SELECTIVE ATTENTION AT EARLY STAGES OF VISUAL PROCESSING

描述(由申请者提供)：在过去的30年里，在理解涉及选择性视觉注意的大脑回路方面取得了巨大的进步。目前的一些模型认为，注意信号起源于高皮质区域(如额叶和顶叶皮质)，然后以自上而下的方式转移到视觉加工的早期阶段。这一模型与视觉通路中从高级阶段到低级阶段的反馈连接的丰富解剖网络的存在是一致的。然而，反馈连接在初级视觉皮质(V-1)和外侧膝状核(LGN)的加工过程中达到最低的阶段。因此，注意力可能通过作用于视觉通路的初始阶段来潜在地调节知觉。与这一假设一致的是，越来越多的证据表明，选择性视觉注意调节了V-1的活动，最近的一项解剖学研究发现了LGN注意调节的第一个证据。选择性视觉注意的一个重要特征是它的视网膜特异性，注意力的焦点可以被限制在视觉空间的非常小的区域。在包括V-1在内的几个皮质区已经显示出显著的特异性，但在LGN中则没有。视觉注意力可以调节LGN活动的证据缺失，因此这是一个重要的证据。目前尚不清楚LGN对视网膜的选择性调节作用有多大。在这项提议中，当动物执行一项需要选择性视觉注意的任务时，将通过同时从多个膝状神经元记录来测量LGN注意调制的视网膜特异性。此外，还将通过同时记录LGN和V-1细胞的感受野在视觉空间中对齐，来研究LGN调制是否可靠地转移到V-1。对选择性视觉注意所涉及的回路的精确了解对于理解大脑如何处理视觉信息很重要。对这一回路的研究最终将导致对严重注意力缺陷的预防和治疗，这种缺陷在许多精神和神经疾病中很常见。

DESCRIPTION (provided by applicant): In the last 30 years, there has been an enormous progress in understanding the brain circuits involved in selective visual attention. Some current models propose that the 'attention signal' originates in high cortical areas (e.g. frontal and parietal cortex) and then is transferred in a top-down fashion to earlier stages in visual processing. This model is consistent with the existence of a rich anatomical network of feedback connections that go from higher to lower stages in the visual pathway. However, feedback connections reach stages as low in processing as the primary visual cortex (V-1 ) and the Lateral Geniculate Nucleus (LGN). Therefore, attention could potentially modulate perception by acting at the initial stages of the visual pathway. Consistent with this hypothesis, increasing evidence indicates that selective visual attention modulates the activity of V-1 and one recent anatomical study found the first evidence for attentional modulations in LGN. An important characteristic of selective visual attention is its retinotopic specificity the focus of attention can be restricted to very small regions of visual space. A remarkable specificity has been demonstrated in several cortical areas including V-1 but not in LGN. The demonstration that visual attention can modulate LGN activity is missing therefore an important piece of evidence. It is not known how retinotopically selective LGN modulations can be. In this proposal, the retinotopic specificity of LGN attentional modulations will be measured by simultaneously recording from multiple geniculate neurons while an animal performs a task that requires selective visual attention. In addition, it will be investigated whether LGN modulations are reliably transferred to V-1 by doing simultaneous recordings from LGN and V-1 cells with receptive fields aligned in visual space. A precise knowledge of the circuits involved in selective visual attention is important to understand how the brain processes visual information. The study of this circuitry will eventually lead to the prevention and treatment of serious attentional deficits that are common in many psychiatric and neurological disorders.