Auditory Neurophysiology Unit, Institute of Neuroscience of Castilla y León, University of Salamanca, Salamanca, Spain.
PLoS One. 2012;7(3):e34297. doi: 10.1371/journal.pone.0034297. Epub 2012 Mar 29.
The ability to detect novel sounds in a complex acoustic context is crucial for survival. Neurons from midbrain through cortical levels adapt to repetitive stimuli, while maintaining responsiveness to rare stimuli, a phenomenon called stimulus-specific adaptation (SSA). The site of origin and mechanism of SSA are currently unknown. We used microiontophoretic application of gabazine to examine the role of GABA(A)-mediated inhibition in SSA in the inferior colliculus, the midbrain center for auditory processing. We found that gabazine slowed down the process of adaptation to high probability stimuli but did not abolish it, with response magnitude and latency still depending on the probability of the stimulus. Blocking GABA(A) receptors increased the firing rate to high and low probability stimuli, but did not completely equalize the responses. Together, these findings suggest that GABA(A)-mediated inhibition acts as a gain control mechanism that enhances SSA by modifying the responsiveness of the neuron.
在复杂的声学环境中检测新声音的能力对生存至关重要。从中脑到皮质水平的神经元适应重复刺激，同时保持对稀有刺激的反应能力，这种现象称为刺激特异性适应（SSA）。SSA 的起源和机制目前尚不清楚。我们使用微电泳应用加巴喷丁来检查中脑听觉处理中心下丘中海马体 A 介导的抑制在 SSA 中的作用。我们发现加巴喷丁减缓了对高概率刺激的适应过程，但并未完全消除它，响应幅度和潜伏期仍然取决于刺激的概率。阻断 GABA(A)受体增加了对高概率和低概率刺激的放电率，但并未完全使反应相等。综上所述，这些发现表明，GABA(A)介导的抑制作用作为一种增益控制机制，通过改变神经元的反应能力来增强 SSA。
