Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults

Age-related episodic memory decline is characterized by striking heterogeneity across individuals. Hippocampal pattern completion is a fundamental process supporting episodic memory. Yet, the degree to which this mechanism is impaired with age, and contributes to variability in episodic memory, remains unclear. We combine univariate and multivariate analyses of fMRI data from a large cohort of cognitively normal older adults (N=100) to measure hippocampal activity and cortical reinstatement during retrieval of trial-unique associations. Trial-wise analyses revealed that (a) hippocampal activity scaled with reinstatement strength, (b) cortical reinstatement partially mediated the relationship between hippocampal activity and associative retrieval, (c) older age weakened cortical reinstatement and its relationship to memory behaviour. Moreover, individual differences in the strength of hippocampal activity and cortical reinstatement explained unique variance in performance across multiple assays of episodic memory. These results indicate that fMRI indices of hippocampal pattern completion explain within-and across-individual memory variability in older adults

Influenza-associated global amnesia and hippocampal imaging abnormality

The acute phase of influenza infection is rarely associated with significant cognitive dysfunction. We describe a case of a 24 year-old man who developed global amnesia in the acute phase of influenza A infection. His deficits resolved over the course of several weeks. Transient abnormalities of diffusion and T2-weighted imaging were seen in the bilateral hippocampi. We review cerebral complications of influenza and discuss the possible role of previously proposed mechanisms in our patient's case

Repetitive transcranial magnetic stimulation directed to a seizure focus localized by high-density EEG: A case report

We demonstrate feasibility of using high-density EEG to map a neocortical seizure focus in conjunction with delivery of magnetic therapy. Our patient had refractory seizures affecting the left leg. A five-day course of placebo stimulation followed a month later by active rTMS was directed to the mapped seizure dipole. Active rTMS resulted in reduced EEG spiking, and shortening of seizure duration compared to placebo. Seizure frequency, however, improved similarly in both placebo and active treatment stages. rTMS-evoked EEG potentials demonstrated that a negative peak at 40 ms - believed to represent GABAergic inhibition - was enhanced by stimulation. Keywords: Seizure, Epilepsy, Repetitive transcranial evoked potentials, Neurostimulation, EEG evoked potential

SPECIAL ISSUE CHILDREN’S READING PERFORMANCE IS CORRELATED WITH WHITE MATTER STRUCTURE MEASURED BY DIFFUSION TENSOR IMAGING

Adult reading skill spans a wide performance range across individuals. This variance in performance begins in childhood. Educational opportunity, the stress and distractions associate

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doi:10.1073/pnas.0608961104 This information is current as of May 2007. High-resolution figures, a citation map, links to PubMed and Google Scholar, etc., can be found at: www.pnas.org/cgi/content/full/104/20/8556 This article cites 47 articles, 15 of which you can access for free at: www.pnas.org/cgi/content/full/104/20/8556#BIBL This article has been cited by other articles: www.pnas.org/cgi/content/full/104/20/8556#otherarticles Receive free email alerts when new articles cite this article- sign up in the box at the top right corner of the article or click here. To reproduce this article in part (figures, tables) or in entirety, see: www.pnas.org/misc/rightperm.shtml To order reprints, see: www.pnas.org/misc/reprints.shtml Temporal-callosal pathway diffusivity predicts phonological skills in childre

Contrast responsivity in MT+ correlates with phonological awareness and

reading measures in childre

Safety, tolerability, and feasibility ofyYoung plasma infusion in the plasma for Alzheimer symptom amelioration study: A randomized clinical trial

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