Commentary: Modulation of Prepulse Inhibition and Startle Reflex by Emotions: A Comparison between Young and Older Adults

The emotion paradox in the aging body and brain

With age, parasympathetic activity decreases, while sympathetic activity increases. Thus, the typical older adult has low heart rate variability (HRV) and high noradrenaline levels. Younger adults with this physiological profile tend to be unhappy and stressed. Yet, with age, emotional experience tends to improve. Why does older adults' emotional well-being not suffer as their HRV decreases? To address this apparent paradox, I present the autonomic compensation model. In this model, failing organs, the initial phases of Alzheimer's pathology, and other age-related diseases trigger noradrenergic hyperactivity. To compensate, older brains increase autonomic regulatory activity in the pregenual prefrontal cortex (PFC). Age-related declines in nerve conduction reduce the ability of the pregenual PFC to reduce hyperactive noradrenergic activity and increase peripheral HRV. But these pregenual PFC autonomic compensation efforts have a significant impact in the brain, where they bias processing in favor of stimuli that tend to increase parasympathetic activity (e.g., stimuli that increase feelings of safety) and against stimuli that tend to increase sympathetic activity (e.g., threatening stimuli). In summary, the autonomic compensation model posits that age-related chronic sympathetic/noradrenergic hyperactivity stimulates regulatory attempts that have the side effect of enhancing emotional well-being.

Age differences in emotion-induced blindness: Positivity effects in early attention

Compared with younger adults, older adults tend to favor positive information more than negative information in their attention and memory. This "positivity effect" has been observed in various paradigms, but at which stage it impacts cognitive processing and how it influences processing other stimuli appearing around the same time remains unclear. Across 4 experiments, we examined how older adults prioritize emotional information in early attention. Both younger and older adults demonstrated emotion-induced blindness-identifying targets in a rapid serial display of pictures with less accuracy after emotional compared with neutral distractors-but older adults demonstrated a positivity bias at this early attentional level. Moreover, the bias toward positive but not negative information in older adults was reduced when they had a working memory load. These results suggest that a selective bias toward positive, but not negative, information occurs early in visual processing, and the bias relies on cognitive control resources. (PsycInfo Database Record (c) 2020 APA, all rights reserved).