Ono T, Nishijo H, Nishino H
Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
J Neurol. 2000 Sep;247 Suppl 5:V23-32. doi: 10.1007/pl00007780.
It has been suggested that the cortico- and limbic-striatal systems are important in various motor functions such as motivated behaviors. In this paper we review our previous studies to investigate neuronal mechanisms of feeding behaviors. We recorded neuronal activity from the amygdala, caudate nucleus, globus pallidus, and substantia nigra during feeding behavior in monkeys, and compared neuronal responses recorded from these brain areas. First, of 710 amygdalar neurons tested, 129 (18.2%) responded to single sensory stimulation (48 to vision, 32 to audition, 49 to ingestion), 142 (20%) to multimodal stimulation, and 20 to only one item with affective significance. Eight food related amygdalar neurons were tested in reversal by salting food or introducing saline, and all responses were modulated by reversal. These results suggest that the amygdala might be important in ongoing recognition of the affective significance of complex stimuli (food-nonfood discrimination). Second, activity was recorded from 351 neurons in the head of the caudate nucleus of monkeys during an operant feeding task. The 16% of these neurons responded in the discrimination phase. Some of these neurons responded specifically to food. The magnitude of these food-specific neurons depended on the rewarding nature of the food (reward value), and was inversely related to the latency of the onset of bar press. Of the caudate neurons, 10% responded in the bar press phase. Activity of most neurons which responded in the bar press phase was not correlated to individual bar presses. Cooling of the dorsolateral prefrontal cortex abolished sustained responses during bar pressing, but did not abolish the feeding behavior. However, bar press speed tended to be delayed by prefrontal cooling. Third, activity of 358 neurons was recorded from the monkey globus pallidus, and 204 neurons responded during the feeding task. In the globus pallidus, few neurons responded to food in the discrimination phase. On the other hand, activity of most responsive neurons changed during bar press and/or ingestion phases. Activity of about half of these responsive neurons was directly related to specific feeding motor acts such as arm extension, flexion, bar pressing, grasping, chewing, etc. Some of these neurons showed motor-related responses with gradual and preparatory responses. These motor-related neurons were located mainly in the caudodorsal part of the globus pallidus. On the other hand, about one third, especially in the rostroventral part of the globus pallidus, showed dissociating responses in that they responded during bar pressing for food or during ingestion in an operant task, but not during bar pressing for nonfood or during forcible ingestion. The response magnitude of the neurons during arm extension and bar pressing depended on the nature of the food. Fourth, activity of 261 neurons was recorded from the substantia nigra pars reticulata. Most of responding neurons (more than two-thirds of the recorded neurons) responded during the bar press and/or ingestion phases. Activity of the one-third of neurons was related to specific motor execution such as arm extension, flexion and bar pressing, but not to motor preparation. These neurons were located mainly in the rostral part of the nucleus. More than one-third of the recorded neurons responded during feeding and/or drinking acts and intra- and perioral sensory stimuli, and were located mainly in the caudomedial part of the nucleus. Based upon these responses and known anatomical evidence, various information including that from the amygdala and prefrontal cortex is integrated in the basal ganglia, and converted to coordinated motivated behaviors such as feeding behavior.
有人提出，皮质 - 纹状体和边缘 - 纹状体系统在诸如动机行为等各种运动功能中很重要。在本文中，我们回顾了我们之前的研究，以探讨进食行为的神经元机制。我们记录了猴子进食行为期间杏仁核、尾状核、苍白球和黑质的神经元活动，并比较了从这些脑区记录的神经元反应。首先，在测试的710个杏仁核神经元中，129个（18.2%）对单一感觉刺激有反应（48个对视觉，32个对听觉，49个对摄取），142个（20%）对多模式刺激有反应，20个仅对具有情感意义的一个项目有反应。通过给食物加盐或注入生理盐水对8个与食物相关的杏仁核神经元进行反转测试，所有反应都受到反转的调节。这些结果表明，杏仁核在持续识别复杂刺激（食物 - 非食物辨别）的情感意义方面可能很重要。其次，在一项操作性进食任务期间，记录了猴子尾状核头部351个神经元的活动。其中16%的神经元在辨别阶段有反应。其中一些神经元对食物有特异性反应。这些食物特异性神经元的反应强度取决于食物的奖励性质（奖励价值），并且与压杆开始的潜伏期呈负相关。在尾状核神经元中，10%在压杆阶段有反应。在压杆阶段有反应的大多数神经元的活动与单个压杆动作无关。背外侧前额叶皮质冷却消除了压杆期间的持续反应，但没有消除进食行为。然而，前额叶冷却往往会延迟压杆速度。第三，记录了猴子苍白球358个神经元的活动，204个神经元在进食任务期间有反应。在苍白球中，很少有神经元在辨别阶段对食物有反应。另一方面，大多数有反应的神经元的活动在压杆和/或摄取阶段发生变化。这些有反应的神经元中约一半的活动与特定的进食运动行为直接相关，如手臂伸展、弯曲、压杆、抓握、咀嚼等。其中一些神经元表现出与运动相关的反应，具有逐渐和预备性的反应。这些与运动相关的神经元主要位于苍白球的尾背侧部分。另一方面，约三分之一，特别是在苍白球的吻腹侧部分，表现出解离反应，即它们在操作性任务中为获取食物而压杆或摄取期间有反应，但在为非食物而压杆或强制摄取期间没有反应。手臂伸展和压杆期间神经元的反应强度取决于食物的性质。第四，记录了黑质网状部261个神经元的活动。大多数有反应的神经元（超过记录神经元的三分之二）在压杆和/或摄取阶段有反应。三分之一的神经元的活动与特定的运动执行相关，如手臂伸展、弯曲和压杆，但与运动准备无关。这些神经元主要位于核的吻部。超过三分之一的记录神经元在进食和/或饮水行为以及口腔内和口腔周围感觉刺激期间有反应，并且主要位于核的尾内侧部分。基于这些反应和已知的解剖学证据，包括来自杏仁核和前额叶皮质的各种信息在基底神经节中整合，并转化为协调的动机行为，如进食行为。
