Filippov Igor V, Williams William C, Krebs Artem A, Pugachev Konstantin S
Department of Physiology and Biophysics, Yaroslavl State Medical Academy, Yaroslavl, 150000, Revolutsionnaya Street 5, Russia.
Brain Res. 2008 Jul 11;1219:66-77. doi: 10.1016/j.brainres.2008.04.011. Epub 2008 Apr 16.
Several available reports demonstrate the presence of infraslow activity (<0.5 Hz) in structures of the auditory system of the brain. It was reported earlier that specific alterations of this activity in the domain of seconds (0.1-0.5 Hz) occurred in the medial geniculate nucleus (MGN) and primary auditory cortex (A1) in response to acoustic stimuli. The present study was performed to test two hypotheses: (1) that potentials in the domain of seconds (0.1-0.5 Hz) reflect specific and direct interactions of the MGN and A1 during neural processing of sensory information, and (2) that low-frequency infraslow potentials in the A1 (<0.1 Hz) are related to brainstem influences originating from the locus coeruleus (LC) and dorsal raphe nucleus (DRN). The experimental subjects were 25 adult rats with chronic stereotaxic electrodes implanted in the MGN, A1, LC, and DRN. The animals were anesthetized and infraslow activity was once recorded under several experimental conditions: (1) in the A1 before and after electrical stimulation of MGN, (2) in the A1 before and after electrical stimulation of LC, and (3) in the A1 before and after electrical stimulation of DRN. The effects of MGN stimulation were limited to overall increases in spectral power in the frequency domain of 0.1-0.5 Hz. Specifically, power increased in the frequencies of 0.1-0.25, 0.35-0.4, and 0.45-0.5 Hz in the A1 after MGN stimulation. The electrical stimulation of either the LC or DRN affected only multisecond activity (0.0167-0.04 Hz) in the A1 in the similar way (increase of powers of multisecond potentials), but it does not induced any changes in the activity with the frequencies of 0.1-0.5 Hz in this structure. These results support tentative conclusions that infraslow activity in the range of 0.1-0.5 Hz is implicated in specific mechanisms of interactions within the MGN-A1 thalamic-cortical system, whereas multisecond potentials (0.0167-0.04 Hz) in A1 are mainly attributed to the influences of brainstem nuclei (like LC and DRN) on general neuronal excitability of this auditory cortical area.
几份现有报告表明，大脑听觉系统结构中存在亚慢波活动（<0.5 Hz）。此前有报道称，响应听觉刺激时，内侧膝状体（MGN）和初级听觉皮层（A1）中这种活动在秒级范围（0.1 - 0.5 Hz）内发生了特定改变。本研究旨在验证两个假设：（1）秒级范围（0.1 - 0.5 Hz）内的电位反映了感觉信息神经处理过程中MGN和A1之间特定且直接的相互作用；（2）A1中低频亚慢波电位（<0.1 Hz）与源自蓝斑（LC）和中缝背核（DRN）的脑干影响有关。实验对象为25只成年大鼠，其慢性立体定位电极植入在MGN、A1、LC和DRN中。动物被麻醉后，在几种实验条件下记录亚慢波活动：（1）在MGN电刺激前后的A1中；（2）在LC电刺激前后的A1中；（3）在DRN电刺激前后的A1中。MGN刺激的影响仅限于0.1 - 0.5 Hz频域内频谱功率的整体增加。具体而言，MGN刺激后，A1中0.1 - 0.25 Hz、0.35 - 0.4 Hz和0.45 - 0.5 Hz频率的功率增加。LC或DRN的电刺激以类似方式（多秒级电位功率增加）仅影响A1中的多秒级活动（0.0167 - 0.04 Hz），但未在该结构中引起0.1 - 0.5 Hz频率活动的任何变化。这些结果支持初步结论，即0.1 - 0.5 Hz范围内的亚慢波活动与MGN - A1丘脑 - 皮层系统内的特定相互作用机制有关，而A1中的多秒级电位（0.0167 - 0.04 Hz）主要归因于脑干核团（如LC和DRN）对该听觉皮层区域一般神经元兴奋性的影响。
