Drucker Daniel M, Kerr Wesley Thomas, Aguirre Geoffrey Karl
Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Neurophysiol. 2009 Jun;101(6):3310-24. doi: 10.1152/jn.91306.2008. Epub 2009 Apr 8.
A central focus of cognitive neuroscience is identification of the neural codes that represent stimulus dimensions. One common theme is the study of whether dimensions, such as color and shape, are encoded independently by separate pools of neurons or are represented by neurons conjointly tuned for both properties. We describe an application of functional magnetic resonance imaging (fMRI) adaptation to distinguish between independent and conjoint neural representations of dimensions by examining the neural signal evoked by changes in one versus two stimulus dimensions and considering the metric of two-dimension additivity. We describe how a continuous carry-over paradigm may be used to efficiently estimate this metric. The assumptions of the method are examined as are optimizations. Finally, we demonstrate that the method produces the expected result for fMRI data collected from ventral occipitotemporal cortex while subjects viewed sets of shapes predicted to be represented by conjoint or independent neural tuning.
认知神经科学的一个核心焦点是识别代表刺激维度的神经编码。一个共同的主题是研究诸如颜色和形状等维度是由不同的神经元群独立编码，还是由对这两种属性都进行联合调谐的神经元来表征。我们描述了功能磁共振成像（fMRI）适应性的一种应用，通过检查由一个与两个刺激维度变化所诱发的神经信号，并考虑二维可加性的度量，来区分维度的独立和联合神经表征。我们描述了如何使用连续延续范式来有效地估计这个度量。该方法的假设以及优化都进行了检验。最后，我们证明该方法对于从腹侧枕颞叶皮层收集的fMRI数据产生了预期结果，同时受试者观看了预计由联合或独立神经调谐所表征的形状集。
