【作者】 张赢心；

【导师】 张季平；

【作者基本信息】 华东师范大学 ， 生理学， 2021， 硕士

【摘要】 对母婴分离的幼鼠发出的隔离声(Isolation calls)已经进行了广泛的研究,这种隔离声为超声叫声(Ultrasonic vocalizations,USVs)。隔离诱导的超声叫声次数的增加表明焦虑加剧。已有的研究发现,隔离声中叫声的频率和持续时间等随年龄而变化。然而,在母婴分离条件下幼鼠发出的隔离声的其他各种声学参数如何随年龄而变化仍缺乏系统的研究。此外,成年大鼠听皮层神经元对幼鼠隔离声编码的神经机制尚不清楚。本研究录制了出生后第1至第21天的幼年大鼠在母婴分离条件下发出的隔离声,分析了隔离声的多种声学参数随年龄的变化。我们进一步在成年大鼠听皮层记录了听神经元对隔离声(自然声)及反向播放的隔离声(反向声)的听反应,观察听皮层神经元对自然声和反向声的偏好特性,以及听皮层神经元对隔离声反应强度的依赖性,并且比较了不同性别成年大鼠听皮层神经元对幼鼠隔离声的反应。我们在幼年大鼠出生后第1天开始连续21天记录了母婴分离条件下幼鼠发出的隔离声。结果发现,幼鼠发出的隔离声中叫声的类型、单位时间内的单个叫声个数、单个叫声频率、单个叫声的时程和相邻两个叫声的间隔时间表现出年龄依赖性的变化;单位时间内叫声的串数、每串叫声的时程、每串叫声的个数和相邻两串叫声的间隔时程也表现随年龄变化而变化的趋势。我们选取了录制的幼鼠隔离声作为声刺激,在三个声刺激强度下(75 d B SPL、65 d B SPL和55 d B SPL),记录了成年大鼠初级听皮层神经元对隔离声的自然声及反向声的听反应。结果表明,初级听皮层绝大多数神经元对自然声的听反应强度高于对反向声的听反应强度,表现出偏好自然声的特性,只有少数神经元偏好反向声、或对二者无显著偏好。此外,大多数听神经元对自然声的反应有强度依赖性,对自然声的听反应强度随声刺激强度的增加而增强。然而,我们并未发现成年大鼠听皮层神经元对幼鼠隔离声的反应强度存在显著性的性别差异。本研究结果为我们理解母婴分离条件下幼年大鼠的隔离声的发育过程以及成年大鼠对种内叫声的编码机制提供了实验证据。更多还原

【Abstract】 Isolation calls generated by infant rats under the conditions of isolation from their mothers have been extensively studied.These isolation calls are generally ultrasonic vocalizations(USVs).An increase in the number of isolation-induced ultrasonic calls indicates increased anxiety.Previous studies have found that the frequency and duration of the isolation calls vary with age.However,there is still a lack of systematic research on how the other acoustic parameters of the isolated calls emitted by infant rats vary with age under the condition of mother-infant separation.In addition,the neural mechanism of the encoding of the isolated calls by the neurons in the auditory cortex of adult rats is still unclear.In this study,we recorded the isolation calls of neonatal rats from day 1 to 21 after birth,and analyzed the changes of various acoustic parameters of the isolation calls with age.We further recorded the auditory responses of auditory cortex neurons in adult rats to isolated sounds(natural calls)and the time-reversed calls,and determine the preference of auditory cortex neurons for natural calls and reversed calls,as well as the dependence of the responses of the auditory cortex neurons on the level of the isolated calls,and compared the gender differences in the response strength of adult rat auditory cortex neurons to the isolated calls.We recorded the isolation calls emitted by infant rats under the conditions of maternal and child separation from postnatal day 1 to days 21.The results showed age-related changes in the types of isolation calls,the call rates,the call frequency,the call duration,and the time interval between two adjacent calls.We also found age-related changes in the number of call trains,the duration of call trains,the number of calls in a train,and the time interval between two adjacent call trains.We used the recorded isolated sounds as acoustic stimuli,and recorded the auditory responses of neurons in the primary auditory cortex of adult rats to natural and reversed calls under three stimuli levels(75 d B SPL,65 d B SPL and 55 d B SPL).The results showed that most neurons in the primary auditory cortex had higher response strength to natural calls than to reverse calls,and showed a preference for natural sounds.Only a few neurons had preference for reversed calls,or had no significant preference for both the natural and reversed calls.In addition,the response of most auditory neurons to natural sound is level-dependent,and the strength of the auditory response to natural sound increases with the increase of sound levels.However,we did not find significant differences in the response strength of neurons in the auditory cortex of adult rats to the isolated calls of infant rats.The results of this study provide experimental evidence for understanding the development of isolated calls in young rats and the encoding mechanism of intraspecific calls in adult rats under the condition of mother-infant separation.更多还原