Spenger C, Josephson A, Klason T, Hoehn M, Schwindt W, Ingvar M, Olson L
Department of Neuroscience, Karolinska Institutet and Karolinska Hospital, Stockholm, S-171 77, Sweden.
Exp Neurol. 2000 Dec;166(2):246-53. doi: 10.1006/exnr.2000.7524.
Stimulation of peripheral nerves activates corresponding regions in sensorimotor cortex. We have applied functional magnetic resonance imaging (fMRI) techniques to monitor activated brain regions by means of measuring changes of blood oxygenation level-dependent contrast during electric stimulation of the forepaw, hindpaw, or tail in rats. During alpha-chloralose anesthesia, artificial respiration, and complete muscle relaxation, stimulations were delivered at 3 Hz via subcutaneous bipolar electrodes with 500-microseconds-current pulses of 0.2-2.0 mA. Single- or multislice gradient echo images were collected during recording sessions consisting of five alternating rest and stimulation periods. Stimulation of the right and left forepaws and hindpaws repeatedly led to robust activation of the contralateral sensorimotor cortex. There was a significant correlation (P < 0.05) between current pulse strength and amount of activation of the sensory cortex during forepaw stimulation. The center of the main cortical representation of the forepaw was situated 3.4 mm lateral to the midline and 5 mm posterior to the rhinal fissure. The main representation of the hindpaw was 2.0 mm lateral to the midline and 6 mm posterior to the rhinal fissure. Tail stimulation gave rise to a strikingly extended bilateral cortical activation, localized along the midline in medial parietal and frontal cortex 4 and 5 mm posterior to the rhinal fissure. In conclusion, the experiments provide evidence that peripheral nerve stimulation induces a fMRI signal in the respective division of the somatosensory cortex in a stimulus-related manner. The marked cortical activation elicited by tail stimulation underlines the key importance of the tail.
外周神经的刺激会激活感觉运动皮层中的相应区域。我们应用功能磁共振成像（fMRI）技术，通过测量大鼠前爪、后爪或尾巴电刺激期间血氧水平依赖对比度的变化，来监测大脑激活区域。在α-氯醛糖麻醉、人工呼吸和完全肌肉松弛的情况下，通过皮下双极电极以3Hz的频率施加刺激，电流脉冲为500微秒，强度为0.2 - 2.0mA。在由五个交替的休息和刺激期组成的记录过程中，采集单切片或多切片梯度回波图像。对左右前爪和后爪的刺激反复导致对侧感觉运动皮层的强烈激活。在前爪刺激期间，电流脉冲强度与感觉皮层的激活量之间存在显著相关性（P < 0.05）。前爪主要皮层代表区的中心位于中线外侧3.4mm，鼻裂后方5mm处。后爪的主要代表区位于中线外侧2.0mm，鼻裂后方6mm处。尾巴刺激引起显著的双侧皮层广泛激活，位于鼻裂后方4至5mm处的内侧顶叶和额叶皮层的中线部位。总之，这些实验提供了证据，表明外周神经刺激以与刺激相关的方式在体感皮层的相应区域诱导出fMRI信号。尾巴刺激引起的明显皮层激活突出了尾巴的关键重要性。
