Latencies Of Na Research Articles

Effect of Music Training on Auditory Brainstem and Middle Latency Responses

Purpose: The auditory system has potentials to reorganize its structure and function in response to environmental changes such as training, experience, learning, injury, and disease. This is called neuroplasticity. A typical example of neuroplasticity is the music training, which demands cognitive and neural challenges resulting in enhanced auditory perception. This study investigated the effect of music training on auditory evoked responses, particularly auditory brainstem and middle latency responses. Methods: Forty college students consisting of twenty students with music training (musicians) and twenty students without music training (non-musicians) participated in the study. All participants have normal ranges in terms of pure tone audiometry, speech audiometry, and tympanometry. Auditory brainstem response (ABR) and auditory middle latency response (AMLR) from both ears were tested. Absolute latencies and amplitudes of waves in ABR and AMLR were obtained and analyzed.Results: The absolute latencies of wave I and V significantly differed between musicians and non-musicians. They were shorter for musicians than for non-musicians. Significant differences were found in the interpeak latencies of wave III-V and I-V between musicians and non-musicians. They were also shorter in musicians than for non-musicians. In addition, there were only significant differences in the latency of Na in AMLR between musicians and non-musicians. It was shorter for a musician than for non-musician.Conclusion: ABR was more sensitive to the efficacy of the music training.

The relationship between electrical auditory middle-latency response components and measures of auditory performance and speech intelligibility in pediatric cochlear implant recipients

Evidence for the utility of electrically-evoked auditory responses, as measures of objective hearing assessments in pediatric cochlear implant (CI) recipients, is proliferating. Recently, we demonstrated the relationship between electrical auditory brainstem response (EABR) and measures of auditory performance and speech intelligibility in pediatric CI users (Wang, Pan, Deshpande, & Ma, 2015). However, the EABR reflects activity only up to the auditory brainstem. The electrical auditory middle-latency response (EAMLR) is sensitive to the functioning of the sub-cortical structures as well as the auditory cortex and thus has greater utility in predicting auditory perception and processing. Here, we present data from 40 pre-lingually hearing impaired, pediatric CI recipients. The relationship between components of the EAMLR (latencies of Na, Pa, Nb, Pb; Na-Pa amplitude; and Na-Pa interval) and measures of auditory performance and speech intelligibility assessed using care-giver rating scales such as Categories of Auditory Performance (CAP) (Archbold, Lutman, & Marshall, 1995) and Speech Intelligibility Rating (SIR) (Allen, Nikolopoulos, Dyar, & O'Donoghue, 2001), respectively, are analyzed. EAMLR profiles of “good” versus “poor” CI users (based on CAP and SIR ratings) will be discussed. Additionally, the effect of age of implantation on the EAMLR, CAP and SIR outcomes will be considered.

Effect of Stimulus Rate and Gender on Auditory Middle Latency Response in Young Adults

Purpose: The main objective of this study was to investigate the effect of stimulus rate and gender on the latency and amplitude of the auditory middle latency response (AMLR) in Korean young females and males. Methods: A total of thirty young subjects consisting of fifteen males and fifteen females participated in the study. The stimulus repetition rate was changed in five steps: 0.5, 1, 2, 4, and 8/s. Results: The results showed significant differences of the stimulus rates on the Na latency, Pa amplitude, and Nb amplitude. With faster stimulus rates, the Na latency and the Nb amplitude slightly increased while the Pa amplitude decreased. The Na, Pa, and Nb latencies were longest with the stimulus rate of 2/s. The Na and Nb amplitudes were largest with the stimulus rate of 4/s while the Pb amplitude was largest with the stimulus rate of 1/s. There were significant differences in the latency of Na and the amplitudes of Na, Pa, Nb, and Pb according to gender. The latencies of Na, Pa, Nb, and Pb in females were longer than in males while the amplitudes of Na, Pa, Nb, and Pb in males are larger than in females. Conclusion: The ranges of optimal stimulus rate to elicit the apparent AMLR waveform were 1-8/s. This provides clinical basic data of stimulus rate and gender-specific norms on the latency and amplitude of the AMLR waveform.

Midlatency auditory evoked potentials during anaesthesia with increasing endexpiratory concentrations of desflurane.

Under general anaesthesia with the volatile anaesthetics halothane, enflurane and isoflurane, midlatency auditory evoked potentials (MLAEP) are suppressed dose-dependently. Therefore, MLAEP have been used to measure depth of anaesthesia and to indicate intraoperative awareness. Desflurane is a new volatile anaesthetic and its effect on MLAEP have not been studied previously. We have studied MLAEP during general anaesthesia with increasing endexpiratory concentrations of desflurane in 12 patients scheduled for elective gynaecological surgery. Auditory evoked potentials were recorded in the awake state and during anaesthesia with endexpiratory steady state concentrations of 1.5, 3.0, 4.5 and 6.0 vol % of desflurane on vertex (positive) and mastoids on both sides (negative). Latencies of the peaks V, Na, Pa, Nb, Pl (ms) and amplitudes Na/Pa, Pa/Nb and Nb/Pl (micro V) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anaesthesia with increasing endexpiratory concentration of desflurane, the latency of the brainstem response V increased only slightly. In contrast, MLAEP showed a marked dose-dependent and statistically significant increase in latencies of Na, Pa, Nb and Pl and decrease in amplitudes of Na/Pa, Pa/Nb and Nb/Pl. Under 6.0 vol % of desflurane MLAEP were severely attenuated or even abolished. Based on these observations, endexpiratory concentrations of > or = 4.5 vol % desflurane should suppress awareness phenomena such as auditory perceptions during anaesthesia.

Middle latency auditory evoked potentials during repeated transitions from consciousness to unconsciousness.

We have investigated the relationship between changes in the middle latency auditory evoked potentials during alternating periods of consciousness and unconsciousness produced by propofol infusion combined with spinal anaesthesia for total knee replacement. Eleven patients completed the study, of whom two had recollection of events after the onset of the anaesthetic. There were no significant differences in heart rate or systolic arterial pressure between any conscious and unconscious period. With the first change from consciousness to unconsciousness, latencies of Na, Pa and Nb increased from mean (SD) starting values of 20.0 (1.4), 31.7 (1.0) and 42.8 (1.6) ms to 22.5 (2.0), 39.3 (2.1) and 57.8 (4.4) ms, respectively. During successive transitions from unconsciousness to consciousness, awake latencies were slightly higher than those of baseline awake, whereas anaesthetised latencies were similar to the ones obtained during the first period of unconsciousness. The consistent changes demonstrated, suggest that the auditory evoked potentials could represent a reliable indicator of potential awareness during anaesthesia.

The Effects of Anesthesia with Increasing End-Expiratory Concentrations of Sevoflurane on Midlatency Auditory Evoked Potentials

We studied midlatency auditory evoked potentials (MLAEP) during general anesthesia with increasing end-expiratory concentrations of sevoflurane in 12 patients scheduled for elective gynecologic surgery. After oral premedication with 20 mg clorazepate dipotassium, anesthesia was induced with etomidate (0.2 mg/kg intravenously [IV]). Vecuronium (0.1 mg/kg) was given for neuromuscular block, and controlled ventilation with sevoflurane in 100% O2 was instituted. Auditory evoked potentials were recorded in the awake state and during anesthesia with end-expiratory steady-state concentrations of 0.5, 1.0, 1.5, and 2.0 vol% of sevoflurane on vertex (positive) and mastoids on both sides (negative). Latencies of peaks V, Na, Pa, Nb, and P1 (ms) and amplitudes of Na/Pa, Pa/Nb, and Nb/P1 (mu V) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia with increasing end-expiratory concentrations of sevoflurane, the latency of the brainstem response V increased slightly. In contrast, MLAEP showed marked dose-dependent, statistically significant increases in the latencies of Na, Pa, Nb, and P1 and decreases in the amplitudes of Na/Pa, Pa/Nb, and Nb/P1. Under 2 vol% of sevoflurane, MLAEPs were severely attenuated or abolished. Based on these observations, >or=to1.5 vol% sevoflurane should suppress phenomena such as auditory perceptions, intraoperative wakefulness, and awareness. (Anesth Analg 1995;81:817-22)