Ernst T, Hennig J
Department of Radiology, University of Freiburg, Germany.
Magn Reson Med. 1994 Jul;32(1):146-9. doi: 10.1002/mrm.1910320122.
A spectroscopic MR technique was used to investigate the time course of the MR signal following a single visual stimulus. Gated experiments demonstrate there is an early response (500 ms after stimulus) leading to a reduction of the MR signal by -0.25% (P = 0.02), whereas a slower response (> 1500 ms after stimulus) results in a signal increase of +0.59% (P = 0.01). The fast negative response may be attributed to increased oxygen consumption, followed by a slower vascular response with overcompensation in blood oxygenation. This explanation would be in agreement with the blood oxygenation level dependent (BOLD) contrast mechanism considered the basis of functional MR. However, other physiological events might also be responsible for the signal drop observed.
一种磁共振波谱技术被用于研究单次视觉刺激后磁共振信号的时间进程。门控实验表明，存在一个早期反应（刺激后500毫秒），导致磁共振信号降低-0.25%（P = 0.02），而较慢的反应（刺激后>1500毫秒）则导致信号增加+0.59%（P = 0.01）。快速的负反应可能归因于氧消耗增加，随后是较慢的血管反应，伴有血液氧合的过度补偿。这种解释与被认为是功能磁共振基础的血氧水平依赖（BOLD）对比机制相符。然而，其他生理事件也可能是观察到的信号下降的原因。
