Kuravi Pradeep, Caggiano Vittorio, Giese Martin, Vogels Rufin
Laboratorium voor Neuro- en Psychofysiologie, Department of Neurosciences, KU Leuven, Campus Gasthuisberg, Leuven, Belgium;
McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts; and.
J Neurophysiol. 2016 Mar;115(3):1324-37. doi: 10.1152/jn.00849.2015. Epub 2015 Dec 23.
In many brain areas, repetition of a stimulus usually weakens the neural response. This "adaptation" or repetition suppression effect has been observed with mass potential measures such as event-related potentials (ERPs), in fMRI BOLD responses, and locally with local field potentials (LFPs) and spiking activity. Recently, it has been reported that macaque F5 mirror neurons do not show repetition suppression of their spiking activity for single repetitions of hand actions, which disagrees with human fMRI adaptation studies. This finding also contrasts with numerous studies showing repetition suppression in macaque inferior temporal cortex, including the rostral superior temporal sulcus (STS). Since the latter studies employed static stimuli, we assessed here whether the use of dynamic action stimuli abolishes repetition suppression in the awake macaque STS. To assess adaptation effects in the STS, we employed the same hand action movies as used when examining adaptation in F5. The upper bank STS neurons showed repetition suppression during the approaching phase of the hand action, which corresponded to the phase of the action for which these neurons responded overall the strongest. The repetition suppression was present for the spiking activity measured in independent single-unit and multiunit recordings as well as for the LFP power at frequencies > 50 Hz. Together with previous data in F5, these findings suggest that adaptation effects differ between F5 mirror neurons and the STS neurons.
在许多脑区，刺激的重复通常会减弱神经反应。这种“适应”或重复抑制效应已在诸如事件相关电位（ERP）等群体电位测量中、功能磁共振成像血氧水平依赖（BOLD）反应中以及局部场电位（LFP）和锋电位活动中被观察到。最近，有报道称，猕猴F5区的镜像神经元对于手部动作的单次重复不会表现出其锋电位活动的重复抑制，这与人类功能磁共振成像适应研究结果不一致。这一发现也与众多显示猕猴颞下皮质（包括颞上沟前部，即STS）存在重复抑制的研究形成对比。由于后一类研究采用的是静态刺激，我们在此评估了动态动作刺激的使用是否会消除清醒猕猴STS中的重复抑制。为了评估STS中的适应效应，我们采用了与在F5区研究适应时相同的手部动作影片。颞上沟上壁的神经元在手部动作的接近阶段表现出重复抑制，这与这些神经元总体反应最强的动作阶段相对应。在独立的单神经元和多神经元记录中测量的锋电位活动以及频率大于50Hz时的LFP功率均存在重复抑制。结合之前在F5区的数据，这些发现表明F5区镜像神经元和STS神经元之间的适应效应存在差异。
