University of California, Irvine, California.
J Cogn Neurosci. 1990 Fall;2(4):358-72. doi: 10.1162/jocn.1990.2.4.358.
An attention mechanism in the pulvinar nucleus of the thalamus appears to be involved in the filtering of a location in a cluttered visual field, according to recent PET data. The mechanism in the pulvinar is assumed to be a particular type of circuit that reciprocally connects thalamic relay cells to cortical cells. This circuit, which is characteristic of thalamic nuclei in general, appears to embody an algorithm that enhances firing in a target set of cells while inhibiting firing in the surrounding set of cells. Recent PET studies have also identified specific areas of cortex that show increased blood flow when humans expect to process particular aspects of visual objects, such as location, shape, color, and movement velocity. An expectation for a particular feature can be regarded as a peaked activity distribution across cortical synaptic space that increases the effectiveness (accuracy and speed) of the perception of that feature and features similar to that feature. The expectation process is assumed to be generated by a thalamic enhancement circuit, which in turn is driven by a cognitive procedure, apparently located in the anterior cingulate area of the cortex. The selection of a particular cognitive procedure is assumed to depend on the momentary relative motivational value associated with it by means of connections to deeper limbic structures. Under usual conditions, the procedure having the dominant motivational value is the one selected.
根据最近的 PET 数据，丘脑的丘脑束核中的注意力机制似乎参与了对杂乱视觉场中位置的过滤。该机制假定是一种特殊类型的回路，该回路将丘脑中继细胞与皮质细胞相互连接。这种普遍存在于丘脑核中的回路似乎体现了一种算法，该算法可增强目标细胞集的发射，同时抑制周围细胞集的发射。最近的 PET 研究还确定了大脑皮层的特定区域，当人类期望处理视觉对象的特定方面（例如位置，形状，颜色和运动速度）时，这些区域的血流量会增加。对特定特征的期望可以被视为皮质突触空间中跨区活动分布的峰值，从而提高对该特征和与该特征相似的特征的感知的有效性（准确性和速度）。期望过程假定是由丘脑增强回路产生的，而丘脑增强回路又由位于大脑皮层前扣带区的认知过程驱动。假定特定认知过程的选择取决于与该过程相关的当前相对动机值，这是通过与更深层的边缘结构的连接来实现的。在通常情况下，选择具有主要动机价值的过程。
