Middle latency response (MLR) of cats was recorded from an electrode on the vertex referred to the ear lobe under general anesthesia with nembutal.
The procedures of this experiment were as follow.
Variation of MLR was investigated by several recording parameters.
The influence of muscle relaxants was examined. Click and several kinds of tone bursts were applied to cats, and six different filter-bands were used, and furthermore, the reliability of the MLR was examined, especially in the low intensity stimuli, by test-retest recordings.
Finally the changes of MLR were experimented when the brain was destructed at the level of the superior colliculi. The result were as follows.
1) The cat's MLR was closely similar to that of human.
2) The muscle relaxants had little influence to the recording of MLR.
3) MLR was detected by using narrow filterbands, for example, 0.3-30Hz, 1/sec of stimulusinterval and abrupt rise time of the stimulus sounds.
4) MLR was quite reliable at the high intensity stimulus level, however, quite variable at around the response-threshold intensity level.
5) MLR was disappeared immediately after destruction of the brain at the level of the superior colliculi.
