声音调幅诱发的豚鼠皮层慢反应及反应阈

SLOW CORTICAL RESPONSE EVOKED BY AMPLITUDE MODULATION OF SOUND AND RESPONSE THRESHOLDS IN GUINEA PIG

在清醒豚鼠记录了声音调幅诱发的皮层慢反应(SCR),并测定了反应阈(△I,以加幅的dB数表示)。调制波是时程200ms的准矩形波,每秒一次。调幅诱发的典型SCR呈正负正三相波,出现在调制开始或结束后40—200ms内。用白噪声、重复短声和纯音作载波,在基幅强度30—90dBSPL的范围内△I仅0.5dB左右,和人的心理物理测试结果相近,表明用SCR测得的△I能代表动物的强度辨别阈。本实验所得的豚鼠△I与I的函数曲线,可算是动物第一条较完整的△I曲线。

AM-evoked slow cortical responses (SCR) were recorded in awake guinea pigs and the response thresholds (ΔI) in terms of amplitude increment in dB were determined. A qua-sirectangular pulse of 200 ms duration and with a repetition rate of I/sec served as the modulator. The typical AM-evoked SCR assumes a positive-negative-positive triphasic waveform appearing 40 -200 ms after the on-set or off-set of modulation. For white noise, for repetitive clicks (1000 pps) and for pure tones (125 Hz-16 kHz) in a very wide carrier level range (30-90 dB SPL), the ΔI values are only around 0.5 dB, quite close to those for human obtained by psychophysical methods, suggesting that the SCR ΔI values can represent the intensity difference limens for the animals, A ΔI curve for guinea pig, i.e., the functional curve of A/ versus, I, is constructed. This ΔI curve is supposed to be the first complete and convincing one for animals.