Neurophysiology Laboratory, Neurosciences Area, CIMA, University of Navarra, Pamplona, Spain.
PLoS One. 2011;6(7):e21814. doi: 10.1371/journal.pone.0021814. Epub 2011 Jul 29.
Oscillatory activity can be widely recorded in the cortex and basal ganglia. This activity may play a role not only in the physiology of movement, perception and cognition, but also in the pathophysiology of psychiatric and neurological diseases like schizophrenia or Parkinson's disease. Ketamine administration has been shown to cause an increase in gamma activity in cortical and subcortical structures, and an increase in 150 Hz oscillations in the nucleus accumbens in healthy rats, together with hyperlocomotion.We recorded local field potentials from motor cortex, caudate-putamen (CPU), substantia nigra pars reticulata (SNr) and subthalamic nucleus (STN) in 20 awake rats before and after the administration of ketamine at three different subanesthetic doses (10, 25 and 50 mg/Kg), and saline as control condition. Motor behavior was semiautomatically quantified by custom-made software specifically developed for this setting.Ketamine induced coherent oscillations in low gamma (~ 50 Hz), high gamma (~ 80 Hz) and high frequency (HFO, ~ 150 Hz) bands, with different behavior in the four structures studied. While oscillatory activity at these three peaks was widespread across all structures, interactions showed a different pattern for each frequency band. Imaginary coherence at 150 Hz was maximum between motor cortex and the different basal ganglia nuclei, while low gamma coherence connected motor cortex with CPU and high gamma coherence was more constrained to the basal ganglia nuclei. Power at three bands correlated with the motor activity of the animal, but only coherence values in the HFO and high gamma range correlated with movement. Interactions in the low gamma band did not show a direct relationship to movement.These results suggest that the motor effects of ketamine administration may be primarily mediated by the induction of coherent widespread high-frequency activity in the motor circuit of the basal ganglia, together with a frequency-specific pattern of connectivity among the structures analyzed.
振荡活动可以广泛地在皮层和基底神经节中记录到。这种活动不仅可能在运动、感知和认知的生理学中发挥作用，而且可能在精神和神经疾病的病理生理学中发挥作用，如精神分裂症或帕金森病。已表明氯胺酮给药会导致皮质和皮质下结构中的γ活动增加，并且在健康大鼠的伏隔核中 150 Hz 振荡增加，同时出现过度运动。我们在 20 只清醒大鼠中记录了运动皮层、尾状核-壳核（CPU）、黑质网状部（SNr）和丘脑底核（STN）的局部场电位，在氯胺酮给药之前和之后，在三种不同的亚麻醉剂量（10、25 和 50mg/Kg）下，并以生理盐水作为对照条件。运动行为通过专门为此环境开发的定制软件半自动地进行量化。氯胺酮诱导低频γ（50Hz）、高频γ（80Hz）和高频（HFO，~150Hz）波段中的相干振荡，在研究的四个结构中表现出不同的行为。虽然这三个峰值的振荡活动在所有结构中都很广泛，但每个频率带的相互作用都呈现出不同的模式。150Hz 的想象相干性在运动皮层和不同的基底神经节核之间最大，而低频γ相干性将运动皮层与 CPU 连接起来，高频γ相干性则更局限于基底神经节核。三个波段的功率与动物的运动活动相关，但只有 HFO 和高频范围内的相干值与运动相关。低频γ带中的相互作用与运动没有直接关系。这些结果表明，氯胺酮给药的运动效应可能主要通过诱导基底神经节运动回路中广泛的高频相干活动来介导，同时还存在分析结构之间的特定频率连接模式。
