Seki Kazuhiko, Perlmutter Steve I, Fetz Eberhard E
Department of Physiology and Biophysics, and Washington National Primate Research Center, University of Washington, Seattle, Washington 98195-7290, USA.
Nat Neurosci. 2003 Dec;6(12):1309-16. doi: 10.1038/nn1154. Epub 2003 Nov 16.
During normal voluntary movements, re-afferent sensory input continuously converges on the spinal circuits that are activated by descending motor commands. This time-varying input must either be synergistically combined with the motor commands or be appropriately suppressed to minimize interference. The earliest suppression could be produced by presynaptic inhibition, which effectively reduces synaptic transmission at the initial synapse. Here we report evidence from awake, behaving monkeys that presynaptic inhibition decreases the ability of afferent impulses to affect postsynaptic neurons in a behaviorally dependent manner. Evidence indicates that cutaneous afferent input to spinal cord interneurons is inhibited presynaptically during active wrist movement, and this inhibition is effectively produced by descending commands. Our results further suggest that this presynaptic inhibition has appropriate functional consequences for movement generation and may underlie increases in perceptual thresholds during active movement.
在正常的自主运动过程中，重新传入的感觉输入不断汇聚到由下行运动指令激活的脊髓回路中。这种随时间变化的输入必须与运动指令协同组合，或者被适当抑制以尽量减少干扰。最早的抑制可能由突触前抑制产生，它有效地减少了初始突触处的突触传递。在这里，我们报告了来自清醒、行为中的猴子的证据，表明突触前抑制以行为依赖的方式降低了传入冲动影响突触后神经元的能力。有证据表明，在主动腕部运动期间，脊髓中间神经元的皮肤传入输入在突触前受到抑制，并且这种抑制是由下行指令有效产生的。我们的结果进一步表明，这种突触前抑制对运动产生具有适当的功能后果，并且可能是主动运动期间知觉阈值增加的基础。
