Sacco Alessandra, Gordon Stephen G, Lomber Stephen G
Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada.
Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada; Department of Physiology, McGill University, Montreal, Quebec, Canada.
Neuroimage. 2025 Mar;308:121047. doi: 10.1016/j.neuroimage.2025.121047. Epub 2025 Jan 23.
In response to sensory deprivation, the brain adapts to efficiently navigate a modified perceptual environment through a process referred to as compensatory crossmodal plasticity, allowing the remaining senses to repurpose deprived regions and networks. A mechanism that has been proposed to contribute to this plasticity involves adaptations within subcortical nuclei that trigger cascading effects throughout the brain. The current study uses 7T MRI to investigate the effect of perinatal deafness on the volumes of subcortical structures in felines, focusing on key sensory nuclei within the brainstem and thalamus. Using both ROI-based and morphometric approaches, the regional macrostructure of four auditory and two visual nuclei were studied, as well as the corresponding volumetric asymmetries within and across groups. In the auditory pathway, significant bilateral volumetric reductions were revealed within the lower-level structures (cochlear nucleus, superior olivary complex, and inferior colliculus), alongside a shrinkage of solely the left medial geniculate body. Within the visual pathway, a significant bilateral volumetric reduction was found in the lateral geniculate nucleus, with the superior colliculus largely unaffected. These regional alterations, along with an extensive loss of volume throughout the brainstem of deprived cats, were attributed to disuse-driven atrophy corresponding to evolved functional demands reflective of a modified perceptual environment. Furthermore, the left-right volumetric symmetries of the control subcortex were preserved following deafness. Overall, the current study reinforces the notion that subcortical structures likely contribute to compensatory crossmodal plasticity prior to cortical processing, and that these deafness-induced adaptations appear to be influenced by both the level of the affected structure within its respective sensory processing hierarchy and the specifics of its afferent profile.
作为对感觉剥夺的反应，大脑通过一种被称为代偿性跨模态可塑性的过程进行适应，以有效地在改变后的感知环境中导航，使其余的感官能够重新利用被剥夺的区域和神经网络。一种被认为有助于这种可塑性的机制涉及皮质下核团内的适应性变化，这些变化会在整个大脑中引发级联效应。本研究使用7T磁共振成像（MRI）来研究围产期耳聋对猫科动物皮质下结构体积的影响，重点关注脑干和丘脑内的关键感觉核团。采用基于感兴趣区（ROI）和形态测量学的方法，研究了四个听觉核团和两个视觉核团的区域宏观结构，以及组内和组间相应的体积不对称性。在听觉通路中，较低级结构（耳蜗核、上橄榄复合体和下丘）内出现了显著的双侧体积减小，同时仅左侧内侧膝状体出现萎缩。在视觉通路中，外侧膝状核出现了显著的双侧体积减小，而上丘基本未受影响。这些区域变化，以及耳聋猫脑干整体体积的大量减少，被归因于对应于反映改变后的感知环境的进化功能需求的废用性萎缩。此外，耳聋后对照动物皮质下结构的左右体积对称性得以保留。总体而言，本研究强化了这样一种观点，即皮质下结构可能在皮质处理之前就对代偿性跨模态可塑性有贡献，而且这些由耳聋引起的适应性变化似乎受到其各自感觉处理层级中受影响结构的水平及其传入特征细节的影响。
