Burstein R, Potrebic S
Department of Neurobiology, Harvard Medical School, Boston, Massachusetts.
J Comp Neurol. 1993 Sep 22;335(4):469-85. doi: 10.1002/cne.903350402.
The amygdala and orbital cortex are thought to play an important role in the regulation of autonomic functions, hormonal secretion, and behavioral expression in response to sensory stimulation. The responsiveness of neurons in these regions to stimulation of cutaneous and visceral organs indicates that sensory information reaches the amygdala and orbital cortex. In the past, a large number of studies have thoroughly documented multiple neural pathways by which sensory information can reach these regions via relay nuclei in the brainstem and diencephalon. Recent studies reported that the amygdala and orbital cortex also receive direct input from the spinal cord. The aim of this study was to determine the magnitude and the origin of these projections in the rat. Injections of the retrograde tracer Fluoro-Gold (FG), restricted to the amygdala, labeled several hundred neurons bilaterally (60% contralateral) throughout the length of the spinal cord. More than 60% of labeled neurons were found in the lateral reticulated area of the deep dorsal horn and the gray matter surrounding the central canal. Many neurons were also found in the lateral spinal nucleus. Labeled neurons were concentrated in upper lumbar and upper cervical segments. Injections of Fluoro-Gold that were centered in the orbital cortex labeled only a small number of neurons (73% contralateral) within the spinal cord. Most labeled neurons were found in the lateral reticulated area. Neurons located in the intermediate zone and the gray matter surrounding the central canal were found mainly in upper lumbar and upper cervical segments. These findings, together with the anterograde tracing observations, provide evidence for direct projections of spinal cord neurons to the amygdala and orbital cortex. Their laminar distribution in the spinal cord and the involvement of the amygdala and orbital cortex in limbic functions suggest that these pathways may play a role in neuronal circuits that enable somatosensory information, including pain, to affect autonomic, endocrine and behavioral functions.
杏仁核和眶额皮质被认为在自主功能调节、激素分泌以及对感觉刺激的行为表达中发挥重要作用。这些区域的神经元对皮肤和内脏器官刺激的反应性表明感觉信息可到达杏仁核和眶额皮质。过去，大量研究已充分记录了多条神经通路，通过这些通路感觉信息可经脑干和间脑的中继核到达这些区域。最近的研究报道，杏仁核和眶额皮质也接受来自脊髓的直接输入。本研究的目的是确定大鼠中这些投射的范围和起源。向杏仁核注射逆行示踪剂荧光金（FG），在脊髓全长双侧标记了数百个神经元（60%为对侧）。超过60%的标记神经元位于深背角的外侧网状区和围绕中央管的灰质中。在外侧脊髓核中也发现了许多神经元。标记神经元集中在上腰段和上颈段。以眶额皮质为中心注射荧光金仅在脊髓内标记了少量神经元（73%为对侧）。大多数标记神经元位于外侧网状区。位于中间带和围绕中央管的灰质中的神经元主要见于上腰段和上颈段。这些发现与顺行示踪观察结果一起，为脊髓神经元向杏仁核和眶额皮质的直接投射提供了证据。它们在脊髓中的分层分布以及杏仁核和眶额皮质在边缘系统功能中的参与表明，这些通路可能在使包括疼痛在内的躯体感觉信息影响自主、内分泌和行为功能的神经回路中发挥作用。
