Systematic analysis of C. elegans embryo behavior reveals a stereotyped developmental progression and a rhythmic pattern of behavioral quiescence

Systematic analysis of rich behavioral recordings is being used to uncover how circuits encode complex behaviors. Here we apply the approach to embryos. What are the first embryonic behaviors and how do they evolve as early neurodevelopment ensues? To address these questions, we present a systematic description of behavioral maturation for Caenorhabditis elegans embryos. Posture libraries were derived from a genetically encoded motion capture suit imaged with light-sheet microscopy and annotated using custom semi-automated tracking software (Multiple Hypothesis Hypergraph Tracking; MHHT). Analysis of cell trajectories, postures, and behavioral motifs revealed a stereotyped developmental progression. Early movement is dominated by flipping between dorsal and ventral coiling, which gradually slows into a period of reduced motility. Late-stage embryos exhibit sinusoidal waves of dorsoventral bends, prolonged bouts of directed motion, and a rhythmic pattern of pausing, which we designate slow wave twitch (SWT). Synaptic transmission is required for late-stage motion but not for early flipping or the intervening inactive phase. A high-throughput behavioral assay and calcium imaging revealed that SWT is elicited by the rhythmic activity of a quiescence-promoting neuron (RIS). Similar periodic quiescent states are seen prenatally in divergent animals and may play an important role in promoting normal developmental outcomes.

Cortical and autonomic responses during staged Taoist meditation: Two distinct meditation strategies

Meditation is a consciousness state associated with specific physiological and neural correlates. Numerous investigations of these correlates reported controversial results which prevented a consistent depiction of the underlying neurophysiological processes. Here we investigated the dynamics of multiple neurophysiological indicators during a staged meditation session. We measured the physiological changes at rest and during the guided Taoist meditation in experienced meditators and naive subjects. We recorded EEG, respiration, galvanic skin response, and photoplethysmography. All subjects followed the same instructions split into 16 stages. In the experienced meditators group we identified two subgroups with different physiological markers dynamics. One subgroup showed several signs of general relaxation evident from the changes in heart rate variability, respiratory rate, and EEG rhythmic activity. The other subgroup exhibited mind concentration patterns primarily noticeable in the EEG recordings while no autonomic responses occurred. The duration and type of previous meditation experience or any baseline indicators we measured did not explain the segregation of the meditators into these two groups. These results suggest that two distinct meditation strategies could be used by experienced meditators, which partly explains the inconsistent results reported in the earlier studies evaluating meditation effects. Our findings are also relevant to the development of the high-end biofeedback systems.

Stimulus dependence of theta rhythmic activity in primate V1 and its potential relevance for visual perception

A growing body of psychophysical research reports theta (3-8 Hz) rhythmic fluctuations in visual perception that are often attributed to an attentional sampling mechanism arising from theta rhythmic neural activity in mid- to high-level cortical association areas. However, it remains unclear to what extent such neuronal theta oscillations might already emerge at early sensory cortex like the primary visual cortex (V1), e.g. from the stimulus filter properties of neurons. To address this question, we recorded multi-unit neural activity from V1 of two macaque monkeys viewing a static visual stimulus with variable sizes, orientations and contrasts. We found that among the visually responsive electrode sites, more than 50 % showed a spectral peak at theta frequencies. Theta power varied with varying basic stimulus properties. Within each of these stimulus property domains (e.g. size), there was usually a single stimulus value that induced the strongest theta activity. In addition to these variations in theta power, the peak frequency of theta oscillations increased with increasing stimulus size and also changed depending on the stimulus position in the visual field. Further analysis confirmed that this neural theta rhythm was indeed stimulus-induced and did not arise from small fixational eye movements (microsaccades). When the monkeys performed a detection task of a target embedded in a theta-generating visual stimulus, reaction times also tended to fluctuate at the same theta frequency as the one observed in the neural activity. The present study shows that a highly stimulus-dependent neuronal theta oscillation can be elicited in V1 that appears to influence the temporal dynamics of visual perception.

Effects of food availability cycles on phase and period of activity/rest rhythm in Drosophila melanogaster

Foraging and feeding are indispensable for survival and their timing depends not only on the metabolic state of the animal but also on the availability of food resources in their environment. Since both these aspects are subject to change over time, these behaviours exhibit rhythmicity in occurrence. As the locomotor activity of an organism is related to its disposition to acquire food, and peak feeding in fruit flies has been shown to occur at a particular time of the day, we asked if cyclic food availability can entrain their rhythmic activity. By subjecting flies to cyclic food availability i.e., feeding/starvation (FS) cycles, we provided food cues contrasting to the preferred activity times and observed if this imposed cycling in food availability could entrain the activity/rest rhythm. We found that phase control, which is a property integral to entrainment, was not achieved despite increasing starvation duration of FS cycles (FS12:12, FS10:14 and FS8:16). We also found that flies subjected to T21 and T26 FS cycles were unable to match period of the activity rhythm to short or long T-cycles. Taken together these results show that external food availability cycles do not entrain the activity/rest rhythm of fruit flies. However, we find that starvation induced hyperactivity causes masking which results in phase changes. Additionally, T-cycle experiments resulted in minor period changes during FS treatment. These findings highlight that food cyclicity by itself may not be a potent zeitgeber but may act in unison with other abiotic factors like light and temperature to help flies time their activity appropriately.

Tensional processes and perception of form in three selected compositions by Kaija Saariaho

<p>The primary feature that gives ‘spectral music’ its stylistic uniqueness within the field of art music is the blurring of the traditionally distinct roles of harmony and timbre, through the use of chords derived from the naturally occurring overtones of instrumental timbre (often referred to as timbre chords). Development of these chords typically occurs very gradually, meaning it is often difficult to perceive the overall form of a spectral work based on the progression through its constituent timbre chords. This approach contrasts with the traditional reliance in both art music and other Western music styles on perceivable pitch-based development as a primary means of providing musical tension and form. Composers of spectral music must rely on the manipulation and development of other musical parameters to provide sufficient interest through ‘foreground ornamentation’ while its underlying harmonic/timbral macrostructure unfolds beneath. This analysis shows how key musical parameters are manipulated over time to provide tension and resolution (or, in Wallace Berry’s terminology, ‘progressive and recessive processes’ ¹ ), giving spectral works a perceivable, dynamic form. Parameters examined include rate of harmonic change, dynamics, spectral/registral spread, rhythmic activity, sound/noise, spectral density and harmonicity/inharmonicity (the latter two providing a spectral analogue to conventional notions of dissonance). Particular focus is placed on the rate of harmonic change in the selected works and changes in the harmonicity/inharmonicity (through spectral distortion) of harmonic material that give spectral music its distinctive harmonic character. The way in which these ‘parameter curves’ intersect with one another is also examined. For this study, three works by Finnish composer Kaija Saariaho are analysed. The works cover a range of forces and display varying degrees of overtly ‘spectral’ influence: Nymphéa (1987) for string quartet and electronics, Du Cristal (1990) for orchestra, and Cendres (1998) for piano, cello and flute. Analysis of the background levels of parametric change reveal how Saariaho manages to maintain microstructural interest in her spectral works while adhering to an underlying macrostructural plan. Findings from this analysis will also be discussed in relation to how they have influenced my own creative output for my MMA portfolio.</p>

Tensional processes and perception of form in three selected compositions by Kaija Saariaho

<p>The primary feature that gives ‘spectral music’ its stylistic uniqueness within the field of art music is the blurring of the traditionally distinct roles of harmony and timbre, through the use of chords derived from the naturally occurring overtones of instrumental timbre (often referred to as timbre chords). Development of these chords typically occurs very gradually, meaning it is often difficult to perceive the overall form of a spectral work based on the progression through its constituent timbre chords. This approach contrasts with the traditional reliance in both art music and other Western music styles on perceivable pitch-based development as a primary means of providing musical tension and form. Composers of spectral music must rely on the manipulation and development of other musical parameters to provide sufficient interest through ‘foreground ornamentation’ while its underlying harmonic/timbral macrostructure unfolds beneath. This analysis shows how key musical parameters are manipulated over time to provide tension and resolution (or, in Wallace Berry’s terminology, ‘progressive and recessive processes’ ¹ ), giving spectral works a perceivable, dynamic form. Parameters examined include rate of harmonic change, dynamics, spectral/registral spread, rhythmic activity, sound/noise, spectral density and harmonicity/inharmonicity (the latter two providing a spectral analogue to conventional notions of dissonance). Particular focus is placed on the rate of harmonic change in the selected works and changes in the harmonicity/inharmonicity (through spectral distortion) of harmonic material that give spectral music its distinctive harmonic character. The way in which these ‘parameter curves’ intersect with one another is also examined. For this study, three works by Finnish composer Kaija Saariaho are analysed. The works cover a range of forces and display varying degrees of overtly ‘spectral’ influence: Nymphéa (1987) for string quartet and electronics, Du Cristal (1990) for orchestra, and Cendres (1998) for piano, cello and flute. Analysis of the background levels of parametric change reveal how Saariaho manages to maintain microstructural interest in her spectral works while adhering to an underlying macrostructural plan. Findings from this analysis will also be discussed in relation to how they have influenced my own creative output for my MMA portfolio.</p>

Cortical and autonomic responses during staged Taoist meditation: two distinct meditation strategies.

Meditation is a consciousness state associated with specific physiological and neural correlates. Numerous investigations of these correlates reported controversial results which prevented a consistent depiction of the underlying neurophysiological processes. Here we investigated the dynamics of multiple neurophysiological indicators during a staged meditation session. We measured the physiological changes at rest and during the guided Taoist meditation in experienced meditators and naive subjects. We recorded EEG, respiration, galvanic skin response, and photoplethysmography. All subjects followed the same instructions split into 16 stages. In the experienced meditators group we identified two subgroups with different physiological markers dynamics. One subgroup showed several signs of general relaxation evident from the changes in heart rate variability, respiratory rate, and EEG rhythmic activity. The other subgroup exhibited mind concentration patterns primarily noticeable in the EEG recordings while no autonomic responses occurred. The duration and type of previous meditation experience or any baseline indicators we measured did not explain the segregation of the meditators into these two groups. These results suggest that two distinct meditation strategies could be used by experienced meditators, which partly explains the inconsistent results reported in the earlier studies evaluating meditation effects. Our findings are also relevant to the development of the high-end biofeedback systems.

Neuromodulation enables temperature robustness and coupling between fast and slow oscillator circuits in Cancer borealis

Acute temperature changes can disrupt neuronal activity and coordination with severe consequences for animal behavior and survival. Nonetheless, two rhythmic neuronal circuits in the crustacean stomatogastric ganglion (STG) and their coordination are maintained across a broad temperature range. However, it remains unclear how this temperature robustness is achieved. Here, we dissociate temperature effects on the rhythm generating circuits from those of upstream ganglia. We demonstrate that heat-activated factors extrinsic to the rhythm generators are essential to the slow gastric mill rhythm's temperature robustness and contribute to the temperature response of the fast pyloric rhythm. The gastric mill rhythm crashed when only the STG circuits were heated. It could be restored when upstream ganglia were heated in addition, and the activity of the peptidergic modulatory projection neuron (MCN1) increased. Correspondingly, MCN1's neuropeptide transmitter stabilized the rhythm and maintained it over a broad temperature range. Extrinsic neuromodulation is thus essential for the oscillatory circuits in the STG and enables neural circuits to maintain function in temperature-compromised conditions. In contrast, integer coupling between pyloric and gastric mill rhythms was independent of whether extrinsic inputs and STG pattern generators were temperature-matched or not, demonstrating that the temperature robustness of the coupling is enabled by properties intrinsic to the rhythm generators. However, at near-crash temperature, integer coupling was maintained only in some animals but was absent in others. This was true despite regular rhythmic activity in all animals, supporting that degenerate circuit properties result in idiosyncratic responses to environ-mental challenges.

Aperiodic EEG activity masks the dynamics of neural oscillations during loss of consciousness from propofol

EEGs are known to provide biomarkers for consciousness. Although EEG correlates of loss of consciousness (LOC) are often ascribed to changes in neural synchrony, mounting evidence suggests that some changes result from asynchronous neural activity. By combining EEG recordings of humans undergoing propofol administration with biophysical modelling, we present here a principled decomposition of EEG changes during LOC into synchronous and asynchronous sources. Our results reveal that IPSP decay rate and mean spike rate shape aperiodic EEG features, and that propofol's effects on these parameters largely explain the changes in EEG spectra following propofol infusion. We further show that traditional spectral EEG analysis likely conflates these effects with changes in rhythmic activity, thereby masking the true dynamics of neural synchrony. We conclude that the well-documented propofol-induced alpha rhythm in fact appears before LOC, and that the moment of LOC is uniquely correlated with the sudden appearance of a delta rhythm.

On the mechanism of the antiarrhythmic action of fabomotizole hydrochloride in alcoholic cardiomyopathy

It is known that the alcoholic cardiomyopathy (ACMP) is the main reason for lethality from chronic alcoholism. For ACMP the risk of development of malignant violations of a heart rhythm which result approximately at 40% of such patients is sudden heart death is extremely high. Materials and methods. Experiments were made on the ACMP translational model developed by us which is formed at rats by the end of the 24th week of compulsory reception of 10 % of ethanol solution. For studying the mechanisms which are the responsible of antiarrhythmic action of a fabomotizole dihydrochloride used a complex of morphohistological, electrophysiological and molecular researches. Results. It is shown that against the background of systematic therapy fabomotizole dihydrochloride (15 mg/kg, i.p.) daily within 28 days after 24 weeks of alcoholization, in comparison with alcoholized control the fat dystrophy of a myocardium significantly decreases and the threshold of electric fibrillation of heart ventricles is restored. According to results of molecular researches, a fabomotizole dihydrochloride significantly suppresses revealed in control alkoholized animals the abnormal mRNA expression of key receptor genes and proteins responsible for maintenance in cardiomyocytes of a homeostasis of ions of Ca++ and regulation of their rhythmic activity: regulatory proteins Epac1 (p = 0.021), Epac2 (p = 0.018), CaM (p = 0.00001) and also RyR2 (p = 0.031), IP3R2 (p = 0.006) receptors. Conclusion. The obtained results suggest that antiarrhythmic action of a fabomotizole dihydrochloride in the conditions of ACMP is connected with its ability to suppress abnormal activity of regulatory proteins Epac2 and RyR2, IP3R2 receptors.