, Mukari SZ, Mohamad M

Malays J Med Sci, 2011 Apr;18(2):3-15.
PMID: 22135581 MyJurnal

In spite of extensive research conducted to study how human brain works, little is known about a special function of the brain that stores and manipulates information-the working memory-and how noise influences this special ability. In this study, Functional magnetic resonance imaging (fMRI) was used to investigate brain responses to arithmetic problems solved in noisy and quiet backgrounds.
Fulltext Multiparametric MRI for the improved diagnostic accuracy of Alzheimer's disease and mild cognitive impairment: Research protocol of a case-control study design

Piersson AD, Ibrahim B, Suppiah S, Mohamad M, Hassan HA, Omar NF, et al.

PLoS One, 2021;16(9):e0252883.
PMID: 34547018 DOI: 10.1371/journal.pone.0252883

BACKGROUND: Alzheimer's disease (AD) is a major neurocognitive disorder identified by memory loss and a significant cognitive decline based on previous level of performance in one or more cognitive domains that interferes in the independence of everyday activities. The accuracy of imaging helps to identify the neuropathological features that differentiate AD from its common precursor, mild cognitive impairment (MCI). Identification of early signs will aid in risk stratification of disease and ensures proper management is instituted to reduce the morbidity and mortality associated with AD. Magnetic resonance imaging (MRI) using structural MRI (sMRI), functional MRI (fMRI), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (1H-MRS) performed alone is inadequate. Thus, the combination of multiparametric MRI is proposed to increase the accuracy of diagnosing MCI and AD when compared to elderly healthy controls.
METHODS: This protocol describes a non-interventional case control study. The AD and MCI patients and the healthy elderly controls will undergo multi-parametric MRI. The protocol consists of sMRI, fMRI, DTI, and single-voxel proton MRS sequences. An eco-planar imaging (EPI) will be used to perform resting-state fMRI sequence. The structural images will be analysed using Computational Anatomy Toolbox-12, functional images will be analysed using Statistical Parametric Mapping-12, DPABI (Data Processing & Analysis for Brain Imaging), and Conn software, while DTI and 1H-MRS will be analysed using the FSL (FMRIB's Software Library) and Tarquin respectively. Correlation of the MRI results and the data acquired from the APOE genotyping, neuropsychological evaluations (i.e. Montreal Cognitive Assessment [MoCA], and Mini-Mental State Examination [MMSE] scores) will be performed. The imaging results will also be correlated with the sociodemographic factors. The diagnosis of AD and MCI will be standardized and based on the DSM-5 criteria and the neuropsychological scores.
DISCUSSION: The combination of sMRI, fMRI, DTI, and MRS sequences can provide information on the anatomical and functional changes in the brain such as regional grey matter volume atrophy, impaired functional connectivity among brain regions, and decreased metabolite levels specifically at the posterior cingulate cortex/precuneus. The combination of multiparametric MRI sequences can be used to stratify the management of MCI and AD patients. Accurate imaging can decide on the frequency of follow-up at memory clinics and select classifiers for machine learning that may aid in the disease identification and prognostication. Reliable and consistent quantification, using standardised protocols, are crucial to establish an optimal diagnostic capability in the early detection of Alzheimer's disease.
Fulltext Low intensity white noise improves performance in auditory working memory task: An fMRI study

Othman E, Yusoff AN, Mohamad M, Abdul Manan H, Giampietro V, Abd Hamid AI, et al.

Heliyon, 2019 Sep;5(9):e02444.
PMID: 31687551 DOI: 10.1016/j.heliyon.2019.e02444

Research suggests that white noise may facilitate auditory working memory performance via stochastic resonance. Stochastic resonance is quantified by plotting cognitive performance as a function of noise intensity. The plot would appear as an inverted U-curve, that is, a moderate noise is beneficial for performance whereas too low and too much noise attenuates performance. However, knowledge about the optimal signal-to-noise ratio (SNR) needed for stochastic resonance to occur in the brain, particularly in the neural network of auditory working memory, is limited and demand further investigation. In the present study, we extended previous works on the impact of white noise on auditory working memory performance by including multiple background noise levels to map out the inverted U-curve for the stochastic resonance. Using functional magnetic resonance imaging (fMRI), twenty healthy young adults performed a word-based backward recall span task under four signal-to-noise ratio conditions: 15, 10, 5, and 0-dB SNR. Group results show significant behavioral improvement and increased activation in frontal cortices, primary auditory cortices, and anterior cingulate cortex in all noise conditions, except at 0-dB SNR, which decreases activation and performance. When plotted as a function of signal-to-noise ratio, behavioral and fMRI data exhibited a noise-benefit inverted U-shaped curve. Additionally, a significant positive correlation was found between the activity of the right superior frontal gyrus (SFG) and performance in 5-dB SNR. The predicted phenomenon of SR on auditory working memory performance is confirmed. Findings from this study suggest that the optimal signal-to-noise ratio to enhance auditory working memory performance is within 10 to 5-dB SNR and that the right SFG may be a strategic structure involved in enhancement of auditory working memory performance.