Kral Andrej, Yusuf Prasandhya A, Land Rüdiger
Institute of AudioNeuroTechnology & Dept. of Experimental Otology, ENT Clinics, Hannover Medical University, Germany; School of Behavioral and Brain Sciences, The University of Texas at Dallas, TX, USA.
Institute of AudioNeuroTechnology & Dept. of Experimental Otology, ENT Clinics, Hannover Medical University, Germany.
Hear Res. 2017 Jan;343:50-63. doi: 10.1016/j.heares.2016.08.017. Epub 2016 Sep 13.
The theory of predictive coding assumes that higher-order representations influence lower-order representations by generating predictions about sensory input. In congenital deafness, one identified dysfunction is a reduced activation of deep layers in the auditory cortex. Since these layers play a central role for processing top-down influences, congenital deafness might interfere with the integration of top-down and bottom-up information flow. Studies in humans suggest more deficits in higher-order than in primary cortical areas in congenital deafness. That opens up the question how well neurons in higher-order areas can be activated by the input through the deprived auditory pathway after restoration of hearing with cochlear implants. Further it is unclear whether their interconnections to lower order areas are impaired by absence of hearing. Corticocortical anatomical fiber tracts and general auditory responsiveness in both primary and higher-order areas are generally preserved in absence of auditory experience. However, the existing data suggest a dichotomy between preservation of anatomical cortical connectivity in congenital deafness and functional deficits in corticocortical coupling. Further, cross-modal reorganization observed in congenital deafness in specific cortical areas appears to be established by functional synaptic changes and rests on anatomically preserved, genetically-predetermined and molecularly patterned circuitry connecting the sensory systems. Current data indicate a reduced corticocortical functional coupling between cortical auditory areas in congenital deafness, both in bottom-up and top-down information stream. Consequently, congenital deafness is likely to result in a deficit in predictive coding that affects learning ability after late cochlear implantation.
预测编码理论假定，高阶表征通过对感觉输入生成预测来影响低阶表征。在先天性耳聋中，一个已确定的功能障碍是听觉皮层深层激活减少。由于这些层在处理自上而下的影响方面起着核心作用，先天性耳聋可能会干扰自上而下和自下而上信息流的整合。对人类的研究表明，先天性耳聋患者高阶皮层区域的缺陷比初级皮层区域更多。这就引出了一个问题，即通过人工耳蜗恢复听力后，高阶区域的神经元能在多大程度上被通过受损听觉通路的输入激活。此外，尚不清楚它们与低阶区域的连接是否因听力缺失而受损。在没有听觉经验的情况下，初级和高阶区域的皮质皮质解剖纤维束和一般听觉反应通常得以保留。然而，现有数据表明，先天性耳聋中解剖学皮质连接的保留与皮质皮质耦合中的功能缺陷之间存在二分法。此外，在先天性耳聋患者特定皮质区域观察到的跨模态重组似乎是由功能性突触变化建立的，并且依赖于连接感觉系统的解剖学上保留、基因上预先确定和分子上有模式的神经回路。目前的数据表明，先天性耳聋患者皮质听觉区域之间的皮质皮质功能耦合在自下而上和自上而下的信息流中均减少。因此，先天性耳聋可能会导致预测编码缺陷，从而影响晚期人工耳蜗植入后的学习能力。
