Behavioral and physiological characterization of sensorimotor gating in the goldfish startle response.
Behavioral and physiological characterization of sensorimotor gating in the goldfish startle response.
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DOI：
10.1152/jn.00959.2007
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发表时间：
2008-03
影响因子：
2.5
通讯作者：
H. Neumeister;T. M. Szabo;T. Preuss
中科院分区：
文献类型：
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作者：
H. Neumeister;T. M. Szabo;T. Preuss
脉冲前抑制（PPI）通常与哺乳动物听觉惊吓行为的衰减有关，可能是在脑干惊吓回路中介导的。然而，PPI的抑制机制尚不清楚。我们通过对金鱼惊逃回路——毛特纳细胞（m细胞）系统的互补行为和体内电生理实验来解决这个问题。在行为学实验中，我们观察到听觉预脉冲-脉冲刺激后惊逃概率的衰减（PPI）为77.5%。在预脉冲-脉冲间刺激间隔（ISIs）范围为20 ~ 600 ms时观察到PPI效应，其幅度在14 dB范围内与预脉冲强度呈线性关系。m细胞是启动惊吓逃逸的感觉运动神经元，对声音脉冲的突触反应的电生理记录显示，在预脉冲后，树突突触后电位（PSP）的幅度减少了21%，体细胞PSP的幅度减少了23%。此外，预脉冲诱发m细胞兴奋性持续下降（500 ms），表现为1)阈值电流增加，2)动作电位（AP）的抑制性分流，以及3)线性化的m细胞膜，有效地阻止m细胞AP的产生。比较m细胞树突和体细胞中预脉冲诱发的抑制性分流的大小和动力学，揭示了树突中不成比例的更大和更持久的抑制。这些结果表明，观察到的ppi型惊吓行为衰减可能与主要在m细胞侧树突介导的不同突触后机制相关。
Prepulse inhibition (PPI) is typically associated with an attenuation of auditory startle behavior in mammals and is presumably mediated within the brainstem startle circuit. However, the inhibitory mechanisms underlying PPI are not yet clear. We addressed this question with complementary behavioral and in vivo electrophysiological experiments in the startle escape circuit of goldfish, the Mauthner cell (M-cell) system. In the behavioral experiments we observed a 77.5% attenuation (PPI) of startle escape probability following auditory prepulse-pulse stimulation. The PPI effect was observed for prepulse-pulse interstimulus intervals (ISIs) ranging from 20 to 600 ms and its magnitude depended linearly on prepulse intensity over a range of 14 dB. Electrophysiological recordings of synaptic responses to a sound pulse in the M-cell, which is the sensorimotor neuron initiating startle escapes, showed a 21% reduction in amplitude of the dendritic postsynaptic potential (PSP) and a 23% reduction of the somatic PSP following a prepulse. In addition, a prepulse evoked a long-lasting (500 ms) decrease in M-cell excitability indicated by 1) an increased threshold current, 2) an inhibitory shunt of the action potential (AP), and 3) by a linearized M-cell membrane, which effectively impedes M-cell AP generation. Comparing the magnitude and kinetics of inhibitory shunts evoked by a prepulse in the M-cell dendrite and soma revealed a disproportionately larger and longer-lasting inhibition in the dendrite. These results suggest that the observed PPI-type attenuation of startle behavior can be correlated to distinct postsynaptic mechanisms mediated primarily at the M-cell lateral dendrite.