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首页> 外文期刊>Journal of vision >Second-order neuronal responses to contrast modulation stimuli in primate visual cortex
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Second-order neuronal responses to contrast modulation stimuli in primate visual cortex

机译：灵长类动物视觉皮质对比调制刺激的二阶神经元反应

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Responses to contrast modulation (CM) and other second-order stimuli have been extensively studied in human psychophysics and neurophysiology in the cat. However the neuronal substrates of second-order responses in non-human primates remain poorly understood. To address this issue we have recorded single neurons in area V2 of anesthetized, paralyzed, carefully refracted macaque monkeys, using both CM stimuli as well as conventional luminance modulation (LM) gratings presented on a linearized CRT monitor. CM stimuli were constructed from stationary sinewave grating carriers, which were modulated by drifting envelope gratings of a lower spatial frequency. Initially using envelope parameters matched to each neuron's optimal LM grating, we systematically varied carrier spatial frequency at a series of carrier orientations. About one-third of visually responsive V2 neurons responded to CM stimuli with a pronounced selectivity to carrier spatial frequencies that were clearly outside the neurona??s passband for LM gratings, and therefore genuine second-order responses rather than luminance artifacts. Many of these neurons were also quite selective to carrier orientation; different neurons were selective for different carrier spatial frequencies and orientations. Using carrier parameters optimized for each neuron, we verified that tuning to CM envelope spatial frequency and orientation was very similar to that for LM gratings. Neurons were tuned to carrier spatial frequencies that were typically 2-4 octaves higher than their optimal envelope spatial frequencies. These results are distinct from CM responses arising from surround suppression (Tanaka & Ohzawa, J Neurophysiol, 2009; Hallum & Movshon, VSS, 2011), which show optimal carrier/envelope frequency ratios of about two. However they more resemble previous human psychophysics for CM (Sutter et al, Vis Res 1995; Dakin & Mareschal, Vis Res, 2000) and some other kinds of second-order stimuli (Kingdom & Keeble, Vis Res, 1999; Meso & Hess, Vis Res 2010), which are best detected at higher carrier/envelope frequency ratios.
机译：对猫的人体心理物理学和神经生理学进行了对比调制（cm）和其他二阶刺激的反应。然而，非人印象中的二阶反应的神经元底物仍然明显差。为了解决这个问题，我们使用CM刺激以及在线性CRT监测器上呈现的CM刺激和常规亮度调制（LM）光栅，在麻醉的，瘫痪，小心折射的猕猴的猴子猴中录制了单一神经元。 CM刺激由固定正弦波光栅载体构成，其通过漂移较低空间频率的包络光栅来调制。最初使用与每个神经元最佳LM光栅匹配的包络参数，我们在一系列载波方向上系统地改变了载波空间频率。在视觉敏感V2神经元中约有三分之一的响应于CM刺激，并具有明显的选择性的载波空间频率，该频率明显地在Neurona的通带外部进行LM光栅，因此是真正的二阶响应而不是亮度伪像。这些神经元中的许多也非常有选择于载体取向;不同的神经元针对不同的载波空间频率和方向选择性。使用针对每个神经元优化的载波参数，我们验证了调谐到CM包络空间频率和方向与LM光栅非常相似。神经元调谐到载体空间频率，其通常比其最佳包络空间频率高2-4个八度。这些结果与来自周围抑制产生的CM响应不同（Tanaka＆Ohzawa，J Neurophysiol，2009; Hallum＆Movshon，VSS，2011），其显示了大约两个的最佳载波/包络频率比。然而，它们更像以前的人类心理物理学为cm（sutter等，Vis 1995; Dakin＆Mareschal，Vis res，2000）以及其他一些类型的二阶刺激（王国和克莱尔，1999年，Meso＆Hess， VIS 2010），最佳地检测到更高的载波/包络频率比。

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