Relation between cortical thickness and frontal lobe P50 response in neurotypical aging: MEG study

Abstract

AbstractBackgroundThe auditory Event Related Potential (ERP) with latency at peak at 50 ms is a potential biomarker of prodromal Alzheimer’s disease (AD). However, the relation between P50 ERP and the thickness of the gray matter over frontal brain regions in healthy individuals over 55 y.o is not well studied. We examined the relation between frontal lobe generator of auditory P50 and degree of the gray matter volume lost in healthy individuals. We hypothesized that reduced thickness in the cingulate cortex is associated with aberrant function of the frontal lobe generator of the P50 response.MethodSeven healthy subjects (ages 58‐72 years, 4 women) participated in the ongoing study. P50 response was calculated from magnetoencephalographic and electroencephalographic data during presentation of 7 tones (30 ms duration) ranging from 500 to 986 Hz. Each tone was preceded by 850 ms period of silence. Free‐surfer computed the cortical thickness for each subject as the distance between the gray/white matter boundary and the pial surface for each pair of vertices. 110 T1‐MPRAGE scans of elderly healthy controls (over 65 yo) from a Neurocognitive aging dataset were used as an average‐control group. To calculate the difference in thickness between averaged control and individual subject, the z‐value was applied. The template of 110‐averaged data was transformed into the subject’s space, and for each vertices we subtracted the mean and divide by the standard deviationResultIn this study we show, that in subjects with less thickness in the cingulate cortex the amplitude of P50 response was enhanced with respect to those subjects who had more cortical thickness (Z value >5 vs. Z value <2). The aberrant function of the frontal lobe generator of P50 response was associated with enchanted amplitude of the P50 in MEG and EEG data.ConclusionOur results suggest that age‐related deficiency in frontal lobe generators of auditory P50 in healthy aging participants is associated with a reduction of gray matter volume in cingulate cortex. Present results support the notion about age‐related changes in modulatory role of frontal lobe generator of auditory P50 that are located at the cingulate cortex.