STIMULUS FEATURES AFFECTING PSYCHOPHYSICAL DETECTION THRESHOLDS FOR ELECTRICAL-STIMULATION OF THE COCHLEA .2. FREQUENCY AND INTERPULSE INTERVAL
STIMULUS FEATURES AFFECTING PSYCHOPHYSICAL DETECTION THRESHOLDS FOR ELECTRICAL-STIMULATION OF THE COCHLEA .2. FREQUENCY AND INTERPULSE INTERVAL
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DOI：
10.1121/1.408155
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发表时间：
1993-09-01
影响因子：
2.4
通讯作者：
MORRIS, DJ
中科院分区：
文献类型：
--
作者：
PFINGST, BE;MORRIS, DJ
作为探索影响检测的刺激特征的一系列实验的一部分，在非人灵长类动物（猕猴）中测量了耳蜗电刺激的心理物理检测阈值。这些猴子接受了操作性条件反射的心理训练。一只耳朵用新霉素处理以破坏毛细胞，并在鼓阶和/或耳蜗壁中植入电极。在实验1中，检测阈值进行了测量的列车的固定持续时间的脉冲和正弦波。对于长持续时间脉冲（1至2 ms/相位），阈值作为频率（脉冲率）的函数降低，在125和210 pps之间的频率达到最小值，然后随着频率的进一步增加而增加。对于持续时间较短的脉冲，阈值通常单调下降的频率的函数，但有时表现出轻微的增加作为频率的函数附近的最高频率测试。通常，固定持续时间脉冲的阈值与频率函数的斜率等于或小于正弦信号的阈值与频率函数的斜率，其中频率和相位持续时间共变。在实验2和3中对其中两种情况进行了额外的观察。在实验2中，测量作为脉冲间间隔的函数的脉冲对的阈值。持续时间作为脉冲间间隔的函数下降到2至4 ms的间隔，然后略有增加。在实验3中，阈值被测量为在两个频率下的刺激持续时间的函数。对于较低频率的脉冲串，持续时间作为刺激持续时间的函数以较大的速率减小，使得两个信号的检测阈值之间的差作为刺激持续时间的函数增大。这些实验表明，刺激频率（即，具有固定相位持续时间的重复率）是电信号检测的重要贡献者。这种贡献可能是由于以下效应的组合：（a）随着频率增加，对刺激的神经响应的数量增加，以及（B）由于脉冲后的不应期或其他兴奋性改变的时期，随着脉冲间间隔变小，这些响应的时间相互作用。
Psychophysical detection thresholds for electrical stimulation of the cochlea were measured in nonhuman primates (macaques) as part of a series of experiments exploring the stimulus features affecting detection. The monkeys were trained psychophysically using operant conditioning. One ear was treated with neomycin to destroy hair cells, and implanted with electrodes in the scala tympani and/or the cochlear wall. In experiment 1, detection thresholds were measured for trains of fixed-duration pulses and for sinusoids. For long-duration pulses (1 to 2 ms/phase), thresholds decreased as a function of frequency (pulse rate), reaching a minimum at a frequency between 125 and 210 pps, then increased as frequency was further increased. For shorter duration pulses, thresholds usually decreased monotonically as a function of frequency but sometimes showed a slight increase as a function of frequency near the highest frequencies tested. Typically slopes of the threshold versus frequency functions for fixed-duration pulses were equal to or less than slopes of threshold versus frequency functions for sinusoidal signals, where frequency and phase duration covaried. Additional observations on two of the cases were made in experiments 2 and 3. In experiment 2, thresholds for pairs of pulses were measured as a function of inter-pulse interval. Thresholds decreased as a function of interpulse interval up to intervals of 2 to 4 ms and then increased slightly. In experiment 3, thresholds were measured as a function of stimulus duration at two frequencies. Thresholds decreased as a function of stimulus duration at a greater rate for the lower frequency pulse train, so that the difference between the detection thresholds for the two signals increased as a function of stimulus duration. These experiments suggest that stimulus frequency (i.e., repetition rate with phase duration fixed) is a significant contributor to the detection of electrical signals. This contribution may be due to a combination of effects of (a) increasing the number of neural responses to the stimulus as frequency is increased, and (b) temporal interactions of those responses, as interpulse intervals become small, due to refractory periods or other periods of altered excitability that follow a pulse.