Psychologists and neuroscientists have had a long-standing interest in the P3, a prominent component of the event-related brain potential. This review aims to integrate knowledge regarding the neural basis of the P3 and to elucidate its functional role in information processing. The authors review evidence suggesting that the P3 reflects phasic activity of the neuromodulatory locus coeruleus-norepinephrine (LC-NE) system. They discuss the P3 literature in the light of empirical findings and a recent theory regarding the information-processing function of the LC-NE phasic response. The theoretical framework emerging from this research synthesis suggests that the P3 reflects the response of the LC-NE system to the outcome of internal decision-making processes and the consequent effects of noradrenergic potentiation of information processing.

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Decision making, the P3, and the locus coeruleus-norepinephrine system.

We reviewed the literature on sleep in psychiatric disorders and evaluated the data by meta-analysis, a statistical method designed to combine data from different studies. A total of 177 studies with data from 7151 patients and controls were reviewed. Most psychiatric groups showed significantly reduced sleep efficiency and total sleep time, accounted for by decrements in non-rapid eye movement sleep. Rapid eye movement sleep time was relatively preserved in all groups, and percentage of rapid eye movement sleep was increased in affective disorders. Reduction in rapid eye movement sleep latency was seen in affective disorders but occurred in other categories as well. Although no single sleep variable appeared to have absolute specificity for any particular psychiatric disorder, patterns of sleep disturbances associated with categories of psychiatric illnesses were observed. Overall, findings for patients with affective disorders differed most frequently and significantly from those for normal controls.

Sleep and Psychiatric Disorders: A Meta-analysis

Cognitive neuroscience continues to build meaningful connections between affective behavior and human brain function. Within the biological sciences, a similar renaissance has taken place, focusing on the role of sleep in various neurocognitive processes and, most recently, on the interaction between sleep and emotional regulation. This review surveys an array of diverse findings across basic and clinical research domains, resulting in a convergent view of sleep-dependent emotional brain processing. On the basis of the unique neurobiology of sleep, the authors outline a model describing the overnight modulation of affective neural systems and the (re)processing of recent emotional experiences, both of which appear to redress the appropriate next-day reactivity of limbic and associated autonomic networks. Furthermore, a rapid eye movement (REM) sleep hypothesis of emotional-memory processing is proposed, the implications of which may provide brain-based insights into the association between sleep abnormalities and the initiation and maintenance of mood disturbances.

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Overnight therapy? The role of sleep in emotional brain processing.

The Genetics of Depression: A Review

As critical as waking brain function is to cognition, an extensive literature now indicates that sleep supports equally important, different yet complementary operations. This review will consider recent and emerging findings implicating sleep and specific sleep-stage physiologies in the modulation, regulation, and even preparation of cognitive and emotional brain processes. First, evidence for the role of sleep in memory processing will be discussed, principally focusing on declarative memory. Second, at a neural level several mechanistic models of sleep-dependent plasticity underlying these effects will be reviewed, with a synthesis of these features offered that may explain the ordered structure of sleep, and the orderly evolution of memory stages. Third, accumulating evidence for the role of sleep in associative memory processing will be discussed, suggesting that the long-term goal of sleep may not be the strengthening of individual memory items, but, instead, their abstracted assimilation into a schema of generalized knowledge. Fourth, the newly emerging benefit of sleep in regulating emotional brain reactivity will be considered. Finally, and building on this latter topic, a novel hypothesis and framework of sleep-dependent affective brain processing will be proposed, culminating in testable predictions and translational implications for mood disorders.

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The Role of Sleep in Cognition and Emotion

Manifestations of sleep disturbances can potentially serve as external criteria for the diagnosis of specific subtypes of major depressive disorder (MDD). Depressed patients generally experience disturbances of sleep continuity and rapid eye movement (REM) sleep. Disturbances in nonrapid eye movement (NREM) sleep (stages III and IV) also occur. Characteristic of primary sleep disturbance in many depressed patients are shortened REM latency periods and instabilities in NREM sleep identified by increases in the number of stage shifts, decreases in the duration of stage III and IV sleep, and a shift towards lighter sleep stages (sleep efficiency disturbances). Treatment modalities for these sleep disturbances include sleep deprivation therapy and antidepressant therapy. Sleep deprivation alone has been only moderately successful, while antidepressant therapy usually results in symptomatic improvement. To restore normative sleep, REM sleep periods and stage III and IV sleep must be returned to normal. Trazodone therapy has been shown to reduce the frequency of arousals, the severity of drowsiness, and the duration of REM sleep, and increase restorative slow wave sleep and stage III and IV NREM sleep.

Sleep and depression.

Memory failures in progressive idiopathic dementia.

Modest facilitation on memory in dementia with combined lecithin and anticholinerestase treatment.

Cholinergic supersensitivity has been postulated to be an etiologic factor in affective disorder. After several pilot dose-response studies, we administered 8 mg of the cholinergic agonist arecoline subcutaneously to eight pairs of normal volunteer identical twins and eight bipolar patients currently euthymic and unmedicated. During the hour following arecoline administration, the Profile of Mood States (POMS) showed an increase in total mood disturbance in both patient and control groups. Mean systolic blood pressure, pulse, plasma cortisol, prolactin, and growth hormone also increased. Anger and elation scores on the POMS showed significant concordance in identical twins, as did change in prolactin, implying that these are the components of drug response possibly influenced by genetic factors. None of these responses differentiated well state patients from controls. Thus, mood, behavioral, and neurochemical responses to arecoline, which appears to have nonspecific neurochemical effects at the dose employed, are not markers of vulnerability to affective illness.

Natraj Sitaram

Papers

Sleep and depression.

Memory failures in progressive idiopathic dementia.

Modest facilitation on memory in dementia with combined lecithin and anticholinerestase treatment.

Behavioral, physiological, and neuroendocrine responses to arecoline in normal twins and “well state” bipolar patients

The association of supersensitive cholinergic REM-induction and affective illness within pedigrees.