Department of Electrical, Electronic, and Information Engineering Guglielmo Marconi, University of Bologna, 40126 Bologna, Italy; and.
Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157.
J Neurosci. 2018 Apr 4;38(14):3453-3465. doi: 10.1523/JNEUROSCI.2631-17.2018. Epub 2018 Mar 1.
The ability to integrate information across multiple senses enhances the brain's ability to detect, localize, and identify external events. This process has been well documented in single neurons in the superior colliculus (SC), which synthesize concordant combinations of visual, auditory, and/or somatosensory signals to enhance the vigor of their responses. This increases the physiological salience of crossmodal events and, in turn, the speed and accuracy of SC-mediated behavioral responses to them. However, this capability is not an innate feature of the circuit and only develops postnatally after the animal acquires sufficient experience with covariant crossmodal events to form links between their modality-specific components. Of critical importance in this process are tectopetal influences from association cortex. Recent findings suggest that, despite its intuitive appeal, a simple generic associative rule cannot explain how this circuit develops its ability to integrate those crossmodal inputs to produce enhanced multisensory responses. The present neurocomputational model explains how this development can be understood as a transition from a default state in which crossmodal SC inputs interact competitively to one in which they interact cooperatively. Crucial to this transition is the operation of a learning rule requiring coactivation among tectopetal afferents for engagement. The model successfully replicates findings of multisensory development in normal cats and cats of either sex reared with special experience. In doing so, it explains how the cortico-SC projections can use crossmodal experience to craft the multisensory integration capabilities of the SC and adapt them to the environment in which they will be used. The brain's remarkable ability to integrate information across the senses is not present at birth, but typically develops in early life as experience with crossmodal cues is acquired. Recent empirical findings suggest that the mechanisms supporting this development must be more complex than previously believed. The present work integrates these data with what is already known about the underlying circuit in the midbrain to create and test a mechanistic model of multisensory development. This model represents a novel and comprehensive framework that explains how midbrain circuits acquire multisensory experience and reveals how disruptions in this neurotypic developmental trajectory yield divergent outcomes that will affect the multisensory processing capabilities of the mature brain.
跨模态信息整合能力增强了大脑检测、定位和识别外部事件的能力。这一过程在高级视丘（superior colliculus，SC）的单个神经元中得到了很好的记录，这些神经元综合了视觉、听觉和/或体感信号的一致组合，以增强其反应的活力。这增加了跨模态事件的生理显著性，从而提高了 SC 介导的对这些事件的行为反应的速度和准确性。然而，这种能力不是回路的固有特征，只有在动物获得足够的协变跨模态事件经验后，才能在出生后发展起来，从而在其特定模态组件之间形成联系。在这个过程中，至关重要的是来自联合皮层的顶盖投射影响。最近的研究结果表明，尽管这一观点很直观，但一个简单的通用联想规则并不能解释这个回路是如何发展其整合这些跨模态输入以产生增强的多感觉反应的能力的。本神经计算模型解释了这一发展如何被理解为从一个默认状态的转变，在这个默认状态中，跨模态 SC 输入是相互竞争的，而在另一个状态中，它们是相互合作的。对于这种转变至关重要的是一个学习规则的运作，该规则要求顶盖传入纤维的共同激活才能参与。该模型成功复制了正常猫和接受特殊经验饲养的公猫和母猫的多感觉发育的发现。通过这样做，它解释了皮质-SC 投射如何利用跨模态经验来塑造 SC 的多感觉整合能力，并使它们适应其将被使用的环境。大脑在跨感觉信息整合方面的非凡能力并非与生俱来，而是在生命早期随着对跨感觉线索的经验获得而发展起来的。最近的实证研究结果表明，支持这种发展的机制必须比以前认为的更复杂。本工作将这些数据与已知的中脑底层回路相结合，创建并测试了一个多感觉发育的机制模型。该模型代表了一个新颖而全面的框架，解释了中脑回路如何获得多感觉经验，并揭示了这种神经典型发育轨迹的中断如何产生不同的结果，从而影响成熟大脑的多感觉处理能力。
