Electrical signals recorded from the brain often show fluctuations between 30-80 Hz, which is called the gamma rhythm. These can be induced by simply viewing images with black and white patterns, called gratings. We recorded brain signals using a non-invasive technique called electroencephalogram (EEG) from ~250 elderly subjects while they viewed gratings, and found that even in healthy subjects, gamma waves weaken with age (Murty et al., 2020). Interestingly, in a subset of subjects with Mild Cognitive Impairment (MCI) or early Alzheimer’s Disease (AD), these waves were substantially weaker than their age matched peers (Murty et al., 2021).

Faculty: Supratim Ray, CNS

References:

Murty DVPS, Manikandan K, Kumar WS, Ramesh RG, Purokayastha S, Nagendra B, Abhishek ML, Balakrishnan A, Javali M, Rao NP and Ray S^† (2021). Stimulus-induced Gamma rhythms are weaker in human elderly with Mild Cognitive Impairment and Alzheimer’s Disease. eLife. 10:e61666 DOI: 10.7554/eLife.61666

Murty DVPS, Manikandan K, Kumar WS, Ramesh RG, Purokayastha S, Javali M, Rao NP and Ray S^† (2020) Gamma oscillations weaken with age in healthy elderly in human EEG. Neuroimage. Vol 215, Article 116826