Effects of Memantine on the Auditory Steady-State and Harmonic Responses to 40 Hz Stimulation Across Species.

Background: Click trains elicit an auditory steady-state response (ASSR) at the driving frequency (1F) and its integer multiple frequencies (2F, 3F, etc.) called harmonics; we call this harmonic response the steady-state harmonic response (SSHR). We describe the 40 Hz ASSR (1F) and 80 Hz SSHR (2F) in humans and rats and their sensitivity to the uncompetitive NMDA antagonist memantine.

Mismatch negativity predicts initial auditory-based targeted cognitive training performance in a heterogeneous population across psychiatric disorders.

Auditory-based targeted cognitive training (ATCT) programs are emerging pro-cognitive therapeutic interventions which aim to improve auditory processing to attenuate cognitive impairment in a "bottom up" manner. Biomarkers of early auditory information processing (EAIP) like mismatch negativity (MMN) and P3a have been used successfully to predict gains from a full 40 h course of ATCT in schizophrenia (SZ). Here we investigated the ability of EAIP biomarkers to predict ATCT performance in a group of subjects (n = 26) across SZ, MDD, PTSD and GAD diagnoses.

Assessing observability of chaotic systems using Delay Differential Analysis.

Observability can determine which recorded variables of a given system are optimal for discriminating its different states. Quantifying observability requires knowledge of the equations governing the dynamics. These equations are often unknown when experimental data are considered.

Delay differential analysis for dynamical sleep spindle detection.

Background: Sleep spindles are involved in memory consolidation and other cognitive functions. Numerous automated methods for detection of spindles have been proposed; most of these rely on spectral analysis in some form. However, none of these approaches are ideal, and novel approaches to the problem could provide additional insights.

Theta Bursts Precede, and Spindles Follow, Cortical and Thalamic Downstates in Human NREM Sleep.

Since their discovery, slow oscillations have been observed to group spindles during non-REM sleep. Previous studies assert that the slow-oscillation downstate (DS) is preceded by slow spindles (10-12 Hz) and followed by fast spindles (12-16 Hz). Here, using both direct transcortical recordings in patients with intractable epilepsy ( = 10, 8 female), as well as scalp EEG recordings from a healthy cohort ( = 3, 1 female), we find in multiple cortical areas that both slow and fast spindles follow the DS.

Midlife anticholinergic drug use, risk of Alzheimer's disease, and brain atrophy in community-dwelling older adults.

Introduction: We examined how long-term anticholinergic (AC) drug use beginning at midlife affects risk of Alzheimer's disease (AD) and rates of brain atrophy in cognitively normal older adults.

Methods: We followed 723 individuals (mean baseline age 52.3 years; mean follow-up interval 20.

Peripheral sphingolipids are associated with variation in white matter microstructure in older adults.

Sphingolipids serve important structural and functional roles in cellular membranes and myelin sheaths. Plasma sphingolipids have been shown to predict cognitive decline and Alzheimer's disease. However, the association between plasma sphingolipid levels and brain white matter (WM) microstructure has not been examined.

Sleep Duration and Subsequent Cortical Thinning in Cognitively Normal Older Adults.

Study Objectives: To determine the association between self-reported sleep duration and cortical thinning among older adults.

Methods: We studied 122 cognitively normal participants in the Baltimore Longitudinal Study of Aging with a mean age = 66.6 y (range, 51-84) at baseline sleep assessment and 69.

Lower gray matter integrity is associated with greater lap time variation in high-functioning older adults.

Background: Lower integrity of cerebral gray matter is associated with higher gait variability. It is not known whether gray matter integrity is associated with higher lap time variation (LTV), a clinically accessible measure of gait variability, high levels of which have been associated with mortality. This study examines the cross-sectional association between gray matter mean diffusivity (MD) and LTV in community-dwelling older adults.

The effect of age and microstructural white matter integrity on lap time variation and fast-paced walking speed.

Macrostructural white matter damage (WMD) is associated with less uniform and slower walking in older adults. The effect of age and subclinical microstructural WM degeneration (a potentially earlier phase of WM ischemic damage) on walking patterns and speed is less clear. This study examines the effect of age on the associations of regional microstructural WM integrity with walking variability and speed, independent of macrostructural WMD.

Region of interest correction factors improve reliability of diffusion imaging measures within and across scanners and field strengths.

Diffusion tensor imaging (DTI) measures are commonly used as imaging markers to investigate individual differences in relation to behavioral and health-related characteristics. However, the ability to detect reliable associations in cross-sectional or longitudinal studies is limited by the reliability of the diffusion measures. Several studies have examined the reliability of diffusion measures within (i.

Longitudinal changes in cortical thinning associated with hypertension.

Background: Cross-sectional studies of the association between hypertension (HTN) and brain atrophy have shown reductions in prefrontal, temporal, and hippocampal volumes, and have identified thinner cortices across the cortical mantle.

Method: In the current study, we followed 96 participants enrolled in the Baltimore Longitudinal Study of Aging over a mean interval of 8 years (mean age at baseline = 68.7) and compared those who are hypertensive (n = 49) throughout the study with those who are normotensive (n = 47).