THE BRAIN-STEM AUDITORY-EVOKED RESPONSE IN THE BIG BROWN BAT (EPTESICUS-FUSCUS) TO CLICKS AND FREQUENCY-MODULATED SWEEPS
THE BRAIN-STEM AUDITORY-EVOKED RESPONSE IN THE BIG BROWN BAT (EPTESICUS-FUSCUS) TO CLICKS AND FREQUENCY-MODULATED SWEEPS
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DOI：
10.1121/1.410318
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发表时间：
1994-08-01
影响因子：
2.4
通讯作者：
MOSS, CF
中科院分区：
文献类型：
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作者：
BURKARD, R;MOSS, CF
进行了三个实验，以评估刺激水平对脑干听觉诱发反应（BAER）在大棕蝙蝠（Eptesicus fuscus），一种使用调频（FM）声纳声音回声定位的影响。实验一考察了点击水平对BAER的影响。滴答声以10 dB步长在30至90 dB pSPL的水平呈现。每只动物对50 dB pSPL及以上水平的咔哒声有可靠的反应，显示BAER在咔哒声发作后的前3-4 ms（波i-iv）内包含4个峰值。随着点击水平的增加，BAER峰振幅增加，峰潜伏期缩短。随着点击水平的增加，i-iv间期也会减少。在实验2中，刺激是1 ms线性FM扫描，频率从100 kHz降低到20 kHz。刺激水平范围为20至90 dB pSPL。对于40 dB pSPL及以上的水平，在所有动物中观察到FM扫描的BAER。这些反应在波形形态上与点击诱发的BAER相似，但值得注意的是，在较高水平的FM扫描中观察到了额外的峰值。该峰值（波ia）出现在较低水平的第一个波（波ib）之前。随着FM扫描水平的增加，峰值潜伏期减少，峰值振幅增加。i-iv间期和ib-iv间期的幅度和行为相似，这表明FM扫描的ib波是对点击刺激的i波反应的同源物。实验3检验了波ia代表比波ib更多的基底耳蜗区域发出的活动的假设。FM扫描（100-20 kHz）以90 dB pSPL呈现，宽带噪声水平升高，直到BAER被消除。该“掩蔽阈值”发生在85 dB SPL噪声下。在掩蔽阈值下，宽带噪声在20至80 kHz的五个截止频率处被陡峭高通滤波。通常，对于56.6 kHz及以下的掩蔽截止频率，波ia被消除，而对于低至28.3 kHz的掩蔽截止频率，通常观察到波ib。这三个实验的结果进行了比较，并与其他哺乳动物BAER研究的数据进行对比。
Three experiments were performed to evaluate the effects of stimulus level on the brain-stem auditory-evoked response (BAER) in the big brown bat (Eptesicus fuscus), a species that uses frequency-modulated (FM) sonar sounds for echolocation. In experiment 1, the effects of click level on the BAER were investigated. Clicks were presented at levels of 30 to 90 dB pSPL in 10-dB steps. Each animal responded reliably to clicks at levels of 50 dB pSPL and above, showing a BAER containing four peaks in the first 3-4 ms from click onset (waves i-iv). With increasing click level, BAER peak amplitude increased and peak latency decreased. A decrease in the i-iv interval also occurred with increasing click level. In experiment 2, stimuli were 1-ms linear FM sweeps, decreasing in frequency from 100 to 20 kHz. Stimulus levels ranged from 20 to 90 dB pSPL. BAERs to FM sweeps were observed in all animals for levels of 40 dB pSPL and above. These responses were similar to the click-evoked BAER in waveform morphology, with the notable exception of an additional peak observed at the higher levels of FM sweeps. This peak (wave ia) occurred prior to the first wave seen at lower levels (wave ib). As the level of the FM sweep increased, there was a decrease in peak latency and an increase in peak amplitude. Similarity in the magnitude and behavior of the i-iv and ib-iv intervals suggests that wave ib to FM sweeps is the homolog of the wave i response to click stimuli. Experiment 3 tested the hypothesis that wave ia represented activity emanating from more basal cochlear regions than wave ib. FM sweeps (100-20 kHz) were presented at 90 dB pSPL, and broadband noise was raised in level until the BAER was eliminated. This ''masked threshold'' occurred at 85 dB SPL of noise. At masked threshold, the broadband noise was steeply high-pass filtered at five cutoff frequencies ranging from 20 to 80 kHz. Generally, wave ia was eliminated for masker cutoff frequencies of 56.6 kHz and below, while wave ib was typically observed for masker cutoffs down to 28.3 kHz. The results of these three experiments are compared and contrasted with data from other mammalian BAER studies.