Binns K E, Salt T E
Department of Visual Science, Institute of Ophthalmology, London, UK.
Vis Neurosci. 1995 May-Jun;12(3):563-71. doi: 10.1017/s0952523800008452.
In visual neurones of the superficial layers of the superior colliculus (SSC), repetitive stimulation causes a progressive decline in the size of the response to the stimulus, usually known as response habituation or response adaptation. A mechanism has been proposed in which habituation results from coactivation of excitatory and inhibitory neurones, and the responses of the inhibitory neurones block the response to subsequent stimulus presentations. Excitatory amino acid (EAA) neurotransmitters mediate visual responses via NMDA and non-NMDA receptors in cat SSC. We have investigated the role of these receptors in the generation of response habituation. Following the iontophoretic application of the EAA antagonists CNQX, AP5 or CPP, repetitive visual stimulation paradigms which normally produce response habituation no longer do so. Indeed the response to each presentation of the stimulus is similar. Intravenous administration of the dissociative anesthetic ketamine (2-10 mg/kg) had similar actions to iontophoretically applied NMDA antagonists. The data imply that intracollicular mechanisms activated by NMDA and non-NMDA receptors contribute to the generation of the inhibitory responses in SCC which lead to response habituation. Furthermore, the effects seen with ketamine anesthesia suggest that the use of ketamine in studies of sensory systems may result in the lack of habituation.
在上丘浅层（SSC）的视觉神经元中，重复刺激会导致对刺激的反应大小逐渐下降，这通常被称为反应习惯化或反应适应。有人提出了一种机制，即习惯化是由兴奋性和抑制性神经元的共同激活引起的，抑制性神经元的反应会阻断对后续刺激呈现的反应。兴奋性氨基酸（EAA）神经递质通过猫SSC中的NMDA和非NMDA受体介导视觉反应。我们研究了这些受体在反应习惯化产生中的作用。在离子导入EAA拮抗剂CNQX、AP5或CPP后，通常会产生反应习惯化的重复视觉刺激范式不再如此。实际上，对每次刺激呈现的反应都是相似的。静脉注射解离麻醉剂氯胺酮（2-10mg/kg）具有与离子导入NMDA拮抗剂相似的作用。数据表明，由NMDA和非NMDA受体激活的丘内机制有助于在SCC中产生抑制性反应，从而导致反应习惯化。此外，氯胺酮麻醉所见的效应表明，在感觉系统研究中使用氯胺酮可能会导致习惯化缺失。
