Effect of emotional state induced by expectation for pain on cortical neuronal activity in awake behaving monkeys

为了阐明疼痛预期引起的情绪状态对皮层神经元活动的影响，在初级躯体感觉皮层(SI)和前扣带回皮质(ACCx)记录了单个神经元的活动，并分析了行为与神经元反应的相关性。当“开灯”灯亮时，猴子们就会按下按钮。然后通过热探头将热刺激施加到面部皮肤上。我们介绍了三种不同类型的检测试验，以检测猴子对热刺激强度的感知强度。1)热检测：T1温度为44~46℃，T2温度为0.2~0.8℃。猴子需要尝试在没有光线的情况下使用热刺激来检测温度变化。2)光检测：当猴子按下按钮时，L1(基本灯)亮起。在4到8秒保持周期之后，在L1上添加L2(小光强度增量)。猴子检测到L2变化的变化并获得奖励。3)热感光：当猴子按下按钮时，L1灯亮。以44-46℃的热度。在4-8秒保持时间后，L2开始。猴子需要检测光线强度的变化变化。SI和ACCx内许多伤害性神经元的放电频率随刺激温度的升高而增加。当猕猴在T2到来之前逃离T1时，伤害性神经元在ACCx的放电频率显著增加。S1伤害性神经元的放电频率与检测潜伏期显著相关，而ACCx神经元的放电频率与检测潜伏期无相关性，提示SI神经元可能参与痛觉的感觉辨别，而ACCx神经元可能参与痛觉的兴奋性，两区的伤害性神经元也可能参与痛觉注意。

In order to clarify the effect of emotional state induced by expectation for pain on cortical neuronal activity, single neuronal activities were recorded form the Primary somatosensory cortex (SI) or Anterior cingulated cortex (ACCx) and the correlation between behavior and neuronal responses were analyzed Monkeys were sitting quietly on the monkey chair. When the "Go light" conies on, monkeys press the button. Then the heat stimulus is applied to the facial skin through the thermal probe. We introduced three different types of detection trials for monkey's perceived intensity of heat stimulus intensity. 1) Heat detection: T1 temperature consists with 44-46℃ and T2 temperature is 0.2-0.8℃. Monkey need to try to detect the temperature change using a heat stimulus without light. 2) Light detection: When the monkey presses the button, L1 (basic light) comes on. After 4 to 8 second hold period, L2 (a small light intensity increment) is added on L1. Monkeys detect the change in L2 change and get reward. 3) Light detection with heat: When the monkeys press the button, L1 light comes on. With 44-46℃ heat. After 4- 8 second hold time, L2 comes on. Monkey need to detect the change in light intensity change. Many nociceptive neurons in SI and ACCx increased firing frequency following increase in stimulus temperature. When monkeys escaped from T1 before T2 coming, nociceptive neurons significantly increased their firing frequency in ACCx. The firing frequency of the S1 nociceptive neurons significantly correlated with detection latency, while ACCx neurons did not show any correlation.These suggest that SI neurons would be involved in sensory discriminative aspect of pain whereas, ACCx nociceptive neurons would be involved in motivational aspect of pain, and also nociceptive neuron sin both areas would be involved in attention of pain.