Auditory event related oscillationd in mild cognitive impairment and its correlation to volumetric magnetic resonance imaging

ABSTRACTBackground: Event-related oscillations (ERO) might be a useful tool for the identification of cognitive deficits. Earlier results showed altered oscillatory responses in Alzheimer?s Disease. The aim of this study was to determine whether it prevails for Mild Cognitive Impairment (MCI) and also whether the auditory oscillatory responses, correlate with volumetric magnetic resonance imaging (vMRI) measurements.Method: Twenty-two consecutive patients with MCI (mean age 74.0 years) and 21 age- and education-matched normal elderly controls (mean age 70.3 years) were participated to the study. The Lesion Annotation and Volume Assessment (LAVA) software was used for volumetric measurments. Auditory oddball paradigm was used in the EEG experiments. The EEG was recorded from F3, Fz, F4, C3, Cz, C4, Tp7, Tp8, P3, Pz, P4, O1, Oz and O2 locations. The maximum peak-to-peak amplitudes for each subject?s averaged oscillatory responses were measured. The ANOVA and pearson correlation were used for statistical analysis.Results: A significant delta peak-to-peak amplitude decrease in MCI group was seen [F(1.41) = 4.84, p = 0.033] for F3, Fz, F4, Cz, C4 and Pz. The results indicate a significant correlation between beta peak-to-peak amplitude at C3 electrode site and left and right hippocampal volume (r = 0.59, p = 0.005); at Tp8 electrode site and left hippocampal volume (r=.465, p=0.034), also significant correlation was found between gamma peak-to-peak amplitude at F3 electrode site and left hippocampal volume (r=.515, p=0.017).Conclusions: Delta oscillatory responses are considered to be related to decision making. ERO can detect early changes in MCI and delta oscillatory responses can be investigated as a candidate biomarker in future studies. The correlation between oscillatory responses and hippocampal volume might reflect the changing dynamics of the brain by aging.Keywords: MCI, Event-Related Oscillations, Delta, Volumetry