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Alzheimer’s Disease (AD) has become a major health issue in recent decades, and there is now growing interest in amnestic mild cognitive impairment (aMCI), an intermediate stage between healthy aging and dementia, usually AD. Event-related brain potential (ERP) studies have sometimes failed to detect differences between aMCI and control participants in the Go-P3 (or P3b, related to target classification processes in a variety of tasks) and NoGo-P3 (related to response inhibition processes, mainly in Go/NoGo tasks) ERP components. The aim of the present study was to evaluate whether the age factor, which is not usually taken into account in ERP studies, modulates group differences in these components. With this aim, we divided two groups of volunteer participants, 34 subjects with aMCI (51–87 years) and 31 controls (52–86 years), into two age subgroups: 69 years or less and 70 years or more. We recorded brain activity while the participants performed a distraction-attention auditory-visual (AV) task. Task performance was poorer in the older than in the younger group, and aMCI participants produced fewer correct responses than the matched controls; but no interactions of the age and group factors on performance were found. On the other hand, Go-P3 and NoGo-N2 latencies were longer in aMCI participants than in controls only in the younger subgroup. Thus, the younger aMCI participants categorized the Go stimuli in working memory and processed the NoGo stimuli (which required response inhibition) slower than the corresponding controls. Finally, the combination of the number of hits, Go-P3 latency and NoGo-N2 latency yielded acceptable sensitivity and specificity scores (0.70 and 0.92, respectively) as regards distinguishing aMCI participants aged 69 years or less from the age-matched controls. The findings indicate age should be taken into account in the search for aMCI biomarkers This study was supported by grants from the Spanish Government, Ministerio de Economía y Competitividad (PSI2014-55316-C3-3-R; PSI2017-89389-C2-2-R), with FEDER Funds; the Galician Government, Consellería de Cultura, Educación e Ordenación Universitaria, Axudas para a Consolidación e Estruturación de Unidades de Investigación Competitivas do Sistema Universitario de Galicia: GRC (GI-1807-USC); Ref: ED431-2017/27, with FEDER funds SI

In the present study we used the event-related brain potentials (ERP) technique and eLORETA (exact low-resolution electromagnetic tomography) method in order to characterize and compare the performance and the spatiotemporal pattern of the brain electrical activity related to the immediate episodic retrieval of information (words) that is being learned relative to delayed episodic retrieval twenty-minutes later. For this purpose, 16 young participants carried out an old/new word recognition task with source memory (word colour). The task included an immediate memory phase (with three study-test blocks) followed (20 min later) by a delayed memory phase with one test block. The behavioural data showed progressive learning and consolidation of the information (old words) during the immediate memory phase. The ERP data to correctly identified old words for which the colour was subsequently recollected (H/H) compared to the correctly rejected new words (CR) showed: (1) a significant more positive-going potential in the 500–675 ms post-stimulus interval (parietal old/new effect, related to recollection), and (2) a more negative-going potential in the 950–1850 ms interval (LPN effect, related to retrieval and post-retrieval processes). The eLORETA data also revealed that the successful recognition of old words (and probably retrieval of their colour) was accompanied by activation of (1) left medial temporal (parahippocampal gyrus) and parietal regions involved in the recollection in both memory phases, and (2) prefrontal regions and the superior temporal gyrus (in the immediate and delayed memory phases respectively) involved in monitoring, evaluating and maintaining the retrieval products. These findings indicate that episodic memory retrieval depends on a network involving medial temporal lobe and frontal, parietal and temporal neocortical structures. That network was involved in immediate and delayed memory retrieval and during the course of memory consolidation, with greater activation of some nodes (mobilization of more processing resources) for the delayed respect to the immediate retrieval condition This study was supported by grants from the Spanish Government, Ministerio de Ciencia e Innovación (PSI2014-55316-C3-3-R; PSI2017-89389-C2-2-R), with FEDER Funds; the Galician Government, Consellería de Cultura, Educación e Ordenación Universitaria, Axudas para a Consolidación e Estruturación de Unidades de Investigación Competitivas do Sistema Universitario de Galicia: GRC (GI-1807-USC); Ref: ED431-2017/27, with FEDER funds SI

Early identification of amnestic mild cognitive impairment (aMCI) subtypes is important for early diagnosis and prognosis of Alzheimer’s disease. Healthy, single-domain (sdaMCI) and multiple-domain aMCI (mdaMCI) participants performed an auditory-visual distraction-attention task. Event-related brain potentials (ERPs) were recorded while the participants performed the task to evaluate Go/NoGo N2 and P3 ERP components. The results showed the expected behavioral and cognitive decline in mdaMCI participants relative to controls (fewer hits, longer reaction times [RTs], slightly smaller Go-N2 and NoGo-N2 amplitudes), while sdaMCI participants showed some decline (slightly longer RTs, smaller Go- and NoGo-N2 amplitudes) along with some unexpected results (a late positive slow wave, PSW) and good levels of execution. In addition, some of these parameters proved to be useful markers. Thus, the number of hits was the best marker for diagnosing mdaMCI participants (distinguishing them from controls, from sdaMCI participants, and from both groups together), while the PSW amplitude was the best marker for diagnosing sdaMCI participants (distinguishing them from controls, and from control & mdaMCI participants).

The aim of this study was to evaluate the effects of aging and attentional capture provoked by novel auditory stimuli on behavior (reaction time [RT], hits) and on response-related brain potentials (preRFP, CRN, postRFP, parietalRP) to target visual stimuli. Twenty-two young, 27 middle-aged, and 24 old adults performed an auditory-visual distraction-attention task. The RTs and latencies of preRFP, postRFP and parietalRT were longer in old and middle-aged than in young participants, reflecting the well-established age-related slowing of processing and performance. The inter-peak latencies (P3b-preRFP, preRFP-parietalRP, parietalRP-postRFP) were also longer in old and middle-aged than in young participants, further indicating an age-related tendency to increased predominance of serial (rather than parallel) processing of information, and that preRFP, CRN, postRFP, and parietalRP represent different cognitive processes from those indexed by the stimulus-related P3b. Finally, a distraction effect in performance (all three groups) and in postRFP latency (only middle-aged group) was also observed.

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. © 2014-IOS Press.

In the present study a face naming reaction time task was employed in order to evaluate the effect of age on performance and on movement related cortical potentials (MRCPs). In addition, the effect of three response categories with different cognitive demands (DON'T KNOW–don't know the name–, KNOW–correct naming– and TOT—tip-of the-tongue state) on performance and on MRCPs in a sample of older adults was evaluated. The same MRCPs found in a previous study in a sample of young adults were identified in older adults. The results indicated that older participants were generally slower at providing responses than young adults, and that both age groups showed longer reaction time in TOT than in DON'T KNOW and KNOW categories. The first component of readiness potential (1st-RP) showed larger amplitude and longer duration in older than in young adults, especially in the TOT category, which would explain the generally slower responses provided by older participants. In addition, in older adults, the 1st-RP was larger in TOT than in the DON'T KNOW category, but a slope reduction and stabilization were observed in TOT from the more demanding stages of stimulus processing. These results may reflect a lengthening in the preparation period in the TOT category, which probably explains the behavioural slowing in this category. The data of the present study suggest differences in the allocation of processing resources between groups, indicating that the sensoriomotor performance should be compromised more in older than in young adults in tasks with high cognitive load.

The tip-of-the-tongue state (TOT) in face naming is a transient state of difficulty in access to a person's name along with the conviction that the name is known. The aim of the present study was to characterize the spatio-temporal course of brain activation in the successful naming and TOT states, by means of magnetoencephalography, during a face-naming task. Following famous face presentations, subjects indicated whether they knew the name, did not know the name, or experienced a TOT state. Next they produced the name aloud, if they could, although they did not indicate whether they retrieved any other information about the person. The TOT state was characterized by lower activation than for successful retrieval, in the 310-520 ms poststimulus interval, localized to left temporal and frontal areas, bilateral parahippocampal gyrus, and right fusiform gyrus, which may underlie the genesis of TOT. Greater activation was also found in the 740-820 ms interval, localized to bilateral occipital, left temporal, and right frontal and parietal areas, corresponding with the unfruitful search for the name after the TOT state was produced. These results showed the differential brain dynamics underlying searching for the name of a known individual according to whether the search was successful or subjectively rated as just short of success.

The aim of the present study was evaluate the movement-related cortical potentials (MRCPs) associated with manual and speech movements during a face naming task carried out by the same participants as in a previous study, in order to: 1) determine whether the slowing down of the reaction time observed in the tip-of-the-tongue (TOT) state was caused by motor processes; 2) compare the MRCPs among the three response categories (tip-of-the-tongue, successful retrieval and not knowing the name); and 3) determine whether the MRCPs modulated the differences in amplitude of the late negative wave among response categories. The first component of readiness potential, the negative slope, the motor potential and the reafferent potential associated with the manual response, and two components associated with the verbal responses—the speech-related motor potential and the speech-related reafferent potential—were identified. The slowing down of reaction time observed in the TOT category may be due to a temporal interruption in the motor programming of the responses due to the TOT state. The longer latency in speech-related components in the KNOW with respect to the TOT category can be attributed to the greater cognitive demands involved in the retrieval of proper names in the former category. The brain activity associated with the preparation and execution of the responses had a differential modulatory effect on the amplitude of the LNW component, which may partially explain the differences between the categories observed in the previous study by Diaz et al. [Diaz, F., Lindin, M., Galdo-Alvarez, S., Facal, D., Juncos-Rabadan, O., 2007. An event-related potentials study of face identification and naming: the tip-of-the-tongue state. Psychophysiology 44, 50–68].

A famous-face naming task was used to establish the electrophysiological characterization of the tip-of-the-tongue (TOT) state, successful naming (K), and nonrecognition (DK). The differences in the direct event-related potentials (ERPs) and in the lateralized readiness potential between those categories were studied. The ERP correlates of recognition and access to semantic and lexical information were similar between K and TOT, but showed amplitude differences with respect to DK. A delayed onset of the response selection was obtained in TOT in comparison with K, suggesting an insufficient activation of phonological information from 360 ms onwards. The continuous search for the name and the conflict monitoring in TOT led to differences in ERP amplitudes between TOT and the other categories from 750 ms onwards as well as to a delayed onset of response preparation, indicating a continuous engagement of processing resources.

Active brain areas and their temporal sequence of activation during the successful retrieval and naming of famous faces (KNOW) and during the tip-of-the-tongue (TOT) state were studied by means of low resolution electromagnetic tomographic analysis (LORETA) applied to event-related potentials. The results provide evidence that adequate activation of a neural network during the first 500 ms following presentation of the photograph--mainly involving the posterior temporal region, the insula, lateral and medial prefrontal areas and the medial temporal lobe--is associated with successful retrieval of lexical-phonological information about the person's name. Significant differences between conditions were observed in the 538-698-ms interval; specifically there was greater activation of the anterior cingulate gyrus (ACC) towards the supplementary motor area (SMA) in the KNOW than in the TOT condition, possibly in relation to the motor response and as a consequence of the successful retrieval of lexical-phonological information about the person.

Studies that have attempted to determine the effects of aging on the brain neural sources of memory retrieval have reported two contrasting age effects: under-recruitment and over-recruitment of several prefrontal areas. However, the causes for these effects are still a matter of debate. In order to study the underlying factors that cause the effects, we compared brain activation in young and older adults, in a successful word retrieval condition, and a failed word retrieval condition: the tip-of-the-tongue state. For this, we used the event-related potentials technique and neural source estimation with low-resolution tomographies. The results showed that the older adults did not display under-recruitment in any brain area in comparison with the young adults. However, they displayed additional prefrontal activation that varied depending on the processing stage and the condition, which supports the hypothesis of selective over-recruitment in older adults.

Event-Related Potentials (ERPs) elicited by congruent and incongruent colour-word stimuli of a Stroop paradigm, in a task in which participants were required to judge the congruence/incongruence of the two dimensions of the stimuli, were recorded in order to study the timing of the semantic conflict. The reaction time to colour-word incongruent stimuli was significantly longer than the reaction time to congruent stimuli (the Stroop effect). A temporal Principal Components Analysis was applied to the data to identify the ERP components. Three positive components were identified in the 300-600 ms interval in response to the congruent and incongruent stimuli: First P3, P3b and PSW. The factor scores corresponding to the First P3 and P3b components were significantly smaller for the incongruent stimuli than for the congruent stimuli. No differences between stimuli were observed in the factor scores corresponding to the PSW or in the ERP latencies. We conclude that the temporal locus of the semantic conflict, which intervenes in generating the Stroop effect, may occur within the time interval in which the First P3 and P3b components are identified, i.e. at approximately 300-450 ms post-stimulus. We suggest that the semantic conflict delays the start of the response selection process, which explains the longer reaction time to incongruent stimuli.

This study examined the effects of aging on the ERP components associated with the different processing stages in a face naming task. Two hundred photographs were presented to 13 young and 10 elderly adults, who had to press a button and then to say the name aloud (KNOW condition), or “Can’t remember” if they were experiencing a tip-of-the-tongue state (TOT condition). Young adults showed larger ERP amplitudes in KNOW than in TOT in the 550–750 and 1550–2000 ms intervals, but the older adults did not show any such differences. The older adults showed a specific lengthening in ERP latencies from 250 ms onwards, and smaller mean amplitudes in the 550–750 ms interval in the KNOW category and in the 750–1000 ms interval in both categories, and a wider and more frontalized scalp topographical distribution of the ERP amplitudes than the young adults. The results may indicate activation of compensatory mechanisms in elderly adults.

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. Copyright © 2006 Society for Psychophysiological Research.

This study evaluated whether P300 amplitude declines in response to repeated presentation of the target in a standard auditory oddball task; to what extent the decrease is affected by the number of targets presented, interrupted by an interblock interval (IBI, 3 min) and consistent. We also aimed to identify factors inducing P300 amplitude decrease and its psychological significance. Two blocks of 500 tonnes (each divided into five subblocks of 100 tones) were presented. First block: P300 amplitude was smaller in the first subblock than in the second, which we attribute to processing resources during the first subblock being divided between the task of identifying the target and the process of estimating subjective probability. Amplitude decreased from the second subblock onwards. The interblock interval was sufficient for amplitude to return to pre-decrease levels. The intrablock decline was replicated in the second block. The decline in P300 amplitude might to reflect a progressive automation of the context-updating operations.