0234 Effects of a Post-Deprivation Nap on Peripheral Levels of Cortisol and Interleukin-6 Following 24-Hour Sleep Deprivation (original) (raw)
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Sustaining Executive Functions During Sleep Deprivation: A
2009
Objectives:Stimulant medications appear effective at restoring simple alertness and psychomotor vigilance in sleep deprived individuals, but it is not clear whether these medications are effective at restoring higher order complex cognitive capacities such as planning, sequencing, and decision making.Design:After 44 hours awake, participants received a double-blind dose of one of 3 stimulant medications or placebo. After 45–50 hours awake, participants were tested on computerized versions of the 5-Ring Tower of Hanoi (TOH), the Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST).Setting:In-residence sleep-laboratory facility at the Walter Reed Army Institute of Research.Participants:Fifty-four healthy adults (29 men, 25 women), ranging in age from 18 to 36 years.Interventions:Participants were randomly assigned to 1 of 3 stimulant medication groups, including caffeine, 600 mg (n = 12), modafinil, 400 mg (n = 12), dextroamphetamine, 20 mg (n = 16), or placebo (n = 14).Measurements and Results:At the doses tested, modafinil and dextroamphetamine groups completed the TOL task in significantly fewer moves than the placebo group, and the modafinil group demonstrated greater deliberation before making moves. In contrast, subjects receiving caffeine completed the TOH in fewer moves than all 3 of the other groups, although speed of completion was not influenced by the stimulants. Finally, the modafinil group outperformed all other groups on indices of perseverative responding and perseverative errors from the WCST.Conclusions:Although comparisons across tasks cannot be made due to the different times of administration, within-task comparisons suggest that, at the doses tested here, each stimulant may produce differential advantages depending on the cognitive demands of the task.Citation:Killgore WDS; Kahn-Greene ET; Grugle NL; Killgore DB; Balkin TJ. Sustaining Executive Functions During Sleep Deprivation: A Comparison of Caffeine, Dextroamphetamine, and Modafinil. SLEEP 2009;32(2):205–216.
The Neurobiology of Executive Function Under Stress and Optimization of Performance
Lecture Notes in Computer Science, 2015
Much basic and clinical research to date has investigated predictors of stress resilience and vulnerability, indicating, for example, that broad impact neurobiological factors, such as neuropeptide Y (NPY) and neuroactive steroids, are mechanistically related to short term stress resilience, as well as longterm patterns of stress-related medical and neuropsychiatric comorbidities. The problem is that we lack good methods for identifying predictors of stress resilience or vulnerability at an individual level, so that human performance and therapeutic interventions can be targeted precisely to underlying points of malfunction for maximum effectiveness. We thus propose modified experimental designs that capitalize on our growing capacities to query and analyze multimodal data across the translational levels of human biology and behavior. We propose that use of these methods in studies of individuals participating in intense military training or returning from deployment could enable better prediction of performance, and development of more effective personalized interventions aimed at optimizing and maintaining stress resilience over time.
Changes in central GABAergic function following acute and repeated stress
1 The function of y-aminobutyric acid (GABA)ergic systems in response to acute and repeated stressful manipulations was evaluated in both the corpus striatum and frontal cerebral cortex ofthe rat. 2 In the corpus striatum the activity ofthe synthetic enzyme for GABA (glutamic acid decarboxylase, GAD) and the levels of GABA were reduced by acute immobilization stress (1 h). GABA turnover was reduced only by acute cold stress (3 h, 4C). 3 In the frontal cerebral cortex no changes were observed after acute stressful manipulations, but repeated stress (0.5 h immobilization per day for 14 days) enhanced both GAD activity and GABA turnover, and reduced GABA levels. 4 In conclusion, it would appear that the GABAergic system in the corpus striatum of the rat is most sensitive to acute stress and that the system in the frontal cerebral cortex area is preferentially responsive to chronic stress. It is speculated that the cortical GABAergic system is responsible for adaptive responses to the adverse conditions prevailing during chronic stress.
Journal of Sleep Research, 2003
SUMMAR Y Daytime performance changes were examined during chronic sleep restriction or augmentation and following subsequent recovery sleep. Sixty-six normal volunteers spent either 3 (n ¼ 18), 5 (n¼ 16), 7 (n ¼ 16), or 9 h (n ¼ 16) daily time in bed (TIB) for 7 days (restriction ⁄ augmentation) followed by 3 days with 8 h daily TIB (recovery). In the 3-h group, speed (mean and fastest 10% of responses) on the psychomotor vigilance task (PVT) declined, and PVT lapses (reaction times greater than 500 ms) increased steadily across the 7 days of sleep restriction. In the 7-and 5-h groups speed initially declined, then appeared to stabilize at a reduced level; lapses were increased only in the 5-h group. In the 9-h group, speed and lapses remained at baseline levels.
Impacto da terapia cognitivo-comportamental nos fatores neurobiológicos relacionados à resiliência
Archives of Clinical Psychiatry (São Paulo), 2011
Resilience, as an outcome variable, has been largely neglected in the field of therapeutics. Our aim was to investigate the effects of cognitive behavioral therapy (CBT) on neurobiological markers of resilience in posttraumatic stress disorder (PTSD) patients. In this single-case experimental research, we assessed physiological (heart rate, respiratory rate, cardiac vagal tone, sympathetic balance and skin conductance) and neuroendocrine (cortisol and dehydroepiandrosterone − DHEA) variables; and psychometric self-report measures (negative affect, resilience, PTSD symptoms, depression, anxiety and social support). Physiological, neuroendocrine and psychometric responses at rest were measured before and after four months of CBT. The patient was a 45-year-old man who had suffered two armed robberies and failed to respond adequately to pharmacological treatment with paroxetine. CBT led to a reduction in heart rate, respiratory rate, sympathetic balance, skin conductance and cortisol. It also led to an increase in cardiac vagal tone and DHEA. Furthermore, CBT promoted reduction of PTSD symptoms, depression, anxiety and negative affect scores and enhancement of resilience and social support scores. CBT in this single case enhanced resilience-related factors such as DHEA, vagal tone, self-reported resilience and social support suggesting that this therapeutic strategy not only contributed to 'anti' pathology effects but to 'pro' well-being. Additionally, our results show the relevance of investigating the effects of psychological treatments in multiple neurobiological systems in the same PTSD patients to unveil the neurobiological underpinnings of resilience factors.
Low Prefrontal GABA Levels Are Associated With Poor Cognitive Functions in Professional Boxers
Frontiers in Human Neuroscience
Cognitive dysfunction has long been recognized as a frequently observed symptom in individuals with repetitive mild traumatic brain injury (rmTBI) such as professional boxers. The exact neurobiological mechanisms underlying this cognitive deficit have not yet been identified, but it is agreed upon that the prefrontal cortex (PFC) is one of the most commonly affected brain regions in professional boxers. Noting the pivotal role of the two major brain metabolites in human cognitive functions, γ-aminobutyric acid (GABA) and glutamate/glutamine (Glx), we hypothesized that alterations in levels of GABA and Glx in the PFC would be prominent and may correlate with cognitive deficits in professional boxers. Twenty male professional boxers (Boxers) and 14 age-matched healthy males who had never experienced any TBI (CON) were recruited. Using a 3T magnetic resonance imaging (MRI) scanner, single-voxel proton magnetic resonance spectroscopy with Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence was performed to evaluate the levels of GABA and Glx in the PFC. Cognitive function was assessed using the memory and attention domains from the Cambridge Neuropsychological Test Automated Battery. The Boxers showed lower GABA level in the PFC compared to the CON, while also showing lower performance in the attention and memory domains. There were no significant between-group differences in Glx levels. Furthermore, the GABA level correlated with memory performance in the Boxers, but not in attention performance. The current findings may suggest that alterations in GABA levels in the PFC may be a potential neurochemical correlate underlying memory dysfunction related to rmTBI.
Ventromedial prefrontal cortex modulates fatigue after penetrating traumatic brain injury
Neurology, 2010
Background: Fatigue is a common and disabling symptom in neurologic disorders including traumatic penetrating brain injury (PBI). Despite fatigue's prevalence and impact on quality of life, its pathophysiology is not understood. Studies on effort perception in healthy subjects, animal behavioral paradigms, and recent evidence in different clinical populations suggest that ventromedial prefrontal cortex could play a significant role in fatigue pathophysiology in neurologic conditions.
NeuroImage
Working memory processes are associated with the dorsolateral prefrontal cortex (dlPFC). Prior research using proton functional magnetic resonance spectroscopy (1 H fMRS) observed significant dlPFC glutamate modulation during letter 2-back performance, indicative of working memorydriven increase in excitatory neural activity. Acute stress has been shown to impair working memory performance. Herein, we quantified dlPFC glutamate modulation during working memory under placebo (oral lactose) and acute stress conditions (oral yohimbine 54mg + hydrocortisone 10mg). Using a double-blind, randomized crossover design, participants (N=19) completed a letter 2-back task during left dlPFC 1 H fMRS acquisition (Brodmann areas 45/46; 4.5cm 3). An automated fitting procedure integrated with LCModel was used to quantify glutamate levels. Working memory-induced glutamate modulation was calculated as percentage change in glutamate levels from passive visual fixation to 2-back levels. Results indicated acute stress significantly attenuated working memory-induced glutamate modulation and impaired 2-back response accuracy, relative to placebo levels. Follow-up analyses indicated 2-back performance significantly modulated glutamate levels relative to passive visual fixation during placebo but not acute stress. Biomarkers, including blood pressure and saliva cortisol, confirmed that yohimbine + hydrocortisone dosing elicited a significant physiological stress response. These findings support a priori hypotheses and demonstrate that acute stress impairs dlPFC function and excitatory activity. This study highlights a neurobiological mechanism through which acute stress may contribute to *