Duncan G H, Bushnell M C, Bates R, Dubner R
J Neurophysiol. 1987 Jan;57(1):289-310. doi: 10.1152/jn.1987.57.1.289.
Medullary dorsal horn neurons with trigeminal sensory properties have been previously shown to have additional responses associated with cues relevant to the successful execution of a behavioral task. These "task-related" responses were evoked by environmental cues but were independent of the specific stimulus parameters. We have examined further the characteristics of task-related responses in medullary dorsal horn neurons of three monkeys. Single-unit activity was recorded while the monkeys were performing behavioral tasks that required them to discriminate thermal or visual stimuli for a liquid reward. Forty-five percent (34/75) of the medullary dorsal horn neurons studied exhibited task-related activity that was significantly correlated with the stereotypical behavioral events that occurred during the tasks. Similar events occurring outside of the task produced no response. In addition to the task-related activity of these medullary dorsal horn neurons, responses to mechanical and/or thermal stimuli presented within the neuron's receptive field were demonstrated in 28 of 34 cases. These sensory responses also were evoked by the same stimuli presented outside of the behavioral task. Fifteen of the neurons with task-related responses could be activated antidromically from thalamic stimulating electrodes. Task-related responses were categorized according to their relationship to the three phases of the behavioral trial: trial initiation, trial continuation, and trial termination. Although an individual task-related response was associated with a single behavioral event, most medullary dorsal horn neurons (30/34) exhibited a reproducible pattern of task-related responses that occurred during more than one phase of the trial. Trial-initiation task-related responses were subdivided depending on their correlation with specific events that occurred within that phase of the trial. One-third of the 18 excitatory trial-initiation responses were associated with the visual stimulus that cued the monkey to begin the trial; the remaining two-thirds were associated with the monkey's press of the button that actually initiated the trial. Trial-continuation task-related responses (observed while the monkey waited for a thermal stimulus that triggered a rewarded motor response) were shown to be independent of the actual temperature of the thermal stimulus. In addition these trial-continuation task-related responses were also noted during trials without a thermal stimulus, in which the trigger cue was the onset of a light (in a visual task).(ABSTRACT TRUNCATED AT 400 WORDS)
先前的研究表明，具有三叉神经感觉特性的延髓背角神经元还会产生与成功执行行为任务相关线索有关的额外反应。这些“与任务相关的”反应由环境线索诱发，但与特定刺激参数无关。我们进一步研究了三只猴子延髓背角神经元中与任务相关反应的特征。在猴子执行行为任务时记录单单位活动，这些任务要求它们辨别热刺激或视觉刺激以获取液体奖励。在所研究的延髓背角神经元中，45%（34/75）表现出与任务相关的活动，这种活动与任务期间发生的刻板行为事件显著相关。在任务之外发生的类似事件则不会引发反应。除了这些延髓背角神经元的与任务相关的活动外，在34例中的28例中还证明了对神经元感受野内呈现的机械和/或热刺激的反应。这些感觉反应也由行为任务之外呈现的相同刺激诱发。15个具有与任务相关反应的神经元可以通过丘脑刺激电极进行逆向激活。与任务相关的反应根据它们与行为试验的三个阶段的关系进行分类：试验开始、试验持续和试验结束。尽管单个与任务相关的反应与单个行为事件相关，但大多数延髓背角神经元（30/34）表现出在试验的多个阶段中出现的可重复的与任务相关反应模式。试验开始时与任务相关的反应根据它们与试验该阶段内发生的特定事件的相关性进行细分。18个兴奋性试验开始反应中有三分之一与提示猴子开始试验的视觉刺激相关；其余三分之二则与猴子实际启动试验的按钮按压相关。试验持续期间与任务相关的反应（在猴子等待触发奖励性运动反应的热刺激时观察到）被证明与热刺激的实际温度无关。此外，在没有热刺激的试验中也注意到了这些试验持续期间与任务相关的反应——在视觉任务中，触发线索是光的出现。（摘要截于400字）
