Harmon Thomas C, Freeman John H
Department of Psychology, University of Iowa, Iowa City, IA, 52242.
Dev Psychobiol. 2015 Mar;57(2):168-76. doi: 10.1002/dev.21272. Epub 2015 Jan 21.
The current study investigated the effects of disrupting the septohippocampal theta system on the developmental emergence of delay eyeblink conditioning. Theta oscillations are defined as electroencephalographic (EEG) waveforms with a frequency between 3-8 Hz. Hippocampal theta oscillations are generated by inputs from the entorhinal cortex and the medial septum. Theta activity has been shown to facilitate learning in a variety of paradigms, including delay eyeblink conditioning. Lesions of the medial septum disrupt theta activity and slow the rate at which delay eyeblink conditioning is learned (Berry & Thompson, [1979] Science 200:1298-1300). The role of the septohippocampal theta system in the ontogeny of eyeblink conditioning has not been examined. In the current study, infant rats received an electrolytic lesion of the medial septum on postnatal day (P) 12. Rats were later given eyeblink conditioning for 6 sessions with an auditory conditioned stimulus on P17-19, P21-23, or P24-26. Lesions impaired eyeblink conditioning on P21-23 and P24-26 but not on P17-19. The results suggest that the septohippocampal system comes online to facilitate acquisition of eyeblink conditioning between P19 and P21. Developmental changes in septohippocampal modulation of the cerebellum may play a significant role in the ontogeny of eyeblink conditioning.
本研究调查了破坏隔海马θ系统对延迟性眨眼条件反射发育出现的影响。θ振荡被定义为频率在3 - 8赫兹之间的脑电图（EEG）波形。海马θ振荡由内嗅皮质和内侧隔的输入产生。θ活动已被证明在包括延迟性眨眼条件反射在内的各种范式中促进学习。内侧隔损伤会破坏θ活动并减缓延迟性眨眼条件反射的学习速度（Berry & Thompson，[1979]《科学》200:1298 - 1300）。隔海马θ系统在眨眼条件反射个体发生中的作用尚未得到研究。在本研究中，幼鼠在出生后第12天接受内侧隔的电解损伤。随后在出生后第17 - 19天、第21 - 23天或第24 - 26天对大鼠进行6次眨眼条件反射训练，使用听觉条件刺激。损伤在出生后第21 - 23天和第24 - 26天损害了眨眼条件反射，但在出生后第17 - 19天没有。结果表明，隔海马系统在出生后第19天至第21天开始发挥作用，以促进眨眼条件反射的习得。隔海马对小脑调节的发育变化可能在眨眼条件反射的个体发生中起重要作用。
