Neural correlates of attentive and pre-attentive control in normal aging
Description
This dissertation examined the influence of aging on the neural correlates of specific attentional subsystems employed in spatial auditory controlled and automatic tasks, and their relationships with higher functioning. Additionally, surveys of daily-life cognitive failures and mindfulness were employed to examine associations between labbased measures and daily life functioning.- Methods - Younger and older participants were recruited from Tulane University and the City of New Orleans, respectively. Older subjects demonstrating signs of cognitive decline were excluded. Higher cognition was assessed by a working memory capacity task and daily life functions were assessed using self-report surveys. Simon task enabled study of differences in controlled attention processing by assessing age-related variability between Compatible (ipsilateral) and InCompatible (contralateral) stimulus-response mappings. Mismatch Negativity (MMN) task examined automatic processing and involved passive observation of a silent movie while repeated auditory stimuli with intermittent deviants were presented in the background. EEG measured neural correlates during both tasks. Analysis included repeated measures ANOVAs. - Results - 30 younger (18-25yrs.) and 30 older (65-80yrs.) subjects participated in both Simon and MMN tasks. Older participants demonstrated worse controlled attention (larger Simon effect) versus younger subjects. A significant age-related decrease in the amplitudes of Simon task ERP components and their delay reflected inefficient allocation of auditory spatial attention in older subjects. Frontal Slow Wave in older subjects correlated with response times, indicating compensatory frontal lobe involvement. The automatic ERP component, MMN, reflected automatic detection and was smaller in older subjects in the frequency versus spatial domain. However, both frequency and location P3a components, reflecting automatic orienting towards deviant sounds were attenuated in he elderly. Higher cognition predicted ERP amplitudes of the automatic MMN task in both age groups and mindfulness was negatively correlated with daily life cognitive failures. - Discussion - Our findings suggest age-related compensation and/or attention disengagement, possibly due to reduced frontal involvement as well as a differential age-related effect on automatic processing of auditory location versus frequency in aging. Correlations between mindfulness and automatic ERP components suggest that personality/attitude might influence automatic cognitive processes. The correlations between automatic processes and higher cognition support the need for further research.