Gellman R, Gibson A R, Houk J C
J Neurophysiol. 1985 Jul;54(1):40-60. doi: 10.1152/jn.1985.54.1.40.
We have recorded from 306 neurons in the inferior olive of six alert cats. Most of the cats were trained to perform a simple task with the forelimb. We observed the neural responses to a wide variety of cutaneous and proprioceptive stimuli, as well as responses during spontaneous and learned active movements. Neurons responsive to somatosensory stimulation were found in all parts of the inferior olive, and they were roughly evenly divided between those responsive to cutaneous stimulation and those responsive to proprioceptive stimulation. In the dorsal accessory olive all neurons were responsive to somatosensory stimulation. In the medial accessory nucleus 88% and in the principal olive 74% of cells were responsive to somatosensory stimulation. Cells responsive to cutaneous stimulation usually had small receptive fields, commonly on the paw. These cells had low-threshold responses to one or more forms of cutaneous stimulation and typically fired one spike at the onset of the stimulus on 80% or more of stimulus applications. Cells responsive to proprioceptive stimulation most commonly responded to passive displacements of a limb. These cells were often very sensitive, responding to linear displacements of less than 1 cm in one specific direction. No cells in our sample responded reliably during active movement by the animal. Only 21% of cells responding to passive proprioceptive stimulation showed any modulation during active movement, and the modulation was weak. Likewise, cells responsive to cutaneous stimulation generally failed to respond when a similar stimulus was produced by an active movement by the animal. Exceptions to this were stimuli produced during exploratory movements or when the receptive field unexpectedly made contact with an object during active movement. Electrical stimulation applied in the inferior olive failed to evoke movements or to modify ongoing movement. Our results are consistent with the hypothesis that inferior olivary neurons function as somatic event detectors responding particularly reliably to unexpected stimuli.
我们记录了6只警觉猫的下橄榄核中的306个神经元。大多数猫经过训练，能用前肢执行一项简单任务。我们观察了对多种皮肤和本体感觉刺激的神经反应，以及自发和习得的主动运动期间的反应。在下橄榄核的所有区域都发现了对体感刺激有反应的神经元，它们大致均匀地分为对皮肤刺激有反应的神经元和对本体感觉刺激有反应的神经元。在背侧副橄榄核中，所有神经元都对体感刺激有反应。在内侧副核中，88%的细胞和在主橄榄核中74%的细胞对体感刺激有反应。对皮肤刺激有反应的细胞通常具有小的感受野，常见于爪子上。这些细胞对一种或多种形式的皮肤刺激具有低阈值反应，并且在80%或更多的刺激施加时，通常在刺激开始时发放一个动作电位。对本体感觉刺激有反应的细胞最常见的是对肢体的被动位移有反应。这些细胞通常非常敏感，对一个特定方向上小于1厘米的线性位移有反应。在动物主动运动期间，我们样本中的细胞没有可靠反应。在被动本体感觉刺激时有反应的细胞中，只有21%在主动运动期间表现出任何调制，并且调制很弱。同样，当动物的主动运动产生类似刺激时，对皮肤刺激有反应的细胞通常没有反应。探索性运动期间产生的刺激或主动运动期间感受野意外与物体接触时产生的刺激除外。在下橄榄核施加电刺激未能引起运动或改变正在进行的运动。我们的结果与以下假设一致，即下橄榄核神经元作为躯体事件探测器发挥作用，对意外刺激的反应特别可靠。
