Alterations In Response Patterns Research Articles

Effect of contralateral stimulation on acoustic reflectance measurements

IntroductionAcoustic reflectance is an important tool in the assessment of middle ear afflictions, and the method is considered advantageous in relation to tympanometry. There has been a growing interest in the study of contralateral acoustic stimulation and its effect on the activation of the efferent auditory pathway. Studies have shown that the introduction of simultaneous stimulation in the contralateral ear generates alterations in auditory response patterns. ObjectiveTo investigate the influence of contralateral stimulation on acoustic reflectance measurements. MethodsCase study of 30 subjects with normal hearing, of both genders, aged 18–30 years. The test and retest acoustic reflectance was conducted in the frequency range 200–6000Hz. The procedure was repeated with the simultaneous presence of contralateral white noise at 30dBNS. ResultsThe analysis of the conditions of test, retest, and test with contralateral noise showed statistical difference at the frequency of 2kHz (p=0.011 and p=0.002 in test and retest, respectively) in the right ear. ConclusionThe activation of the auditory efferent pathways through contralateral acoustic stimulation produces alterations in response patterns of acoustic reflectance, increasing sound reflection and modifying middle ear acoustical energy transfer.

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: II. Three-choice olfactory serial reversal task and an extra-dimensional shift (EDS).

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: II. Three-choice olfactory serial reversal task and an extra-dimensional shift (EDS).

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: I. Two-choice olfactory serial reversal task.

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: I. Two-choice olfactory serial reversal task.

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: II. Three-choice olfactory serial reversal task and an extra-dimensional shift (EDS)

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: II. Three-choice olfactory serial reversal task and an extra-dimensional shift (EDS)

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: I. Two-choice olfactory serial reversal task

Enduring alterations in response patterns in rats exposed to lead (Pb) during early development: I. Two-choice olfactory serial reversal task

Viability of neuromuscular tissues in hyperbaric gaseous environments containing variable N 2:He content ratios

The rat phrenic nerve-diaphragm preparation (PN-D) working in isometric mode under saturation with hyperbaric gaseous N 2/He/O 2(20%):CO 2 (3%) environments was subjected to variable N 2:He partial pressure ratios, at total pressures up to 300 psia. Elements of twitch response augmentation (transient) followed by progressive response blockade were observed, as a function of total pressure and of the N 2:He gas ratio. At high values of the ratio hyperbaric work at a given total pressure was characterized by a brief period (<20 min) of twitch response augmentation (<20%) followed by progression into irreversible blockade. As atmospheric N 2 was replaced by successive increments of He, the magnitude of PN-D response augmentation was increased, reaching a peak value near 80% above control levels at an N 2:He ratio of 1:1. The duration of augmentation was also increased markedly at ratios near 1:1. However, still further replacement of N 2 by He up to complete removal of N 2 resulted in progressive lessening of the augmentation (both magnitude and duration) of PN-D working behavior in hyperbaric atmospheres, and a subsequent shift into blockade which intensified with increased working time. These alterations in response patterns are interpreted in terms of possible interactions of the two diluent gases He and N 2 with neuromuscular receptors, leading to changes in tissue function and viability.

Hypothalamic regulation of female sexual behaviour; establishment of behavioural oestrus in spayed guinea-pigs following hypothalamic lesions.

Summary. Individual characteristics of sexual behaviour were empirically determined for twenty-seven spayed female guinea-pigs given three standardized tests after injection with 0·0034 mg of oestradiol benzoate and, 36 hr later, 0·4 mg of progesterone. Following this preoperative series of tests, hypothalamic lesions were produced electrolytically at different loci with various parameters of current duration and intensity. Alterations in the patterns of sexual behaviour displayed on three postoperative tests with identical hormonal treatments were evaluated statistically for each individual. Posteroventral hypothalamic lesions involving mammillary and premammillary structures were not associated with significant behavioural changes (N equals 4). Mid-ventral lesions were associated with alterations in response patterns in all but two animals. The behavioural changes were not correlated with size of lesions. Nine females with complete behavioural losses failed to display any signs of receptivity postoperatively. Ten showed statistically significant but incomplete losses in one or more of the components comprising the pattern of sexual behaviour, and two females displayed behavioural oestrus postoperatively in the absence of exogenous hormone. Lesions in females with behavioural oestrus appear to be more anterior and possibly more medial than those which eliminate sexual behaviour. Uteri of behavioural-oestrous females were atrophic suggesting that no oestrogen was provided by endogenous sources. The results suggest that mechanisms for both the facilitation and inhibition of female sexual behaviour exist within the hypothalamus. Moreover, hypothalamic regulation of reproductive behaviour is quantitative in nature, not 'all-or-none', and a range of partial deficits in behaviour can be observed after hypothalamic damage.