George Stothart

Glass Shape Influences Consumption Rate for Alcoholic Beverages

Background High levels of alcohol consumption and increases in heavy episodic drinking (binge drinking) are a growing public concern, due to their association with increased risk of personal and societal harm. Alcohol consumption has been shown to be sensitive to factors such as price and availability. The aim of this study was to explore the influence of glass shape on the rate of consumption of alcoholic and non-alcoholic beverages. Methods This was an experimental design with beverage (lager, soft drink), glass (straight, curved) and quantity (6 fl oz, 12 fl oz) as between-subjects factors. Social male and female alcohol consumers (n = 159) attended two experimental sessions, and were randomised to drink either lager or a soft drink from either a curved or straight-sided glass, and complete a computerised task identifying perceived midpoint of the two glasses (order counterbalanced). Ethical approval was granted by the Faculty of Science Research Ethics Committee at the University of Bristol. The primary outcome measures were total drinking time of an alcoholic or non-alcoholic beverage, and perceptual judgement of the half-way point of a straight and curved glass. Results Participants were 60% slower to consume an alcoholic beverage from a straight glass compared to a curved glass. This effect was only observed for a full glass and not a half-full glass, and was not observed for a non-alcoholic beverage. Participants also misjudged the half-way point of a curved glass to a greater degree than that of a straight glass, and there was a trend towards a positive association between the degree of error and total drinking time. Conclusions Glass shape appears to influence the rate of drinking of alcoholic beverages. This may represent a modifiable target for public health interventions.

Early visual evoked potentials and mismatch negativity in Alzheimer's disease and mild cognitive impairment

BACKGROUND Cortical visual association areas are highly vulnerable to Alzheimers disease (AD) microscopic pathology. Visual evoked potentials (VEPs) provide the tools to examine the functional integrity of these areas and may provide useful indicators of early disease progression. OBJECTIVE To assess the functional integrity of visual association area processing in AD and amnestic mild cognitive impairment (aMCI) using VEPs. METHODS We investigated the visual processing of healthy older adults (n = 26), AD (n = 20), and aMCI (n = 25) patients in a visual oddball paradigm designed to elicit the visual P1, N1, and visual mismatch negativity (vMMN). RESULTS AD patients showed a significant reduction of P1 and N1 VEP amplitudes and aMCI patients showed a reduction in N1 amplitude compared to healthy older adults. P1 amplitude in response to deviant stimuli and vMMN amplitude were found to be associated with the degree of cognitive impairment as measured by the Mini-Mental State Examination. CONCLUSIONS Changes in VEPs in AD may be a consequence of the microscopic AD pathology typically found in the extrastriate cortex. Neural measures of visual processing may help to better characterize subgroups of aMCI patients likely to develop AD. Additionally, VEPs and vMMN may provide objective markers of cognitive decline.

Evoked potentials reveal age-related compensatory mechanisms in early visual processing

Understanding the effects of aging on sensory processing must be the starting point for any examination of age-related changes in cognition and behavior. Previous studies of the neurophysiological effects of healthy aging on sensory processing have attributed changes in auditory evoked responses to reduced inhibition from frontocortical areas on primary auditory processing or to a global slowing of neural responses. We investigated whether the age-related changes in visual evoked potentials can be primarily accounted for by similar deficits in frontocortical inhibition or processing speed. Using evoked potentials, we examined the primary visual processing of younger (mean age, 20.0 years) and older (mean age, 76.8 years) adults in a visual oddball paradigm. We found that the pattern of early visual responses cannot be explained via reduced frontocortical inhibition or a reduction in speed of visual processing. Rather our results point toward the existence of a robust compensatory neural response to impoverished sensory input in aging.

Caffeine abstinence: an ineffective and potentially distressing tinnitus therapy.

Abstract The effect of phased caffeine withdrawal and abstention on tinnitus severity was assessed using a pseudo-randomized, double-blinded, placebo-controlled crossover trial of 30 days duration. Sixty-six volunteers who experienced tinnitus and who usually consumed at least 150 mg/day of caffeine participated. The intervention was a direct replacement of usual caffeinated tea/coffee with double-blinded supplies, under one of two conditions. Condition 1: Maintenance followed by phased withdrawal. Condition 2: Phased withdrawal followed by reintroduction and maintenance. Tinnitus severity was measured by the total score of the Tinnitus Questionnaire on Days 1, 15, and 30. Secondary measures included twice daily self-rated symptoms relevant to tinnitus and caffeine withdrawal. Caffeine had no effect on tinnitus severity, the mean difference between caffeinated and decaffeinated days being –0.04 (95% confidence interval –1.99 to 1.93), p=0.97. Significant acute adverse symptoms of caffeine withdrawal were observed. No evidence was found to justify caffeine abstinence as a therapy to alleviate tinnitus, but acute effects of caffeine withdrawal might add to the burden of tinnitus. Sumario Se evaluó el efecto del retiro paulatino y la abstención de la cafeína sobre la severidad del acufeno mediante un ensayo clínico de 30 días, pseudo-aleatorio, doble ciego, con control de placebo y transversal. Participaron sesenta y seis voluntarios que experimentaban acufeno y que usualmente consumían al menos 150 mg/día de cafeína. La intervención fue un reemplazo directo de café y/o té cafeinado con suministros doble ciego bajo una de estas dos condiciones: Condición 1. Mantenimiento seguido de retiro paulatino. Condición 2. Retiro paulatino seguido de reintroducción y mantenimiento. La severidad del acufeno fue medida mediante la puntuación total del cuestionario de acufeno en los días 1, 15 y 30. Dentro de las mediciones secundarias se incluyó una autoevaluación de los síntomas relativos al acufeno y a la abstención de cafeína. La cafeína no tuvo efecto en la severidad del acufeno. La diferencia media entre los días con cafeína y sin ella fue de -0.04 (intervalo de confianza del 95% -1.99 a 1.93), P=0.97. Se observaron efectos adversos agudos significativos por la abstención de cafeína. No se encontró evidencia que justificara la abstinencia de cafeína como tratamiento para aliviar el acufeno, pero los efectos agudos del retiro de la cafeína puede agregarse a la carga del acufeno.

Oscillatory characteristics of the visual mismatch negativity: what evoked potentials aren't telling us

The visual mismatch negativity (vMMN) response is typically examined by subtracting the average response to a deviant stimulus from the response to the standard. This approach, however, can omit a critical element of the neural response, i.e., the non-phase-locked (“induced”) oscillatory activity. Recent investigations of the oscillatory characteristics of the auditory mismatch negativity (aMMN) identified a crucial role for theta phase locking and power. Oscillatory characteristics of the vMMN from 39 healthy young adults were investigated in order to establish whether theta phase locking plays a similar role in the vMMN response. We explored changes in phase locking, overall post-stimulus spectral power as well as non-phase-locked spectral power compared to baseline (−300 to 0 ms). These were calculated in the frequency range of 4–50 Hz and analysed using a non-parametric cluster based analysis. vMMN was found intermittently in a broad time interval 133–584 ms post-stimulus and was associated with an early increase in theta phase locking (75–175 ms post-stimulus) that was not accompanied by an increase in theta power. Theta phase locking in the absence of an increase in theta power has been associated with the distribution and flow of information between spatially disparate neural locations. Additionally, in the 450–600 ms post-stimulus interval, deviant stimuli yielded a stronger decrease in non-phase-locked alpha power than standard stimuli, potentially reflecting a shift in attentional resources following the detection of change. The examination of oscillatory activity is crucial to the comprehensive analysis of a neural response to a stimulus, and when combined with evoked potentials (EPs) provide a more complete picture of neurocognitive processing.

Double peaked P1 visual evoked potentials in healthy ageing.

OBJECTIVES To robustly examine the prevalence of the double peaked P1 visual evoked potential in healthy younger and older adult populations. METHODS The evoked potentials and spectral power changes to simple visual stimuli of 26 healthy younger (M=20.0 y) and 26 healthy older adults (M=76.0 y) were examined. RESULTS Group and individual analyses showed a clear effect of age on P1 morphology and amplitude. Older adults showed significantly lower P1 amplitude and 44% of older adults showed a double peaked P1 compared to 12% of younger adults. Double peaked P1 responses were associated with an increase in spectral power in the gamma range. CONCLUSIONS The double peaked P1 may be more prevalent in older adults than previously demonstrated and may represent a de-synchronisation of the cortical sources of the visual P1 in healthy ageing. Increased power in post stimulus gamma in the double peak group may be indicative of compensatory neural processing. SIGNIFICANCE Clinically the prevalence of the double peaked P1 may have been underestimated, and its reflectance of demyelinating disease overestimated. Experimentally the results suggest that any investigation of visual processing in older adults must control for early changes in P1 morphology.

Neural correlates of cigarette health warning avoidance among smokers

Highlights • Smokers implicitly and explicitly avoid cigarette health warnings.• Smokers and non-smokers lectroencephalography (EEG) responses to cigarette health warnings were compared.• Smokers show no difference in early perceptual processing (P1, vMMN and P3).• Smokers show reduced later cognitive responses (Late Positive Potential).• Smokers show reduced sensitivity to cigarette health warnings emotional content

A frontal attention mechanism in the visual mismatch negativity.

Highlights • We examine frontal mechanisms underlying the visual mismatch negativity.• EEG and fMRI activity was examined in respect to unattended oddball stimuli.• Left inferior frontal gyrus was associated with changes in the stimuli.• Our findings correspond to similarly implicated regions in the auditory domain.

A fast and implicit measure of semantic categorisation using steady state visual evoked potentials

&NA; There is a great need for objective measures of perception and cognition that are reliable at the level of the individual subject. Although traditional electroencephalography (EEG) techniques can act as valid bio‐markers of cognition, they typically involve long recording times and the computation of group averages. To overcome these well‐known limitations of EEG, vision scientists have recently introduced a steady state method known as fast periodic visual stimulation (FPVS). This method allows them to study visual discrimination at the individual level. Inspired by their work, we examined whether FPVS could be used equally effectively to capture abstract conceptual processes. Twenty subjects (20.9 (±2.1) yrs, 6 male) were asked to complete a FPVS‐oddball paradigm that assessed their spontaneous ability to differentiate between rapidly presented images on the basis of semantic, rather than perceptual, properties. At the group level, this approach returned a reliable oddball detection response after only 50 s of stimulus presentation time. Moreover, a stable oddball response was found for each participating individual within 100 s. As such, the FPVS‐oddball paradigm returned an objective, non‐verbal marker of semantic categorisation in single subjects in under two minutes. This finding establishes the FPVS‐oddball paradigm as a powerful new tool in cognitive neuroscience. HighlightsNeural measures of cognition stable at the individual subject level are needed.Semantic categorisation is assessed using EEG steady‐state oddball paradigms.Single subjects show stable responses after less than one minute of recording time.