Dowman R, Wolpaw J R
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201.
Electroencephalogr Clin Neurophysiol. 1989 Jan;72(1):69-80. doi: 10.1016/0013-4694(89)90032-1.
We recorded spinal reflexes and cortical somatosensory evoked potentials (SEPs), elicited by stretching the biceps or the triceps muscle or by electrically stimulating the posterior tibial nerve, from monkeys throughout the day. Amplitudes of the spinal stretch reflex (SSR) and of its electrically evoked analogue, the H-reflex, varied diurnally: both were greatest midway through the lights-off period and smallest during the lights-on period. Stretch-evoked and electrically evoked SEP amplitudes also varied diurnally, but were out of phase with the spinal reflex rhythms. The H-reflex is elicited by direct stimulation of the nerve and thus, unlike the SSR, bypasses the muscle spindle. The H-reflex diurnal rhythm and the phase difference between the spinal reflex and SEP diurnal rhythms indicate that these rhythms are mediated at least in part by central mechanisms. Furthermore, both the spinal reflex and SEP diurnal rhythms appeared to be entrained by the light-dark cycle, which suggests that they may be coupled to the same oscillator. Besides their theoretical importance, these rhythms have important implications for experimental and clinical studies of spinal reflexes and SEPs. These rhythms are especially pertinent to the interpretation of long-term monitoring studies, as are often carried out in the Intensive Care Unit and during lengthy neurosurgical procedures.
我们在一整天的时间里，记录了猴子在拉伸肱二头肌或肱三头肌，或电刺激胫后神经时所引发的脊髓反射和皮层体感诱发电位（SEP）。脊髓牵张反射（SSR）及其电诱发类似物H反射的幅度呈现昼夜变化：两者在熄灯期的中途最大，在开灯期最小。牵张诱发和电诱发的SEP幅度也呈现昼夜变化，但与脊髓反射节律不同步。H反射是通过直接刺激神经诱发的，因此与SSR不同，它绕过了肌梭。H反射的昼夜节律以及脊髓反射和SEP昼夜节律之间的相位差异表明，这些节律至少部分是由中枢机制介导的。此外，脊髓反射和SEP昼夜节律似乎都受明暗周期的影响，这表明它们可能与同一个振荡器相关联。除了其理论重要性外，这些节律对脊髓反射和SEP的实验及临床研究也具有重要意义。这些节律对于长期监测研究的解读尤为重要，如在重症监护病房和长时间的神经外科手术中经常进行的研究。
