GABAA inhibition controls response gain in visual cortex.
GABAA inhibition controls response gain in visual cortex.
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DOI：
10.1523/jneurosci.5753-10.2011
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发表时间：
2011-04-20
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影响因子：
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通讯作者：
Carandini M
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文献类型：
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作者：
Katzner S;Busse L;Carandini M
GABAA抑制被认为在感觉皮层中发挥多种作用，例如控制反应性和敏感性，锐化选择性和介导竞争性相互作用。为了测试这些建议，我们记录在猫初级视觉皮层（V1）的局部离子电渗的gabazine，选择性GABAA拮抗剂。加巴嗪使反应性提高了高达300%。它稍微降低了对刺激方向和方向的选择性，通常是通过提高对所有方向的反应。引人注目的是，加巴嗪既不影响对比敏感度，也不影响交叉方向抑制，即不同方向刺激叠加时的竞争。这些结果被一个简单的模型捕获，其中GABAA抑制具有与兴奋相同的选择性，并保持对不需要的刺激的反应低于阈值。我们的结论是GABAA抑制V1有助于提高刺激的选择性，但不负责叠加刺激之间的竞争。它通过调节V1神经元的响应增益来控制它们的灵敏度，而不影响它们的输入增益。
GABAA inhibition is thought to play multiple roles in sensory cortex, such as controlling responsiveness and sensitivity, sharpening selectivity, and mediating competitive interactions. To test these proposals we recorded in cat primary visual cortex (V1) following local iontophoresis of gabazine, the selective GABAA antagonist. Gabazine increased responsiveness by as much as 300%. It slightly decreased selectivity for stimulus orientation and direction, often by raising responses to all orientations. Strikingly, gabazine affected neither contrast sensitivity nor cross-orientation suppression, the competition seen when stimuli of different orientation are superimposed. These results were captured by a simple model where GABAA inhibition has the same selectivity as excitation, and keeps responses to unwanted stimuli below threshold. We conclude that GABAA inhibition in V1 helps enhance stimulus selectivity but is not responsible for competition among superimposed stimuli. It controls the sensitivity of V1 neurons by adjusting their response gain, without affecting their input gain.