Functional and structural correlates of the aging brain: Relating visual cortex (V1) gamma band responses to age‐related structural change

Abstract

The gamma band response is thought to be a key neural signature of information processing in the mammalian brain, yet little is known about how age-related maturation influences the gamma-band response. Recent MRI based studies have shown that brain maturation is accompanied by clear structural changes in both grey and white matter, yet the correspondence of these changes to brain function is unclear. The objective of this study was to relate visual cortex (V1) gamma-band responses to age-related structural change. We evaluated MEG measured gamma-band responses to contrast gratings stimuli and structural MRIs from participants observed from 2 separate research centers (MEG lab at CUBRIC, Cardiff University, UK, and the Lurie Family Foundations MEG Imaging Center, (CHOP) at the Children’s Hospital of Philadelphia). Pooled participant data (N=59) ranged in age from 8.7 to 45.3 yrs. We assessed linear associations between age and MEG gamma-band frequency and amplitude, as well as between age and MRI volumetric parameters of the occipital lobe. Our MEG findings revealed a significant negative correlation for gamma band frequency vs. age. Volumetric brain analysis from the occipital lobe also revealed significant negative correlations between age and the cortical thickness of pericalcarine and cuneus areas. Our functional MEG and structural MRI findings shows regionally specific changes due to maturation and may thus be informative for understanding physiological processes of neural development, maturation, and age-related decline. In addition, this study represents (to our knowledge), the first published demonstration of multi-centre data sharing across MEG centers.

Subjective Size Perception Depends on Central Visual Cortical Magnification in Human V1

“…Age is a determinant of cortical thickness and may be related to changing neurotransmitter levels [21]. However, we found no correlations between the age of participants and illusion strength (small: ρ = 0.08, p = 0.706, [−0.3, 0.46]; large: ρ = 0.17, p = 0.393, [−0.2, 0.54]) or V1 surface area (ρ = −0.13, p = 0.515, [−0.47, 0.32]).…”

Visual stimulus eccentricity affects human gamma peak frequency

“…It appears that each individual's 'baseline' gamma peak frequency is different, but that it is modulated in a similar way by the stimulus properties and task demands outlined above. The inter-individual variability has been related to age (Gaetz et al, 2012), and to differences in properties of the visual cortex, such as the size of area V1 (Schwarzkopf et al, 2012), and occipital GABA-concentration ). Together, this might explain the peak frequency's being under strong genetic control (van Pelt et al, 2012).…”

Significant reductions in human visual gamma frequency by the gaba reuptake inhibitor tiagabine revealed by robust peak frequency estimation

“…Across individuals, peak gamma frequency correlates with psychophysical performance in visual discrimination tasks [Dickinson et al, 2015; Edden et al, 2009]. Inter‐individual differences in frequency appear to be strongly genetically determined [van Pelt et al, 2012], though the individual peak frequency decreases with age [Gaetz et al, 2012; Muthukumaraswamy et al, 2010; Robson et al, 2015]. Nevertheless, peak gamma frequency is highly reproducible over shorter time scales, and thus represents a suitable measure for within‐subject designs [Muthukumaraswamy et al, 2010; Swettenham et al, 2009].…”