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With the aim of identifying event-related potential (ERP) correlates of the tip-of-the-tongue (TOT) state, we employed a task involving identification and naming of the faces of famous people with three response categories: KNOW (correct naming), DON'T KNOW (name not known), and TOT. Before 450 ms, no differences are observed between TOT and KNOW conditions in ERPs related to face processing and recognition. The smaller mean amplitude in TOT than in KNOW responses over the 550-750-ms interval and the N-TOT difference wave are correlates of the onset of the TOT state, probably reflecting a division of processing resources and low activation of the lexical-phonological route. The smaller amplitude of a late negative wave (between 1350 and 1550 ms) in TOT than in DON'T KNOW responses, and the P-TOT difference wave, seem to indicate that an important amount of processing resources is engaged in resolving the TOT.

The first aim of this study was to explore the relation between cognitive reserve, age, and neuropsychological functioning in a healthy sample; and second, to determine the risk of showing cognitive deficits as a function of cognitive reserve. One hundred forty-six healthy participants between the ages of 20 and 79 were submitted to neuropsychological assessment, focusing on attention, memory, visuo-construction, conceptualization and reasoning. Premorbid IQ as measured with the Wechsler Adult Intelligence Scale Vocabulary subtest was used as a proxy of cognitive reserve. Multivariate regression analysis with age and premorbid IQ as explanatory factors revealed a significant effect in all neuropsychological tests. Logistic regression revealed that participants with low cognitive reserve were more likely to obtain deficient scores (< or =1.5 SD below the mean) in the cognitive domains of attention (odds ratio [OR], 3.13; 95% confidence interval [CI], 1.059.29), memory (OR, 6.17; 95% CI, 1.69-22.61) and global functioning (OR, 6.44; 95% CI, 2.56-16.22) than participants with high cognitive reserve. Results suggest that cognitive reserve acts as a protective factor against the expression of cognitive decline related to age in healthy individuals.

Working memory (WM) involves three cognitive events: information encoding, maintenance, and retrieval; these are supported by brain activity in a network of frontal, parietal and temporal regions. Manipulation of WM load and duration of the maintenance period can modulate this activity. Although such modulations have been widely studied using the event-related potentials (ERP) technique, a precise description of the time course of brain activity during encoding and retrieval is still required. Here, we used this technique and principal component analysis to assess the time course of brain activity during encoding and retrieval in a delayed match to sample task. We also investigated the effects of memory load and duration of the maintenance period on ERP activity. Brain activity was similar during information encoding and retrieval and comprised six temporal factors, which closely matched the latency and scalp distribution of some ERP components: P1, N1, P2, N2, P300, and a slow wave. Changes in memory load modulated task performance and yielded variations in frontal lobe activation. Moreover, the P300 amplitude was smaller in the high than in the low load condition during encoding and retrieval. Conversely, the slow wave amplitude was higher in the high than in the low load condition during encoding, and the same was true for the N2 amplitude during retrieval. Thus, during encoding, memory load appears to modulate the processing resources for context updating and post-categorization processes, and during retrieval it modulates resources for stimulus classification and context updating. Besides, despite the lack of differences in task performance related to duration of the maintenance period, larger N2 amplitude and stronger activation of the left temporal lobe after long than after short maintenance periods were found during information retrieval. Thus, results regarding the duration of maintenance period were complex, and future work is required to test the time-based decay theory predictions.

It has been suggested that changes in some event-related potential (ERP) parameters associated with controlled processing of stimuli could be used as biomarkers of amnestic mild cognitive impairment (aMCI). However, data regarding the suitability of ERP components associated with automatic and involuntary processing of stimuli for this purpose are not conclusive. In the present study, we studied the Mismatch Negativity (MMN) component, a correlate of the automatic detection of changes in the acoustic environment, in healthy adults and adults with aMCI (age range: 50–87 years). An auditory-visual attention-distraction task, in two evaluations separated by an interval of between 18 and 24 months, was used. In both evaluations, the MMN amplitude was significantly smaller in the aMCI adults than in the control adults. In the first evaluation, such differences were observed for the subgroup of adults between 50 and 64 years of age, but not for the subgroup of 65 years and over. In the aMCI adults, the MMN amplitude was significantly smaller in the second evaluation than in the first evaluation, but no significant changes were observed in the control adult group. The MMN amplitude was found to be a sensitive and specific biomarker of aMCI, in both the first and second evaluation.

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Although many studies have demonstrated decline in attention and executive function (especially in inhibitory control) in healthy aging and Alzheimer's disease (AD), similar studies concerning mild cognitive impairment (MCI) are scarce. In the present study, we evaluated how the cognitive decline associated with amnestic MCI (aMCI) affects these processes, analyzing the N2 and P3 components of event-related potentials (ERPs) during the response (Go) and inhibition of response (NoGo) to different stimuli. ERPs were analyzed in 63 healthy and 30 aMCI adults (aged 50 to 87 years) during performance of a Go/NoGo auditory-visual attention-distraction task. aMCI adults showed poorer execution (longer response times and fewer correct responses) and smaller Go-N2 and NoGo-N2 amplitudes than control adults, whereas P3 amplitudes and N2 and P3 latencies did not differ between the groups. These results show that aMCI is associated with decline in executive function and stimuli evaluation in working memory.

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