Barry Kristin M, Robertson Donald, Mulders Wilhelmina H A M
The Auditory Laboratory, School of Human Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Biomedicines. 2021 Jan 14;9(1):77. doi: 10.3390/biomedicines9010077.
In the adult auditory system, loss of input resulting from peripheral deafferentation is well known to lead to plasticity in the central nervous system, manifested as reorganization of cortical maps and altered activity throughout the central auditory pathways. The auditory system also has strong afferent and efferent connections with cortico-limbic circuitry including the prefrontal cortex and the question arises whether this circuitry is also affected by loss of peripheral input. Recent studies in our laboratory showed that PFC activation can modulate activity of the auditory thalamus or medial geniculate nucleus (MGN) in normal hearing rats. In addition, we have shown in rats that cochlear trauma resulted in altered spontaneous burst firing in MGN. However, whether the PFC influence on MGN is changed after cochlear trauma is unknown. We investigated the effects of electrical stimulation of PFC on single neuron activity in the MGN in anaesthetized Wistar rats 2 weeks after acoustic trauma or sham surgery. Electrical stimulation of PFC showed a variety of effects in MGN neurons both in sham and acoustic trauma groups but inhibitory responses were significantly larger in the acoustic trauma animals. These results suggest an alteration in functional connectivity between PFC and MGN after cochlear trauma. This change may be a compensatory mechanism increasing sensory gating after the development of altered spontaneous activity in MGN, to prevent altered activity reaching the cortex and conscious perception.
在成人听觉系统中，众所周知，外周去传入导致的输入丧失会引发中枢神经系统的可塑性，表现为皮质图谱的重组以及整个中枢听觉通路活动的改变。听觉系统还与包括前额叶皮质在内的皮质 - 边缘回路有着强大的传入和传出连接，于是问题就出现了，即该回路是否也会受到外周输入丧失的影响。我们实验室最近的研究表明，在听力正常的大鼠中，前额叶皮质的激活可以调节听觉丘脑或内侧膝状体核（MGN）的活动。此外，我们在大鼠身上发现，耳蜗损伤会导致内侧膝状体核的自发放电突发改变。然而，耳蜗损伤后前额叶皮质对内侧膝状体核的影响是否发生变化尚不清楚。我们研究了在声创伤或假手术后2周，对麻醉的Wistar大鼠的前额叶皮质进行电刺激对内侧膝状体核单个神经元活动的影响。在前额叶皮质进行电刺激在假手术组和声创伤组的内侧膝状体核神经元中均显示出多种效应，但在声创伤动物中抑制性反应明显更大。这些结果表明耳蜗损伤后前额叶皮质与内侧膝状体核之间的功能连接发生了改变。这种变化可能是一种补偿机制，在内侧膝状体核自发放电改变后增加感觉门控，以防止改变的活动到达皮质和意识感知。
