Transcranial magnetic stimulation-evoked EEG/cortical potentials in physiological and pathological aging.

The frontal cortex undergoes macrostructural and microstructural changes across the lifespan. These changes can be entirely physiological, such as the ones occurring in elderly individuals who are cognitively intact, or pathological, such as the ones occurring in patients with Alzheimer's disease. Here, we use simultaneous electroencephalography (EEG) and transcranial magnetic stimulation (TMS) to study how the excitability of the frontal cortex changes during healthy and pathological aging. Hence, we compared the TMS-evoked EEG potentials collected in healthy elderly individuals with the ones collected in healthy young individuals, and in patients with Alzheimer's disease. We have shown that the EEG response to TMS of the left superior frontal cortex is not affected by physiological aging but is markedly altered by cognitive impairment.