McMahon David B T, Olson Carl R
Department of Neuroscience, University of Pittsburgh, Pennsylvania, USA.
J Neurophysiol. 2007 May;97(5):3532-43. doi: 10.1152/jn.01042.2006. Epub 2007 Mar 7.
In tasks requiring judgments about visual stimuli, humans exhibit repetition priming, responding with increased speed when a stimulus is repeated. Repetition priming might depend on repetition suppression, a phenomenon first observed in monkey inferotemporal cortex (IT) whereby, when a stimulus is repeated, the strength of the neuronal visual response is reduced. If the reduction resulted in sharpening of the cortical representation of the stimulus, and did not just scale it down, then speeded processing might result. To explore the relation between repetition priming and repetition suppression, we monitored neuronal activity in IT while monkeys performed a symmetry decision task. We found 1) that monkeys exhibit repetition priming, 2) that IT neurons simultaneously exhibit repetition suppression, 3) that repetition priming and repetition suppression do not vary in a significantly correlated fashion across trials, and 4) that repetition suppression scales down the representation of the stimulus without sharpening it. We conclude that repetition suppression accompanies repetition priming but is unlikely to be its cause.
在需要对视觉刺激进行判断的任务中，人类表现出重复启动效应，即当刺激重复出现时，反应速度会加快。重复启动效应可能依赖于重复抑制，这是一种最初在猴子颞下皮质（IT）中观察到的现象，即当刺激重复时，神经元视觉反应的强度会降低。如果这种降低导致刺激的皮质表征更加清晰，而不仅仅是缩小其规模，那么可能会导致处理速度加快。为了探究重复启动效应与重复抑制之间的关系，我们在猴子执行对称决策任务时监测了IT中的神经元活动。我们发现：1）猴子表现出重复启动效应；2）IT神经元同时表现出重复抑制；3）重复启动效应和重复抑制在各试验中没有显著的相关性变化；4）重复抑制会缩小刺激的表征规模，而不会使其更加清晰。我们得出结论，重复抑制伴随着重复启动效应，但不太可能是其原因。
