Tuning for shape dimensions in macaque inferior temporal cortex
Tuning for shape dimensions in macaque inferior temporal cortex
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DOI：
10.1111/j.1460-9568.2005.04202.x
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发表时间：
2005-07-01
影响因子：
3.4
通讯作者：
Vogels, R
中科院分区：
文献类型：
--
作者：
Kayaert, G;Biederman, I;Vogels, R
人们普遍认为，分布的钟形调谐（例如径向基函数）的猕猴下颞（IT）神经元的形状选择性的特点，类似于早期视觉皮层中发现的方向或空间频率调谐。要证明这种调谐特性，需要测试神经元对形状沿着维度的不同值的响应。我们记录了单个猕猴IT神经元对矩形和三角形沿着简单形状维度（例如锥形和轴曲率）的变化的反应。神经元表现出系统的反应调制沿着这些尺寸，最大的反应，平均而言，最高的值的尺寸，例如，最弯曲的形状。在测试值的范围内，响应函数是单调的，而不是钟形。多维尺度的神经反应表明，这些简单的形状尺寸正交编码的IT神经元：的程度和方向的反应调制（即增加或减少响应沿着一个维度）是独立的不同的尺寸。此外，对于曲率相关和其他简单形状尺寸的组合，联合调谐是可分离的，这是很好地预测的产品的调谐为每个尺寸。维度调谐的独立性可能为多维刺激的心理物理判断的独立性提供了神经基础。
It is widely assumed that distributed bell-shaped tuning (e.g. Radial Basis functions) characterizes the shape selectivity of macaque inferior temporal (IT) neurons, analogous to the orientation or spatial frequency tuning found in early visual cortex. Demonstrating such tuning properties requires testing the responses of neurons for different values along dimensions of shape. We recorded the responses of single macaque IT neurons to variations of a rectangle and a triangle along simple shape dimensions, such as taper and axis curvature. The neurons showed systematic response modulation along these dimensions, with the greatest response, on average, to the highest values on the dimensions, e.g. to the most curved shapes. Within the range of values tested, the response functions were monotonic rather than bell-shaped. Multi-dimensional scaling of the neural responses showed that these simple shape dimensions were coded orthogonally by IT neurons: the degree and direction of responses modulation (i.e. the increase or decrease of responses along a dimension) was independent for the different dimensions. Furthermore, for combinations of curvature-related and other simple shape dimensions, the joint tuning was separable, that is well predicted by the product of the tuning for each of the dimensions. The independence of dimensional tuning may provide the neural basis for the independence of psychophysical judgements of multidimensional stimuli.