Do the Changes of Event-Related Potentials and Frequency Band Responses to Sensory Stimuli Correlate to Age Cognitive Decline?

Abstract

Cognitive decline and symptoms of attention deficits, executive dysfunction, and memory impairments describe dementia in the elderly. This review focuses on particular frequency oscillations that occur within the affected brain regions which could be used to classify some idiopathic dementias as specific diseases and could contribute additional information to the clinical data in evaluating age changes that are of benefit for a treatment of cognitive alterations. The main question, whether the changes of event-related potentials (ERPs) and frequency band responses (ERBRs) for sensory stimuli are related to plasticity in neural recruitment during stabilization of sensory/cognitive mechanisms accompanying aging or are underlying pathological changes, remains unknown. We review the effect of aging on low (δ, θ, α) and high (β1, β2, γ1, γ2) ERBRs in an auditory discrimination sensorimotor tasks (low–frequency – right hand movement, high–frequency tone – left movement) at frontal, central, parietal and occipital cortical locations at short latency (post–stimulus interval 0–250 ms; putative sensory processing period) and long latency (250–600 ms; putative cognitive period). High tone stimulation and movement requirements lead to a delay of ERP components in elderly subjects and their amplitudes diminish with increasing age. The amplitudes of β2, γ, and low-frequency activity are more pronounced with progressive age, but the β1 component is less affected by age during the sensory processing. The age difference with respect to scalp distribution is tone-independent for δ/θ, but not for α-activity. Age- and tone-dependent α-changes are focused on frontal and sensorimotor areas. The low- and high-frequency amplitudes during the cognitive processing diminish with increasing age, except for the frontal β2 and γ high tone responses, while the β1 activity is more widespread than in the shorter latency period. This age difference increases in fronto–parietal direction more expressed after high tone stimulation. The age influences more the cognitive processes than the sensory ones.