Altered Cortical Thicknesses of Left Pars Opercularis and Left Lateral Occipital Gyrus Can Be Associated with Psychotic Symptoms in Patients with Alzheimer's Disease

OBJECTIVE: The aims of this study was to present an association between the presence of psychotic symptoms and cortical thicknesses/subcortical volumes in patients with Alzheimer's disease (AD). METHODS: Fourteen AD patients with psychotic symptoms and 41 without psychotic symptoms underwent 3T MRI scanning. After adjusting the effects of confounding variables, the cortical thicknesses were compared between the AD patients with and without psychotic symptoms in multiple regions, across the continuous cortical surface. In addition, the subcortical volumes were compared with a structure-by-structure manner. RESULTS: AD patients with psychotic symptoms were characterized by significant smaller cortical thickness of left pars opercularis (F=4.67, p=0.02) and left lateral occipital gyrus (F=6.05, p=0.04) rather than those without psychotic symptoms, after adjusting the effects of age and scores on the Stroop test, non-psychotic items of Neuropsychiatry Inventory and Clinical Dementia Rating, triglyceride level and total intracranial volume. However, there were no significant differences in the subcortical volume between the two groups. CONCLUSION: These results suggest that AD psychosis may reflect more severe deterioration of neuropathologic change in specific brain region.

Brain Activation Due to Various Visual Stimuli: A Pilot Study using Fixed-effects Analysis on Healthy Participants / Jurnal Sains Kesihatan Malaysia

Ocular abnormalities have apparent effects on brain activation. However, neuroimaging data about the ocular characteristics of healthy participants are still lacking to be compared with data for patients with ocular pathology. The objective of this multiple participants’ functional magnetic resonance imaging (fMRI) studies was to investigate the brain activation characteristics of healthy participants when they view stimuli of various shapes, pattern and size. During the fMRI scans, the participants view the growing ring, rotating wedge, fl ipping hour glass/bow tie, quadrant arc and full checker board stimuli. All stimuli have elements of black-and-white checkerboard pattern. Statistical parametric mapping (SPM) was used in generating brain activation via fi xed-effects (FFX) and conjunction analyses. The stimuli of various shapes, pattern and size produce different brain activation with more activation concentrated in the left hemisphere. These results are supported by the conjunction analysis which indicated that the left pre-central, post-central, superior temporal and occipital gyrus as well as the left cingulate cortices were involved when the participants viewed each given stimulus. Differential activation analysis showed activation with high specifi city in the occipital region due to the stimuli of various shapes, pattern and size. The activation in the right middle temporal gyrus was found to be signifi cantly higher in response to moving stimuli as compared to stationary stimuli. This confi rms the involvement of the right middle temporal gyrus in the observation of movements. The black-and-white checkerboard stimuli of various shapes, pattern and size, stationary and moving was found to 1) activate visual as well as other cortices in temporal and parietal lobes, 2) cause asymmetry in brain function and 3) exhibit functional integration characteristics in several brain areas.

Region-wise gray matter volume alterations in brain of adolescents with attention deficit hyperactive disorder : A voxel based morphometric analysis.

Attention Deficit Hyperactive Disorder (ADHD) is a behavioral neuropsychiatric disorder affecting an estimated 5% of school-age children worldwide with symptoms persisting into adulthood in 80% of cases. Presently clinical diagnosis and treatment of ADHD relies on behavioral disturbances than on detecting underlying defective brain regions. Therapeutic outcome in treatment of ADHD may be more positive if defective brain region in clinically diagnosed ADHD is detected by voxel based morphometric (VBM) analysis that measures voxel-wise global and regional focal volume differences in structural magnetic resonance images (sMRI) of brain. This study was designed to detect any region-specific gray matter (GM) volume defects in sMRI of ADHD adolescents by VBM analysis. Thirty sMRI datasets matched for sex, handedness of adolescents aged between 11.66 and 20.47 years (mean age 16.27±2.48 years) obtained from NeuroImage webpage, were selected (Control n=15; ADHD combined type n=15). These sMRI were analyzed by VBM technique and compared using statistical parametric mapping (SPM). Significant regional GM volume deficits (P<0.05) was specifically identified in left cuneus and middle occipital gyrus in ADHD, after voxel-wise false discovery rate correction over the whole brain compared to matched controls. Deficit of GM volume in occipital cortex detected by VBM analysis in ADHD children, suggests defects of visual processing affecting attention mechanisms.