Monotonic coding of numerosity in macaque lateral intraparietal area.
Monotonic coding of numerosity in macaque lateral intraparietal area.
复制标题
猕猴侧向内部区域的数值编码。
DOI：
10.1371/journal.pbio.0050208
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发表时间：
2007-08
期刊：
影响因子：
9.8
通讯作者：
Platt, Michael L.
中科院分区：
文献类型：
--
作者：
Roitman, Jamie D.;Brannon, Elizabeth M.;Platt, Michael L.
任何孩子都知道，计数的第一步是将单个元素相加，但负责这一过程的大脑机制仍然不清楚。在这里，我们第一次表明，猴子外侧顶内区的神经元群体以分级的方式编码其经典感受野内的元素总数，在很宽的数值范围内（2-32）。此外，调制的神经元活动的视觉量迅速发展，在100毫秒内的刺激发作，是独立的注意，奖励的期望，或刺激属性，如大小，密度，或颜色。这些神经元的反应类似于数字处理计算模型中假设的“累加器神经元”的输出。数值累加器神经元可以向编码特定基数值（诸如“4”）的神经元提供输入，这在先前的工作中已经描述。我们的发现可以解释人类顶叶皮层损伤后视觉空间和数字缺陷的频繁关联。任何一个孩子都知道，要回答“有多少”这个问题，必须从把一组中的单个物体加起来开始。除了人类之外，这种认知能力也被鸟类和猴子等各种动物所分享。令人惊讶的是，负责这一过程的确切大脑机制仍然未知。大脑顶叶皮层的损伤会破坏基本的数学技能，功能成像研究表明，当人们进行基本计算时，这一区域会被激活。为了了解顶叶皮层是如何影响数字行为的，我们研究了猴子在电脑屏幕上看一排点时顶叶皮层神经元的活动。我们发现，顶叶神经元的反应是渐进的，因为显示器中的元素总数在很宽的值范围内（2-32）变化。这些神经元类似于“累加神经元”，被认为是计数的第一阶段。这些信息可以被其他对特定基数反应最好的神经元使用，例如“4”，正如先前的研究所报道的那样。我们的研究结果支持计算机模型，将求和和数字识别的过程分开，也可以解释顶叶皮层损伤导致数字和空间混淆的事实。猴子外侧顶内区（LIP）的神经元在延迟扫视任务中对视觉阵列中的项目数量以分级方式作出反应，这表明神经元“总结”单个元素以代表累积的幅度。
As any child knows, the first step in counting is summing up individual elements, yet the brain mechanisms responsible for this process remain obscure. Here we show, for the first time, that a population of neurons in the lateral intraparietal area of monkeys encodes the total number of elements within their classical receptive fields in a graded fashion, across a wide range of numerical values (2–32). Moreover, modulation of neuronal activity by visual quantity developed rapidly, within 100 ms of stimulus onset, and was independent of attention, reward expectations, or stimulus attributes such as size, density, or color. The responses of these neurons resemble the outputs of “accumulator neurons” postulated in computational models of number processing. Numerical accumulator neurons may provide inputs to neurons encoding specific cardinal values, such as “4,” that have been described in previous work. Our findings may explain the frequent association of visuospatial and numerical deficits following damage to parietal cortex in humans. As any child knows, to answer the question “how many,” one must start by adding up individual objects in a group. Extending beyond humans, this cognitive ability is shared by animals as diverse as birds and monkeys. Surprisingly, the exact brain mechanisms responsible for this process remain unknown. Damage to a brain area known as the parietal cortex disrupts basic mathematical skills, and functional imaging studies show that this area is activated when people perform basic computations. To understand how parietal cortex contributes to numerical behavior, we studied the activity of neurons in this area in monkeys while they looked at arrays of dots on a computer screen. We found that parietal neurons responded progressively as the total number of elements in the display was varied across a wide range of values (2–32). These neurons resemble “accumulator neurons” that have been suggested to serve as the first stage in counting. This information could be used by other neurons that respond best for a particular cardinal number, such as “4,” as has been reported in prior studies. Our findings support computer models that separate the processes of summing and numerical identification, and may also explain the fact that parietal cortex damage causes both numerical and spatial confusion. Neurons in the lateral intraparietal area (LIP) in monkeys respond in a graded fashion to the number of items in a visual array during a delayed saccade task, suggesting that the neurons "sum up" individual elements to represent accumulated magnitude.
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2.5
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BARASH, S;BRACEWELL, RM;ANDERSEN, RA
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