Rhythmic Timing Research Articles

It’s all a matter of timing: Temporal mechanisms for production and encoding of acoustic signals

Studies of acoustic communication in teleost fish have identified basic principles underlying both the motor control of acoustic signaling and the sensory encoding of the physical attributes of those signals. Parental male midshipman fish excavate denlike nests under rocky shelters in the intertidal and subtidal zones along the western coast of the United States and Canada. Nesting males generate long duration, multi-harmonic signals with a sinusoidallike appearance that are known as ‘‘hums.’’ Observations of courtship behavior together with phonotaxis experiments support the hypothesis that the hum functions as a mate call. Early studies showed that a rhythmically active, pacemaker-motoneuron circuit in the hindbrain establishes the temporal features of hums [Bass and Baker, J. Neurobiol. 21, 1155 (1990)]. Recent studies suggest that temporal coding in the auditory midbrain contributes to the segregation of, and discrimination between, concurrent acoustic signals which form acoustic beats like those generated by the overlapping hums of nesting male midshipman during the breeding season [Bodnar and Bass, J. Neurosci. 17, 7553 (1997)]. Hence, the rhythmic timing of action potentials is important for both acoustic signaling and reception. [Work supported by NIH and NSF.]

Quantitative analysis of Drosophila period gene transcription in living animals.

To determine the in vivo regulatory pattern of the clock gene period (per), the authors recently developed transgenic Drosophila carrying a luciferase cDNA fused to the promoter region of per. They have now carried out noninvasive, high time-resolution experiments allowing high-throughput monitoring of circadian bioluminescence rhythms in individual living adults for several days. This immediately solved several problems (resulting directly from individual asynchrony within a population) that have accompanied previous biochemical experiments in which groups of animals were sacrificed at each time point. Furthermore, the authors have developed numerical analysis methods for automatically determining rhythmicity associated with bioluminescence records from single flies. This has revealed some features of per gene transcription that were previously unappreciated and provides a general strategy for the analysis of rhythmic time series in the study of molecular rhythms.

Multiple Components of the Perception of Musical Sequences: A Cognitive Neuroscience Analysis and Some Implications for Auditory Imagery

A neurologically plausible model of the auditory perception of musical sequences is proposed, and some implications are derived for auditory imagery. In line with a cognitive neuroscience approach, a componential analysis of the major functions required of auditory perception and imagery for musical sequences is first carried out, and a minimal model of auditory imagery and perception is outlined. The minimal model makes a clear distinction between the processing subsystems required for analyzing pitch and rhythm. It also incorporates an auditory buffer for the brief retention of relatively unprocessed auditory input, an attention subsystem that permits selective intake of relevant auditory information, a memory subsystem for melodic strings that combines the outputs of pitch and rhythmic analyses into a long-term, flexible representation of the musical sequence, and an associative memory system that links the results of perceptual analyses of music with extraperceptual (semantic and episodic) information about the musical string. The present theory builds on a recent model of music perception proposed by Peretz (1993) and also accounts for data from studies of patients with disorders of rhythmic processing, thus indicating the close relationship between auditory perception and imagery for rhythmic sequences, timing, and motor processes. Recent data are used to refine and extend the minimal model and provide an organizing framework for current laboratory work.

The performance of Mozart: Study of rhythmic timing by skilled musicians.

The performance of Mozart: Study of rhythmic timing by skilled musicians.

Interactional and phonetic aspects of immediate echolalia in autism: A case study

A case study is presented of an autistic boy aged 11 years. The analysis is based on audio-visual recordings made in both his home and school. The focus of the study is on that subset of immediate echolalia that has been referred to as pure echoing. Using an approach informed by conversation analysis and descriptive phonetics, distinctions are drawn between different forms of pure echo. It is argued that one of these forms, what we call ‘unusual echoes’, has distinctive interactional and phonetic properties which do not have a counterpart in the speech of non-autistic children. These principally consist of a particular segmental and suprasegmental relationship to the prior adult turn, a particular rhythmic timing and a functional opaqueness. This behaviour is set within the context of this child's general communicative behaviour which, in various ways, places a premium on the use of repetition skills. These skills also inform the child's use of repetition in unusual echoes, though here the interactional a...

Circadian rhythmicity in vertebrate retinas: Regulation by a photoreceptor oscillator

Circadian regulation of retinal function has now been shown in all classes of vertebrates and attempts are now under way to understand the mechanisms underlying this regulation. The functions and organization of retinal rhythm mechanisms seem to vary among species and types of rhythms. To some extent this reflects the experimental advantages of different systems, but it also seems to reflect real variation in control mechanisms among species. Many aspects of retinal function, from gene transcription to complex intercellular interactions, are regulated by circadian oscillators (Fig. 8). Circadian clock regulation of the visual system ranges from dramatic, spontaneous rhythmicity in melatonin synthesis and disc shedding in some species to subtle rhythmic regulation of responsiveness to light and dark signals in other species. Most of the known retinal rhythms, as well as a circadian oscillator, are localized in photoreceptors. This suggests that circadian rhythmicity is fundamental for normal photoreceptor function. Some of the intracellular and paracrine components of the pathways linking different retinal rhythms have been identified. However, because of the complex feedback interactions present in the system, it is still difficult to draw strong conclusions about the causal relationships among rhythms. For example, melatonin is rhythmic and regulates dopamine release, but it is not clear that the rhythms in dopamine are driven directly by melatonin rhythms. Dopamine can modulate melatonin rhythms, but it is not necessary for generation of those rhythms (Cahill and Besharse, 1993). The recently discovered circadian regulation of photoreceptor gene expression (Pierce et al., 1993; Yoshida et al., 1993; Green and Besharse, 1994) may underlie rhythmicity at higher levels of organization. It will be important to determine which other photoreceptor genes are also regulated by circadian mechanisms and whether common factors are involved. Mechanisms of the photoreceptor oscillator itself are now approachable in a few experimental preparations, including Xenopus eyecups and photoreceptor layers and chick retinal cell cultures (Cahill and Besharse, 1991, 1993; Pierce et al., 1993). These in vitro preparations eliminate systemic influences from the interpretation of experimental results. Furthermore, by measuring the timing of rhythmicity, it is possible to distinguish oscillator responses to experimental manipulations from acute changes in rhythmic variables. This is the key to unraveling the mechanisms underlying retinal circadian rhythmicity.

Motor Performance of Stutterers and Nonstutterers on Timing and Force Control Tasks

Recently it has been suggested that speech and manual timing tasks share a common central process (Franz, Zelaznik, & Smith, 1992): Because stuttering is thought to be related to deficits in motoric processes such as timing, stutterers (n = 15) were compared with a set of age-, education-, and sex-matched nonstutterers on timing and isometric force-production tasks. In the timing tasks, subjects flexed and extended the right index finger at the metacarpophalangeal joint at cycle durations of 600, 500, 400, 300, and 200 ms. In the force-production tasks, subjects generated isometric forces to match target force levels displayed on a cathode-ray tube (CRT) screen. There were five levels of force, ranging from.11 to 7.85 newtons. Overall, there were no differences in timing and force-production performance between stutterers and nonstutterers. These results are similar to those obtained recently by Hulstijn, Summers, van Lieshout, and Peters (1992). We suggest that stuttering is not characterized by a general deficit in rhythmic timing. Instead, the motor deficit associated with stuttering should be viewed as speech specific.

Sequel to History: Postmodernism and the Crisis of Representational Time.

Sequel to History offers a comprehensive definition of postmodernism as a reformation of time. Elizabeth Deeds Ermarth uses a diversified theoretical approachdrawing on post-structuralism, feminism, new historicism, and twentieth-century scienceto demonstrate the crisis of our dominant idea of history and its dissolution in the rhythmic time of postmodernism. She enlarges this definition in discussions of several crises of cultural identity: the crisis of the object, the crisis of the subject, and the crisis of the sign. Finally, she explores the relation between language and time in post-modernism, proposing an arresting theory of her own about the rhythmic nature of postmodern temporality. Because the postmodern construction of time appears so clearly in narrative writing, each part of this work is punctuated by a rhythm section on a postmodern narrative (Robbe-Grillet's Jealousy, CortNBzar's Hopscotch, and Nabokov's Ada); these extended readings provide concrete illustrations of Ermarth's theoretical positions. As in her critically acclaimed Realism and Consensus in the English Novel, Ermarth ranges across disciplines from anthropology and the visual arts to philosophy and history. For its interdisciplinary character and its lucid definition of postmodernism, Sequel to History will appeal to all those interested in the humanities.

Hypothalamic dysthermia in persons with brain damage.

Brain injury causing dysthermia has appeared to be not uncommon in institutionalized people with mental retardation. We sought to determine the characteristics and risks of patients of one institution. Of 1100 residents surveyed over 10 years 92 were reported to have unexplained high or low body temperatures, and 48 were monitored. Core temperatures were taken by non-invasive thermometers recording continuously for 24 h. Results were related to clinical conditions and aetiologies of mental retardation. Twenty-one per cent of the residents monitored showed hyperthermia, often related to prenatal metabolic or chromosomal abnormalities. Forty-two per cent had hypothermia, related to other causes of brain injury. Seventy-five per cent had abnormal patterns, including flat or exaggerated rhythms, reversed day-night cycle, unusual fluctuations, or sleep phase delay. Sixty-two per cent of 21 deaths to date have occurred in hypothermic patients. Occasional discrepancies between history of dysthermia and monitored results are best explained by fluctuations of temperature control over several days, probably due to changes in timing of hypothalamic rhythmicity. This could be better delineated by longer periods of monitoring.

Development of the photoreceptor outer segment-like cilia of the CSF-contacting pinealocytes of the ferret (Putorius furo).

The postnatal development of the pineal organ of the ferret (Putorius furo) was investigated electron-microscopically with special interest given to the cerebrospinal fluid (CSF)-contacting pinealocytes and their large, vesiculated cilia. In the pineal of the newborn ferrets, there is a lumen--a pineal ventricle--which is a diverticle of the third ventricle of the diencephalon. The luminal surface of the pineal is bordered by ependymal cells and CSF-contacting pinealocytes. A sensory, 9 x 2 + 0 type cilium arises from the free surface of the pinealocytes and thickens in the first week. There are mitotic figures in the wall of the pineal ventricle, being reduced to a pineal recess during the second and third postnatal week. In two week-old animals, vesicles appear in the cilia of the pinealocytes. The vesicles may form rows and fill the enlarged cilium at the third week. Near the basal bodies, a proximal connecting piece remains narrow and free of vesicles. In older animals, there are multivesicular and dense bodies in the pineal cilia. The reduction of the pineal ventricle closes the CSF-contacting cilia in the intercellular spaces. Axon-like processes of pinealocytes form synaptic ribbon-containing terminals on secondary pineal neurons. Axons of pineal neurons enter the fiber bundles of the pineal tract running to the habenular nuclei. All these structures do not differ from the light conducting pathway of the submammalian pineals. The ultrastructure of the cilia investigated resembles that of the developing outer segments of the retina and represents a preserved light perceiving structure of the mammalian pinealocytes. Further studies are necessary to elucidate whether the early differentiation of the cilia and synapses indicates a timing of the circadian light rhythmicity in young ferrets by direct pineal photosensitivity.

Rhythm and the timing of movement sequences

Many motor skills involve a sequence of movements phased over a period of time. The present study investigated the importance of rhythmic timing structures in the acquisition and control of a serial key-pressing task. Four groups of subjects received extensive practice on 9-element finger sequences varying in the form of the inherent temporal structure. Following a training period, the stability of the various timing patterns was examined by requiring subjects to perform the key-pressing task concurrently with a verbal memory task. The memory task involved reporting back a sequence of visually-presented words with a lag of one word. A comparison was made of performance on the two tasks under dual task and control (single task) conditions. The results suggested that “natural” rhythmic timing structures require less attention for production than “unnatural” temporal patterns. A breakdown of the temporal patterns into “within-group” and “between-group” intervals showed that patterns containing within-group intervals that related as 1:1 or 1:2 evidenced good stability under dual-task conditions. These results were taken as support for the suggestion by Fraisse (1946) that the perception and production of rhythms can be understood by an internal representation that allows only two distinct durations that relate as 1:2. Furthermore, it was suggested that relative timing may become an invariant property of motor program representation only in those instances in which the timing sequence completely fits the internal timing structure.

Auditory lateralization: An effect of rhythm

Recall of monaurally presented semantically anomalous sentences, which had either neutral or rhythmic timing, was tested at the right ear, at the left ear, and on transfer from one ear to the other. The component words, being computer stored digitized waveforms, had identical acoustic structure in the two conditions. In the rhythmic condition there was not only an overall advantage in the second half of the experiment but also an asymmetric transfer effect such that this advantage did not appear when the left ear was tested after the right. It is proposed that functional lateralization be viewed as an adaptive, dynamic, organizational factor.

Effects of pinealectomy and ocular enucleation on diurnal periodicity of Leucocytozoon smithi (Haemosporina) gametocytes in the peripheral blood of domestic turkeys.

ABSTRACT. Domestic turkeys naturally infected with Leucocytozoon smithi were blinded by bilateral ocular enucleation, pinealectomized, sham‐pinealectomized, pinealectomized plus enucleated, or maintained as controls. Groups of turkeys were acclimated to either light‐dark periods of 14L:10D or “darkness” with intermittent periods (10–20 min) of red light at irregular hours approximately every three days as required for maintenance of turkeys. Peripheral gametocyte numbers of L. smithi in all groups were determined every 2 h over a 36 h period. Under 14L: 10D photoperiod, no observable difference in the pattern of gametocyte circadian rhythmicity between pinealectomized, enucleated, pinealectomized plus enucleated, and control turkeys was noted. Although mean parasitemias differed among groups, peak gametocyte numbers occurred between 1000 and 1800 h; how parasitemias occurred between 2000 and 0400 h. However, the phase of gametocyte rhythmicity in pinealectomized plus enucleated turkey hosts did exhibit a lag with reference to other hosts when examined by least squares fits of simple harmonics. Under conditions of “darkness” with intermittent, irregular periods of red light, L. smithi gametocyte numbers of individual turkeys, pinealectomized, sham‐pinealectomized, or maintained as controls, exhibited a circadian periodicity though parasite cycles were out of phase with the natural photoperiod to which the turkeys previously had been exposed. A slight drift out of phase of L. smithi gametocyte periodicity occurred among turkeys in the sham‐pinealectomized and the control groups while a considerably more prominent drift out of phase was seen among the parasite rhythmicity patterns of the pinealectomized birds. Data indicate that the pineal gland of the turkey did not directly mediate L. smithi gametocyte circadian periodicity, although an indirect involvement in regulating the timing of parasite rhythmicity is suggested.

The Role of Timing in Motor Program Representation

A motor program is the representation in memory that controls the sequential structure of a motor skill. The present research was an attempt to determine the degree to which the timing and sequencing components of a motor skill are related in motor-program representation in a serial key-pressing task. Four groups practiced on event sequences varying in the form of the inherent temporal structure. Following training subjects attempted to execute the event sequences from memory as quickly as possible where the maintenance of the inherent temporal structure was not required. Under speed instructions the entire sequence was speeded up, but performance was still strongly influenced by the overall temporal structure acquired during training. The results suggested that the relative timing of events is an integral part of motor program representation, particularly in skills involving rhythmic timing structures. This paper is based on a doctoral dissertation at the University of Oregon, Dr. Steven W. Keele, sponsor. The research was supported by a contract from the Office of Naval Research, Contract No. N00014-67-A-0046-004 to S. W. Keele.

Reproduction of distillers' yeasts

AbstractDistillers' yeasts, strains of Saccharomyces cerevisiae, although capable of sexual reproduction, in distillery practice reproduce asexually, by budding. A cell may bring forth another one in 50 min. With every ounce of whiskey produced, 30 billion new cells come to existence. Within a few days, in 4–8 propagation stages, a test tube full of culture will populate 100,000 gallons beer with 150 million cells per ml. Rate of reproduction, the number of new cells per each original cell varies from 5 to 50 in the various propagation stages. The number of new cells produced in a given nutrient is independent from the number of initial cells; and the utilization of the nutrient increases with the dilution of the substrate. Although distillers' yeasts may reproduce at such extremes as 1–46°C, 2½–10½ pH, presence of 0–15% alcohol by volume, and 0.1–25% sugar content, in distillery practice the factors are so selected to maintain conditions close to the optimum. When placed in the nutrient the initial cells will measure the chemical and physical characteristics of the new living space and the cell population, and will prepare a design of reproduction best suited to the conditions. The design includes a symmetry in the grouping of the cells and a rhythmic timing in starting new buds. Each healthy cells is biologically equal to the others and is capable of performing all functions characteristic of the strain. In spite of the sensitive coordination system between the individual cells that regulates their activity, marked differences exist among the cells to the degree of cell individuality. Distillers yeasts are superbly equipped to live and reproduce.