Buia Calin I, Tiesinga Paul H
Computational Neurophysics Laboratory, Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC 27599-3255, USA.
J Neurophysiol. 2008 May;99(5):2158-82. doi: 10.1152/jn.01004.2007. Epub 2008 Feb 20.
Receptive fields of neurons in cortical area V4 are large enough to fit multiple stimuli, making V4 the ideal place to study the effects of selective attention at the single-neuron level. Experiments have revealed evidence for stimulus competition and have characterized the effect thereon of spatial and feature-based attention. We developed a biophysical model with spiking neurons and conductance-based synapses. To account for the comprehensive set of experimental results, it was necessary to include in the model, in addition to regular spiking excitatory (E) cells, two types of interneurons: feedforward interneurons (FFI) and top-down interneurons (TDI). Feature-based attention was mediated by a projection of the TDI to the FFI, stimulus competition was mediated by a cross-columnar excitatory connection to the FFI, whereas spatial attention was mediated by an increase in activity of the feedforward inputs from cortical area V2. The model predicts that spatial attention increases the FFI firing rate, whereas feature-based attention decreases the FFI firing rate and increases the TDI firing rate. During strong stimulus competition, the E cells were synchronous in the beta frequency range (15-35 Hz), but with feature-based attention, they became synchronous in the gamma frequency range (35-50 Hz). We propose that the FFI correspond to fast-spiking, parvalbumin-positive basket cells and that the TDI correspond to cells with a double-bouquet morphology that are immunoreactive to calbindin or calretinin. Taken together, the model results provide an experimentally testable hypothesis for the behavior of two interneuron types under attentional modulation.
大脑皮层V4区神经元的感受野足够大，能够容纳多个刺激，这使得V4区成为在单神经元水平研究选择性注意效应的理想场所。实验揭示了刺激竞争的证据，并描述了基于空间和特征的注意对其产生的影响。我们开发了一个具有脉冲神经元和基于电导的突触的生物物理模型。为了解释这一系列全面的实验结果，除了常规的脉冲发放兴奋性（E）细胞外，模型中还必须包含两种中间神经元：前馈中间神经元（FFI）和自上而下的中间神经元（TDI）。基于特征的注意由TDI到FFI的投射介导，刺激竞争由与FFI的跨柱兴奋性连接介导，而空间注意由来自大脑皮层V2区的前馈输入活动增加介导。该模型预测，空间注意会提高FFI的发放率，而基于特征的注意会降低FFI的发放率并提高TDI的发放率。在强烈的刺激竞争期间，E细胞在β频率范围（15 - 35赫兹）内同步，但在基于特征的注意下，它们在γ频率范围（35 - 50赫兹）内同步。我们提出FFI对应于快速发放、小清蛋白阳性的篮状细胞，而TDI对应于对钙结合蛋白或钙视网膜蛋白免疫反应的具有双花形态的细胞。综上所述，模型结果为两种中间神经元类型在注意调制下的行为提供了一个可通过实验检验的假设。
