The hypothesis that reduced accessibility to relevant information can negatively affect problem solving in a remote associate test (RAT) was tested by using, immediately before the RAT, a retrieval practice procedure to hinder access to target solutions. The results of 2 experiments clearly showed that, relative to baseline, target words that had been competitors during selective retrieval were much less likely to be provided as solutions in the RAT, demonstrating that performance in the problem-solving task was strongly influenced by the predetermined accessibility status of the solutions in memory. Importantly, this was so even when participants were unaware of the relationship between the memory and the problem-solving procedures in the experiments. This finding is consistent with an inhibitory account of retrieval-induced forgetting effects and, more generally, constitutes support for the idea that the activation status of mental representations originating in a given task (e.g., episodic memory) can unwittingly have significant consequences for a different, unrelated task (e.g., problem solving). (PsycINFO Database Record

Synaptic dysfunction, a key pathophysiological hallmark of Alzheimer’s disease (AD), may account for abnormal memory-related EEG patterns in prodromal AD. Here, we investigate to what extent oscillatory EEG changes during memory encoding and/or retrieval enhance the accuracy of medial temporal lobe (MTL) atrophy in predicting conversion from amnestic mild cognitive impairment (aMCI) to AD. As expected, aMCI individuals that, within a 2-year follow-up period, developed dementia (N = 16) compared to healthy older (HO) (N = 26) and stable aMCI (N = 18) showed poorer associative memory, greater MTL atrophy, and lower capacity to recruit alpha oscillatory cortical networks. Interestingly, encoding-induced abnormal alpha desynchronized activity over the posterior cingulate cortex (PCC) at baseline showed significantly higher accuracy in predicting AD than the magnitude of amygdala atrophy. Nevertheless, the best accuracy was obtained when the two markers were fitted into the model (sensitivity = 78%, specificity = 82%). These results support the idea that synaptic integrity/function in the PCC is affected during prodromal AD and has the potential of improving early detection when combined with MRI biomarkers.

People with amnestic mild cognitive impairment (aMCI), compared to healthy older adults (HO), benefit less from semantic congruent cues during episodic encoding. The presence of the apolipoprotein E (APOE) ɛ4 makes this congruency benefit smaller, but the neural correlates of this deficit are unknown. Here, we estimated the source generators of EEG oscillatory activity associated with successful encoding of face-location associations preceded by semantically congruent and incongruent cues in HO (N = 26) and aMCI subjects (N = 34), 16 of which were ɛ4 carriers (ɛ4(+) ) and 18 ɛ4 noncarriers (ɛ4(-) ). Source estimation was performed in those spectrotemporal windows where the power of low-alpha, high-alpha, and beta oscillatory activity differed either between congruent and incongruent faces or between groups. Differences in high-alpha and beta-oscillatory dynamics indicated that aMCI ɛ4(+) are unable to activate lateral regions of the temporal lobe involved in associative memory and congruency benefit in HO. Interestingly, and regardless of APOE genotype, aMCI activated additional regions relative to HO, through alpha oscillations. However, only activation in a distributed fronto-temporo-parietal network in ɛ4 noncarriers was paralleled by enhanced memory. On the contrary, the redundant prefrontal activation shown by aMCI ɛ4(+) did not prevent performance from decreasing. These results indicate that the effect of aMCI-related degeneracy on functional networks is constrained by the presence of APOE ɛ4. Whereas individuals with aMCI ɛ4(-) activate attentional, perceptual and semantic compensatory networks, aMCI ɛ4(+) show reduced processing efficiency and capacity.