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P Prinz

Publications and source records attributed to P Prinz.

At least 19 recordsLinked to original sources
PubMed2002

Temporal modulation transfer functions in auditory receptor fibres of the locust ( Locusta migratoria L.).

The temporal resolution of auditory receptors of locusts was investigated by applying noise stimuli with sinusoidal amplitude modulations and by computing temporal modulation transfer functions. These transfer functions showed mostly bandpass characteristics, which are rarely found in other species at the level of receptors. From the upper cut-off frequencies of the modulation transfer functions the minimum integration times were calculated. Minimum integration times showed no significant correlation to the receptor spike rates but depended strongly on the body temperature. At 20 degrees C the average minimum integration time was 1.7 ms, dropping to 0.95 ms at 30 degrees C. The values found in this study correspond well to the range of minimum integration times found in birds and mammals. Gap detection is another standard paradigm to investigate temporal resolution. In locusts and other grasshoppers application of this paradigm yielded values of the minimum detectable gap widths that are approximately twice as large than the minimum integration times reported here.

Acoustic Stimulation↗
PubMed2001

Representation of acoustic communication signals by insect auditory receptor neurons.

Despite their simple auditory systems, some insect species recognize certain temporal aspects of acoustic stimuli with an acuity equal to that of vertebrates; however, the underlying neural mechanisms and coding schemes are only partially understood. In this study, we analyze the response characteristics of the peripheral auditory system of grasshoppers with special emphasis on the representation of species-specific communication signals. We use both natural calling songs and artificial random stimuli designed to focus on two low-order statistical properties of the songs: their typical time scales and the distribution of their modulation amplitudes. Based on stimulus reconstruction techniques and quantified within an information-theoretic framework, our data show that artificial stimuli with typical time scales of >40 msec can be read from single spike trains with high accuracy. Faster stimulus variations can be reconstructed only for behaviorally relevant amplitude distributions. The highest rates of information transmission (180 bits/sec) and the highest coding efficiencies (40%) are obtained for stimuli that capture both the time scales and amplitude distributions of natural songs. Use of multiple spike trains significantly improves the reconstruction of stimuli that vary on time scales <40 msec or feature amplitude distributions as occur when several grasshopper songs overlap. Signal-to-noise ratios obtained from the reconstructions of natural songs do not exceed those obtained from artificial stimuli with the same low-order statistical properties. We conclude that auditory receptor neurons are optimized to extract both the time scales and the amplitude distribution of natural songs. They are not optimized, however, to extract higher-order statistical properties of the song-specific rhythmic patterns.

Acoustic Stimulation↗
PubMed2001

Urinary free cortisol and sleep under baseline and stressed conditions in healthy senior women: effects of estrogen replacement therapy.

The purpose of this study was to examine the effects of a mild 24-h stress (indwelling IV catheter) on cortisol and sleep in postmenopausal women, and to evaluate differences due to estrogen replacement therapy (ERT) status. This study, conducted in the General Clinical Research Center at the University of Washington Medical Center, examined sleep, cortisol and sleep-cortisol relationships in both baseline and stress conditions, and compared women on ERT with women not on ERT. Forty-two women (age=69.6 +/- 6.2 years [SD]), of whom 20 were on ERT, participated. Urinary free cortisol (UFC) levels and sleep polysomnography were measured over both 24-baseline and stress condition. Sleep was impaired in the stress condition for both groups; mean UFC levels were higher, sleep efficiency and minutes of stages 2, 3 and 4 sleep were reduced, and morning risetime was earlier in the stress than baseline condition. For the combined groups, age-controlled correlations between 24-h UFC and sleep were significant in both conditions: at baseline, UFC levels were associated with earlier time of rising and less REM sleep, and under stress with reduced sleep efficiency, there was reduced minutes of stages 2, 3, 4 sleep, reduced REM sleep, and an earlier risetime. The pattern of negative significant correlations between UFC and sleep/sleep timing remained when plasma estrogen was statistically controlled; however, when groups were examined separately, the significant negative UFC-sleep relationships were confined to the non ERT group. Elevated 24-h UFC is associated with impaired sleep and earlier awakening in older women not on ERT, but not in women on ERT.

Aged↗
PubMed1999

Glial hyperpolarization upon nerve root stimulation in the leech Hirudo medicinalis.

Hyperpolarizing responses in neuropil glial cells evoked by nerve root stimulation were studied in the central nervous system of the leech Hirudo medicinalis using intracellular recording and extracellular stimulation techniques. From a mean resting potential of -60.5 +/- 1.0, the glial membrane was hyperpolarized by -8.6 +/- 0.8 mV, via stimulation of the dorsal posterior nerve root in an isolated ganglion. Nerve root stimulation evoked biphasic or depolarizing responses in glial cells with resting potentials around -70 mV (Rose CR, Deitmer JW. J. Neurophysiol. 73:125-131, 1995). The hyperpolarizing response was reduced by the ionotropic glutamate receptor antagonist CNQX (50 microM) to 58% of its initial amplitude. In 15 mM Ca2+/15 mM Mg(2+)-saline the hyperpolarization was reduced by 44%. The hyperpolarization that persisted in high-divalent cation saline was not affected by CNQX. Bath-applied glutamate (500 microM) and kainate (2 microM) elicited glial hyperpolarizations that were sensitive to CNQX and 10 mM Mg2+/1 mM Ca(2+)-saline. The 5-HT-antagonist methysergide did not affect the hyperpolarizations evoked by nerve root stimulation. The results show that in the leech glial membrane responses to neuronal activity include not only depolarizations, as shown previously, but also hyperpolarizations, which are mediated by direct and indirect neuron-glial communication pathways. In the indirect pathway, glutamate is a transmitter between neurons.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1997

A study of the relationship between American sign language and English literacy.

This article presents the findings of a study of the relationship between American Sign Language (ASL) skills and English literacy among 160 deaf children. Using a specially designed test of ASL to determine three levels of ASL ability, we found that deaf children who attained the higher two levels significantly outperformed children in the lowest ASL ability level in English literacy, regardless of age and IQ. Furthermore, although deaf children with deaf mothers outperformed deaf children of hearing mothers in both ASL and English literacy, when ASL level was held constant, there was no difference between these two groups, except in the lowest level of ASL ability. The implication of this research is straightforward and powerful: Deaf children's learning of English appears to benefit from the acquisition of even a moderate fluency in ASL.

Journal Article↗
PubMed1990

[Experiences in the application of tissue transplants in Bützow district hospital].

In 15 years 63 Transplantations were done. 17 times with autogenous and 46 times with allogeneic transplants. Main indications were relapsed- and scar herniations, ruptures of achilles tendon and acromio-clavicular luxation. Advantages of allogeneic transplantation in comparison with autogenous transplantations will be demonstrated. It is referred to the consistent use of principles of aseptic, antiseptic and the careful atraumatic surgical technique in transplantation.

Dura Mater↗
PubMed1987

Nipple involvement and multicentricity in breast cancer. A study on whole organ sections.

Our study examined 166 patients with breast cancer with a mean age of 63 years. Each patient underwent mastectomy with the organ being investigated by histological giant sections and additional small sections from the nipple. Nipple involvement was found in 64 cases (38%). Multifocal carcinoma occurred in 76 patients. Further multicentric carcinomatous foci (36 cases) demonstrated a significant increase in affected nipples. Additional atypical ductal or lobular hyperplasia was observed in 53 cases and showed involvement in 34. Nine carcinomas of ductal origin were combined with lobular carcinoma in situ, all cases proved to have carcinomatous changes in the nipple. It is concluded that apart from the well-known influence of advanced tumor stages and tumor localization, nipple involvement correlates with multicentricity and multifocality of breast cancer as a disease of the whole organ.

Adenoma↗
PubMed1983

Sleep disturbances in the institutionalized aged.

One hundred eighty nursing home residents, not psychotic or demented, average age 82 years, were administered a 30-minute structured interview to identify and characterize their sleeping patterns, health status, medications, psychosocial environment, and living conditions. In addition, both the residents and the night nurses rated quality of sleep on a five-point scale. Residents and nurses on all shifts also rated appetite and exercise on five-point scales. Residents were classified as having a sleep disturbance if they met at least one of the following criteria and reported poor sleep quality: onset of sleep latency greater than 30 minutes, three or more nighttime awakenings, and less than six hours sleep per night. Forty-five per cent of the residents met at least one clinical research criterion. Residents with sleep disturbance rated their sleep quality significantly lower than their peers not meeting research criteria. However, the nurses' ratings did not discriminate problem sleepers, and they correlated poorly with the residents' ratings. These subjective patient evaluations are discussed in relation to nursing evaluations, prescription of hypnotic medications, and other variables.

Aged↗
PubMed1981

On the use of repeated measures designs in psychopharmacology.

A popular paradigm in psychopharmacology is the repeated measures design. Unfortunately the test of equal means across the repeated trials requires an assumption that is often untenable and which can lead to erroneous interpretations. In order to minimize this bias three approaches have been suggested. The authors discuss the three approaches in the context of a psychopharmacologic example.

Analysis of Variance↗