Beat Processing Is Pre-Attentive for Metrically Simple Rhythms with Clear Accents: An ERP Study

The perception of a regular beat is fundamental to music processing. Here we examine whether the detection of a regular beat is pre-attentive for metrically simple, acoustically varying stimuli using the mismatch negativity (MMN), an ERP response elicited by violations of acoustic regularity irrespective of whether subjects are attending to the stimuli. Both musicians and non-musicians were presented with a varying rhythm with a clear accent structure in which occasionally a sound was omitted. We compared the MMN response to the omission of identical sounds in different metrical positions. Most importantly, we found that omissions in strong metrical positions, on the beat, elicited higher amplitude MMN responses than omissions in weak metrical positions, not on the beat. This suggests that the detection of a beat is pre-attentive when highly beat inducing stimuli are used. No effects of musical expertise were found. Our results suggest that for metrically simple rhythms with clear accents beat processing does not require attention or musical expertise. In addition, we discuss how the use of acoustically varying stimuli may influence ERP results when studying beat processing.     

Dance and Music in “Gangnam Style”: How Dance Observation Affects Meter Perception

Dance and music often co-occur as evidenced when viewing choreographed dances or singers moving while performing. This study investigated how the viewing of dance motions shapes sound perception. Previous research has shown that dance reflects the temporal structure of its accompanying music, communicating musical meter (i.e. a hierarchical organization of beats) via coordinated movement patterns that indicate where strong and weak beats occur. Experiments here investigated the effects of dance cues on meter perception, hypothesizing that dance could embody the musical meter, thereby shaping participant reaction times (RTs) to sound targets occurring at different metrical positions.In experiment 1, participants viewed a video with dance choreography indicating 4/4 meter (dance condition) or a series of color changes repeated in sequences of four to indicate 4/4 meter (picture condition). A sound track accompanied these videos and participants reacted to timbre targets at different metrical positions. Participants had the slowest RT’s at the strongest beats in the dance condition only. In experiment 2, participants viewed the choreography of the horse-riding dance from Psy’s “Gangnam Style” in order to examine how a familiar dance might affect meter perception. Moreover, participants in this experiment were divided into a group with experience dancing this choreography and a group without experience. Results again showed slower RTs to stronger metrical positions and the group with experience demonstrated a more refined perception of metrical hierarchy. Results likely stem from the temporally selective division of attention between auditory and visual domains. This study has implications for understanding: 1) the impact of splitting attention among different sensory modalities, and 2) the impact of embodiment, on perception of musical meter. Viewing dance may interfere with sound processing, particularly at critical metrical positions, but embodied familiarity with dance choreography may facilitate meter awareness. Results shed light on the processing of multimedia environments.     

Coupling interval from slow to tachycardiac pacing decides sustained alternans pattern

We discovered that the coupling beat interval from a slow to a tachycardiac pacing period considerably affected the pattern of the beat-to-beat alternation of the tachycardia-induced sustained contractile alternans. We analyzed the relationship between the coupling interval and the pattern and amplitude of the alternans in the isovolumic left ventricle of canine blood-perfused hearts. The alternans pattern and amplitude varied transiently over the first 30-50 beats and became gradually stable over the first minute in all 12 hearts. We discovered that stable alternans, even under the same tachycardiac pacing, had three different strong-weak beat patterns depending on the coupling interval. A relatively short coupling interval produced a representative sustained alternans of the strong and weak beats. A relatively long coupling interval produced a similar sustained alternans but in a reversed order of even- and odd-numbered beats counted from the coupling interval. However, sustained alternans disappeared after 1-3 specific coupling intervals. We conclude that ventricular pacing rate does not solely determine the pattern and amplitude of sustained contractile alternans induced by tachycardia.     

Activating and Relaxing Music Entrains the Speed of Beat Synchronized Walking

Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is ‘activating’ in the sense that it increases the speed, and some music is ‘relaxing’ in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation.     

A high-density EEG investigation into steady state binaural beat stimulation

Binaural beats are an auditory phenomenon that has been suggested to alter physiological and cognitive processes including vigilance and brainwave entrainment. Some personality traits measured by the NEO Five Factor Model have been found to alter entrainment using pulsing light stimuli, but as yet no studies have examined if this occurs using steady state presentation of binaural beats for a relatively short presentation of two minutes. This study aimed to examine if binaural beat stimulation altered vigilance or cortical frequencies and if personality traits were involved. Thirty-one participants were played binaural beat stimuli designed to elicit a response at either the Theta (7 Hz) or Beta (16 Hz) frequency bands while undertaking a zero-back vigilance task. EEG was recorded from a high-density electrode cap. No significant differences were found in vigilance or cortical frequency power during binaural beat stimulation compared to a white noise control period. Furthermore, no significant relationships were detected between the above and the Big Five personality traits. This suggests a short presentation of steady state binaural beats are not sufficient to alter vigilance or entrain cortical frequencies at the two bands examined and that certain personality traits were not more susceptible than others.     

Computation of the internal forces in cilia: application to ciliary motion, the effects of viscosity, and cilia interactions.

This paper presents a simple and reasonable method for generating a phenomenological model of the internal mechanism of cilia. The model uses a relatively small number of parameters whose values can be obtained by fitting to ciliary beat shapes. Here, we use beat patterns observed in Paramecium. The forces that generate these beats are computed and fit to a simple functional form called the "engine." This engine is incorporated into a recently developed hydrodynamic model that accounts for interactions between neighboring cilia and between the cilia and the surface from which they emerge. The model results are compared to data on ciliary beat patterns of Paramecium obtained under conditions where the beats are two-dimensional. Many essential features of the motion, including several properties that are not built in explicitly, are shown to be captured. In particular, the model displays a realistic change in beat pattern and frequency in response to increased viscosity and to the presence of neighboring cilia in configurations such as rows of cilia and two-dimensional arrays of cilia. We found that when two adjacent model cilia start beating at different phases they become synchronized within several beat periods, as observed in experiments where two flagella are brought into close proximity. Furthermore, examination of various multiciliary configurations shows that an approximately antiplectic wave pattern evolves autonomously. This modeling evidence supports earlier conjectures that metachronism may occur, at least partially, as a self-organized phenomenon due to hydrodynamic interactions between neighboring cilia.     

Coding conspecific identity and motion in the electric sense

Interactions among animals can result in complex sensory signals containing a variety of socially relevant information, including the number, identity, and relative motion of conspecifics. How the spatiotemporal properties of such evolving naturalistic signals are encoded is a key question in sensory neuroscience. Here, we present results from experiments and modeling that address this issue in the context of the electric sense, which combines the spatial aspects of vision and touch, with the temporal aspects of audition. Wave-type electric fish, such as the brown ghost knifefish, Apteronotus leptorhynchus, used in this study, are uniquely identified by the frequency of their electric organ discharge (EOD). Multiple beat frequencies arise from the superposition of the EODs of each fish. We record the natural electrical signals near the skin of a "receiving" fish that are produced by stationary and freely swimming conspecifics. Using spectral analysis, we find that the primary beats, and the secondary beats between them ("beats of beats"), can be greatly influenced by fish swimming; the resulting motion produces low-frequency envelopes that broaden all the beat peaks and reshape the "noise floor". We assess the consequences of this motion on sensory coding using a model electroreceptor. We show that the primary and secondary beats are encoded in the afferent spike train, but that motion acts to degrade this encoding. We also simulate the response of a realistic population of receptors, and find that it can encode the motion envelope well, primarily due to the receptors with lower firing rates. We discuss the implications of our results for the identification of conspecifics through specific beat frequencies and its possible hindrance by active swimming.     

The mechanism of large, excitation-dependent influx of 45Ca in the guinea-pig ventricular myocardium

In the previous papers (Lewartowski et al. 1982; Pytkowski et al. 1983) we found that excitation-dependent uptake of 45Ca (EDU) ranges in the vascularly perfused guinea-pig ventricular myocardium from 40-359 mumol/kg of wet weight per single steady-state beat or post-rest beat. The present paper describes an attempt to find whether slow calcium channel or Na/Ca exchange provides the route of this large 45Ca influx. We found that EDU during steady-state stimulation (60/min) was completely blocked by both D-600 (1 mg/l) and Ni (2 mmol/l) whereas EDU in post-rest beats was blocked only by Ni. Low Na+ perfusion (50 mmol/l) increased transiently EDU in steady-state beats. This surplus EDU was not blocked by D-600 nor by Ni. Noradrenaline infused at the rate sufficient to increase contractile force by 50% at least doubled EDU both in the steady-state and in post-rest beats. It is proposed that Na/Ca exchange does not participate significantly to EDU under physiological conditions. The changes in this uptake evoked by the applied interventions could be expected if its route was provided by the slow Ca channel.     

Intrinsic Quantum Beats of Atomic Populations and Their Nanoscale Realization Through Resonant Plasmonic Antenna

In the coherently trapped populations of a four-level atom, we demonstrated the quantum beats with different mechanism, which originate from the interference between transition channels with different dipole moments. The beat frequency is determined by the intrinsic atomic parameters, i.e., the spacing of upper levels and ratio of dipole moments. The resonant plasmonic nanoantenna, as a candidate for the creation of anisotropic vacuum, was proposed to achieve the nanoscale realization of the quantum beats, spontaneous emission cancellation, and Rabi oscillation in two-photon correlations through the enhanced near-field and modified decay rates.     

Peripheral encoding of behaviorally relevant acoustic signals in a vocal fish: harmonic and beat stimuli

Nesting male midshipman fish, Porichthys notatus, emit simple, long-duration sounds known as hums, which are attractive to gravid females. While hums share the multi-harmonic structure typical of many vertebrate communication sounds, their lack of amplitude modulation gives individual hums unusually simple temporal envelopes. However, hums often overlap, producing beats in the summed acoustic waveform. This study presents responses of individual saccular afferent fibers to two-tone harmonic and beat stimuli presented via an underwater loudspeaker. Spike activity was quantified as vector strength of synchronization and average spike rate. Responses to harmonic stimuli depended on harmonic phase; these effects apparently resulted primarily from variation in waveform fine temporal structure rather than auditory non-linearities. At most phases, addition of the harmonic enhanced afferent synchronization compared to the fundamental alone. Two-tone beat stimuli evoked stronger synchronization to the component frequencies than to the beat modulation rate. Vector strength tended to be higher to the lower frequency component, and this pattern appeared to derive from afferent tuning. Midshipman saccular afferents encoded both the temporal envelope and waveform fine structure of these naturalistic signals, information that may be important in conspecific communication.     

Effects of temperature on tilt evoked swimming in the crabs Carcinus and Macropipus

1. 1.|Integrated muscle activity, total number of limb beats and the maximum instantaneous limb beat frequency were measured in crabs during a standardized tilt regime at a series of different water temperatures between 10 and 25°C.

2. 2.|Total integrated activity and total number of limb beats showed a general increase for a decrease in temperature in all groups. Frequency of limb beat was always higher for Macropipus depurator than for Carcinus maenas, with M. depurator showing an increase and C. maenas a decrease in frequencies at extreme temperatures.

3. 3.|The temperature of acclimation of C. maenas affected the response of the crab in all parameters studied while all the results can be related to the size and normal environmental temperature range of the two species studied.

Some regularities of the pulse rate variability

Histograms of heart rate for 878 persons of both sexes aged from 3 to 83 years have been analyzed. The total data sampling was more than one hundred thousand pulse beats. Summary bar charts (variance pulsograms) were built up separately for men and women. Within the range of 60–75 beat/min, the peaks with the beat rates corresponding to 60, 61, 63, 65, 68, and 75 beat/min were observed, their values being twice as big as those of the neighboring ones. Within the range of 79–99 beat/min, minima were observed with beat rates of 79, 87, 91, 94, 97, and 99 beat/min. The distribution of these beat rates can be approximately described by the members of Fibonacci series from the determining beat rate of about 59–60 beat/min (maxima) and about 101/102 beat/min towards a decrease in the beat rate (minima). The determining beat rates of about 60, 101, and 162 beat/min may be evidence of the hierarchy, which is also approximately described by the array close to the Fibonacci series. Within the range of 101 to 115 beat/min, the peaks for men are marked that correspond to the harmonic series with a period of 2 beat/min, i.e., 101, 103, …, 115 beat/min.     

The Significance of Ventricular Premature Beats in the Diagnosis of Septal Infarction

Two hundred and twenty electrocardiograms containing premature ventricular beats were reviewed. Twenty of these contained premature ventricular beats of a myocardial infarction pattern, that is, one consisting of a significant Q wave followed by an R wave. A review of the case histories of these 20 patients disclosed that all 20 had angina pectoris and/or myocardial infarction. Postmortem examinations were performed in seven, and the presence of myocardial infarction was verified. In three instances, only the premature ventricular beat disclosed the myocardial infarction pattern while the normally conducted beats did not. In these three cases the postmortem examination confirmed the presence of septal infarction.     

An ultrasonic biotelemetry system for the continuous monitoring of tail-beat rate from free-swimming fish

A telemetry system for the continuous monitoring of tail beats, and hence swimming activity, from loch-dwelling brown trout, Salmo trutta L., is described. Tail beats are detected by electromyography and are transmitted using a specially-developed miniature ultrasonic transmitter. The output from the transmitter is relayed to a remote recording station using a radio-transponder buoy. Data analysed to date show that on average fish are active for only 9% of the time. Tail beat rates rarely exceeded 2.5 tail-beats per second (TB/s) corresponding to a velocity of 1 body length per second. The fish showed a 'preferred' tail-beat rate of 1.0–2.0 TB/s and consequently they rarely swam at speeds which would incur oxygen debt.     

Masking of fetal supraventricular tachycardia by electronic monitoring artefact.

In a fetus of 42 weeks'' gestation electronic monitoring demonstrated a heart rate of 120 beats/min that lacked the normal variability. Auscultation with a fetoscope revealed the true rate to be 240 beats/min. When used in the external Doppler mode the fetal monitor had a 250-ms refractory period after the recognition of a fetal cardiac event. This precluded recognition of the next beat and produced the artefactual halving of the heart rate. With the increasing reliance upon electronic fetal monitoring, those practising obstetrics should be aware of the possibility of artefacts and ensure that they can recognize truly representative information about the fetus.     

Electrical Brain Responses to an Auditory Illusion and the Impact of Musical Expertise

The presentation of two sinusoidal tones, one to each ear, with a slight frequency mismatch yields an auditory illusion of a beating frequency equal to the frequency difference between the two tones; this is known as binaural beat (BB). The effect of brief BB stimulation on scalp EEG is not conclusively demonstrated. Further, no studies have examined the impact of musical training associated with BB stimulation, yet musicians'' brains are often associated with enhanced auditory processing. In this study, we analysed EEG brain responses from two groups, musicians and non-musicians, when stimulated by short presentation (1 min) of binaural beats with beat frequency varying from 1 Hz to 48 Hz. We focused our analysis on alpha and gamma band EEG signals, and they were analysed in terms of spectral power, and functional connectivity as measured by two phase synchrony based measures, phase locking value and phase lag index. Finally, these measures were used to characterize the degree of centrality, segregation and integration of the functional brain network. We found that beat frequencies belonging to alpha band produced the most significant steady-state responses across groups. Further, processing of low frequency (delta, theta, alpha) binaural beats had significant impact on cortical network patterns in the alpha band oscillations. Altogether these results provide a neurophysiological account of cortical responses to BB stimulation at varying frequencies, and demonstrate a modulation of cortico-cortical connectivity in musicians'' brains, and further suggest a kind of neuronal entrainment of a linear and nonlinear relationship to the beating frequencies.     

Recording long‐term heart rate in Paranotothenia angustata using an electronic datalogger

A unique heart beat datalogging device was either surgically implanted into the peritoneal cavity (internal‐fish) or attached by nylon anchor tags to the dorsal fin rays (external‐fish) of the black cod Paranotothenia angustata . Both groups had a mean ±  s . e . heart rate of c . 46 beats min⁻¹ after 24 h, and by 20 days external‐fish showed a significant reduction (34 ± 3 beats min⁻¹) whereas internal‐fish did not (44 ± 2 beats min⁻¹). In demersal fishes external attachment of an electronic recording device may be preferable to surgical implantation.     

First record of the drumming signals of stoneflies Capnopsis Morton, 1896 and Protonemura Kempny, 1898 genera (Plecoptera,Capniidae and Nemouridae)

The male drumming signal of Capnopsis schilleri is studied for the first time. It is a monophasic call composed of 4–8 beats with a decreasing frequency. In the present paper, the drumming signals of some Protonemura species are also recorded and described for the first time both in males (Protonemura alcazaba, Protonemura meyeri and Protonemura navacerrada) and females (P. meyeri, P. navacerrada and Protonemura pyrenaica). The male call is very homogeneous in all the studied species and they consist of a repetition of 2–11 sequences of 6–31 beats, with an inter‐beat interval ranging from 0.034 to 0.088 s. The females have monophasic long signals consisting of a repetition of 5 to 109 beats with an inter‐beat interval of 0.061 to 0.159 s. It is extraordinary that females produced signals when males were absent, and so the female signal can be also considered as a call and not only an answer, as usually pointed out in stoneflies.     

Hypometabolism in torpid goldsinny wrasse subjected to rapid reductions in seawater temperature

Goldsinny Ctenolabrus rupestris were subjected to rapid, environmentally realistic, reductions in temperature at 2° C increments from 10 to 4° C over a 3-day period in full-strength sea water. In separate experiments, oxygen uptake measurements and ultrasound recordings of heart rate and opercular motion were carried out at regular intervals over the same temperature regime. Mean oxygen uptake rates fell from 0.042 to 0.028 ml O₂ g⁻¹ h⁻¹ between 10 and 6° C respectively (Q₁₀=2.71). Between 6 and 4° C mean rates decreased from 0.028 to 0.008 ml O₂ g⁻¹ h⁻¹ (Q₁₀=542). Mean opercular motion and heart beat rates decreased from 49.5 and 60.3 beats min⁻¹ respectively at 10° C to 18.7 and 18.0 beats min⁻¹ respectively at 4° C. Most goldsinny subjected to 4° C were observed in a torpid state and would not react to external stimulation. Opercular motion was erratic at 4° C and would at times cease altogether for periods up to 1.3 min duration. Heart movement was diffcult to detect at 4° C and may also have ceased for prolonged periods. Q₁₀ values for opercular motion and heart beat rates recorded between 6 and 4° C were 6.39 and 24.52 respectively compared with values of 2.42 and 2.93 respectively recorded between 10 and 8° C. Such large depressions in metabolism appear not to have been reported previously for a marine fish species. No goldsinny mortalities were recorded at any temperature. The possibility that hypometabolic torpor is an adaptive strategy for goldsinny survival at low environmental temperatures is discussed.     

Observations of cardiac beating behaviors of wild‐type and mutant Drosophilae with optical coherence tomography

Time‐resolved optical coherence tomography (OCT) scanning images of wild‐type and mutant fruit flies (Drosophila melanogaster), illustrating the heartbeat patterns for evaluating their cardiac functions, are demonstrated. Based on the heartbeat patterns, the beat rate and the relative phase between the first two heart segments can be evaluated. The OCT scanning results of mutant flies with impaired proteasome function in cardiac muscles show irregular heartbeat patterns and systematically decreased average beat rates, when compared with the regular patterns of ～4.97 beats/s in average beat rate of the wild‐type. In both wild‐type and proteasome mutant flies, the beatings at different locations in the same heart segment are essentially synchronized. However, between different heart segments, although the beating in the second segment shows a lag in phase behind that of the first segment in a wild‐type, in a proteasome mutant, the beating in the second segment becomes significantly leading that of the first segment. Besides the comparison between the wild‐type and proteasomal mutant flies, the influences of using different methods for immobilizing flies during OCT scanning on the heart functions are demonstrated. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)