Search PubMed⌕ Search

Biomedical subjects

J C Saunders

Publications and source records attributed to J C Saunders.

At least 127 records · Page 7Linked to original sources
PubMed1969

Behavioral discrimination of click intensity in cat.

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.

Animals↗
PubMedDate not supplied

Middle-ear development. V: Development of umbo sensitivity in the gerbil.

PURPOSE: The development of the umbo response in the gerbil was studied in order to further elucidate the contribution of the middle ear to the development of auditory function. MATERIALS AND METHODS: Laser interferometry was used to study the development of umbo velocity in Mongolian gerbils between 10 days after birth and maturity. RESULTS: Before 15 days after birth, immaturities in the middle ear prevented any reliable measures of middle-ear motion. However, between 15 and 20 days after birth, a 10 dB improvement in umbo velocity was noted in the low-frequency (0.5 to 2.0 kHz) region of the umbo response. This improvement in sensitivity was correlated to an increased admittance due to an expanding bulla volume. Interestingly, umbo velocity remained relatively constant in the mid- and high-frequency regions of the response curve between 15 and 42 days after birth. The umbo response in the adult gerbil was decidedly different when compared with the response at 42 days after birth. CONCLUSION: We speculate that a decrease in bulla volume along with increased ossicular mass contributed to the changes in the adult umbo response. When the maturation of the umbo response was compared with more central ontogenetic measures, it became apparent that structures more central to the middle ear continued to develop well past the time the middle ear was structurally and functionally mature.

Acoustic Stimulation↗
PubMedDate not supplied

Middle ear structure in the chinchilla: a quantitative study.

The anatomic features of the chinchilla middle ear were identified and various aspects of the conductive apparatus were measured in a number of specimens by different methods. These aspects included area measures of the tympanic membrane, stapes footplate, oval window, and round window; middle-ear volume; dimensions of the ossicles, the length of their rotational axes as well as the malleus to incus lever ratio. We also weighed the ossicles. The findings are discussed with reference to their possible significance for auditory signal processing in the chinchilla.

Animals↗
PubMedDate not supplied

Family functioning in families providing care for a family member with schizophrenia.

The purpose of this study is to explore the influences of family coping behaviors, psychological distress, social support, and patient behavioral problems on family functioning in families providing care for a member with schizophrenia. Family stress theory provided the theoretical framework for this study. A convenience sample of 58 families providing care for a family member with schizophrenia was recruited from a metropolitan area in a southeastern state. The majority of the caregivers were mothers who were married and college educated. The mean age of the caregiver was 59 years, with an average of 17 years in providing care for the family member. Findings indicate that family psychological distress and patient behavioral problems are important factors in family functioning. This knowledge may be useful for mental health nurses in assessing families and developing nursing interventions.

Adaptation, Psychological↗
PubMedDate not supplied

Olivocochlear bundle activity recorded in awake cats.

Multi-unit activity was recorded in awake cats from the crossed olivocochlear bundle (COCB). Miniature stainless stell concentric electrodes were chronically implanted onto the floor of the fourth ventricle of six animals. There was no activity at the electrode tip in anesthetized animals, while in awake cats a great deal of unit activity could be seen. A correlation between COCB activity and ongoing behavioral activity such as scratching, grooming, yawning, or orientation could not be established. It was found, however, that the multi-unit responses in the COCB statistically increased their firing rate during acoustic stimulation, and a 500-Hz tone was found to be most effective. The electrode locations were histologically confirmed. The present results are similar to other data that describe unit activity in the olivocochlear bundle of decerebrate cats. The capacity to record from this fiber tract in awake animals, however, provides a new tool for studying the peripheral efferent pathway of the auditory system.

Acoustic Stimulation↗
PubMedDate not supplied

Measures of middle ear admittance during experimentally induced changes in middle ear volume in the hamster.

The relation between middle ear admittance measured at the tympanic membrane and middle ear volume was studied in adult hamsters. A modified tympanometric procedure was used to measure complex admittance at eight test frequencies. Middle ear volume was varied by injecting small amounts of water into the bulla cavity. As bulla volume decreased, the value of admittance magnitude also decreased. The measured values of admittance magnitude could be accurately predicted by the equation for admittance magnitude until the bulla was about 70% filled. The results confirm that measures of middle ear admittance reflect the volume of the middle ear cavity as would be expected of a pure compliance. Where such measures are available in man, they might be used to predict the degree of fluid intrusion into the middle ear cavity.

Acoustic Impedance Tests↗
PubMedDate not supplied

Evoked responses from inferior colliculus as an index of hearing thresholds in guinea pigs.

Bipolar electrodes were implanted in the inferior colliculus of 10 healthy guinea pigs, and visual detection level thresholds of auditory evoked responses were obtained at 17 frequencies between 0.5 and 20.0 kHz. One microvolt isopotential curves from the round window for the same test frequencies were obtained in these animals. A comparison between the evoked response threshold curves and previous reports of the behavioral audiogram reveals a favorable correlation. The cochlear potential curve, however, appears to be a less efficient predictor of the audibility curve than the evoked response thresholds. The utility of evoked response audiometry from the inferior colliculus for quickly assessing auditory thresholds in the guinea pig is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

Hydrofitness devices for strengthening upper extremity muscles.

Our evaluation of hydrofitness devices for strengthening arm muscles has revealed several important determinants of their performance. Most importantly, the device's frontal projection should be in the shape of a paddle whose surface area can be varied to meet the individual exerciser's needs. Its weight should be light to minimize the inertial forces encountered in charging the velocity of paddle movement. Its handle should have a relatively large circumference without digital profiling. These optimal performance parameters have been recently incorporated into a new hydrofitness device that will be commercially available for aquatic exercise programs for strengthening upper extremity muscles.

Adult↗