Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK.
Neuroimage. 2011 Jan 1;54(1):170-81. doi: 10.1016/j.neuroimage.2010.08.031. Epub 2010 Aug 20.
Most animals detect sudden changes in trains of repeated stimuli but only some can learn a wide range of sensory patterns and recognise them later, a skill crucial for the evolutionary success of higher mammals. Here we use a neural model mimicking the cortical anatomy of sensory and motor areas and their connections to explain brain activity indexing auditory change and memory access. Our simulations indicate that while neuronal adaptation and local inhibition of cortical activity can explain aspects of change detection as observed when a repeated unfamiliar sound changes in frequency, the brain dynamics elicited by auditory stimulation with well-known patterns (such as meaningful words) cannot be accounted for on the basis of adaptation and inhibition alone. Specifically, we show that the stronger brain responses observed to familiar stimuli in passive oddball tasks are best explained in terms of activation of memory circuits that emerged in the cortex during the learning of these stimuli. Such memory circuits, and the activation enhancement they entail, are absent for unfamiliar stimuli. The model illustrates how basic neurobiological mechanisms, including neuronal adaptation, lateral inhibition, and Hebbian learning, underlie neuronal assembly formation and dynamics, and differentially contribute to the brain's major change detection response, the mismatch negativity.
大多数动物都能察觉重复刺激序列中的突然变化，但只有一些动物能够学习广泛的感觉模式，并在以后识别它们，这种技能对于高等哺乳动物的进化成功至关重要。在这里，我们使用一种模拟感觉和运动区域的皮质解剖结构及其连接的神经模型，来解释大脑活动索引听觉变化和记忆访问。我们的模拟表明，虽然神经元适应和皮质活动的局部抑制可以解释在重复的不熟悉声音在频率上发生变化时观察到的变化检测的某些方面，但仅基于适应和抑制无法解释由具有已知模式（如有意义的单词）的听觉刺激引起的大脑动力学。具体来说，我们表明，在被动Oddball 任务中对熟悉刺激的更强的大脑反应最好用在学习这些刺激期间在皮质中出现的记忆电路的激活来解释。对于不熟悉的刺激，不存在这种记忆电路及其所带来的激活增强。该模型说明了包括神经元适应、侧向抑制和赫布学习在内的基本神经生物学机制如何在神经元集合的形成和动态中起基础性作用，并对大脑的主要变化检测反应——失匹配负波（mismatch negativity）产生不同的贡献。
