Cortical systems for multimodal sensory integration

经典观点的并行感觉处理和多模态整合协会多模态皮质区已受到挑战，越来越多的证据表明，收购和初级感觉皮质内的感觉信息的初始处理可以影响另一种感觉方式。例如，在人类中，初级视觉皮层可以在触觉辨别任务期间被激活。此外，在正常或实验性的多通道重连动物中，听觉皮层的神经元可以对躯体感觉或视觉刺激做出反应。听觉皮层的跨模态激活的证据也来自对音乐家和聋人的成像研究。除了正常人初级感觉皮层的跨通道激活外，这种激活在早期失明受试者的听觉和触觉刺激中也清楚地显示出来。这些研究结果支持最近的演示主要的听觉和视觉皮层区域之间的直接和间接的解剖连接在啮齿动物，食肉动物和非人类灵长类动物。虽然多感官知觉和整合的重要性是公认的，潜在的神经基板仍然不清楚。它已被假设，多感觉整合主要是一个“自下而上”的过程，其中不同的方式收敛在更高阶的多模态区域的大脑皮层。另外，还强调了从多式联运地区到多式联运地区的反馈（“自上而下”）预测。虽然皮质连接已被广泛研究，精细的微电路和参与特定连接的皮质细胞的表型一般缺乏。这项建议的主要目标是调查的精细结构的皮层轴突和细胞参与多感觉整合在皮层水平。这将允许的模型系统，需要解释综合知觉的生理学的阐述。

The classical view of parallel sensory processing and multimodal integration in association multimodal cortical areas has been challenged by the increasing evidence that the acquisition and initial processing of sensory information within primary sensory cortices can be influenced by another sensory modality. For instance, in human, the primary visual cortex can be activated during tactile discrimination tasks. In addition, neurons in the auditory cortex can respond to somatosensory or to visual stimuli alone in normal or in experimentally intermodal rewired animals. Evidence for cross-modal activation of the auditory cortex also comes from imaging studies in musicians and in deaf subjects. In addition to cross-modal activations of primary sensory cortices in normal subjects, such activation are clearly shown in auditory and tactile stimulation in early blind subjects. These findings are supported by recent demonstrations of direct and indirect anatomical connections between primary auditory and visual cortical areas in rodents, carnivores and in non-human primates. Although the importance of multisensory perception and integration is well-established, the underlying neural substrates have remained unclear. It has been hypothesized that multisensory integration is predominantly a 'bottom-up' process, where different modalities converge in higher order multimodal areas in the cerebral cortex. Alternatively, feedback ('top-down') projections from multimodal to unimodal areas have been stressed. Although cortical connectivity has been widely studied, fine microcircuitry and phenotypes of cortical cells engaged in particular connections are generally lacking. The main objectives of this proposal is to investigate the fine structure of cortical axons and of cells involved in multisensory integration at the cortical level. This will allow for the elaboration of model systems that are needed to explain the physiology of integrated perception.