Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA.
Exp Brain Res. 2010 Jan;200(3-4):239-50. doi: 10.1007/s00221-009-1977-0. Epub 2009 Aug 22.
Activity in thalamocortical circuits depends strongly on immediate past experience. When the successive activity is attenuated on short timescales, this phenomenon is known as adaptation. Adaptive processes may be effectively initiated by ongoing exposure to sensory stimuli and/or direct electrical stimulation of neural tissue. Ongoing high-frequency electrical stimulation is increasingly employed as a treatment for a variety of neurological disorders. Neural stimulation with similar parameters to therapeutic electrical stimulation may modulate the way in which cortical neurons respond and adapt to sensory stimuli. Here, we studied the effects of high-frequency stimulation of the somatosensory thalamus on the transmission of sensory signals in thalamocortical circuits. We examined how whisker-evoked sensory inputs in layer IV cortical barrels are affected by concurrent 100 Hz thalamic electrical stimulation and how the latter modulates sensory-evoked adaptation. Even in the presence of ongoing thalamic stimulation, sensory transmission in thalamocortical circuits is maintained. However, cortical responses to whisker deflections are reduced in an intensity-dependent fashion and can be nearly abolished with high intensity currents. The electrical stimulation-induced reduction in cortical responsiveness likely reflects engagement of circuit mechanisms that normally produce sensory adaptation.
丘脑皮质回路的活动强烈依赖于近期的经验。当连续活动在短时间尺度上减弱时，这种现象被称为适应。适应过程可以通过持续暴露于感觉刺激和/或直接电刺激神经组织来有效地启动。持续的高频电刺激越来越多地被用作治疗各种神经疾病的一种手段。具有类似治疗性电刺激参数的神经刺激可能会调节皮质神经元对感觉刺激的反应和适应方式。在这里，我们研究了躯体感觉丘脑的高频刺激对丘脑皮质回路中感觉信号传递的影响。我们研究了在 100Hz 丘脑电刺激的同时，如何影响第四层皮质桶中由胡须引发的感觉输入，以及后者如何调节感觉诱发的适应。即使在持续的丘脑刺激存在的情况下，丘脑皮质回路中的感觉传递也得以维持。然而，皮质对胡须偏斜的反应以强度依赖的方式减弱，并且可以用高强度电流几乎消除。电刺激诱导的皮质反应降低可能反映了通常产生感觉适应的回路机制的参与。
