Behavioral studies in young adults have shown that working memory capacity (WMC), the ability to maintain and manipulate items in memory, may be associated with individual differences in selective attention. Changes in WMC may also reflect reduced controlled attention and/or increased distractibility observed in aging. Age and individual differences in selective attention may be further modulated by bottom-up manipulations of perceptual load. This project assessed the neural basis of age and individual differences in WMC by measuring auditory (N100) and long-latency (P300, slow wave) event-related potentials (ERPs) associated with selective attention. Young (n=29) and older (n=22) adults with high and lower WMC discriminated pure tone targets (1000 Hz) from nontargets at midline. Perceptual load was manipulated using nontarget frequency (low load=500 Hz, high load=950 Hz). White noise distracters were presented at 0° or +/-90˚. Amplitudes of target-P3b, distracter-N100 and P3a under low load, and nontarget slow wave under high load decreased with age. Latencies of target/nontarget N100 and P3b increased with age under low load. High WMC in young showed enhanced target N100 and nontarget slow wave under high load and reduced distracter N100 amplitude. High vs. lower WMC in older conveyed increasing vs. decreasing P3a latency from Fz to Pz, respectively. High WMC in older also conveyed enhanced slow wave over time. Age differences in controlled attention (N100, P3b) automatic orienting (N100, P3a) and sustained attention (slow wave) were modulated by perceptual load and may reflect changes in underlying neural networks. WMC in young were related to individual differences in early attentional (N100) and sustained (slow wave) processing but not later automatic orienting (P3a) or stimulus classification (P3b). WMC differences in older were shown in early automatic orienting (P3a) and sustained attention (slow wave) / acase@tulane.edu

The brain is composed of multiple systems that interact during cognition and behavior. Concurrently performing two or more tasks that compete for processing from a common system resource typically results in decremented performance, referred to as interference, for one or more of the tasks as compared to single-task performance. This interference is a hallmark of the dual-task experimental design. The purpose of this experiment is to investigate the involvement of cerebellar cortex in trace eyeblink conditioning by utilizing the traditional dual-task design. Timed-interval finger tapping, a motor function mediated by the cerebellar cortex, and several different cognitive tasks representing dissociable distributed brain memory systems were co-administered with trace eyeblink conditioning. If cerebellar cortex is involved in trace eyeblink conditioning, then timed-interval finger tapping should significantly interfere with acquisition rate for conditioned responding. Performance variables from trace eyeblink conditioning were analyzed to investigate interference effects of timed-interval finger tapping and the various cognitive tasks. Results from a series of mixed model repeated measures ANOVAs indicate that the acquisition rate and magnitude of trace conditioning was not significantly reduced in the timed-interval tapping group compared to the control group, although participants did demonstrate evidence of inferior learning. This finding suggests that cerebellar cortex is not critically involved during acquisition of trace conditioning, however it is to be interpreted with caution as methodological and theoretical confounds may preclude a straightforward conclusion. / Psychology

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