Richardson R T, DeLong M R
Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Neurosci. 1990 Aug;10(8):2528-40. doi: 10.1523/JNEUROSCI.10-08-02528.1990.
In previous studies involving monkeys performing behavioral tasks, neurons in the nucleus basalis frequently had significant changes in discharge rate when the animal made a movement in response to a sensory stimulus in order to obtain a reward. To determine whether such responses of basalis neurons are primarily sensory or motor in nature, the activity of single basalis neurons was recorded in monkeys performing a go/no-go (GNG) task which provided a dissociation between sensory and motor neuronal responses. In a sample of 425 basalis neurons, 326 (77%) had significant changes in firing in at least one phase of the GNG task. Most of the task-related neurons (70%) responded in the choice phase in which the animal either made an arm movement (go condition) or kept its arm motionless (no-go condition) in order to obtain a water reward. Of 253 neurons that responded in the choice phase, 88% had changes in firing in the no-go condition that were equal to or, in some cases, greater than the changes in firing in the go condition. Therefore, most responses of basalis neurons in the choice phase could not be specific for the arm movement because they occurred when there was no arm movement at all. The visual stimulus presented in the choice phase was also presented earlier on each trial in the cue phase. Although 70% of the task-related basalis neurons responded in the choice phase, only 5% had detectable changes in firing in the cue phase. Of 251 neurons responding in the cue or choice phase, 59% had significantly larger changes in firing in the choice phase than in the cue phase, whereas only one neuron had a larger response in the cue phase. Therefore, most responses of basalis neurons in the choice phase could not be specific for the visual stimulus because similar responses did not occur when the same stimulus was presented in the cue phase. These results indicate that the frequent responses of basalis neurons in the choice phase are neither purely sensory nor motor in nature, but are highly dependent on the context of the stimulus or movement. The neuronal responses in the choice phase may reflect either transient increases in arousal or decision-making processes.
在先前涉及猴子执行行为任务的研究中，当动物为了获得奖励而根据感觉刺激做出动作时，基底核中的神经元放电率经常会发生显著变化。为了确定基底核神经元的这种反应本质上主要是感觉性的还是运动性的，在执行“去/不去”（GNG）任务的猴子中记录了单个基底核神经元的活动，该任务使得感觉神经元反应和运动神经元反应得以分离。在425个基底核神经元样本中，326个（77%）在GNG任务的至少一个阶段中放电有显著变化。大多数与任务相关的神经元（70%）在选择阶段做出反应，在该阶段动物要么做出手臂动作（去条件），要么保持手臂不动（不去条件）以获得水奖励。在选择阶段做出反应的253个神经元中，88%在不去条件下的放电变化等于或在某些情况下大于去条件下的放电变化。因此，基底核神经元在选择阶段的大多数反应不可能是针对手臂动作的特异性反应，因为它们在根本没有手臂动作时也会出现。在选择阶段呈现的视觉刺激在每次试验的提示阶段也会更早呈现。虽然70%与任务相关的基底核神经元在选择阶段做出反应，但只有5%在提示阶段有可检测到的放电变化。在提示阶段或选择阶段做出反应的251个神经元中，59%在选择阶段的放电变化显著大于提示阶段，而只有一个神经元在提示阶段有更大的反应。因此，基底核神经元在选择阶段的大多数反应不可能是针对视觉刺激的特异性反应，因为当相同刺激在提示阶段呈现时不会出现类似反应。这些结果表明，基底核神经元在选择阶段的频繁反应在本质上既不是纯粹的感觉性反应也不是运动性反应，而是高度依赖于刺激或动作的背景。选择阶段的神经元反应可能反映了觉醒的短暂增加或决策过程。
