Optimising Cognitive Enhancement: Systematic Assessment of the Effects of tDCS Duration in Older Adults

Transcranial direct current stimulation (tDCS) supports cognition and brain function in older adults but there is an absence of research to devise optimal stimulation protocols. This is the first systematic exploration into the effects of stimulation duration in the ageing population. Ten minutes of anodal stimulation significantly improved task-switching speed from baseline. Sham-control and 20 min variants did not. The findings are a vital step towards the refinement of stimulation to enhance executive function in older adults

Immigrants as Americanizers: The Americanization Movement of the Early Twentieth Century

This thesis aims to prove that the Americanization movement was crucial in that it provoked immigrants to devise their own ways in which they could demonstrate their loyalty to America and forge links between Americanism and their cultural pride. Immigrants transformed themselves into a new type of American by exhibiting love for both their home and adopted countries. On the one hand, they were acutely aware of the ever-present demand to exhibit their dedication to America during the Great War, but they also took much of the patriotic ardor that was forced upon them and reshaped it in order to support and promote their own ethnic causes. The native-born Americanizers responsible for Americanization publications underestimated immigrant potential and desire to participate. Although immigrants did benefit from a certain number of opportunities offered by native-born Americanizers, what was expressed in the Foreign Language Press and other immigrant writings reveals that the immigrants were better suited to acclimate themselves rather than those appointed by the government, public schools, or private organizations. While native-born Americanizers sought ways to teach immigrants about America and its history, traditions, language, and government, many remained unmindful of the fact that the newly arrived Southern and Eastern European immigrants were practicing one of the earliest forms of cultural pluralism and were also interested in teaching native-born Americans about their own cultures. The following case studies are used to analyze various Americanization methods employed during the Americanization Movement: 1) The works of Frances A. Kellor and Americanization literature by John Foster Carr and the Daughters of the American Revolution; 2) The Carnegie Studies published during the early 1920s; and, 3) Foreign Language Press articles from The Chicago Foreign Language Press Survey as well as immigrant works, including those by Carol Aronovici and Israel Zangwill

Reaction Time Decomposition as a Tool to Study Subcortical Ischemic Vascular Cognitive Impairment

Background:The study of reaction time (RT) and its intraindividual variability (IIV) in aging, cognitive impairment, and dementia typically fails to investigate the processing stages that contribute to an overall response. Applying “mental chronometry” techniques makes it possible to separately assess the role of processing components during environmental interaction.Objective:To determine whether RT and IIV-decomposition techniques can shed light on the nature of underlying deficits in subcortical ischemic vascular cognitive impairment (VCI). Using a novel iPad task, we examined whether VCI deficits occur during both initiation and movement phases of a response, and whether they are equally reflected in both RT and IIV.Methods:Touch cancellation RT and its IIV were measured in a group of younger adults (n = 22), cognitively healthy older adults (n = 21), and patients with VCI (n = 21) using an iPad task.Results:Whereas cognitively healthy aging affected the speed (RT) of response initiation and movement but not its variability (IIV), VCI resulted in both slowed RT and increased IIV for both response phases. Furthermore, there were group differences with respect to response phase.Conclusion:These results indicate that IIV can be more sensitive than absolute RT in separating VCI from normal aging. Furthermore, compared to cognitively healthy aging, VCI was characterized by significant deficits in planning/initiating action as well as performing movements. Such deficits have important implications for real life actions such as driving safety, employment, and falls risk

The neurobiological mechanisms of transcranial direct current stimulation: insights from human neuroimaging and psychophysics

The research aimed to investigate the neurobiological basis of transcranial direct current stimulation (tDCS); a neuromodulation technique capable of inducing prolonged changes in behavioural performance. The past 15 years have seen a dramatic increase in tDCS-oriented studies, yet the underpinnings of the method are not completely understood. Consequently, this series of experiments was designed to investigate the mechanisms that contribute to the effects of the method. Focusing on neuroimaging, modulations of excitatory and inhibitory neurochemicals were assessed using Magnetic Resonance Spectroscopy (MRS); incorporating distinct spectral editing sequences to define the precise role of inhibitory neurotransmission. Additionally, concurrent DC stimulation and Magnetoencephalography (MEG) was developed, which permitted the novel investigation of excitatory and inhibitory processes via the influence of tDCS on electrophysiological responses in the motor and visual systems. This simultaneous tDCS-MEG investigation is one of only a few existing studies and was the first such endeavour by a group based in the United Kingdom. Finally, a unique psychophysical approach was adopted whereby variations of a vibrotactile adaptation task were utilised to assess the effects of tDCS on amplitude discrimination ability. The paradigms used were specifically chosen due to their physiological similarity to tDCS, thereby enabling inferences on the underpinnings of the method on the basis of changes in somatosensory task performance. These studies provided varying degrees of support for the neurobiological mechanisms proposed in the existing literature, most likely reflecting the influence of distinctions in stimulation protocols and the presence of individual difference factors thought to modify responses to stimulation. Consequently, in addition to the established insights regarding the underpinnings of tDCS, valuable perspectives on the optimisation of stimulation-based methodology were achieved by conducting the outlined investigations

Anodal tDCS improves attentional control in older adults

To provide insight into the benefits of tDCS, this study used an age-optimised stimulation protocol whereby key parameters (amplitude, duration, and electrode configuration) were selected in accordance with knowledge of stimulation effects, specific to the ageing brain. Participants completed three sessions of double-blind, anodal or sham stimulation, in conjunction with a novel task switching paradigm. The results show that only those who were administered anodal tDCS exhibited an increase in task switching speed (p < .01, d = 1.36)