Brüggemann J, Shi T, Apkarian A V
Department of Neurosurgery, SUNY Health Science Center at Syracuse 13210.
J Neurosci. 1994 Nov;14(11 Pt 2):6796-814. doi: 10.1523/JNEUROSCI.14-11-06796.1994.
The response properties of 106 visceroceptive lateral thalamic neurons were investigated in anesthetized squirrel monkeys. Most neurons were located in the ventral posterior lateral nucleus (VPL), and a smaller number of cells was also found in a variety of thalamic nuclei around VPL. Ninety (85%) of these cells responded to distension of the urinary bladder, the distal colon, and/or the lower esophagus. The majority of the visceral-responsive cells also had convergent somatic and multivisceral responses (71% of the 85%). A small population (6%) was visceral specific; that is, these neurons were not activated with somatic stimuli. Visceral responses were excitatory, inhibitory, or mixed, and most were either visceral nociceptive specific (65%) or visceral wide-dynamic-range type (34%). Very few visceral responses (1%) could be classified as low threshold. The incidence of these response types were highly dependent on the specific viscus stimulated. Most visceral responses were able to code stimulus duration and intensity. The majority (69%) of the visceroceptive neurons had somatic low-threshold convergent input mainly from the surface of the lower body. The somatic receptive field locations and the somatic response properties seem unrelated to the convergent visceral input and the visceral response properties, although there were some exceptions. No obvious viscerotopical organization was found in VPL. The results lead us to propose two different modes of representation for processing of and distinguishing between visceral and somatic inputs: a distributed population code for visceral inputs, and a local code for somatic inputs. Based on these codes, we discuss a new hypothesis for referred pain.
在麻醉的松鼠猴中研究了106个内脏感觉性丘脑外侧核神经元的反应特性。大多数神经元位于腹后外侧核（VPL），在VPL周围的各种丘脑核中也发现了少量细胞。其中90个（85%）细胞对膀胱、远端结肠和/或食管下段的扩张有反应。大多数内脏反应性细胞也具有汇聚的躯体和多内脏反应（85%中的71%）。一小部分（6%）是内脏特异性的；也就是说，这些神经元不会被躯体刺激激活。内脏反应有兴奋性、抑制性或混合性，大多数是内脏伤害性特异性（65%）或内脏广动力范围类型（34%）。极少数内脏反应（1%）可归类为低阈值。这些反应类型的发生率高度依赖于所刺激的特定内脏。大多数内脏反应能够编码刺激持续时间和强度。大多数（69%）内脏感觉神经元具有主要来自下半身表面的躯体低阈值汇聚输入。躯体感受野位置和躯体反应特性似乎与汇聚的内脏输入和内脏反应特性无关，尽管有一些例外。在VPL中未发现明显的内脏拓扑组织。这些结果使我们提出两种不同的模式来处理和区分内脏和躯体输入：内脏输入的分布式群体编码和躯体输入的局部编码。基于这些编码，我们讨论了一个关于牵涉痛的新假说。
