Department of Psychology and Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, USA.
J Neurosci. 2012 Jul 11;32(28):9626-38. doi: 10.1523/JNEUROSCI.6488-11.2012.
The developing brain responds to the environment by using statistical correlations in input to guide functional and structural changes-that is, the brain displays neuroplasticity. Experience shapes brain development throughout life, but neuroplasticity is variable from one brain system to another. How does the early loss of a sensory modality affect this complex process? We examined cross-modal neuroplasticity in anatomically defined subregions of Heschl's gyrus, the site of human primary auditory cortex, in congenitally deaf humans by measuring the fMRI signal change in response to spatially coregistered visual, somatosensory, and bimodal stimuli. In the deaf Heschl's gyrus, signal change was greater for somatosensory and bimodal stimuli than that of hearing participants. Visual responses in Heschl's gyrus, larger in deaf than hearing, were smaller than those elicited by somatosensory stimulation. In contrast to Heschl's gyrus, in the superior-temporal cortex visual signal was comparable to somatosensory signal. In addition, deaf adults perceived bimodal stimuli differently; in contrast to hearing adults, they were susceptible to a double-flash visual illusion induced by two touches to the face. Somatosensory and bimodal signal change in rostrolateral Heschl's gyrus predicted the strength of the visual illusion in the deaf adults in line with the interpretation that the illusion is a functional consequence of the altered cross-modal organization observed in deaf auditory cortex. Our results demonstrate that congenital and profound deafness alters how vision and somatosensation are processed in primary auditory cortex.
发育中的大脑通过利用输入中的统计相关性来响应环境，从而引导功能和结构的变化，也就是说，大脑表现出神经可塑性。经验会影响一生的大脑发育，但神经可塑性在不同的大脑系统之间存在差异。那么，感官的早期丧失如何影响这个复杂的过程呢？我们通过测量对空间上配准的视觉、体感和双模态刺激的 fMRI 信号变化，来研究先天性耳聋患者中听觉皮层的解剖定义子区——Heschl 回的跨模态神经可塑性。在耳聋的 Heschl 回中，体感和双模态刺激的信号变化大于听力参与者。耳聋患者的 Heschl 回中的视觉反应大于听力，但小于体感刺激引起的反应。与 Heschl 回不同，在颞上皮质中，视觉信号与体感信号相当。此外，耳聋成年人对双模态刺激的感知方式不同；与听力成年人相比，他们容易受到两个触摸面部引起的双闪光视觉错觉的影响。Heschl 回的前外侧体感和双模态信号变化与耳聋成年人的视觉错觉强度相关，这与听觉皮层中观察到的跨模态组织改变导致错觉的功能后果的解释一致。我们的研究结果表明，先天性和严重的耳聋会改变大脑对视觉和体感信息的处理方式。
