Home About us Contact
|
Home About us Contact | ||
|
|
||
Latency Response (latency + response)
Selected AbstractsGPR30 Differentially Regulates Short Latency Responses of Luteinising Hormone and Prolactin Secretion to OestradiolJOURNAL OF NEUROENDOCRINOLOGY, Issue 9 2009D. Lebesgue Rapid, nongenomic actions of 17,-oestradiol (E2) on hypothalamic neurones that may be relevant to reproductive function were described decades ago. The orphan G protein-coupled receptor, GPR30, was recently shown to bind oestrogens and to trigger rapid signalling in vitro, and is expressed in several rat and human brain regions, including the hypothalamus. We used two complementary approaches to investigate the role of GPR30 in hypothalamic responses to E2 that are relevant to reproductive physiology. Serial blood sampling after the acute administration of the selective GPR30 agonist G1 was used to assess the role of GPR30 in short latency negative-feedback inhibition of luteinising hormone (LH) secretion and facilitation of prolactin secretion in ovariohysterectomised female rats. In vivo RNA interference (RNAi), mediated by adeno-associated virus-expressing small hairpin RNA (shRNA) infused into the mediobasal hypothalamus, was used to study the effects of GPR30 knockdown on these rapid responses to E2. Longer-term actions of E2 on female sexual behaviour (lordosis) were also examined in female rats subjected to in vivo RNAi. Administration of E2 or G1 triggered a short latency surge of prolactin secretion, and animals subjected to GPR30 RNAi showed significantly less E2 -dependent prolactin release than animals receiving control virus. G1 did not mimic E2 negative-feedback inhibition of LH secretion, and GPR30 RNAi did not interfere with E2 suppression of LH or facilitation of lordosis behaviour. These findings suggest that activation of GPR30 promotes short latency prolactin secretion but does not mediate E2 negative-feedback inhibition of LH secretion or E2 facilitation of female reproductive behaviour. [source] Attenuated human auditory middle latency response and evoked 40-Hz response to self-initiated soundsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2009Pamela Baess Abstract For several modalities, it has been shown that the processing of sensory information generated by our own actions is attenuated relative to the processing of sensory information of externally generated stimuli. It has been proposed that the underlying mechanism builds predictions about the forthcoming sensory input and forwards them to the respective sensory processing levels. The present study investigated whether early auditory processing is suppressed by the top-down influences of such an internal forward model mechanism. To this end, we compared auditory middle latency responses (MLRs) and evoked 40-Hz responses elicited by self-initiated sounds with those elicited by externally initiated but otherwise identical sounds. In the self-initiated condition, the amplitudes of the Pa (27,33 ms relative to sound onset) and Nb (40,46 ms) components of the MLRs were significantly attenuated when compared to the responses elicited by click sounds presented in the externally initiated condition. Similarly, the evoked activity in the 40-Hz and adjacent frequency bands was attenuated. Considering that previous research revealed subcortical and auditory cortex contributions to MLRs and 40-Hz responses, our results support the existence of auditory suppression effects with self-initiated sounds on temporally and structurally early auditory processing levels. This attenuation in the processing of self-initiated sounds most probably contributes to the optimal processing of concurrent external acoustic events. [source] Effect of hypoxia on the auditory system of goat fetuses during extrauterine incubationJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 2 2003Nobuko Nishioka Abstract Aim:, To investigate the effect of hypoxia on the auditory system in fetuses, we attempted to analyze the auditory brainstem response, the middle latency response, and changes of several physiological parameters of goat fetuses during extrauterine incubation. Methods:, We conducted extrauterine incubation of five goat fetuses at around 127 days of gestation (term = 148 days). Their physiological parameters, such as fetal heart rate, mean blood pressure, flow rate of carotid artery, as well as the auditory brainstem response and middle latency response, were recorded prior to and during hypoxia, and the two sets of data were compared with each other. Results:, In all five cases, the fetal heart rate decreased from 178 ± 12.2 b.p.m. to 144 ± 15.2 b.p.m. during hypoxia, while mean blood pressure and flow rate of carotid artery increased from 37.3 ± 3.7 mmHg to 43.2 ± 5.1 mmHg, and from 38.5 ± 5.5 mL/min to 47.0 ± 5.1 mL/min, respectively. The latency of the auditory brainstem response's wave V and of the middle latency response's Pa wave elongated from 5.24 ± 0.24 ms to 5.69 ± 0.20 ms, and from 19.2 ± 1.6 ms to 20.9 ± 1.4 ms, respectively. Conclusions:, Although fetal compensatory reactions, such as increases in mean blood pressure and flow rate of carotid artery during hypoxia were recognized, elongation of latency, and decrement of amplitude were observed in the auditory brainstem response and middle latency response. These results suggest that hypoxia itself influences the auditory system of the fetus. [source] Attenuated human auditory middle latency response and evoked 40-Hz response to self-initiated soundsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2009Pamela Baess Abstract For several modalities, it has been shown that the processing of sensory information generated by our own actions is attenuated relative to the processing of sensory information of externally generated stimuli. It has been proposed that the underlying mechanism builds predictions about the forthcoming sensory input and forwards them to the respective sensory processing levels. The present study investigated whether early auditory processing is suppressed by the top-down influences of such an internal forward model mechanism. To this end, we compared auditory middle latency responses (MLRs) and evoked 40-Hz responses elicited by self-initiated sounds with those elicited by externally initiated but otherwise identical sounds. In the self-initiated condition, the amplitudes of the Pa (27,33 ms relative to sound onset) and Nb (40,46 ms) components of the MLRs were significantly attenuated when compared to the responses elicited by click sounds presented in the externally initiated condition. Similarly, the evoked activity in the 40-Hz and adjacent frequency bands was attenuated. Considering that previous research revealed subcortical and auditory cortex contributions to MLRs and 40-Hz responses, our results support the existence of auditory suppression effects with self-initiated sounds on temporally and structurally early auditory processing levels. This attenuation in the processing of self-initiated sounds most probably contributes to the optimal processing of concurrent external acoustic events. [source] Click and Low-, Middle-, and High-Frequency Toneburst Stimulation of the Canine CochleaJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2002G. Ter Haar A method was developed to deliver tonebursts ranging in frequency from 1 to 32 kHz for frequency-specific assessment of the canine cochlea. Brainstem auditory-evoked responses (early latency responses, 0,10 ms) to a click (CS) and to 1-, 2-, 4-, 8-, 12-, 16-, 24-, and 32-kHz toneburst stimulations (TS) were compared at 80-dB sound pressure level stimulus (SPL) intensity in 10 adult dogs. All stimulations yielded a 5,7 positive wave pattern, with the exception of the 1-kHz TS, which evoked a frequency-following response (FFR). Thresholds were lowest for the CS and the 12- and 16-kHz TS. All individual peak latencies for TS were significantly (P, .05) longer than for CS. Peak I latencies were significantly (P,.05) shorter for the 12- and 16-kHz TS than for the other TS. Interpeak latencies I-V were significantly (P, .05) longer for the 4- to 32-kHz TS than for CS. Differences in interpeak latencies I,III were not significant. Amplitudes of waves I and V were significantly (P, .05) lower for TS than for CS, except for higher wave V amplitude (P, .05) at 2- and 32-kHz TS. Peak I-V amplitude ratios were significantly (P, .05) higher for the 2-, 4-, 16-, 24-, and 32-kHz TS and lower for the 8- and 12-kHz TS, compared to CS. We conclude that reproducible information on frequency specificity of the canine cochlea can be obtained by TS. This report provides a normative database for parameters needed to evaluate frequency-specific hearing loss in dogs. [source] | ||||||||||