• 作者： 任晃蓀
• 作者服務機構： 美國密蘇里州大學生物系
• 中文摘要： 本文為作者近年來從動物行為及神經生理兩方面對蝙蝠回音定位系統的研究綜述。 從行為上研究蝙蝠回音定位最簡單的方法為障礙躲避法。簡言之，即測量蝙蝠由實驗室一端飛至他端時，穿越置於實驗室中央位置一排彼此相隔等距（30厘米）的障礙物（銅絲或魚線）的成功率。據最近研究結果顯示，蝙蝠成功地穿越一排與其飛行途徑的垂直方向做簡諧運動的障礙物的成功率，要比其穿越靜止的同排障礙物的成功率為高；然而當蝙蝠完成穿越同排障礙物的訓練過程後，其穿越上述兩種不同情況的障礙物的成功率則幾乎相等。本文試從動物行為的觀點對上述實驗結果加以討論。 從電生理方面的研究結果顯示，蝙蝠小腦的極大部份具有對聲刺激有所反應的神經元。從對122此種小腦聽神經元研究結果顯示，其反應潛伏期介于4至34微秒之間，最佳頻率則介于22及92.5千赫之間。大部份的神經元的最低閥值則低于70分貝，由于蝙蝠本身係利用強度高達105至110分貝，頻率為110下降至25千赫的下降調頻信號從事回音定位的行為，上述小腦的聽神經元顯然具有從事接受蝙蝠本身所發出的回音定位訊號及由障礙物反射而回的回音的能力。
• 英文摘要： The echolocation system of the bat is studied by behaviorally testing the obstacle-avoidance abilityof the bat and neurophysiologically studying the signal processing in the bat's cerebellum. When freshly caught bats were made to negotiate an array of stationary and moving wires, theyavoided moving wires more successfully than stationary ones. However, the percentage of misses in bothtest conditions became comparable after they were trained to negotiate the wires. Such a difference inperformance before and after training is discussed and correlated with the biological relevance of the stimuli(stationary and moving wires) to the bat and the motivation of the animal during the test. Electrophysiological study on the cerebellum of the bat shows that a large area of the bat's cere-bellum contain units responding to acoustic signals. 221 units isolated had latencies ranged from 4 to 34msec and best frequencies had between 22 and 92.5 kHz. Most of these units had a minimum thresholdbelow 70 dB SPL. Since bats use very intense (105-110 dB SPL) signals sweeping from 110 kHz down to25 kHz for echolocation, these cerebellar auditory units are apparently capable of coding the bat's ownemitted signals and returning echoes.
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