RESPONSES OF THE SUPRACHIASMATIC NUCLEUS TO RETINOHYPOTHALAMIC TRACT VOLLEYS IN A SLICE PREPARATION OF THE MOUSE HYPOTHALAMUS
RESPONSES OF THE SUPRACHIASMATIC NUCLEUS TO RETINOHYPOTHALAMIC TRACT VOLLEYS IN A SLICE PREPARATION OF THE MOUSE HYPOTHALAMUS
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DOI：
10.1016/0006-8993(89)91336-x
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发表时间：
1989-02-06
期刊：
影响因子：
2.9
通讯作者：
MENAKER, M
中科院分区：
文献类型：
--
作者：
CAHILL, GM;MENAKER, M
使用包括整个 SCN、视交叉和视神经的下丘脑切片制备物研究了小鼠视交叉上核 (SCN) 对来自视网膜下丘脑束 (RHT) 的刺激突触输入的电生理反应。单单元活动的细胞外记录揭示了腹外侧 SCN 中的神经元群，这些神经元在刺激对侧视神经后平均潜伏期 10 毫秒被激活。这些神经元显然接收来自 RHT 突触的直接兴奋输入。其他 SCN 神经元可能通过中间神经元的输入以较长的潜伏期被激活。视神经齐射在 SCN 中引起的群体场电位由交叉中视束轴突产生的钙不敏感瞬变组成，随后是突触后活动产生的钙敏感波。突触后波具有场 EPSP 的形式，在背外侧 SCN 中为负，在腹外侧 SCN 中为正，其上叠加了相反极性的群体尖峰。群体峰值与单突触单个单元反应发生在相同的潜伏期，这些反应都发现在场电位反转点附近或腹侧。这些发现表明，腹外侧 SCN 中的神经元受到背侧延伸树突上的突触的兴奋。发现视神经中 RHT 的传导速度为 0.59±。 0.03 mm/ms，而视束射速为 2.4 .+-。 0.75 毫米/毫秒。 RHT 的低传导速度表明，在视神经内，这些轴突在视神经中很薄和/或无髓鞘。
The electrophysiological responses of the mouse suprachiasmatic nucleus (SCN) to stimulated synaptic input from the retinohypothalamic tract (RHT) were investigated using a hypothalamic slice preparation that includes the entire SCN, optic chiasm and optic nerves. Extracellular recordings of single-unit activity reveal a population of neurons in the ventrolateral SCN that are activated at a median latency of 10 ms after stimulation of the contralateral optic nerve. These neurons apparently receive direct excitatory input from RHT synapes. Other SCN neurons are activated at longer latencies, possibly through input from interneurons. The population field potentials evoked in the SCN by optic nerve volleys consist of a calcium-insensitive transient generated by optic tract axons in the chiasm, followed by calcium-sensitive waves generated by postsynaptic activity. The postsynaptic waves have the form of a field EPSP, negative in the dorsolateral SCN and positive in the ventrolateral SCN, upon which is superimposed a population spike of opposite polarity. The population spike occurs at the same latency as the monosynaptic single unit responses, which were all found near or ventral to the point of reversal of field potential. These findings suggest that neurons in the ventrolateral SCN are excited by synapses on dorsally extended dendrites. The conduction velocity of the RHT in the optic nerve was found to be 0.59 .+-. 0.03 mm/ms, while that of the optic tract volley was 2.4 .+-. 0.75 mm/ms. The low conduction velocity of the RHT indicates that, within the optic nerve, these axons are thin and/or unmyelinated in the optic nerve.