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PubMed2001

Measurement of auditory temporal processing using modified masking period patterns.

A common metric of auditory temporal processing is the difference in the threshold for a pure-tone signal masked by either unmodulated or amplitude-modulated noise. This technique may be viewed as a modification of the masking period pattern technique. Such measurements have been proposed as an efficient means of estimating auditory temporal resolution in a clinical setting, although in many cases threshold differences may reflect additional spectro-temporal processes. The primary purpose of the present experiment was to examine interactions among signal frequency and masker bandwidth and the effects of modulation frequency on modified masking period patterns. The results revealed unmodulated-modulated threshold differences that increased with increasing masker bandwidth and decreased with increasing modulation frequency. There was little effect of signal frequency for narrow-band noise maskers that were equal in absolute bandwidth across frequency. However, unmodulated-modulated threshold differences increased substantially with increasing signal frequency for bandwidths proportional to the signal frequency and for wideband maskers. Although the results are interpreted in terms of a combination of both within-channel and across-channel cues, the specific contributions of these cues in particular conditions are difficult to ascertain. Because modified masking period patterns depend strongly upon a number of specific stimulus parameters, and because it is difficult to determine with any precision the underlying perceptual processes, this technique is not recommended for use as a clinical measure of auditory temporal processing.

Acoustic Stimulation↗

PubMed1970

P-chlorophenylalanine methyl ester: an aphrodisiac?

P-Chlorophenylalanine methyl ester and the ester plus pargyline have been reported to facilitate sexual mounting behavior in animals, but these studies have shown only a facilitation of homosexual mounting. The present study indicates that these agents do not enhance the probability or frequency of heterosexual interactions in rats.

Animals↗

PubMed1998

Macroscopic quantum interference from atomic tunnel arrays

Interference of atomic de Broglie waves tunneling from a vertical array of macroscopically populated traps has been observed. The traps were located in the antinodes of an optical standing wave and were loaded from a Bose-Einstein condensate. Tunneling was induced by acceleration due to gravity, and interference was observed as a train of falling pulses of atoms. In the limit of weak atomic interactions, the pulse frequency is determined by the gravitational potential energy difference between adjacent potential wells. The effect is closely related to the ac Josephson effect observed in superconducting electronic systems.

Journal Article↗

PubMed1983

Normalizing effect of an adrenocorticotropic hormone (4-9) analog ORG 2766 on disturbed social behavior in rats.

Short-term isolation increased the frequency of social interactions in rats tested in pairs, while pairs of rats placed in an unfamiliar test cage and subjected to a high level of illumination spent less time in active social contact. These changes in social behavior elicited by environmental manipulations were counteracted by treatment with the adrenocorticotropic hormone (4-9) analog ORG 2766. The peptide's normalizing effect may be mediated by endogenous opioid systems.

Adrenocorticotropic Hormone↗

PubMed1999

Frequency organization and responses to complex sounds in the medial geniculate body of the mustached bat.

The auditory cortex of the mustached bat (Pteronotus parnellii) displays some of the most highly developed physiological and organizational features described in mammalian auditory cortex. This study examines response properties and organization in the medial geniculate body (MGB) that may contribute to these features of auditory cortex. About 25% of 427 auditory responses had simple frequency tuning with single excitatory tuning curves. The remainder displayed more complex frequency tuning using two-tone or noise stimuli. Most of these were combination-sensitive, responsive to combinations of different frequency bands within sonar or social vocalizations. They included FM-FM neurons, responsive to different harmonic elements of the frequency modulated (FM) sweep in the sonar signal, and H1-CF neurons, responsive to combinations of the bat's first sonar harmonic (H1) and a higher harmonic of the constant frequency (CF) sonar signal. Most combination-sensitive neurons (86%) showed facilitatory interactions. Neurons tuned to frequencies outside the biosonar range also displayed combination-sensitive responses, perhaps related to analyses of social vocalizations. Complex spectral responses were distributed throughout dorsal and ventral divisions of the MGB, forming a major feature of this bat's analysis of complex sounds. The auditory sector of the thalamic reticular nucleus also was dominated by complex spectral responses to sounds. The ventral division was organized tonotopically, based on best frequencies of singly tuned neurons and higher best frequencies of combination-sensitive neurons. Best frequencies were lowest ventrolaterally, increasing dorsally and then ventromedially. However, representations of frequencies associated with higher harmonics of the FM sonar signal were reduced greatly. Frequency organization in the dorsal division was not tonotopic; within the middle one-third of MGB, combination-sensitive responses to second and third harmonic CF sonar signals (60-63 and 90-94 kHz) occurred in adjacent regions. In the rostral one-third, combination-sensitive responses to second, third, and fourth harmonic FM frequency bands predominated. These FM-FM neurons, thought to be selective for delay between an emitted pulse and echo, showed some organization of delay selectivity. The organization of frequency sensitivity in the MGB suggests a major rewiring of the output of the central nucleus of the inferior colliculus, by which collicular neurons tuned to the bat's FM sonar signals mostly project to the dorsal, not the ventral, division. Because physiological differences between collicular and MGB neurons are minor, a major role of the tecto-thalamic projection in the mustached bat may be the reorganization of responses to provide for cortical representations of sonar target features.

Animals↗

PubMed1982

Langur monkey (Presbytis entellus) development. The first 3 months of life.

Observation for the first 3 months of life of 19 Indian langur monkey infants (Presbytis entellus) living in well-established colony social groups revealed complex and related patterns of social development. This is a period of rapidly increasing infant motor ability and increasing infant-initiated independence. Infant transfer, a behavior initiated by others towards the infant and a characteristic of the species, occurs most frequently in weeks 1 and 2, then steadily declines to low frequency in weeks 11 and 12. Infants are not punished or rejected, and to the extent the mother allows, the infant leaves her. She leaves her infant infrequently. The infant widens its radius of activity and increases the kinds and frequency of active interactions it has with others in the group. Patterns of behavior appear to develop in tandem during key periods of early life. Week 1 is the time of greatest dependence with 100% contact at first. During weeks 3 and 4, the infant efficiently expresses itself and can actively prevent transfers. Week 4 sees a constellation of major changes and a rising infant drive for independence. Play increases as do interactions with other immatures. Carrying decreases as the infant is able to follow. Some restraints are observed because of a new set of infant management problems presented to the mother. Throughout the first 3 months of life the mother is the focus of her infant's attention and activities--she is crucial to its survival. The 3-month-old infant is an active strategist with many options of action and choices of behavior and social partners.

Animals↗

PubMed1987

Mating patterns in the golden lion tamarin (Leontopithecus rosalia): continuous receptivity and concealed estrus.

Sociosexual behavior was monitored on a daily basis for 3 months in 5 pairs of golden lion tamarins (Leontopithecus rosalia). Urine samples were collected daily from each female and urinary estrogen cycles were determined by radioimmunoassay. Mounts and copulations were observed during all phases of the estrogen cycle. Peaks or regular cycles in sexual behavior were not documented. There were no significant changes in affiliative behavior by females or males that were associated with changes in urinary estrogen values. A negative relationship between pair bond duration and frequency of sexual interactions was observed: newly established pairs exhibited 2-6 times more frequent sexual behavior than a long-established pair. The lack of a conspicuous sexual signal in female golden lion tamarins may be related to a pattern of continuous sexual receptivity. Both reproductive patterns, concealed estrus and continuous receptivity, are explicable in relation to either monogamous or polyandrous mating systems.

Animals↗

PubMedDate not supplied

Cardiac transplantation: a review for the intensivists.

Cardiac transplantation has now become accepted therapy for the treatment of end-stage heart disease in both children and adults, and literally thousands of patients are bearers of cardiac grafts. Because of these patients' susceptibility to infections, rejection, coronary disease, and malignancy, as well as to serious illnesses unrelated to their transplantation, they will often be encountered at hospital centers both close to their homes and distant from the site of their surgery. The intensive care unit physician's role will be a demanding one when caring for these patients because of the broad differential diagnosis of infections, frequency of drug interactions and altered immunosuppression, and continuous uncertainty regarding the possibility of rejection, particularly during the first year after transplantation.

Coronary Artery Disease↗

PubMed1992

The importance of nonverbal communication during the preanesthesia period.

This article discusses the phenomenon of nonverbal communication as evidenced between preoperative patients and the nurses attending them. Ten such patients and the nursing group assigned to them were directly observed for frequency of nonverbal interaction during the period immediately preceding surgery. Patients' nonverbal expressions of tension, fear, anxiety, and so on were noted, videotaped, and then analyzed according to three categories of interaction: positive, neutral, and negative. Of 2,173 registered nonverbal interactions, 65.1% (1,416) were rated as negative, a finding that should alert nurses to the need to identify patients' manifestations of anxiety so as to provide assurance and a sense of courage preceding surgery. Positive means of communicating nonverbally are discussed.

Anxiety↗

PubMed2000

Recommendations for mechanical ventilation during donor care.

The organ procurement coordinator usually directs adjustments to the mechanical ventilator during donor care. It is often difficult to achieve optimal oxygen uptake and carbon dioxide removal while avoiding barotrauma or undesirable effects on the cardiac output. Interrelationships among a variety of ventilator parameters must be understood in order to achieve the desired goal of providing the best organs possible. These recommendations review the key ventilator parameters of tidal volume; positive end-expiratory pressure; auto-positive end-expiratory pressure; fraction of inspired oxygen; and flowrate and frequency and their interactions in controlling peak, plateau, and mean and end-expiratory airway pressures.

Adolescent↗

PubMed2004

Social function in schizophrenia and schizoaffective disorder: associations with personality, symptoms and neurocognition.

BACKGROUND: Research has indicated that stable individual differences in personality exist among persons with schizophrenia spectrum disorders predating illness onset that are linked to symptoms and self appraised quality of life. Less is known about how closely individual differences in personality are uniquely related to levels of social relationships, a domain of dysfunction in schizophrenia more often linked in the literature with symptoms and neurocognitive deficits. This study tested the hypothesis that trait levels of personality as defined using the five-factor model of personality would be linked to social function in schizophrenia. METHODS: A self-report measure of the five factor model of personality was gathered along with ratings of social function, symptoms and assessments of neurocognition for 65 participants with schizophrenia or schizoaffective disorder. RESULTS: Univariate correlations and stepwise multiple regression indicated that frequency of social interaction was predicted by higher levels of the trait of Agreeableness, fewer negative symptoms, better verbal memory and at the trend level, lesser Neuroticism (R2 =.42, p <.0001). In contrast, capacity for intimacy was predicted by fewer negative symptoms, higher levels of Agreeableness, Openness, and Conscientiousness and at the trend level, fewer positive symptoms (R2 =.67, p <.0001). CONCLUSIONS: Taken together, the findings of this study suggest that person-centered variables such as personality, may account for some of the broad differences seen in outcome in schizophrenia spectrum disorders, including social outcomes. One interpretation of the results of this study is that differences in personality combine with symptoms and neurocognitive deficits to affect how persons with schizophrenia are able to form and sustain social connections with others.

Adult↗

PubMedDate not supplied

Alternative field methods for measuring hearing protector performance.

In comparison with the mandatory noise reduction rating (NRR) testing of every hearing protector sold in the United States, real-world tests of hearing protector attenuation are scarce. This study evaluated data from three potential field-test methods as compared with the subject-fit data from Method B of ANSI S12.6-1997 for the E.A.R(R) Express trade mark Pod Plug trade mark. The new field-test methods were the FitCheck headphone (FCH) method, FitCheck in sound field (FCSF) method, and bone-conduction loudness balance (BCLB) method, all of which can be administered in small single-person audiometric booths such as are commonly found in industry. Twenty normal-hearing and audiometrically competent subjects naive to hearing protector use were tested with the laboratory and the three field-test methods in a repeated-measures design. Repeated-measures models with structured covariance matrices were used to analyze the data. Significant effects were found for method, frequency, and first-order frequency-by-gender and frequency-by-method interactions. These effects and interactions were expected given the different psychophysical tasks. The FCSF and BCLB methods provided attenuations that were not significantly different from those found with Method B. Although the attenuations measured for the FCH method were statistically different (greater) than the attenuations from the other methods, the differences were within the magnitude of acceptable test-retest audiometric variability. The results suggest that the FCH and FCSF methods were both feasible and reliable methods for field testing. The FCH method is limited to testing earplugs, and the FCSF requires additional equipment to outfit the test booth, but could be used for testing all types of protectors.

Adolescent↗

PubMed1999

Resonators in insect sound production: how insects produce loud pure-tone songs.

In a resonant vibration, two reactive elements, such as a mass and a spring, interact: the resonant frequency depends on the magnitude of these two elements. The build-up and decay of the vibration depend on the way the resonator is driven and on the damping in the system. The evidence for the existence of resonators in insect sound production is assessed. The mechanics of different types of sound-producing system found in insects is described. Mechanical frequency-multiplier mechanisms, which convert the relatively slow contraction of muscles to the higher frequency of the sound, are commonly used to convert the comparatively slow muscle contraction rate to the higher frequency of the sound. The phasing and rate of mechanical excitation may also affect the frequency and duration of the sound that is produced. Although in many insects the song may appear to be produced by the excitation of a simple resonator, the song frequency may not be constant, suggesting that other factors, such as the mechanism of excitation, or variation of the effective mass or elasticity of the system during sound production, may be additional determinants of the song frequency. Loud, and hence efficient, transduction of the energy of a mechanical resonator into sound may involve a second stage of transduction which, by damping the resonator, may compromise tonal purity. Some insect singers resolve this problem by tuning both stages of transduction to the same frequency, thereby maintaining tonal purity.

Animals↗

PubMed2002

FDA adverse event reports on statin-associated rhabdomyolysis.

OBJECTIVE: To determine the number of cases of statin-associated rhabdomyolysis reported to the Food and Drug Administration for 6 statins and to profile the cases. METHODS: A retrospective analysis of all domestic and foreign reports of statin-associated rhabdomyolysis between November 1997 and March 2000 was conducted. Outcome measures included the total number of reports (initial plus follow-up), the number of unique cases, age, gender, percentages of report codes and role codes, and frequencies of concomitant interacting drugs that may have precipitated rhabdomyolysis, outcomes codes, and report source codes. RESULTS: There were 871 reports of statin-associated rhabdomyolysis in the 29-month time frame examined, representing 601 cases. The following number of cases were associated with each of the individual statins: simvastatin, 215 (35.8%); cerivastatin, 192 (31.9%); atorvastatin, 73 (12.2%); pravastatin, 71 (11.8%); lovastatin, 40 (6.7%); and fluvastatin, 10 (1.7%). Drugs that may have interacted with the statins were present in the following number of cases: mibefradil (n = 99), fibrates (n = 80), cyclosporine (n = 51), macrolide antibiotics (n = 42), warfarin (n = 33), digoxin (n = 26), and azole antifungals (n = 12). The reports of 62.1% of cases were classified as expedited. Statins were designated as the primary suspect in 72.0% of the cases. Death was listed as the outcome in 38 cases. The majority of reports (n = 556) were from health professionals. CONCLUSIONS: Compared with the other statins, simvastatin and cerivastatin were implicated in a relatively higher number of reports. Because of the various limitations of a spontaneous reporting-system database, caution is urged when interpreting the relative number of cases reported.

Adverse Drug Reaction Reporting Systems↗

PubMed2006

An investigation of the relationship between anxiety and depression and urge incontinence in women: development of a psychological model.

OBJECTIVES: The study investigated the association between anxiety and depression and urge incontinence and the direction of causal pathways between these variables. DESIGN: A prospective longitudinal postal survey. METHOD: A random sample of women aged 40 years or more, registered with a general practitioner in Leicestershire or Rutland, was mailed a postal questionnaire. The questionnaire included questions on general health, urinary symptoms and the Hospital Anxiety and Depression Scale (HADS). In total, 12,568 women responded to the baseline postal survey (65.3% response rate) and 9,596 to the first annual follow-up (79.8% response rate). The prevalence and one-year incident rates of these symptoms were compared and contrasted, whilst controlling for confounding variables. RESULTS: A significant proportion of women with urge incontinence reported symptoms of anxiety (56.6%) and depression (37.6%). Anxiety and depression were associated with a number of urinary symptoms and were not exclusive to urge incontinence. Incident cases of anxiety and depression were predicted by the presence of urge incontinence at baseline. Incident cases of urge incontinence were predicted by anxiety at baseline, but not depression. Anxiety, urge incontinence and frequency appeared to interact and exacerbate each other. CONCLUSIONS: The findings demonstrated the relevance of emotional factors in the development and maintenance of urge incontinence. Currently, assessment and treatment protocols for urge incontinence concentrate on physical symptoms and toilet behaviours. A more integrated psychological model of urge incontinence is proposed.

Adult↗

PubMed1989

Cardiovascular effects of high-frequency oscillatory and jet ventilation.

To determine the effects of mean airway pressure on hemodynamics during high-frequency ventilation, we ventilated five cats (wt 2.8 +/- 0.6 kg) using both HFOV (frequencies 3 to 20 Hz) and HFJV (frequencies 4 to 8 Hz) at Paw values ranging from 2 to 12 cm H2O. Combinations of frequency and tidal volume that maintained normocapnia were employed in random order before and after reduction of static compliance of the respiratory system by lung lavage. Heart rate was comparable during both modes of high-frequency ventilation. During both HFOV and HFJV, the cardiac output decreased and PVR increased in normal and surfactant-deficient cats as Paw was elevated (all p less than 0.01, ANOVA). For both HFOV and HFJV linear regression of Paw and cardiac output yielded comparable slopes and y-intercepts. Lung lavage reduced the effect of Paw but did not eliminate it. Changes in ventilatory frequency did not affect cardiac output or PVR. We conclude that the interaction between high-frequency ventilation and cardiovascular function is largely determined by Paw and compliance and is independent of ventilator frequency and the type of ventilator used.

Animals↗

PubMed2006

Development of interaction measures based on adaptive non-linear time series analysis of biomedical signals.

An important feature of interaction between two signal components is the direction of the interaction. Recently, different methods have been developed and applied for detecting the direction of interactions. Besides frequency-dependent methods, Granger causality is a well-known frequency-independent approach. One popular linear approach is based on autoregressive modeling of the underlying process and evaluates prediction errors under different past assumptions. In the present study, this linear concept is extended to self-exciting threshold autoregressive models, which cover a wider class of processes. An approach for the definition of a state-dependent Granger causality is given and applied to simulated data.

Algorithms↗

PubMed2004

Linearity of cortical receptive fields measured with natural sounds.

How do cortical neurons represent the acoustic environment? This question is often addressed by probing with simple stimuli such as clicks or tone pips. Such stimuli have the advantage of yielding easily interpreted answers, but have the disadvantage that they may fail to uncover complex or higher-order neuronal response properties. Here, we adopt an alternative approach, probing neuronal responses with complex acoustic stimuli, including animal vocalizations. We used in vivo whole-cell methods in the rat auditory cortex to record subthreshold membrane potential fluctuations elicited by these stimuli. Most neurons responded robustly and reliably to the complex stimuli in our ensemble. Using regularization techniques, we estimated the linear component, the spectrotemporal receptive field (STRF), of the transformation from the sound (as represented by its time-varying spectrogram) to the membrane potential of the neuron. We find that the STRF has a rich dynamical structure, including excitatory regions positioned in general accord with the prediction of the classical tuning curve. However, whereas the STRF successfully predicts the responses to some of the natural stimuli, it surprisingly fails completely to predict the responses to others; on average, only 11% of the response power could be predicted by the STRF. Therefore, most of the response of the neuron cannot be predicted by the linear component, although the response is deterministically related to the stimulus. Analysis of the systematic errors of the STRF model shows that this failure cannot be attributed to simple nonlinearities such as adaptation to mean intensity, rectification, or saturation. Rather, the highly nonlinear response properties of auditory cortical neurons must be attributable to nonlinear interactions between sound frequencies and time-varying properties of the neural encoder.

Acoustic Stimulation↗