Scheffler K, Bilecen D, Schmid N, Tschopp K, Seelig J
MR Center and Biocenter, University of Basel, Switzerland.
Cereb Cortex. 1998 Mar;8(2):156-63. doi: 10.1093/cercor/8.2.156.
Functional magnetic resonance imaging is a non-invasive method for the detection of focal brain activity at high spatial resolution. Acoustic stimulation leads to a blood oxygenation level dependent signal change in the plane of the superior temporal gyrus. The dependence of this response in the auditory cortex on binaural, monaural left and monaural right acoustic stimulation for 10 healthy subjects and five monaural deaf patients is described. Acoustic stimulation consists of 1000 Hz pulsed sine tones at a pulse rate of 6 Hz and a sound pressure level of 95 dB. For monaural stimulation, normal-hearing subjects revealed a strong lateralization of cortical response towards the contralateral hemisphere. The lateralization ratios between left and right hemispheric response areas were 3.4-5.2 for monaural stimulation and nearly balanced for binaural stimulation. Additionally, the sum of cortical activation volumes induced by monaural left and right stimulation was approximately 30% smaller than for binaural stimulation, indicating either inhibitory mechanisms or neuronal facilitation within the auditory pathways. For monaural deaf subjects the lateralization ratio between left to right response was just 1.3 towards the contralateral hemisphere of the healthy ear, which is comparable to binaural responses of normal-hearing subjects. This observation seems to indicate a plasticity or a reorganization of auditory pathways of monaural deaf patients.
功能磁共振成像是一种用于在高空间分辨率下检测局灶性脑活动的非侵入性方法。听觉刺激会导致颞上回平面内的血氧水平依赖信号发生变化。本文描述了10名健康受试者和5名单侧耳聋患者的听觉皮层中这种反应对双耳、单耳左和单耳右听觉刺激的依赖性。听觉刺激由频率为1000 Hz、脉冲率为6 Hz且声压级为95 dB的脉冲正弦音组成。对于单耳刺激，听力正常的受试者表现出皮层反应向对侧半球的强烈侧化。单耳刺激时左右半球反应区域之间的侧化率为3.4 - 5.2，而双耳刺激时则几乎平衡。此外，单耳左和右刺激诱发的皮层激活体积之和比双耳刺激时小约30%，这表明听觉通路中存在抑制机制或神经元易化作用。对于单侧耳聋受试者，向健康耳对侧半球的左右反应侧化率仅为1.3，这与听力正常受试者的双耳反应相当。这一观察结果似乎表明单侧耳聋患者的听觉通路具有可塑性或发生了重组。
