Weak with laughter

Evolution of laughter from play

In this hypothesis, I discuss how laughter from physical play could have evolved to being induced via visual or even verbal stimuli, and serves as a signal to highlight incongruity that could potentially pose a threat to survival. I suggest how laughter's induction could have negated the need for physical contact in play, evolving from its use in tickling, to tickle-misses, and to taunting, and I discuss how the application of deep learning neural networks trained on images of spectra of a variety of laughter types from a variety of individuals or even species, could be used to determine such evolutionary pathways via the use of latent space exploration.

First They Scream, Then They Laugh: The Cognitive Intersections of Humor and Fear

On the surface, fear and humor seem like polar opposite states of mind, yet throughout our lives they continually interact. In this paper, we synthesize neurobiological, psychological, and evolutionary research on fear and humor, arguing that the two are deeply connected. The evolutionary origins of humor reside in play, a medium through which animals benignly explore situations and practice strategies, such as fight or flight, which would normally be accompanied by fear. Cognitively, humor retains the structure of play. Adopting a view of humor as requiring two appraisals, a violation appraisal and a benign appraisal, we describe how fear-inducing stimuli can be rendered benignly humorous through contextual cues, psychological distance, reframing, and cognitive reappraisal. The antagonistic relationship between humor and fear in terms of their neurochemistry and physiological effects in turn makes humor ideal for managing fear in many circumstances. We review five real-world examples of humor and fear intersecting, presenting new data in support of our account along the way. Finally, we discuss the possible therapeutic relevance of the deep connection between humor and fear.

Development and Validation of the Pediatric Hypersomnolence Survey

BACKGROUND AND OBJECTIVES

Narcolepsy and idiopathic hypersomnia usually begin in early adolescence, but diagnostic delays ranging from 5 to 10 years are common, affecting disease burden. To improve early identification of these treatable conditions, we developed and validated the Pediatric Hypersomnolence Survey (PHS).

METHODS

Content was developed through literature review, patient focus groups, interviews with experts in the field, and field testing. We then validated the 14-item self-reported survey across 3 hospitals and web recruitment from patient groups. In the validation phase, we recruited a total of 331 participants (patients with narcolepsy type 1 [n = 64], narcolepsy type 2 [n = 34], idiopathic hypersomnia [n = 36], and other sleep disorders [n = 97] and healthy controls [n = 100], ages 8-18 years) to complete the survey. We assessed a range of psychometric properties, including discriminant diagnostic validity for CNS disorders of hypersomnolence using receiver operating characteristic curve analysis and reliability across a 1-week period.

RESULTS

Confirmatory factor analysis indicated a 4-domain solution with good reliability expressed by satisfactory omega values. Across groups, the PHS total score showed appropriate positive correlations with other validated surveys of sleepiness (r = 0.65-0.78, p < 0.001) and negative correlations with multiple sleep latency test measures (mean sleep latency: r = -0.27, p = 0.006; number of sleep-onset REM periods: r = 0.26, p = 0.007). Compared to controls and patients with other sleep disorders, the area under the curve for participants with narcolepsy or idiopathic hypersomnia was 0.87 (standard error 0.02, 95% CI 0.83-0.91) with high sensitivity (81.3, 95% CI 73.7%-87.5%) and specificity (81.2%, 95 CI 75.1%-86.4%). Test-retest reliability was r = 0.87.

DISCUSSION

The PHS is a valid and reliable tool for clinicians to identify pediatric patients with narcolepsy and idiopathic hypersomnia. Implemented in clinical practice, the PHS will potentially decrease diagnostic delays and time to treatment, ultimately reducing disease burden for these debilitating conditions.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the PHS accurately identifies patients with central disorders of hypersomnolence.

Clinical Characteristics of Cataplectic Attacks in Type 1 Narcolepsy

PURPOSE OF REVIEW

Narcolepsy is a central disorder of hypersomnolence with symptoms of excessive daytime sleepiness, sleep paralysis, and cataplexy. Cataplexy is the sudden loss of muscle tone in either the face, neck, trunk, and/or limbs, leading to a loss of voluntary muscle control. This article reviews recent research on the clinical characteristics of cataplexy.

RECENT FINDINGS

Longitudinal research in adults suggests that there may be a remission of cataplectic severity after symptom stabilization. First-line treatment options for cataplexy include sodium oxybate and pitolisant, with many drugs such as AXS-12, FT218, and JZP258 under investigation. Patients with cataplexy reported greater limitations of daily activities such as driving and exercise compared to patients without cataplexy. Cataplexy remains a challenge for children and adults with narcolepsy and can interfere with daily activities. There is no cure for narcolepsy, but cataplexy can be well-managed with current and promising new treatment options on the horizon.

Therapy for Cataplexy

Purpose of the review

Cataplexy, an involuntary loss of muscle activity triggered by strong emotions is the most impressive symptom in narcolepsy. This review gives an overview of the current understanding of cataplexy and its available treatment options.

Recent findings

With the discovery of hypocretin/orexin, the understanding of the pathophysiology of cataplexy advanced in the past decades. In the recent years, with the development of new anticataplectic agents (e.g., Pitolisant) symptomatic treatment of cataplexy has further improved. Abrupt cessation of anticataplectic medication especially antidepressants increase the risk of status cataplecticus, a virtually continuous series of long-lasting cataplectic attacks.

Summary

Cataplexies still remain an under-recognized phenomenon due to missing diagnostic measures. Treatment for cataplexy still remains symptomatic but new agents with better tolerability and usability are continuously developed. New therapeutic actions either targeting the autoimmune mechanisms underlying orexin cell death or substituting orexin action are promising treatments for the near future.

The Sublaterodorsal Tegmental Nucleus Functions to Couple Brain State and Motor Activity during REM Sleep and Wakefulness

Appropriate levels of muscle tone are needed to support waking behaviors such as sitting or standing. However, it is unclear how the brain functions to couple muscle tone with waking behaviors. Cataplexy is a unique experiment of nature in which muscle paralysis involuntarily intrudes into otherwise normal periods of wakefulness. Cataplexy therefore provides the opportunity to identify the circuit mechanisms that couple muscle tone and waking behaviors. Here, we tested the long-standing hypothesis that muscle paralysis during cataplexy is caused by recruitment of the brainstem circuit that induces muscle paralysis during REM sleep. Using behavioral, electrophysiological, and chemogenetic strategies, we found that muscle tone and arousal state can be decoupled by manipulation of the REM sleep circuit (the sublaterodorsal tegmental nucleus [SLD]). First, we show that silencing SLD neurons prevents motor suppression during REM sleep. Second, we show that activating these same neurons promotes cataplexy in narcoleptic (orexin^-/-) mice, whereas silencing these neurons prevents cataplexy. Most importantly, we show that SLD neurons can decouple motor activity and arousal state in healthy mice. We show that SLD activation triggers cataplexy-like attacks in wild-type mice that are behaviorally and electrophysiologically indistinguishable from cataplexy in orexin^-/- mice. We conclude that the SLD functions to engage arousal-motor synchrony during both wakefulness and REM sleep, and we propose that pathological recruitment of SLD neurons could underlie cataplexy in narcolepsy.

Narcolepsy and emotional experience: a review of the literature

Narcolepsy is a chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. This disease affects significantly the overall patient functioning, interfering with social, work, and affective life. Some symptoms of narcolepsy depend on emotional stimuli; for instance, cataplectic attacks can be triggered by emotional inputs such as laughing, joking, a pleasant surprise, and also anger. Neurophysiological and neurochemical findings suggest the involvement of emotional brain circuits in the physiopathology of cataplexy, which seems to depending on the dysfunctional interplay between the hypothalamus and the amygdala associated with an alteration of hypocretin levels. Furthermore, behavioral studies suggest an impairment of emotions processing in narcolepsy-cataplexy (NC), like a probable coping strategy to avoid or reduce the frequency of cataplexy attacks. Consistently, NC patients seem to use coping strategies even during their sleep, avoiding unpleasant mental sleep activity through lucid dreaming. Interestingly, NC patients, even during sleep, have a different emotional experience than healthy subjects, with more vivid, bizarre, and frightening dreams. Notwithstanding this evidence, the relationship between emotion and narcolepsy is poorly investigated. This review aims to provide a synthesis of behavioral, neurophysiological, and neurochemical evidence to discuss the complex relationship between NC and emotional experience and to direct future research.

Melanin-concentrating hormone neurons contribute to dysregulation of rapid eye movement sleep in narcolepsy

The lateral hypothalamus contains neurons producing orexins that promote wakefulness and suppress REM sleep as well as neurons producing melanin-concentrating hormone (MCH) that likely promote REM sleep. Narcolepsy with cataplexy is caused by selective loss of the orexin neurons, and the MCH neurons appear unaffected. As the orexin and MCH systems exert opposing effects on REM sleep, we hypothesized that imbalance in this REM sleep-regulating system due to activity in the MCH neurons may contribute to the striking REM sleep dysfunction characteristic of narcolepsy. To test this hypothesis, we chemogenetically activated the MCH neurons and pharmacologically blocked MCH signaling in a murine model of narcolepsy and studied the effects on sleep-wake behavior and cataplexy. To chemoactivate MCH neurons, we injected an adeno-associated viral vector containing the hM3Dq stimulatory DREADD into the lateral hypothalamus of orexin null mice that also express Cre recombinase in the MCH neurons (MCH-Cre::OX-KO mice) and into control MCH-Cre mice with normal orexin expression. In both lines of mice, activation of MCH neurons by clozapine-N-oxide (CNO) increased rapid eye movement (REM) sleep without altering other states. In mice lacking orexins, activation of the MCH neurons also increased abnormal intrusions of REM sleep manifest as cataplexy and short latency transitions into REM sleep (SLREM). Conversely, a MCH receptor 1 antagonist, SNAP 94847, almost completely eliminated SLREM and cataplexy in OX-KO mice. These findings affirm that MCH neurons promote REM sleep under normal circumstances, and their activity in mice lacking orexins likely triggers abnormal intrusions of REM sleep into non-REM sleep and wake, resulting in the SLREM and cataplexy characteristic of narcolepsy.

Cataplexy

Remarkably and almost invariably, the clinical phenomenon of cataplexy results from the loss of around 40 000 hypocretin-containing neurones in the lateral hypothalamus in the context of narcolepsy type 1. Cataplexy reflects the dysregulation of rapid-eye-movement (REM) sleep, such that REM-sleep atonia intrudes inappropriately into wakefulness as brief episodes of either focal or total paralysis of voluntary muscle. The semiology of cataplexy differs between adults and children. A defining and enigmatic aspect is that certain emotional stimuli usually trigger the episodes. Cataplexy can be the most disabling symptom of the narcolepsy syndrome, severely limiting normal activities of daily living. Antidepressant drug therapy at relatively low doses is the traditional treatment; these most likely work through inhibiting REM sleep, predominantly by increasing brain monoamine concentrations. Sodium oxybate is probably the most effective drug for severe cataplexy, taken before overnight sleep and once through the night; its precise mechanism of action remains obscure. Pitolisant is a new agent for treating the excessive daytime sleepiness of narcolepsy that also helps cataplexy control by increasing histamine concentrations in the hypothalamus. Further understanding of the neurobiology of cataplexy and how it relates to hypocretin deficiency should improve our understanding of the brain's emotional processing and provide insights into REM sleep and its control.

Automatic detection of cataplexy

OBJECTIVE

Although being the most specific symptom of narcolepsy type 1 (NT1), cataplexy is currently investigated by clinical interview only, with potential diagnostic pitfalls. Our study aimed at testing the accuracy of an automatic video detection of cataplexy in NT1 patients vs. non-cataplectic subjects undergoing a standardized test with emotional stimulation.

METHODS

Fifteen drug-naive NT1 patients and 15 age- and sex-balanced non-cataplectic subjects underwent a standardized video recording procedure including emotional stimulation causing laughter. Video recordings were visually inspected by human scorers to detect three typical cataplexy facial motor patterns (ptosis, mouth opening and head drop), and then analysed by SHIATSU (Semantic-based HIearchical Automatic Tagging of videos by Segmentation using cUts). Expert-based and automatic attack detection was compared in NT1 patients and non-cataplectic subjects.

RESULTS

All NT1 patients and none of the non-cataplectic subjects displayed cataplexy during emotional stimulation. Automatic detection correlated well with experts' assessments in NT1 with an overall accuracy of 81%. In non-cataplectic subjects, automatic detection falsely identified cataplexy in two out of 15 (13.3%) subjects who showed active eyes closure during intense laughter as a confounder with ptosis.

CONCLUSIONS

Automatic cataplexy detection by applying SHIATSU to a standardized test for video documentation of cataplexy is feasible, with an overall accuracy of 81% compared to human examiners. Further studies are warranted to enlarge the range of elementary motor patterns detected, analyse their temporal/spatial relations and quantify cataplexy for diagnostic purposes.

Brain Circuitry Controlling Sleep and Wakefulness

PURPOSE OF REVIEW

This article outlines the fundamental brain mechanisms that control sleep-wake patterns and reviews how pathologic changes in these control mechanisms contribute to common sleep disorders.

RECENT FINDINGS

Discrete but interconnected clusters of cells located within the brainstem and hypothalamus comprise the circuits that generate wakefulness, non-rapid eye movement (non-REM) sleep, and REM sleep. These clusters of cells use specific neurotransmitters, or collections of neurotransmitters, to inhibit or excite their respective sleep- and wake-promoting target sites. These excitatory and inhibitory connections modulate not only the presence of wakefulness or sleep, but also the levels of arousal within those states, including the depth of sleep, degree of vigilance, and motor activity. Dysfunction or degeneration of wake- and sleep-promoting circuits is associated with narcolepsy, REM sleep behavior disorder, and age-related sleep disturbances.

SUMMARY

Research has made significant headway in identifying the brain circuits that control wakefulness, non-REM, and REM sleep and has led to a deeper understanding of common sleep disorders and disturbances.

Cataplexy and Its Mimics: Clinical Recognition and Management

OPINION STATEMENT

This review describes the diagnosis and management of cataplexy: attacks of bilateral loss of muscle tone, triggered by emotions and with preserved consciousness. Although cataplexy is rare, its recognition is important as in most cases, it leads to a diagnosis of narcolepsy, a disorder that still takes a median of 9 years to be diagnosed. The expression of cataplexy varies widely, from partial episodes affecting only the neck muscles to generalized attacks leading to falls. Moreover, childhood cataplexy differs from the presentation in adults, with a prominent facial involvement, already evident without clear emotional triggers ('cataplectic facies') and 'active' motor phenomena especially of the tongue and perioral muscles. Next to narcolepsy, cataplexy can sometimes be caused by other diseases, such as Niemann-Pick type C, Prader Willi Syndrome, or lesions in the hypothalamic or pontomedullary region. Cataplexy mimics include syncope, epilepsy, hyperekplexia, drop attacks and pseudocataplexy. They can be differentiated from cataplexy using thorough history taking, supplemented with (home)video recordings whenever possible. Childhood narcolepsy, with its profound facial hypotonia, can be confused with neuromuscular disorders, and the active motor phenomenona resemble those found in childhood movement disorders such as Sydenham's chorea. Currently, the diagnosis of cataplexy is made almost solely on clinical grounds, based on history taking and (home) videos. Cataplexy shows remarkable differences in childhood compared to adults, with profound facial hypotonia and complex active motor phenomena. Over time, these severe symptoms evolve to the milder adult phenotype, and this pattern is crucial to recognize when assessing the outcome of uncontrolled case series with potential treatments such as immunomodulation. Symptomatic treatment is possible with antidepressants and sodium oxybate. Importantly, management also needs to involve sleep hygiene advice, safety measures whenever applicable and guidance with regard to the social sequelae of cataplexy.

Narcolepsy

Narcolepsy is a chronic sleep disorder that has a typical onset in adolescence and is characterized by excessive daytime sleepiness, which can have severe consequences for the patient. Problems faced by patients with narcolepsy include social stigma associated with this disease, difficulties in obtaining an education and keeping a job, a reduced quality of life and socioeconomic consequences. Two subtypes of narcolepsy have been described (narcolepsy type 1 and narcolepsy type 2), both of which have similar clinical profiles, except for the presence of cataplexy, which occurs only in patients with narcolepsy type 1. The pathogenesis of narcolepsy type 1 is hypothesized to be the autoimmune destruction of the hypocretin-producing neurons in the hypothalamus; this hypothesis is supported by immune-related genetic and environmental factors associated with the disease. However, direct evidence in support of the autoimmune hypothesis is currently unavailable. Diagnosis of narcolepsy encompasses clinical, electrophysiological and biological evaluations, but simpler and faster procedures are needed. Several medications are available for the symptomatic treatment of narcolepsy, all of which have quite good efficacy and safety profiles. However, to date, no treatment hinders or slows disease development. Improved diagnostic tools and increased understanding of the pathogenesis of narcolepsy type 1 are needed and might lead to therapeutic or even preventative interventions.

Quantitative Laughter Detection, Measurement, and Classification-A Critical Survey

The study of human nonverbal social behaviors has taken a more quantitative and computational approach in recent years due to the development of smart interfaces and virtual agents or robots able to interact socially. One of the most interesting nonverbal social behaviors, producing a characteristic vocal signal, is laughing. Laughter is produced in several different situations: in response to external physical, cognitive, or emotional stimuli; to negotiate social interactions; and also, pathologically, as a consequence of neural damage. For this reason, laughter has attracted researchers from many disciplines. A consequence of this multidisciplinarity is the absence of a holistic vision of this complex behavior: the methods of analysis and classification of laughter, as well as the terminology used, are heterogeneous; the findings sometimes contradictory and poorly documented. This survey aims at collecting and presenting objective measurement methods and results from a variety of different studies in different fields, to contribute to build a unified model and taxonomy of laughter. This could be successfully used for advances in several fields, from artificial intelligence and human-robot interaction to medicine and psychiatry.

The Brain Correlates of Laugh and Cataplexy in Childhood Narcolepsy

The brain suprapontine mechanisms associated with human cataplexy have not been clarified. Animal data suggest that the amygdala and the ventromedial prefrontal cortex are key regions in promoting emotion-induced cataplectic attacks. Twenty-one drug-naive children/adolescent (13 males, mean age 11 years) with recent onset of narcolepsy type 1 (NT1) were studied with fMRI while viewing funny videos using a "naturalistic" paradigm. fMRI data were acquired synchronously with EEG, mylohyoid muscle activity, and the video of the patient's face. Whole-brain hemodynamic correlates of (1) a sign of fun and amusement (laughter) and of (2) cataplexy were analyzed and compared. Correlations analyses between these contrasts and disease-related variables and behavioral findings were performed.

SIGNIFICANCE STATEMENT

In this study we reported for the first time in humans the brain structures whose neural activity is specifically and consistently associated with emotion-induced cataplexy. To reach this goal drug-naive children and adolescents with recent onset narcolepsy type 1 were investigated. In narcolepsy caused by hypocretin/orexin deficiency, cataplexy is associated with a marked increase in neural activity in the amygdala, the nucleus accumbens, and the ventromedial prefrontal cortex, which represent suprapontine centers that physiologically process emotions and reward. These findings confirm recent data obtained in the hypocretin knock-out mice and suggest that the absence of hypothalamic hypocretin control on mesolimbic reward centers is crucial in determining cataplexy induced by emotions. Emotion-induced laughter occurred in 16 patients, and of these 10 showed cataplexy for a total of 77 events (mean duration = 4.4 s). Cataplexy was marked by brief losses of mylohyoid muscle tone and by the observation of episodes of facial hypotonia, jaw drop, and ptosis. During laughter (without cataplexy) an increased hemodynamic response occurred in a bilateral network involving the motor/premotor cortex and anterior cingulate gyrus. During cataplexy, suprapontine BOLD signal increase was present in the amygdala, frontal operculum-anterior insular cortex, ventromedial prefrontal cortex, and the nucleus accumbens; BOLD signal increases were also observed at locus ceruleus and in anteromedial pons. The comparison of cataplexy versus laugh episodes revealed the involvement of a corticolimbic network that processes reward and emotion encompassing the anterior insular cortex, the nucleus accumbens, and the amygdala.

REM Sleep at its Core - Circuits, Neurotransmitters, and Pathophysiology

Rapid eye movement (REM) sleep is generated and maintained by the interaction of a variety of neurotransmitter systems in the brainstem, forebrain, and hypothalamus. Within these circuits lies a core region that is active during REM sleep, known as the subcoeruleus nucleus (SubC) or sublaterodorsal nucleus. It is hypothesized that glutamatergic SubC neurons regulate REM sleep and its defining features such as muscle paralysis and cortical activation. REM sleep paralysis is initiated when glutamatergic SubC cells activate neurons in the ventral medial medulla, which causes release of GABA and glycine onto skeletal motoneurons. REM sleep timing is controlled by activity of GABAergic neurons in the ventrolateral periaqueductal gray and dorsal paragigantocellular reticular nucleus as well as melanin-concentrating hormone neurons in the hypothalamus and cholinergic cells in the laterodorsal and pedunculo-pontine tegmentum in the brainstem. Determining how these circuits interact with the SubC is important because breakdown in their communication is hypothesized to underlie narcolepsy/cataplexy and REM sleep behavior disorder (RBD). This review synthesizes our current understanding of mechanisms generating healthy REM sleep and how dysfunction of these circuits contributes to common REM sleep disorders such as cataplexy/narcolepsy and RBD.

Classifying syncope

An unambiguous definition of syncope is important for care, research and teaching purposes. Unfortunately, many published definitions described 'syncope' as a broad category of transient loss of consciousness (TLOC) but still appeared to use a much narrower concept, creating confusion. The ESC-classification from 2001 and subsequently distinguished between 'transient loss of consciousness', i.e. disorders sharing unconsciousness of short duration with a rapid and spontaneous recovery and syncope, the form of TLOC that is due to cerebral hypoperfusion. Adding the cerebral hypoperfusion element sets syncope apart from other forms of TLOC, mostly epileptic seizures and psychogenic attacks. We provide short descriptions of different forms of syncope and other forms of TLOC.

Transient loss of consciousness and syncope

Syncope describes a sudden and brief transient loss of consciousness (TLOC) with postural failure due to cerebral global hypoperfusion. The term TLOC is used when the cause is either unrelated to cerebral hypoperfusion or is unknown. The most common causes of syncopal TLOC include: (1) cardiogenic syncope (cardiac arrhythmias, structural cardiac diseases, others); (2) orthostatic hypotension (due to drugs, hypovolemia, primary or secondary autonomic failure, others); (3) neurally mediated syncope (cardioinhibitory, vasodepressor, and mixed forms). Rarely neurologic disorders (such as epilepsy, transient ischemic attacks, and the subclavian steal syndrome) can lead to cerebal hypoperfusion and syncope. Nonsyncopal TLOC may be due to neurologic (epilepsy, sleep attacks, and other states with fluctuating vigilance), medical (hypoglycemia, drugs), psychiatric, or post-traumatic disorders. Basic diagnostic workup of TLOC includes a thorough history and physical examination, and a 12-lead electrocardiogram (ECG). Blood testing, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, echocardiography, head-up tilt test, carotid sinus massage, Holter monitoring, and loop recorders should be obtained only in specific contexts. Management strategies involve pharmacologic and nonpharmacologic interventions, and cardiac pacing.

Amygdala lesions reduce cataplexy in orexin knock-out mice

Narcolepsy is characterized by excessive sleepiness and cataplexy, sudden episodes of muscle weakness during waking that are thought to be an intrusion of rapid eye movement sleep muscle atonia into wakefulness. One of the most striking aspects of cataplexy is that it is often triggered by strong, generally positive emotions, but little is known about the neural pathways through which positive emotions trigger muscle atonia. We hypothesized that the amygdala is functionally important for cataplexy because the amygdala has a role in processing emotional stimuli and it contains neurons that are active during cataplexy. Using anterograde and retrograde tracing in mice, we found that GABAergic neurons in the central nucleus of the amygdala heavily innervate neurons that maintain waking muscle tone such as those in the ventrolateral periaqueductal gray, lateral pontine tegmentum, locus ceruleus, and dorsal raphe. We then found that bilateral, excitotoxic lesions of the amygdala markedly reduced cataplexy in orexin knock-out mice, a model of narcolepsy. These lesions did not alter basic sleep-wake behavior but substantially reduced the triggering of cataplexy. Lesions also reduced the cataplexy events triggered by conditions associated with high arousal and positive emotions (i.e., wheel running and chocolate). These observations demonstrate that the amygdala is a functionally important part of the circuitry underlying cataplexy and suggest that increased amygdala activity in response to emotional stimuli could directly trigger cataplexy by inhibiting brainstem regions that suppress muscle atonia.

Complex movement disorders at disease onset in childhood narcolepsy with cataplexy

Narcolepsy with cataplexy is characterized by daytime sleepiness, cataplexy (sudden loss of bilateral muscle tone triggered by emotions), sleep paralysis, hypnagogic hallucinations and disturbed nocturnal sleep. Narcolepsy with cataplexy is most often associated with human leucocyte antigen-DQB1*0602 and is caused by the loss of hypocretin-producing neurons in the hypothalamus of likely autoimmune aetiology. Noting that children with narcolepsy often display complex abnormal motor behaviours close to disease onset that do not meet the classical definition of cataplexy, we systematically analysed motor features in 39 children with narcolepsy with cataplexy in comparison with 25 age- and sex-matched healthy controls. We found that patients with narcolepsy with cataplexy displayed a complex array of ‘negative’ (hypotonia) and ‘active’ (ranging from perioral movements to dyskinetic–dystonic movements or stereotypies) motor disturbances. ‘Active’ and ‘negative’ motor scores correlated positively with the presence of hypotonic features at neurological examination and negatively with disease duration, whereas ‘negative’ motor scores also correlated negatively with age at disease onset. These observations suggest that paediatric narcolepsy with cataplexy often co-occurs with a complex movement disorder at disease onset, a phenomenon that may vanish later in the course of the disease. Further studies are warranted to assess clinical course and whether the associated movement disorder is also caused by hypocretin deficiency or by additional neurochemical abnormalities.

Clinical and urodynamic effect of methylphenidate for the treatment of giggle incontinence (enuresis risoria)

AIMS

We retrospectively investigated the efficacy of methylphenidate (MPH) in giggle incontinence (GI), and the relationship between GI and urodynamic parameters.

METHODS

Nine (n = 9) female GI patients underwent 1 year of treatment with 5 mg MPH. Three questionnaires, voiding diaries, and UDS were conducted before and after treatment. The severity of GI was classified into mild, moderate, and severe. Clinical success was characterized as: full response, response, partial response, and non-response.

RESULTS

The mean age of all patients was 16.2 ± 2.3 years. Five patients had mild, one had moderate, and three had severe grade incontinent. All patients reported complete cessation of wetting after MPH treatment. The mean duration of asymptomatic period was 7 ± 3.2 months. There were no statistically significant score changes in all three questionnaires: Urgency Perception Scale (UPS), Overactive Bladder Symptom Score (OABSS) and Primary Overactive Symptom Questionnaire (POSQ), and voiding diaries (P > 0.05). In UDS, there were no statistically significant altered parameters, except maximum urethral closure pressure (MUCP) and maximum urethral pressure (MUP). After treatment, the mean MUCP was increased from 52.2 ± 6.8 to 73.0 ± 5.4 cmH(2) O (P < 0.05), and the mean MUP was increased from 48.6 ± 7.3 to 70.2 ± 5.0 cmH(2) O (P < 0.05).

CONCLUSIONS

MPH can be a viable option for the primary treatment of GI, and it may be related to increasing urethral closure pressure. It was not possible to establish if a relationship between GI and detrusor overactivity exists.

Sleep state switching

We take for granted the ability to fall asleep or to snap out of sleep into wakefulness, but these changes in behavioral state require specific switching mechanisms in the brain that allow well-defined state transitions. In this review, we examine the basic circuitry underlying the regulation of sleep and wakefulness and discuss a theoretical framework wherein the interactions between reciprocal neuronal circuits enable relatively rapid and complete state transitions. We also review how homeostatic, circadian, and allostatic drives help regulate sleep state switching and discuss how breakdown of the switching mechanism may contribute to sleep disorders such as narcolepsy.

Animal models of narcolepsy

Narcolepsy is a debilitating sleep disorder with excessive daytime sleepiness and cataplexy as its two major symptoms. Although this disease was first described about one century ago, an animal model was not available until the 1970s. With the establishment of the Stanford canine narcolepsy colony, researchers were able to conduct multiple neurochemical studies to explore the pathophysiology of this disease. It was concluded that there was an imbalance between monoaminergic and cholinergic systems in canine narcolepsy. In 1999, two independent studies revealed that orexin neurotransmission deficiency was pivotal to the development of narcolepsy with cataplexy. This scientific leap fueled the generation of several genetically engineered mouse and rat models of narcolepsy. To facilitate further research, it is imperative that researchers reach a consensus concerning the evaluation of narcoleptic behavioral and EEG phenomenology in these models.

Prevalence of narcolepsy-cataplexy in Korean adolescents

BACKGROUND

Narcolepsy typically begins between adolescence and early adulthood causing severe neuropsychiatric impairments, but few prevalence studies are available on adolescent narcoleptics. In the present study, we investigated the prevalence of narcolepsy-cataplexy in adolescents.

METHODS

In total 20,407 students, aged 14-19 years, participated in this study. Ullanlinna Narcolepsy Scale (UNS) was applied to all subjects and those with a UNS score of > or =14 were contacted by phone for semi-structured interview. Subjects then suspected of having narcolepsy participated in a laboratory investigation, which included polysomnography and HLA typing, or were interviewed in detail by telephone.

RESULTS

Three subjects were finally diagnosed as narcolepsy with cataplexy and seven subjects might be diagnosed as narcolepsy without cataplexy. Among three narcoleptics with cataplexy, two subjects were HLA-DQB1*0602 and DRB1*1501 positive, but one subject had no test of HLA typing. The prevalence of narcolepsy with cataplexy in Korean adolescence was thus determined to be 0.015% (95% confidence interval = 0.0-0.0313%).

CONCLUSION

This epidemiologic study is the first of its type on adolescent narcolepsy to use the International Classification of Sleep Disorders, 2nd edition (ICSD-2) diagnostic criteria. Considering those cases with an onset after adolescence were not included, the prevalence of narcolepsy with cataplexy determined in the present study is comparable with that of other studies in adults.

Drive to the human respiratory muscles

The motor control of the respiratory muscles differs in some ways from that of the limb muscles. Effectively, the respiratory muscles are controlled by at least two descending pathways: from the medulla during normal quiet breathing and from the motor cortex during behavioural or voluntary breathing. Neurophysiological studies of single motor unit activity in human subjects during normal and voluntary breathing indicate that the neural drive is not uniform to all muscles. The distribution of neural drive depends on a principle of neuromechanical matching. Those motoneurones that innervate intercostal muscles with greater mechanical advantage are active earlier in the breath and to a greater extent. Inspiratory drive is also distributed differently across different inspiratory muscles, possibly also according to their mechanical effectiveness in developing airway negative pressure. Genioglossus, a muscle of the upper airway, receives various types of neural drive (inspiratory, expiratory and tonic) distributed differentially across the hypoglossal motoneurone pool. The integration of the different inputs results in the overall activity in the muscle to keep the upper airway patent throughout respiration. Integration of respiratory and non-respiratory postural drive can be demonstrated in respiratory muscles, and respiratory drive can even be observed in limb muscles under certain circumstances. Recordings of motor unit activity from the human diaphragm during voluntary respiratory tasks have shown that depending on the task there can be large changes in recruitment threshold and recruitment order of motor units. This suggests that descending drive across the phrenic motoneurone pool is not necessarily consistent. Understanding the integration and distribution of drive to respiratory muscles in automatic breathing and voluntary tasks may have implications for limb motor control.

A threshold theory of the humor response

The humor response has long been considered mysterious, and it is given relatively little attention in modern experimental psychology, in spite of the fact that numerous studies suggest that it has substantial benefits for mood and health. Existing theories of humor fail to account for some of the most basic humor phenomena. On most occasions when a humor response occurs, certain verbal or visual stimuli (the "setup" stimuli, which function as an establishing operation) must precede a critical stimulus (such as a "punch line" or the final panel or critical feature of a cartoon), which then occasions a sudden "revelation" or "understanding"; this revelation is often accompanied by the humor response. We suggest that the setup stimuli increase the strength of the revelatory response to a point just below the threshold of awareness and that the critical stimulus, properly designed and timed, edges the revelatory response to a point just above threshold. We also suggest that it is this threshold phenomenon that produces most instances of the humor response. We discuss these issues in the context of some notable humor of Carl Rogers and B. F. Skinner.

An approach to daytime wetting in children

Daytime wetting is a common problem with various causes that can usually be identified through a careful history, thorough physical examination, and urinalysis. Conservative approaches to therapy have a successful outcome in most children. Invasive diagnostic imaging studies and pharmacologic or surgical intervention are necessary only for carefully selected children.

The clinical spectrum of narcolepsy with cataplexy: a reappraisal

In the absence of a golden standard for the diagnosis of narcolepsy, the clinical spectrum of disorder remains controversial. The aims of this study were (1) to determine frequency and characteristics of sleep-wake symptoms in patients with narcolepsy with cataplexy, (2) to compare clinical characteristics with results of ancillary tests, and (3) to identify factors that discriminate narcolepsy from other conditions with excessive daytime sleepiness (EDS). We prospectively studied 57 narcoleptics with cataplexy, 56 patients with non-narcoleptic hypersomnia (H), and 40 normal controls (No). Based on suggested and published criteria, we differentiated between narcoleptics with definite cataplexy (N) and narcoleptics without definite cataplexy (possible cataplexy, NpC). Assessment consisted of questionnaires [all patients and controls, including the Ullanlinna Narcolepsy Score (UNS)], polysomnography (all patients), multiple sleep latency test (MSLT) and human leukocyte antigen typing (in most narcoleptics). A new narcolepsy score based on five questions was developed. Data were compared with those of 12 hypocretin-deficient narcoleptics (N-hd). There were significant differences between N and NpC (including mean sleep latency on MSLT), but none between N and N-hd. A score of sleep propensity during active situations (SPAS) and the frequency of sleep paralysis/hallucinations at sleep onset, dreams of flying, and history of sleep shouting discriminated N from H and No (P < 0.001). Cataplexy-like symptoms in H (18%) and No (8%) could be discriminated from 'true' cataplexy in N on the basis of topography of motor effects, triggering emotions and triggering situations (P < 0.001). Our narcolepsy score had a similar sensitivity (96% versus 98%) but a higher specificity (98% versus 56%) than the UNS. Analysis of co-occurring symptoms in narcolepsy revealed two symptom complexes: EDS, cataplexy, automatic behaviors; and sleep paralysis, hallucinations, parasomnias. Low/undetectable cerebrospinal fluid hypocretin-1 levels and a history of definite cataplexy identify similar subgroups of narcoleptics. Specific questions on severity of EDS (SPAS score) and characteristics of cataplexy allow the recognition of subgroups of narcoleptics and their differentiation from non-narcoleptic EDS patients, including those reporting cataplexy-like episodes. The existence of co-occurring symptoms supports the hypothesis of a distinct pathophysiology of single narcoleptic symptoms.

Pharmacotherapy for cataplexy

A variety of medications representing several major drug classes improve cataplexy in patients with narcolepsy. These include aminergic reuptake inhibitors such as venlafaxine and clomipramine as well as sodium oxybate. This review is intended to familiarize readers with the safety and efficacy of these medications, thus enabling clinicians to optimize their management of cataplexy.

Is motor inhibition during laughter due to emotional or respiratory influences?

We compared the effects of laughter and several respiratory movements on spinal motor excitability to unravel their respective influences. We measured H-reflexes in 13 healthy volunteers during 10 different tasks (including laughter, simulated laughter, and various respiratory movements). We compared the percentage that remained of the initial H-reflex during each task with that during a neutral task. H-reflex percentage differed between the neutral task (79.4 +/- 16.1%), true laughter (43.7 +/- 17.9%), and simulated laughter (66.6 +/- 24.3%), and between the two latter tasks. Coughing also resulted in H-reflex suppression, but not as deeply as true laughter. During the other respiratory maneuvers, the H-reflex increased compared to the neutral task. Our finding that true laughter evoked more H-reflex depression than simulated laughter suggests that mirth on its own depresses the H-reflex. This mechanism may also be involved in the pathophysiology of cataplexy, the main symptom of narcolepsy.

Tickle

Tickle is a familiar sensation that may have two components: a light or feather-type noxious sensation termed by Hall and Allin as knismesis, and a heavy or laughter-associated sensation termed gargalesis. Studies on the sensation of tickle have generally been on one sensation or the other, but not on both. In pleasurable, laughter-associated tickle there are elements of touch and pleasure, but the sensation may be a synthesis of touch and itch, with receptors, neural pathways or central receptors different from knismesis. It is unclear why some skin sites are more ticklish than other sites. Laughter-associated tickle might best be considered a social behavior rather than a reflex. This behavior provides interaction between mother and child, helps to integrate a child with peers and adults in play, and may become part of the mating ritual or sexual foreplay. In tickle play there are elements of dominance and submission, with accompanying laughter and withdrawal developed as the signals of submission. In this scenario, ticklish areas of skin might be considered those areas most vital to the ticklee and allowed to be invaded in the dominance submission play.