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目的研究下丘不同亚区神经元相位锁定反应及其潜伏期,探讨下丘不同亚区时间信息的神经传入差异。方法采用单极玻璃镀膜钨丝电极记录14只豚鼠下丘单神经元单位的动作电位。双耳给予持续时间200ms的纯音,频率范围为50～3000Hz,用Level-Crossing Detector (Tucker-Davies Technologies)记录神经元单位的特征性频率,频率反应面积(Frequency response area)及围刺激时间柱形图(Peristimulus time his-togram)。在记录结束时,用5μA电流通电10s作一电损伤标记,退出电极,在相距大约1mm处作另一电损伤标记。用计算机软件重建周期柱形图(Period histogram),并计算向量强度(Vector strength)。利用组织学切片,细胞色素氧化酶染色法染色,重建记录神经元的部位。结果165个神经元单位的记录部位能通过组织学方法确定,其中11个位于背皮层的外侧部,18个位于外核,134个位于中央核。73%的背皮层神经元单位显示对纯音的相位锁定反应,33%的外核神经元单位发生相位锁定反应,75%的中央核神经元单位显示对纯音的相位锁定反应。在下丘锁相反应神经元中,74%的神经元单位(63/85)的相位随刺激频率变化图为线性,26%的神经元单位呈现为非线性。不同亚区的潜伏期范围为:中央核,4.6～15.4ms[(8.2±2.8)ms];背皮层,12.8～21.3ms[(16.5±3.4)ms];外核,12.1～14ms[(13.4±0.9)ms]。结论下丘三个亚区的相位锁定反应及潜伏期各不相同,其相位锁定的神经传入不同。下丘神经元不仅接受来自下级听觉中枢核团的传入,可能还接受来自上级听觉中枢核团和听觉皮层的相位锁定神经传入。
Objective To study the neuron phase-lock reaction and its incubation period in different sub-regions of the inferior colliculus and to explore the difference of neural afferent in different sub-regions of inferior colliculus. Methods Monopolar glass-coated tungsten electrodes were used to record the action potentials of single neuron units in the inferior colliculus of 14 guinea pigs. Both ears were given a pure tone with a duration of 200 ms and a frequency range of 50-3000 Hz. The characteristic frequency, frequency response area and peristaltic time column of the neurons were recorded by a Level-Crossing Detector (Tucker-Davies Technologies) Peristimulus time his-togram. At the end of the recording, a current of 10 μs was energized for 10 seconds as an electrical damage marker, exiting the electrode and another electrical damage marker at a distance of about 1 mm. Reconstruct the Period histogram using computer software and calculate the vector strength. Histological sections and cytochrome oxidase staining were used to stain the neurons. Results The locations of 165 neurons were identified histologically. Of these, 11 were located in the lateral part of the dorsal cortex, 18 in the outer and 134 in the central nucleus. Seventy-three percent of the dorsal cortical neurons showed a phase-locked response to pure tone, 33% of the extranodal neuronal units phase-locked, and 75% of the central nuclear neurons showed phase-locked responses to pure tone. In the inferior colliculus phase response neurons, 74% of the neuronal units (63/85) showed a linear phase change with the stimulation frequency, and 26% of the neurons showed non-linearity. The latency in different subregions ranged from 4.6 to 15.4 ms [(8.2 ± 2.8) ms], from 12.8 to 21.3 ms (16.5 ± 3.4 ms) to the central nucleus, from 12.1 to 14 ms (13.4 ± 0.9) ms]. Conclusion The three subregions of the inferior colliculus have different phase-locking responses and different incubation periods, and their phase-locked nerves are different. Inferior collicular neurons not only receive afferent from subordinate auditory central nuclei but may also receive phase-locked neurotransmission from superior auditory central nucleus and auditory cortex.