Adrian R. Willoughby

Effects of Working Memory Load on Visual Selective Attention: Behavioral and Electrophysiological Evidence

Working memory and attention interact in a way that enables us to focus on relevant items and maintain current goals. The influence of working memory on attention has been noted in several studies using dual task designs. Multitasking increases the demands on working memory and reduces the amount of resources available for cognitive control functions such as resolving stimulus conflict. However, few studies have investigated the temporal activation of the cortex while multitasking. The present study addresses the extent to which working memory load influences early (P1) and late (P300) attention-sensitive event-related potential components using a dual task paradigm. Participants performed an arrow flanker task alone (single task condition) or concurrently with a Sternberg memory task (dual task condition). In the flanker task, participants responded to the direction of a central arrow surrounded by congruent or incongruent arrows. In the dual task condition, participants were presented with a Sternberg task that consisted of either four or seven consonants to remember prior to a short block of flanker trials. Participants were slower and less accurate on incongruent versus congruent trials. Furthermore, accuracy on incongruent trials was reduced in both dual task conditions. Likewise, P300 amplitude to incongruent flanker stimuli decreased when working memory load increased. These findings suggest that interference from incongruent flankers was more difficult to suppress when working memory was taxed. In addition, P1 amplitude was diminished on all flanker trials in the dual task condition. This result indicates that top-down attentional control over early visual processing is diminished by increasing demands on working memory. Both the behavioral and electrophysiological results suggest that working memory is critical in maintaining attentional focus and resolving conflict.

Preparation for action: Psychophysiological activity preceding a motor skill as a function of expertise, performance outcome, and psychological pressure

Knowledge of the psychophysiological responses that characterize optimal motor performance is required to inform biofeedback interventions. This experiment compared cortical, cardiac, muscular, and kinematic activity in 10 experts and 10 novices as they performed golf putts in low- and high-pressure conditions. Results revealed that in the final seconds preceding movement, experts displayed a greater reduction in heart rate and EEG theta, high-alpha, and beta power, when compared to novices. EEG high-alpha power also predicted success, with participants producing less high-alpha power in the seconds preceding putts that were holed compared to those that were missed. Increased pressure had little impact on psychophysiological activity. It was concluded that greater reductions in EEG high-alpha power during preparation for action reflect more resources being devoted to response programming, and could underlie successful accuracy-based performance.

Measures of sleep and cardiac functioning during sleep using a multi-sensory commercially-available wristband in adolescents.

To validate measures of sleep and heart rate (HR) during sleep generated by a commercially-available activity tracker against those derived from polysomnography (PSG) in healthy adolescents. Sleep data were concurrently recorded using FitbitChargeHR™ and PSG, including electrocardiography (ECG), during an overnight laboratory sleep recording in 32 healthy adolescents (15 females; age, mean±SD: 17.3±2.5years). Sleep and HR measures were compared between FitbitChargeHR™ and PSG using paired t-tests and Bland-Altman plots. Epoch-by-epoch analysis showed that FitbitChargeHR™ had high overall accuracy (91%), high sensitivity (97%) in detecting sleep, and poor specificity (42%) in detecting wake on a min-to-min basis. On average, FitbitChargeHR™ significantly but negligibly overestimated total sleep time by 8min and sleep efficiency by 1.8%, and underestimated wake after sleep onset by 5.6min (p<0.05). Within FitbitChargeHR™ epochs of sleep, the average HR was 59.3±7.5bpm, which was significantly but negligibly lower than that calculated from ECG (60.2±7.6bpm, p<0.001), with no change in mean discrepancies throughout the night. FitbitChargeHR™ showed good agreement with PSG and ECG in measuring sleep and HR during sleep, supporting its use in assessing sleep and cardiac function in healthy adolescents. Further validation is needed to assess its reliability over prolonged periods of time in ecological settings and in clinical populations.

Insomnia in women approaching menopause: Beyond perception

The menopausal transition is marked by increased prevalence in disturbed sleep and insomnia, present in 40-60% of women, but evidence for a physiological basis for their sleep complaints is lacking. We aimed to quantify sleep disturbance and the underlying contribution of objective hot flashes in 72 women (age range: 43-57 years) who had (38 women), compared to those who had not (34 women), developed clinical insomnia in association with the menopausal transition. Sleep quality was assessed with two weeks of sleep diaries and one laboratory polysomnographic (PSG) recording. In multiple regression models controlling for menopausal transition stage, menstrual cycle phase, depression symptoms, and presence of objective hot flashes, a diagnosis of insomnia predicted PSG-measured total sleep time (p < 0.01), sleep efficiency (p = 0.01) and wakefulness after sleep onset (WASO) (p = 0.01). Women with insomnia had, on average, 43.5 min less PSG-measured sleep time (p < 0.001). There was little evidence of cortical EEG hyperarousal in insomniacs apart from elevated beta EEG power during REM sleep. Estradiol and follicle stimulating hormone levels were unrelated to beta EEG power but were associated with the frequency of hot flashes. Insomniacs were more likely to have physiological hot flashes, and the presence of hot flashes predicted the number of PSG-awakenings per hour of sleep (p = 0.03). From diaries, women with insomnia reported more WASO (p = 0.002), more night-to-night variability in WASO (p < 0.002) and more hot flashes (p = 0.012) compared with controls. Women who develop insomnia in the approach to menopause have a measurable sleep deficit, with almost 50% of the sample having less than 6h of sleep. Compromised sleep that develops in the context of the menopausal transition should be addressed, taking into account unique aspects of menopause like hot flashes, to avoid the known negative health consequences associated with insufficient sleep and insomnia in midlife women.

Menstrual Cycle-Related Variation in Physiological Sleep in Women in the Early Menopausal Transition

CONTEXT Most studies show sleep homeostasis and continuity remain stable across the menstrual cycle in young women. The influence of the menstrual cycle on physiological sleep in midlife women is unknown. OBJECTIVE The objective of the study was to assess the impact of menstrual cycle phase on the polysomnogram and electroencephalographic (EEG) features of sleep in midlife women, accounting for the presence of an insomnia disorder. DESIGN AND PARTICIPANTS This was a laboratory study of 20 women in the early menopausal transition (48.8 ± 2.9 y), 11 with a Diagnostic and Statistical Manual of Mental Disorders, fourth edition, diagnosis of insomnia, studied on one night each in the follicular and luteal menstrual cycle phases. MAIN OUTCOME MEASURES Polysomnographic and sleep EEG indices were measured. RESULTS Both groups of women had more awakenings (P = .003) and arousals (P = .025) per hour of sleep and less percentage slow wave sleep (P = .024) when progesterone was raised (≥3 ng/mL(-1)) during the luteal compared with the follicular phase. Both groups had greater spindle density (P = .007), longer spindles (P = .037), and increased 14-17 Hz EEG activity in the luteal phase (P < .05), although for the 15- to 16-Hz bin, this effect was significant only in women without insomnia (P < .001). Women with insomnia had a shorter sleep duration (P = .012), more wakefulness after sleep onset (P = .031), and a lower sleep efficiency (P = .034) than women without insomnia, regardless of menstrual cycle phase. CONCLUSION Sleep is more disrupted in the luteal phase compared with the follicular phase in midlife women, whether or not they have an insomnia disorder. There is a prominent increase in sleep spindles and spindle frequency activity in the luteal phase, likely an effect of progesterone and/or its neuroactive metabolites acting on sleep regulatory systems.

Premovement high‐alpha power is modulated by previous movement errors: Indirect evidence to endorse high‐alpha power as a marker of resource allocation during motor programming

Abstract Previous electroencephalographic studies have identified premovement high‐alpha power as a predictor of movement accuracy; less frontal‐central high‐alpha power is associated with accurate movements (e.g., holed golf putts), and could reflect more cognitive resources being allocated to response programming. The present experiment tested this interpretation. Ten expert and ten novice golfers completed 120 putts while high‐alpha power was recorded and analyzed as a function of whether the previous putt was holed (i.e., a correct response) or missed (i.e., an error). Existing evidence indicates that more resources are allocated to response programming following errors. We observed less premovement high‐alpha power following errors, especially in experts. Our findings provide indirect evidence that high‐alpha power is an inverse marker of the amount of resources allocated to motor response programming.

Age-Related Differences in Sleep Architecture and Electroencephalogram in Adolescents in the National Consortium on Alcohol and Neurodevelopment in Adolescence Sample.

STUDY OBJECTIVES To investigate age-related differences in polysomnographic and sleep electroencephalographic (EEG) measures, considering sex, pubertal stage, ethnicity, and scalp topography in a large group of adolescents in the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA). METHODS Following an adaptation/clinical screening night, 141 healthy adolescents (12-21 y, 64 girls) had polysomnographic recordings, from which sleep staging and EEG measures were derived. The setting was the SRI International Human Sleep Laboratory and University of Pittsburgh Pediatric Sleep Laboratory. RESULTS Older age was associated with a lower percentage of N3 sleep, accompanied by higher percentages of N2, N1, and rapid eye movement (REM) sleep. Older boys compared with younger boys had more frequent awakenings and wakefulness after sleep onset, effects that were absent in girls. Delta (0.3-4 Hz) EEG power in nonrapid eye movement NREM sleep was lower in older than younger adolescents at all electrode sites, with steeper slopes of decline over the occipital scalp. EEG power in higher frequency bands was also lower in older adolescents than younger adolescents, with equal effects across electrodes. Percent delta power in the first NREM period was similar across age. African Americans had lower EEG power across frequency bands (delta to sigma) compared with Caucasians. Finally, replacing age with pubertal status in the models showed similar relationships. CONCLUSIONS Substantial differences in sleep architecture and EEG were evident across adolescence in this large group, with sex modifying some relationships. Establishment and follow-up of this cohort allows the investigation of sleep EEG-brain structural relationships and the effect of behaviors, such as alcohol and substance use, on sleep EEG maturation.

Emotional modulation of pain-related evoked potentials

Highlights • Pain-related evoked potentials were similarly influenced by emotional priming.• The amplitude of both N2 and P2 decreased monotonically from viewing neutral to pleasant to unpleasant pictures.• Cortical processing of trigeminal nociception is modulated by emotion.• Reductions in pain-related evoked potentials may be explained by the ability of affective pictures to grab attention.

K-Complexes: Interaction between the Central and Autonomic Nervous Systems during Sleep

STUDY OBJECTIVES To investigate the relationship between K-complexes (KCs) and cardiac functioning. METHODS Forty healthy adolescents aged 16-22 y (19 females) participated in the study. Heart rate (HR) fluctuations associated with spontaneous and evoked KCs were investigated on two nights, one with (event-related potential night) and one without auditory tones presented across the night. RESULTS There was a clear biphasic cardiac response to evoked and spontaneous KCs, with an initial acceleration in HR followed by a deceleration (P < 0.001). HR acceleration occurred immediately to KCs in response to tones presented in the first third of the interbeat interval, but was delayed a beat when the tone occurred later in the cardiac cycle (P < 0.05). Sex differences were also evident. Pretone baseline HR was higher, and the magnitude of the HR response was blunted and delayed, in female compared to male adolescents (P < 0.001). Also, pretone baseline HR was lower when a tone elicited a KC compared to when it did not (P < 0.001), suggesting that KCs are possibly more likely to be elicited by external stimuli in states of reduced cardiac activation. CONCLUSIONS The strict dependency observed between KCs and cardiac control indicates a potential role of KCs in modulating the cardiovascular system during sleep. Sex differences in the KC-cardiac response indicate the sensitivity of this measure in capturing sex differences in cardiac regulatory physiology.

Cardiac autonomic function during sleep: Effects of alcohol dependence and evidence of partial recovery with abstinence

Chronic alcoholism is associated with the development of cardiac and peripheral autonomic nervous system (ANS) pathology. The aim of the present study was to evaluate the extent to which recovery in ANS function could be demonstrated over the first 4 months of abstinence. Fifteen alcoholics (7 women) were studied on three occasions: within a month of detoxification, at approximately 2 months post-detox, and at 4 months post-detox. Thirteen control subjects (6 women) were also studied on three occasions with inter-study intervals matching those of the alcoholics. Six alcoholics relapsed, 48.7 ± 27.9 days following the initial PSG session. ANS function was assessed in the first part of stable non-rapid eye movement sleep. Frequency-domain power spectral analysis of heart rate variability (HRV) produced variables including: heart rate (HR), total power (TP; an index representing total HR variability), High Frequency power (HFa; an index reflecting cardiac vagal modulation), HF proportion of total power (HFprop sympathovagal balance), and HF peak frequency (HFpf; an index reflecting respiration rate). Overall, high total and high frequency variability and low sympathovagal balance and myocardial contractility are considered as desired conditions to promote cardiovascular health. At initial assessment, alcoholics had a higher HR (p < 0.001) and respiratory rate (p < 0.01), and lower vagal activity (HFa; p < 0.01) than controls. Alcoholics showed evidence of recovery in HR (p = 0.039) and HFa (p = 0.031) with 4 months of abstinence. Alcoholics with higher TP at the initial visit showed a greater improvement in TP from the initial to the 4 month follow-up session (r = 0.75, p < 0.05). Alcoholics showed substantial recovery in HR and vagal modulation of HRV with 4 months of abstinence, with evidence that the extent of recovery in HRV may be partially determined by the extent of alcohol dependence-related insult to the cardiac ANS system. These data support other studies showing recovery in a number of ANS, central nervous system, and behavioral domains with abstinence, even in those with long-term dependence.