Tucker Thomas R, Fitzpatrick David
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Neurosci. 2006 Dec 27;26(52):13537-47. doi: 10.1523/JNEUROSCI.3723-06.2006.
Large-scale changes in luminance are known to exert a significant suppressive or masking effect on visual perception, but the neural substrate for this effect remains unclear. In this report, we describe the results of experiments using in vivo intracellular recording to explore the impact of luminance transients on the responses of orientation-selective neurons in layer 2/3 of tree shrew primary visual cortex. By measuring changes in excitatory and inhibitory conductances, we find that instantaneous changes in luminance evoke strong cortical inhibition. When combined with visual stimuli that would otherwise yield strong excitatory responses, luminance transients produce significant reductions in excitation as well as increases in inhibition. As a result, luminance transients significantly delay the emergence of orientation tuned cortical responses, and virtually eliminate ongoing responses to effective stimuli. We conclude that cortical inhibition is a critical factor in luminance-evoked cortical suppression and the likely substrate for luminance-induced visual masking phenomenon.
已知亮度的大规模变化会对视觉感知产生显著的抑制或掩蔽效应，但这种效应的神经基础仍不清楚。在本报告中，我们描述了使用体内细胞内记录实验的结果，以探究亮度瞬变对树鼩初级视觉皮层第2/3层方向选择性神经元反应的影响。通过测量兴奋性和抑制性电导的变化，我们发现亮度的瞬时变化会引起强烈的皮层抑制。当与原本会产生强烈兴奋性反应的视觉刺激相结合时，亮度瞬变会导致兴奋性显著降低以及抑制性增加。结果，亮度瞬变显著延迟了方向调谐皮层反应的出现，并几乎消除了对有效刺激的持续反应。我们得出结论，皮层抑制是亮度诱发皮层抑制的关键因素，也是亮度诱导视觉掩蔽现象的可能基础。
