Atypical Neurophysiology Underlying Episodic and Semantic Memory in Adults with Autism Spectrum Disorder

Individuals with autism spectrum disorder (ASD) show atypicalities in episodic memory (Boucher et al. in Psychological Bulletin, 138 (3), 458-496, 2012). We asked participants to recall the colours of a set of studied line drawings (episodic judgement), or to recognize line drawings alone (semantic judgement). Cycowicz et al. (Journal of Experimental Child Psychology, 65, 171-237, 2001) found early (300 ms onset) posterior old-new event-related potential effects for semantic judgements in typically developing (TD) individuals, and occipitally focused negativity (800 ms onset) for episodic judgements. Our results replicated findings in TD individuals and demonstrate attenuated early old-new effects in ASD. Late posterior negativity was present in the ASD group, but was not specific to this time window. This non-specificity may contribute to the atypical episodic memory judgements characteristic of individuals with ASD

The importance of understanding individual differences in Down syndrome

In this article, we first present a summary of the general assumptions about Down syndrome (DS) still to be found in the literature. We go on to show how new research has modified these assumptions, pointing to a wide range of individual differences at every level of description. We argue that, in the context of significant increases in DS life expectancy, a focus on individual differences in trisomy 21 at all levels—genetic, cellular, neural, cognitive, behavioral, and environmental—constitutes one of the best approaches for understanding genotype/phenotype relations in DS and for exploring risk and protective factors for Alzheimer’s disease in this high-risk population

Calculations of responses to representative neutron spectra of albedo neutron dosemeters incorporating LiF thermoluminescent detectors

The responses to representative neutron spectra from the Health Physics Research Reactor in the USA of some albedo dosemeter configurations using commercially available LiF TLD chips have been calculated, and methods suggested for correcting the energy response of albedo dosemeters

Quantitative analysis of the effects of physiologic brain motion on point-resolved spectroscopy

Although single-voxel proton MR spectroscopy is a noninvasive method that enables measurement of brain metabolite concentrations, it has been shown that physiologic brain motion causes inaccuracies in measurement of metabolite concentrations and increases the overall SD of the measurements when the stimulated echo acquisition mode (STEAM) is used. We tested the hypothesis that the point-resolved spectroscopy (PRESS) technique is less sensitive to physiologic brain motion than the STEAM technique. In 10 healthy subjects, spectra were obtained from a voxel located in the left basal ganglia by using the PRESS sequence with cardiac gating and without water suppression to assess global phase change as a function of physiologic brain motion. This was accomplished by acquiring data at various time delays from the R wave throughout the cardiac cycle. Subsequently, spectra were obtained in 10 healthy subjects by using PRESS both without and with cardiac gating, and with water suppression, to determine whether brain motion resulted in a statistically significant difference in mean and SD of measured metabolite concentration. At various time delays from the R wave throughout the cardiac cycle, no significant global phase difference was noted in water signal intensity. In addition, when PRESS data were obtained both without and with cardiac gating (by using an optimal delay obtained from previously published data by using STEAM), no significant difference was seen in measured metabolite concentrations and SDs. The PRESS technique is relatively insensitive to physiologic brain motion

Subarachnoid Hemorrhage Due to Isolated Spinal Artery Aneurysm in Four Patients

Spinal artery aneurysms are usually found with arteriovenous malformations or other entities that increase hemodynamic stress. Isolated spinal artery aneurysms are rare. Four patients who presented with the acute onset of lower back pain underwent MR imaging, which revealed spinal subarachnoid hemorrhage. In all patients, work-up yielded a diagnosis of isolated spinal aneurysm, and operative treatment was successful. In the appropriate clinical setting, spinal aneurysm should be considered as a possible cause of spinal subarachnoid hemorrhage. © American Society of Neuroradiology