Department of Neurological and Movement Sciences, University of Verona, I-37129 Verona, Italy, Department of Physiology, McGill University, Montreal, Quebec, H3A 0G4, Canada, Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, I-56126 Pisa, Italy, Stella Maris Foundation IRCCS, I-56128 Pisa, Italy, and National Institute of Neuroscience, I-37134 Verona, Italy.
J Neurosci. 2013 Nov 20;33(47):18583-96. doi: 10.1523/JNEUROSCI.3465-13.2013.
Visually responsive neurons typically exhibit a monotonic-saturating increase of firing with luminance contrast of the stimulus and are able to adapt to the current spatiotemporal context by shifting their selectivity, therefore being perfectly suited for optimal contrast encoding and discrimination. Here we report the first evidence of the existence of neurons showing selective tuning for contrast in area V4d of the behaving macaque (Macaca mulatta), i.e., narrow bandpass filter neurons with peak activity encompassing the whole range of visible contrasts and pronounced attenuation at contrasts higher than the peak. Crucially, we found that contrast tuning emerges after a considerable delay from stimulus onset, likely reflecting the contribution of inhibitory mechanisms. Selective tuning for luminance contrast might support multiple functions, including contrast identification and the attentive selection of low contrast stimuli.
视觉反应神经元通常表现出与刺激亮度对比度单调饱和的增加，并能够通过改变其选择性来适应当前的时空上下文，因此非常适合最佳对比度编码和辨别。在这里，我们首次报告了在行为猕猴（Macaca mulatta）的 V4d 区存在对对比度具有选择性调谐的神经元的证据，即具有峰值活动包含整个可见对比度范围且在高于峰值的对比度下明显衰减的窄带通滤波器神经元。至关重要的是，我们发现对比度调谐在刺激开始后相当长的延迟后才出现，这可能反映了抑制机制的贡献。对亮度对比度的选择性调谐可能支持多种功能，包括对比度识别和对低对比度刺激的注意力选择。
