Temporal association between sleep spindles and ripples in the human anterior and mediodorsal thalamus.

Sleep spindles are major oscillatory components of Non-Rapid Eye Movement (NREM) sleep, reflecting hyperpolarization-rebound sequences of thalamocortical neurons. Reports suggest a link between sleep spindles and several forms of high-frequency oscillations which are considered as expressions of pathological off-line neural plasticity in the central nervous system. Here we investigated the relationship between thalamic sleep spindles and ripples in the anterior and mediodorsal nuclei (ANT and MD) of epilepsy patients. Whole-night LFP from the ANT and MD were co-registered with scalp EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing a Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles were present in the human ANT and MD and roughly, 20% of them were associated with ripples. Ripple-associated thalamic sleep spindles were characterized by longer duration and exceeded pure spindles in terms of spindle power as indicated by time-frequency analysis. Furthermore, ripple amplitude was modulated by the phase of sleep spindles within both thalamic nuclei. No signs of pathological processes were correlated with measures of ripple and spindle association, furthermore, the density of ripple-associated sleep spindles in the ANT showed a positive correlation with verbal comprehension. Our findings indicate the involvement of the human thalamus in coalescent spindle-ripple oscillations of NREM sleep.

Lateralized tactile stimulation during NREM sleep globally increases both slow and fast frequency activities.

Slow frequency activity during non-rapid eye movement (NREM) sleep emerges from synchronized activity of widely distributed thalamo-cortical and cortico-cortical networks, reflecting homeostatic and restorative properties of sleep. Slow frequency activity exhibits a reactive nature, and can be increased by acoustic stimulation. Although non-invasive brain stimulation is a promising technique in basic and clinical sleep research, sensory stimulation studies focusing on modalities other than the acoustic are scarce. We explored here the potential of lateralized vibro-tactile stimulation (VTS) of the finger to locally modify electroencephalographic activity during nocturnal NREM sleep. Eight seconds-long sequences of vibro-tactile pulses were delivered at a rate of 1 Hz either to the left or to the right index finger, in addition to a sham condition, in fourteen healthy participants. VTS markedly increased slow frequency activity that peaked between 1-4 Hz but extended to higher (~13 Hz) frequencies, with fronto-central dominance. Enhanced slow frequency activity was accompanied by increased (14-22 Hz) fast frequency power peaking over central and posterior locations. VTS increased the amplitude of slow waves, especially during the first 3-4 s of stimulation. Noticeably, we did not observe local-hemispheric effects, that is, VTS resulted in a global cortical response regardless of stimulation laterality. VTS moderately increased slow and fast frequency activities in resting wakefulness, to a much lower extent compared to NREM sleep. The concomitant increase in slow and fast frequency activities in response to VTS indicates an instant homeostatic response coupled with wake-like, high-frequency activity potentially reflecting transient periods of increased environmental processing.

Lateralized rhythmic acoustic stimulation during daytime NREM sleep enhances slow waves.

Slow wave sleep (SWS) is characterized by the predominance of delta waves and slow oscillations, reflecting the synchronized activity of large cortical neuronal populations. Amongst other functions, SWS plays a crucial role in the restorative capacity of sleep. Rhythmic acoustic stimulation (RAS) during SWS has been shown a cost-effective method to enhance slow wave activity. Slow wave activity can be expressed in a region-specific manner as a function of previous waking activity. However, it is unclear whether slow waves can be enhanced in a region-specific manner using RAS. We investigated the effects of unilaterally presented rhythmic acoustic sound patterns on sleep electroencephalographic (EEG) oscillations. Thirty-five participants received during SWS 12-second long rhythmic bursts of pink noise (at a rate of 1 Hz) that alternated with non-stimulated, silent periods, unilaterally delivered into one of the ears of the participants. As expected, RAS enhanced delta power, especially in its low-frequency components between 0.75 and 2.25 Hz. However, increased slow oscillatory activity was apparent in both hemispheres regardless of the side of the stimulation. The most robust increases in slow oscillatory activity appeared during the first 3-4 seconds of the stimulation period. Furthermore, a short-lasting increase in theta and sigma power was evidenced immediately after the first pulse of the stimulation sequences. Our findings indicate that lateralized RAS has a strong potential to globally enhance slow waves during daytime naps. The lack of localized effects suggests that slow waves are triggered by the ascending reticular system and not directly by specific auditory pathways.

Modern health worries - the dark side of spirituality?

Modern health worries (MHWs) are widespread in modern societies. MHWs were connected to both negative and positive psychological characteristics in previous studies. The study aimed to investigate the relationships among intuitive-experiential information processing style, spirituality, MHWs, and psychological well-being. Members of the Hungarian Skeptic Society (N = 128), individuals committed to astrology (N = 601), and people from a non-representative community sample (N = 554) completed questionnaires assessing intuitive-experiential information processing style, spirituality, modern health worries (MHWs), and psychological well-being. Astrologers showed higher levels of spirituality, intuitive-experiential thinking, and modern health worries than individuals from the community sample; and skeptics scored even lower than the latter group with respect to all three constructs. Within the community sample, medium level connections between measures of spirituality and the experiential thinking style, and weak to medium level correlations between spirituality and MHWs were found. The connection between MHWs and experiential thinking style was completely mediated by spirituality. Individuals with higher levels of spirituality are particularly vulnerable to overgeneralized messages on health related risks. Official communication of potential risks based on rational scientific reasoning is not appropriate to persuade them as it has no impact on the intuitive-experiential system.

Somatic symptoms and holistic thinking as major dimensions behind modern health worries.

BACKGROUND: Modern health worries (MHWs) were related to somatic symptoms and to preference of holistic healing methods in previous studies. PURPOSE: The study aimed to investigate the contribution of symptom-related and holism-related factors to MHWs. METHODS: Participants (visitors of an Internet news portal; N = 16152; 64.1 % males) completed a questionnaire assessing MHWs, somatosensory amplification, somatic symptoms, positive and negative affect, spirituality, holistic health beliefs, and various aspects of health care utilization (both conventional and alternative). RESULTS: Exploratory factor analysis with oblique rotation revealed two independent dimensions ("Somatic symptom distress" and "Holism") MHWs were involved with factor loadings of 0.294 and 0.417, respectively. The existence of two factors was supported by the results of confirmatory factor analysis. No practically significant interaction between the two factors was found in binary logistic regression analysis. Positive and negative affect, somatosensory amplification, spirituality, and holistic health beliefs were positively connected, while self-rated health status was negatively connected to MHWs even after controlling for socio-demographic and treatment-related variables. CONCLUSIONS: Holistic thinking and symptom-related behavioral and psychological factors are independently associated with MHWs. Modern health worries can be conceptualized as symptom-related by-products of a holistic-spiritual worldview.

[Nightmares in the bedroom of science: mapping of a neglected sleep disorder]. / Rémálmok a tudomány hálószobájában: Egy elhanyagolt alvászavar feltérképezése.

Nightmares are intense and unpleasant dream experiences that characterize approximately 4 percent of the adult population at least on a weekly basis. Nightmare frequency is often co-morbid with other mental complaints; however, recent results indicate that nightmare disorder is independent from waking mental dysfunctions. Nightmare disorder is intimately related to poor subjective sleep quality, and according to polysomnographic studies nightmare subjects' sleep is characterized by increased sleep fragmentation and hyper-arousal. These findings suggest that instead of the psychopathological perspective nightmare disorder should be viewed as a specific sleep disorder that requires targeted treatment. Nevertheless, in order to choose the adequate treatment procedure clinicians should examine the co-morbid mental disorders as well taking into consideration the severity of nightmare distress, the latter supposed to be the mediator between nightmare frequency and waking mental dysfunctions.

Mindfulness and dream quality: the inverse relationship between mindfulness and negative dream affect.

The aim of the study was to examine the relationship of mindfulness to the emotional quality of dreaming. In our questionnaire-based study, comprising the data of 587 undergraduate students we examined the association between trait anxiety, perceived stress, trait mindfulness, negative dream affect and dream anxiety. Our results indicate that mindfulness is inversely related to disturbed dreaming and predicts less severe dream disturbances after controlling for trait anxiety. Moreover, the results of the applied hierarchical regression analysis suggest that mindfulness is associated with reduced dream anxiety by moderating the extent of waking anxiety. Our findings extend previous research relating mindfulness, emotional regulation and sleep quality to the domain of dream research. We suggest that mindfulness is a possible protective factor against dream disturbances.