Both healthy and pathological aging entail some degree of cognitive and neural decline. Executive functions appear to be particularly affected by aging (Hasher &Zacks, 1988). Executive function has traditionally been associated most strongly with the prefrontal cortex (PFC), but recent research has shown that interactions between PFC and sensory association cortex also play an important role in executive processes. The broad objective of this proposal is to shed further light on how top-down executive processes affect activity in category-selective extrastriate (CSE) cortex, developing paradigms first in healthy young adults and then using them to study these processes'decline in older adults.
Specific Aim #1 : Examine mechanisms by which top-down processes suppress as well as enhance percepts and representations in young adults. Two functional magnetic resonance imaging (fMRI) studies will examine how perceptual and reflective attention processes act to suppress activity in CSE cortex related to non-attended stimuli.
This aim has particular relevance to the mission of the NIA as recent studies have shown specific deficits in top-down suppression in older adults (Gazzaley et al., 2005), but relatively little is known about the specific mechanisms underlying such suppression, especially for reflective attention.
Specific Aim #2 : Analyze the information content of activity in CSE cortex caused by reflective processing. It is thought that activity in CSE cortex induced by reflective processes (e.g., working memory, mental imagery) represents information about the specific item in mind, but there is relatively little evidence for this in the literature. This fMRI experiment is aimed at decoding item information in CSE cortex during mental imagery. Future studies will then examine how information representation differs in young and older adults. This research is designed to further our knowledge of how the human brain performs high-level cognitive operations, collectively called """"""""executive functions,"""""""" which are known to be particularly susceptible to the cognitive decline that occurs in both healthy and pathological aging. The research plan includes three brain imaging experiments aimed at determining how several simple executive operations affect activity in areas of the brain involved in processing visual information. The ultimate goal is to compare the brain activity of younger adults to older adults while performing different types of executive functions in order to study how these processes deteriorate as people age.
| Johnson, Matthew R; McCarthy, Gregory; Muller, Kathleen A et al. (2015) Electrophysiological Correlates of Refreshing: Event-related Potentials Associated with Directing Reflective Attention to Face, Scene, or Word Representations. J Cogn Neurosci 27:1823-39 |
| Johnson, Matthew R; Higgins, Julie A; Norman, Kenneth A et al. (2013) Foraging for thought: an inhibition-of-return-like effect resulting from directing attention within working memory. Psychol Sci 24:1104-12 |
