Periodicity of a noninvasive measure of cardiac vagal tone during non-rapid eye movement sleep in non-sleep deprived and sleep-deprived normal subjects

Normal autonomic neurophysiology of postural orthostatic tachycardia and recommended physiological assessments in postural orthostatic tachycardia syndrome

The current surge of interest in postural orthostatic tachycardia syndrome commonly known as POTS requires good knowledge of the very complex physiology involved, but this is currently lacking. The often overlooked normal physiology of orthostasis is reviewed including the definition of normal postural orthostatic tachycardia. An illustrated functional anatomy that embeds orthostatic tachycardia within the learned and skilful motor functions in the human population is presented. The four physiological phases of orthostasis and the role of tachycardia are described in a laboratory-controlled and progressive orthostatic stress in normal human volunteers. Standardized surrogate measures of autonomic control were used to quantify the trigger level for excessive tachycardia and the minimum autonomic control required to sustain viable arterial blood pressure during severe orthostatic stress in normal human volunteers. Tachycardia during orthostasis is part of a "democratic" contribution by four cardiovascular parameters of which the chronotropic function of the heart is just one of the parameters contributing toward cardiovascular compensation. It is adjusted during orthostasis in proportion to contributions from the other three parameters, namely inotropic function of the heart, windkessel vascular resistance and venous vascular capacitance. The physiological effects of the two stressors during orthostasis, gravity and isometric contraction of skeletal muscles are reviewed. A model of how the four cardiovascular parameters are regulated during orthostasis to achieve proportionate contributions is proposed emphasizing the necessity to quantify individual contributions from all these four parameters. Any one or more of these parameters may be compromised due to disease requiring disproportionate contribution of the prevailing magnitude of orthostatic tachycardia in an individual. It therefore requires neurophysiological assessment of the autonomic regulation of all the four cardiovascular parameters to assess the condition fully. We recommend here some current and novel neurophysiological methods that use modern medical technology to quantify laboratory standardized surrogate measures of some of these cardiovascular parameters including central parasympathetic regulation in postural orthostatic tachycardia syndrome.

The Human Nature of Music

Music is at the centre of what it means to be human - it is the sounds of human bodies and minds moving in creative, story-making ways. We argue that music comes from the way in which knowing bodies (Merleau-Ponty) prospectively explore the environment using habitual 'patterns of action,' which we have identified as our innate 'communicative musicality.' To support our argument, we present short case studies of infant interactions using micro analyses of video and audio recordings to show the timings and shapes of intersubjective vocalizations and body movements of adult and child while they improvise shared narratives of meaning. Following a survey of the history of discoveries of infant abilities, we propose that the gestural narrative structures of voice and body seen as infants communicate with loving caregivers are the building blocks of what become particular cultural instances of the art of music, and of dance, theatre and other temporal arts. Children enter into a musical culture where their innate communicative musicality can be encouraged and strengthened through sensitive, respectful, playful, culturally informed teaching in companionship. The central importance of our abilities for music as part of what sustains our well-being is supported by evidence that communicative musicality strengthens emotions of social resilience to aid recovery from mental stress and illness. Drawing on the experience of the first author as a counsellor, we argue that the strength of one person's communicative musicality can support the vitality of another's through the application of skilful techniques that encourage an intimate, supportive, therapeutic, spirited companionship. Turning to brain science, we focus on hemispheric differences and the affective neuroscience of Jaak Panksepp. We emphasize that the psychobiological purpose of our innate musicality grows from the integrated rhythms of energy in the brain for prospective, sensation-seeking affective guidance of vitality of movement. We conclude with a Coda that recalls the philosophy of the Scottish Enlightenment, which built on the work of Heraclitus and Spinoza. This view places the shared experience of sensations of living - our communicative musicality - as inspiration for rules of logic formulated in symbols of language.

The ontogenesis of narrative: from moving to meaning

Narrative, the creation of imaginative projects and experiences displayed in expressions of movement and voice, is how human cooperative understanding grows. Human understanding places the character and qualities of objects and events of interest within stories that portray intentions, feelings, and ambitions, and how one cares about them. Understanding the development of narrative is therefore essential for understanding the development of human intelligence, but its early origins are obscure. We identify the origins of narrative in the innate sensorimotor intelligence of a hypermobile human body and trace the ontogenesis of narrative form from its earliest expression in movement. Intelligent planning, with self-awareness, is evident in the gestures and motor expressions of the mid-gestation fetus. After birth, single intentions become serially organized into projects with increasingly ambitious distal goals and social meaning. The infant imitates others’ actions in shared tasks, learns conventional cultural practices, and adapts his own inventions, then names topics of interest. Through every stage, in simple intentions of fetal movement, in social imitations of the neonate, in early proto-conversations and collaborative play of infants and talk of children and adults, the narrative form of creative agency with it four-part structure of ‘introduction,’ ‘development,’ ‘climax,’ and ‘resolution’ is present. We conclude that shared rituals of culture and practical techniques develop from a fundamental psycho-motor structure with its basic, vital impulses for action and generative process of thought-in-action that express an integrated, imaginative, and sociable Self. This basic structure is evident before birth and invariant in form throughout life. Serial organization of single, non-verbal actions into complex projects of expressive and explorative sense-making become conventional meanings and explanations with propositional narrative power. Understanding the root of narrative in embodied meaning-making in this way is important for practical work in therapy and education, and for advancing philosophy and neuroscience.

Autism as a developmental disorder in intentional movement and affective engagement

We review evidence that autistic spectrum disorders have their origin in early prenatal failure of development in systems that program timing, serial coordination and prospective control of movements, and that regulate affective evaluations of experiences. There are effects in early infancy, before medical diagnosis, especially in motor sequencing, selective or exploratory attention, affective expression and intersubjective engagement with parents. These are followed by retardation of cognitive development and language learning in the second or third year, which lead to a diagnosis of ASD. The early signs relate to abnormalities that have been found in brain stem systems and cerebellum in the embryo or early fetal stage, before the cerebral neocortex is functional, and they have clear consequences in infancy when neocortical systems are intensively elaborated. We propose, with evidence of the disturbances of posture, locomotion and prospective motor control in children with autism, as well as of their facial expression of interest and affect, and attention to other persons' expressions, that examination of the psychobiology of motor affective disorders, rather than later developing cognitive or linguistic ones, may facilitate early diagnosis. Research in this area may also explain how intense interaction, imitation or "expressive art" therapies, which respond intimately with motor activities, are effective at later stages. Exceptional talents of some autistic people may be acquired compensations for basic problems with expectant self-regulations of movement, attention and emotion.

Interictal autonomic abnormalities in idiopathic Rolandic epilepsy

We investigated 50 young patients with a diagnosis of Rolandic Epilepsy (RE) for the presence of abnormalities in autonomic tone compared with 50 young patients with idiopathic generalized epilepsy with absences and 50 typically developing children of comparable age. We analyzed time domain (N-N interval, pNN50) and frequency domain (High Frequency (HF), Low Frequency (LF) and LF/HF ratio) indices from ten-minute resting EKG activity. Patients with RE showed significantly higher HF and lower LF power and lower LF/HF ratio than controls, independent of the epilepsy group, and did not show significant differences in any other autonomic index with respect to the two control groups. In RE, we found a negative relationship between both seizure load and frequency of sleep interictal EEG abnormalities with parasympathetic drive levels. These changes might be the expression of adaptive mechanisms to prevent the excessive sympathetic drive seen in patients with refractory epilepsies.

Pre-ictal autonomic changes

Autonomic measures frequently alter with seizure activity and with brain state and so theoretically, there could be pre-ictal changes in autonomic function. However, there are considerable confounders. First, the measurement of autonomic function is not straightforward; heart rate and measures derived form heart rate have been those that have used the most in assessing changes in autonomic function. Second, autonomic function can vary considerably over the 24h cycle and can change suddenly depending on internal and external stimuli (e.g. fear, pain) and so any measures of changes in autonomic function will lose specificity. Third, changes in autonomic function in response to seizures, depends upon the individual, seizure type and spread of the seizure and even then can vary from seizure to seizure in the same individual. The idea that there will be well-defined, unique autonomic changes that occur in the pre-ictal period is very unlikely. These factors make it unlikely that autonomic function monitoring can be used successfully as a means of seizure prediction. However, in sleep, changes in autonomic function relate to changes in arousal state and since such states and the transition between such states may predict seizure occurrence in certain individuals, autonomic function could be a helpful determinant of seizure risk at certain stages of sleep. This hypothesis has, however, yet to be tested.

All-night EEG power spectral analysis of the cyclic alternating pattern components in young adult subjects

OBJECTIVE

To analyze in detail the frequency content of the different EEG components of the Cyclic Alternating Pattern (CAP), taking into account the ongoing EEG background and the nonCAP (NCAP) periods in the whole night polysomnographic recordings of normal young adults.

METHODS

Sixteen normal healthy subjects were included in this study. Each subject underwent one polysomnographic night recording; sleep stages were scored following standard criteria. Subsequently, each CAP A phase was detected in all recordings, during NREM sleep, and classified into 3 subtypes (A1, A2, and A3). The same channel used for the detection of CAP A phases (C3/A2 or C4/A1) was subdivided into 2-s mini-epochs. For each mini-epoch, the corresponding CAP condition was determined and power spectra calculated in the frequency range 0.5-25 Hz. Average spectra were obtained for each CAP condition, separately in sleep stage 2 and SWS, for each subject. Finally, the first 6h of sleep were subdivided into 4 periods of 90 min each and the same spectral analysis was performed for each period.

RESULTS

During sleep stage 2, CAP A subtypes differed from NCAP periods for all frequency bins between 0.5 and 25 Hz; this difference was most evident for the lowest frequencies. The B phase following A1 subtypes had a power spectrum significantly higher than that of NCAP, for frequencies between 1 and 11 Hz. The B phase after A2 only differed from NCAP for a small but significant reduction in the sigma band power; this was evident also after A3 subtypes. During SWS, we found similar results. The comparison between the different CAP subtypes also disclosed significant differences related to the stage in which they occurred. Finally, a significant effect of the different sleep periods was found on the different CAP subtypes during sleep stage 2 and on NCAP in both sleep stage 2 and SWS.

CONCLUSIONS

CAP subtypes are characterized by clearly different spectra and also the same subtype shows a different power spectrum, during sleep stage 2 or SWS. This finding underlines a probable different functional meaning of the same CAP subtype during different sleep stages. We also found 3 clear peaks of difference between CAP subtypes and NCAP in the delta, alpha, and beta frequency ranges which might indicate the presence of 3 frequency components characterizing CAP subtypes, in different proportion in each of them. The B component of CAP differs from NCAP because of a decrease in power in the sigma frequency range.

SIGNIFICANCE

This study shows that A components of CAP might correspond to periods in which the very-slow delta activity of sleep groups a range of different EEG activities, including the sigma and beta bands, while the B phase of CAP might correspond to a period in which this activity is quiescent or inhibited.

Inter-rater reliability of sleep cyclic alternating pattern (CAP) scoring and validation of a new computer-assisted CAP scoring method

OBJECTIVE

To assess inter-rater reliability between different scorers, from different qualified sleep research groups, in scoring visually the Cyclic Alternating Pattern (CAP), to evaluate the performances of a new tool for the computer-assisted detection of CAP, and to compare its output with the data from the different scorers.

METHODS

CAP was scored in 11 normal sleep recordings by four different raters, coming from three sleep laboratories. CAP was also scored in the same recordings by means of a new computer-assisted method, implemented in the Hypnolab 1.2 (SWS Soft, Italy) software. Data analysis was performed according to the following steps: (a) the inter-rater reliability of CAP parameters between the four different scorers was carried out by means of the Kendall W coefficient of concordance; (b) the analysis of the agreement between the results of the visual and computer-assisted analysis of CAP parameters was also carried out by means of the Kendall W coefficient; (c) a 'consensus' scoring was obtained, for each recording, from the four scorings provided by the different raters, based on the score of the majority of scorers; (d) the degree of agreement between each scorer and the consensus score and between the computer-assisted analysis and the consensus score was quantified by means of the Cohen's k coefficient; (e) the differences between the number of false positive and false negative detections obtained in the visual and in the computer-assisted analysis were also evaluated by means of the non-parametric Wilcoxon test.

RESULTS

The inter-rater reliability of CAP parameters quantified by the Kendall W coefficient of concordance between the four different scorers was high for all the parameters considered and showed values above 0.9 for total CAP time, CAP time in sleep stage 2 and percentage of A phases in sequence; also CAP rate showed a high value (0.829). The most important global parameters of CAP, including total CAP rate and CAP time, scored by the computer-assisted analysis showed a significant concordance with those obtained by the raters. The agreement between the computer-assisted analysis and the consensus scoring for the assignment of the CAP A phase subtype was not distinguishable from that expected from a human scorer. However, the computer-assisted analysis provided a number of false positives and false negatives significantly higher than that of the visual scoring of CAP.

CONCLUSIONS

CAP scoring shows good inter-rater reliability and might be compared in different laboratories the results of which might also be pooled together; however, caution should always be taken because of the variability which can be expected in the classical sleep staging. The computer-assisted detection of CAP can be used with some supervision and correction in large studies when only general parameters such as CAP rate are considered; more editing is necessary for the correct use of the other results.

SIGNIFICANCE

This article describes the first attempt in the literature to evaluate in a detailed way the inter-rater reliability in scoring CAP parameters of normal sleep and the performances of a human-supervised computerized automatic detection system.

Spectral analyses of electroencephalography and heart rate variability during sleep in normal subjects

We investigated the relationship between electroencephalogram (EEG) activity and autonomic nervous system function using spectral analyses of EEG and heart rate variability (HRV) in healthy subjects during sleep. Eleven subjects were enrolled in this study. From EEG, the spectral edge frequencies (SEFs including SEF50, SEF90 and SEF95) were calculated. From electrocardiogram (ECG), the spectral powers of low-frequency band (LF: 0.04-0.15 Hz), high-frequency band (HF: 0.15-0.4 Hz) and the ratio of LF to HF (LF/HF) were calculated. During sleep, each set of data was obtained as the average of a 5-min measurement. We found that SEFs and LF/HF or LF decreased simultaneously and periodically, suggesting simultaneous depression of EEG activity and relative sympathetic activity, and SEFs significantly correlated with LF/HF and LF in all subjects during sleep, but not with HF. The existence of a clear correlation of SEFs with LF or LF/HF may offer a simple approach to estimate the relationship between EEG activity and autonomic nervous system function during sleep.

CAP and arousals in the structural development of sleep: an integrative perspective

OBJECTIVES

It is known that the number of arousals per hour of sleep increases linearly across life, while the amount of cyclic alternating pattern (CAP) undergoes a u-shaped evolution. The present study aimed at investigating the differences, overlaps and age-related distribution of arousals and CAP components, i.e. subtypes A1, A2, A3. The relationship between the phase A subtypes and the structural organization of sleep was also evaluated.

METHODS

Forty healthy subjects were examined. Polysomnographic analysis was performed according to the scoring rules for sleep stages, CAP and American Sleep Disorders Association arousals.

RESULTS

Arousals occurred more frequently during CAP (40 events per hour) than in total sleep time (18 events per hour), non-rapid eye movement (NREM) sleep (20 events per hour), and rapid eye movement (REM) sleep (12 events per hour). Within CAP, arousals always coincided with a subtype A2 or A3. Both arousals and subtypes A2 and A3 showed a similar evolution with relation to age (linear positive), and to the amounts of light NREM sleep (linear positive) and deep NREM sleep (linear negative). In contrast, subtypes A1 showed a u-shaped profile across the life span and appeared closely related (linear positive) to the time spent in stages 3 and 4. Almost 90% of arousals occurring in NREM sleep were preceded in the previous 3s by a K-complex or a delta burst, indicating a topical involvement of slow electroencephalographic (EEG) components in the arousal build-up.

CONCLUSIONS

Arousals show only one side of the multi-faceted activation complexes, whereas the three subtypes of CAP provide a graded picture of arousal features from the strongest A3 subtypes, showing a prevalence of EEG desynchrony, to the weakest A1 phases, which are dominated by EEG synchrony and represent the prevalent components of CAP (60% of all the phase A subtypes).

Reproducibility of a non-invasive real-time measure of cardiac parasympathetic activity

The NeuroScope is a new device which produces a continuous real-time index of cardiac parasympathetic activity (the CIPA) and accurately measures RR intervals. The reproducibility of the CIPA has not yet been assessed. This study was designed to assess the reproducibility of a 5 minute recording of the CIPA using the NeuroScope and compare it with that of conventional heart rate variability (HRV) measures. 50 subjects (31 male, 19 female) aged 21-77 years were recruited. 11 of these were apparently healthy and 39 were patients with a variety of cardiological problems. Two 5 minute recordings of CIPA and RR intervals for each subject were made with a 2-3 minute break between recordings. The limits of agreement for the CIPA were such that the second estimate was between 72 and 140% of the first estimate, 95% of the time. The limits of agreement for other indices of HRV, namely SDNN, rMSSD, In low-frequency HRV and In high-frequency HRV, were 61-157%, 68-153%, 77-131% and 76-133%. The short-term reproducibility of a 5 minute recording of CIPA is moderate and better than simple time-domain but not frequency-domain measures of HRV.

The Mozart Effect

This review deals with the Mozart Effect, an improvement of performance while listening to Mozart music. Previous studies have shown improved spatial temporal reasoning and improved IQ test results and neurophysiological changes, mainly increased coherence among different groups of subjects. This review emphasizes the effect on epileptiform patterns, both generalized and focal; provides an example of a chronic effect over a period of 1-2 days; addresses the distinctive aspects of the music to account for this phenomenon and shows that long-term periodicity in the power of the music is a special quality; and deals with the melodic line and shows that Mozart repeats the melodic line much more frequently than other well-known composers. It is likely that the superorganization of the cerebral cortex resonates with great organization found in Mozart music.

Changes in direct current (DC) potentials and infra-slow EEG oscillations at the onset of the luteinizing hormone (LH) pulse

An essential function of the neuroendocrine system lies in the coordination of hypothalamo-pituitary secretory activity with neocortical neuronal activity. Cortical direct current (DC) potential shifts and EEG were monitored in conjunction with the circulating concentration of luteinizing hormone (LH) in humans while asleep to assess a hypothalamic-neocortical interaction. The onset of an LH pulse was accompanied (i) at frontocortical locations by a transient positive DC potential shift of approximately 3 min duration and peak amplitude 50 microV; (ii) at frontal and central locations by an increase in power of infra-slow EEG oscillations for periodicities between 64 and 320 s. Results uniquely demonstrate a coupling of hypothalamo-pituitary activity with regulation of neocortical excitability.

The Mozart effect: distinctive aspects of the music--a clue to brain coding?

The goal of this study was to determine distinctive aspects of Mozart music that may explain the "Mozart Effect," specifically, the decrease in seizure activity. As many as 81 musical selections of Mozart, but also 67 of J.C. Bach, 67 of J.S. Bach, 39 of Chopin and 148 from 55 other composers were computer analyzed to quantify the music in search of any distinctive aspect and later to determine the degree to which a dominant periodicity could be found. Long-term periodicity (especially 10-60 sec, mean and median of 30 sec), was found often in Mozart music but also that of the two Bachs, significantly more often than the other composers and was especially absent in the control music that had no effect on epileptic activity in previous studies. Short-term periodicities were not significantly different between Mozart and the Bachs vs. the other composers. The conclusion is that one distinctive aspect of Mozart music is long-term periodicity that may well resonate within the cerebral cortex and also may be related to coding within the brain.

Origin and Significance of the Cyclic Alternating Pattern (CAP). REVIEW ARTICLE

This article reviews the 15 years of studies conducted on the cyclic alternating pattern (CAP), the electro- encephalogram (EEG) marker of arousal instability during sleep. Starting from the limits and drawbacks of conventional sleep parameters (macrostructure), investigation of the underground world (microstructure) is extensively carried out with particular attention to K-complexes and other arousal-related phasic events of non-rapid eye movement (NREM) sleep. The continuity between conventional and non-conventional arousals is stressed in the light of autonomic function and motor activity evidence. The similarities and differences between CAP and arousals are thoroughly illustrated as well as the putative biological bases of these phenomena. The oscillatory nature of CAP, the involvement of CAP in the modulation of EEG synchrony, the sleep-maintenance properties of CAP in response to arousing stimuli, the clinical applications of CAP parameters and the promising availability of automatic scoring systems are highlighted.