Sainsbury R S, Harris J L, Rowland G L
Department of Psychology, University of Calgary, Alberta, Canada.
Physiol Behav. 1987;41(5):489-93. doi: 10.1016/0031-9384(87)90085-0.
Previous research has consistently demonstrated that there are two types of theta which can be recorded from the hippocampus of a variety of species. Type 1 theta occurs during voluntary movements such as walking, running and rearing while type 2 theta occurs during alert immobility. Large amplitude irregular activity (LIA) occurs during more automatic behaviors such as grooming and chewing as well as during non-alert immobility. Type 2 theta can be readily elicited in the unrestrained guinea pig and rabbit. While spontaneous type 2 theta rarely occurs in the rat, short trains of type 2 theta have been observed during conditioning. The purpose of the present study was to examine the relationship between type 2 theta and inescapable shock when the temporal characteristics of the conditioning stimulus (CS) were varied. Three conditioning paradigms (delay, trace, random) were utilized. Type 2 theta production increased over time as a function of the number of shocks and was not due to conditioning. There were no differences in the three groups in the occurrence of type 2 theta during CS presentations or during the inter-stimulus intervals. Previously neutral sensory stimulation also produced type 2 theta after conditioning in all groups. The inescapable shocks placed the rat in a high state of arousal which subsequently sensitized the animal to produce type 2 theta. The data was used to support the hypothesis that a state of arousal is a necessary precursor for the production of type 2 theta.
先前的研究一直表明，在多种物种的海马体中可记录到两种θ波。1型θ波出现在诸如行走、奔跑和站立等自主运动过程中，而2型θ波出现在警觉性静止状态期间。大幅度不规则活动（LIA）出现在诸如梳理毛发和咀嚼等更自动的行为过程中，以及非警觉性静止状态期间。2型θ波在未受束缚的豚鼠和兔子中很容易诱发。虽然2型θ波在大鼠中很少自发出现，但在条件反射过程中观察到了短串的2型θ波。本研究的目的是在改变条件刺激（CS）的时间特征时，研究2型θ波与不可逃避电击之间的关系。使用了三种条件反射范式（延迟、痕迹、随机）。2型θ波的产生随电击次数的增加而增加，且并非由条件反射所致。在CS呈现期间或刺激间隔期间，三组在2型θ波的出现方面没有差异。先前的中性感觉刺激在所有组的条件反射后也产生了2型θ波。不可逃避的电击使大鼠处于高度觉醒状态，随后使动物对产生2型θ波变得敏感。这些数据被用来支持这样一种假设，即觉醒状态是产生2型θ波的必要前提。
